[lvgl] Don't animate page change when not requested (#15069)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.ai/instructions.md

@@ -286,6 +286,7 @@ This document provides essential context for AI models interacting with this pro
 *   **Documentation Contributions:**
     *   Documentation is hosted in the separate `esphome/esphome-docs` repository.
     *   The contribution workflow is the same as for the codebase.
+    *   When editing a component's documentation page, also update the corresponding component index page to ensure both pages remain in sync.
 
 *   **Best Practices:**
     *   **Component Development:** Keep dependencies minimal, provide clear error messages, and write comprehensive docstrings and tests.

.clang-tidy.hash

@@ -1 +1 @@
-ce05c28e9dc0b12c4f6e7454986ffea5123ac974a949da841be698c535f2083e
+9f5d763f95ff720024f3fdddba2fad3801e2bfe00b7cc2124e6d68c17d3504c6

.github/PULL_REQUEST_TEMPLATE.md

@@ -6,8 +6,9 @@
 
 - [ ] Bugfix (non-breaking change which fixes an issue)
 - [ ] New feature (non-breaking change which adds functionality)
-- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
-- [ ] Developer breaking change (an API change that could break external components)
+- [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected) — [policy](https://developers.esphome.io/contributing/code/#what-constitutes-a-c-breaking-change)
+- [ ] Developer breaking change (an API change that could break external components) — [policy](https://developers.esphome.io/contributing/code/#what-is-considered-public-c-api)
+- [ ] Undocumented C++ API change (removal or change of undocumented public methods that lambda users may depend on) — [policy](https://developers.esphome.io/contributing/code/#c-user-expectations)
 - [ ] Code quality improvements to existing code or addition of tests
 - [ ] Other
 
@@ -24,7 +25,7 @@
 - [ ] ESP32
 - [ ] ESP32 IDF
 - [ ] ESP8266
-- [ ] RP2040
+- [ ] RP2040/RP2350
 - [ ] BK72xx
 - [ ] RTL87xx
 - [ ] LN882x

.github/actions/build-image/action.yaml

@@ -47,7 +47,7 @@ runs:
 
     - name: Build and push to ghcr by digest
       id: build-ghcr
-      uses: docker/build-push-action@601a80b39c9405e50806ae38af30926f9d957c47 # v6.19.1
+      uses: docker/build-push-action@d08e5c354a6adb9ed34480a06d141179aa583294 # v7.0.0
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false
@@ -73,7 +73,7 @@ runs:
 
     - name: Build and push to dockerhub by digest
       id: build-dockerhub
-      uses: docker/build-push-action@601a80b39c9405e50806ae38af30926f9d957c47 # v6.19.1
+      uses: docker/build-push-action@d08e5c354a6adb9ed34480a06d141179aa583294 # v7.0.0
       env:
         DOCKER_BUILD_SUMMARY: false
         DOCKER_BUILD_RECORD_UPLOAD: false

.github/actions/restore-python/action.yml

@@ -22,7 +22,7 @@ runs:
         python-version: ${{ inputs.python-version }}
     - name: Restore Python virtual environment
       id: cache-venv
-      uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+      uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
       with:
         path: venv
         # yamllint disable-line rule:line-length

.github/scripts/auto-label-pr/constants.js

@@ -14,6 +14,7 @@ module.exports = {
     'chained-pr',
     'core',
     'small-pr',
+    'medium-pr',
     'dashboard',
     'github-actions',
     'by-code-owner',
@@ -27,6 +28,7 @@ module.exports = {
     'new-feature',
     'breaking-change',
     'developer-breaking-change',
+    'undocumented-api-change',
     'code-quality',
     'deprecated-component'
   ],

.github/scripts/auto-label-pr/detectors.js

@@ -1,5 +1,13 @@
 const fs = require('fs');
 const { DOCS_PR_PATTERNS } = require('./constants');
+const {
+  COMPONENT_REGEX,
+  detectComponents,
+  hasCoreChanges,
+  hasDashboardChanges,
+  hasGitHubActionsChanges,
+} = require('../detect-tags');
+const { loadCodeowners, getEffectiveOwners } = require('../codeowners');
 
 // Strategy: Merge branch detection
 async function detectMergeBranch(context) {
@@ -20,15 +28,13 @@ async function detectMergeBranch(context) {
 // Strategy: Component and platform labeling
 async function detectComponentPlatforms(changedFiles, apiData) {
   const labels = new Set();
-  const componentRegex = /^esphome\/components\/([^\/]+)\//;
   const targetPlatformRegex = new RegExp(`^esphome\/components\/(${apiData.targetPlatforms.join('|')})/`);
 
-  for (const file of changedFiles) {
-    const componentMatch = file.match(componentRegex);
-    if (componentMatch) {
-      labels.add(`component: ${componentMatch[1]}`);
-    }
+  for (const comp of detectComponents(changedFiles)) {
+    labels.add(`component: ${comp}`);
+  }
 
+  for (const file of changedFiles) {
     const platformMatch = file.match(targetPlatformRegex);
     if (platformMatch) {
       labels.add(`platform: ${platformMatch[1]}`);
@@ -90,20 +96,14 @@ async function detectNewPlatforms(prFiles, apiData) {
 // Strategy: Core files detection
 async function detectCoreChanges(changedFiles) {
   const labels = new Set();
-  const coreFiles = changedFiles.filter(file =>
-    file.startsWith('esphome/core/') ||
-    (file.startsWith('esphome/') && file.split('/').length === 2)
-  );
-
-  if (coreFiles.length > 0) {
+  if (hasCoreChanges(changedFiles)) {
     labels.add('core');
   }
-
   return labels;
 }
 
 // Strategy: PR size detection
-async function detectPRSize(prFiles, totalAdditions, totalDeletions, totalChanges, isMegaPR, SMALL_PR_THRESHOLD, TOO_BIG_THRESHOLD) {
+async function detectPRSize(prFiles, totalAdditions, totalDeletions, totalChanges, isMegaPR, SMALL_PR_THRESHOLD, MEDIUM_PR_THRESHOLD, TOO_BIG_THRESHOLD) {
   const labels = new Set();
 
   if (totalChanges <= SMALL_PR_THRESHOLD) {
@@ -111,6 +111,11 @@ async function detectPRSize(prFiles, totalAdditions, totalDeletions, totalChange
     return labels;
   }
 
+  if (totalChanges <= MEDIUM_PR_THRESHOLD) {
+    labels.add('medium-pr');
+    return labels;
+  }
+
   const testAdditions = prFiles
     .filter(file => file.filename.startsWith('tests/'))
     .reduce((sum, file) => sum + (file.additions || 0), 0);
@@ -131,80 +136,33 @@ async function detectPRSize(prFiles, totalAdditions, totalDeletions, totalChange
 // Strategy: Dashboard changes
 async function detectDashboardChanges(changedFiles) {
   const labels = new Set();
-  const dashboardFiles = changedFiles.filter(file =>
-    file.startsWith('esphome/dashboard/') ||
-    file.startsWith('esphome/components/dashboard_import/')
-  );
-
-  if (dashboardFiles.length > 0) {
+  if (hasDashboardChanges(changedFiles)) {
     labels.add('dashboard');
   }
-
   return labels;
 }
 
 // Strategy: GitHub Actions changes
 async function detectGitHubActionsChanges(changedFiles) {
   const labels = new Set();
-  const githubActionsFiles = changedFiles.filter(file =>
-    file.startsWith('.github/workflows/')
-  );
-
-  if (githubActionsFiles.length > 0) {
+  if (hasGitHubActionsChanges(changedFiles)) {
     labels.add('github-actions');
   }
-
   return labels;
 }
 
 // Strategy: Code owner detection
 async function detectCodeOwner(github, context, changedFiles) {
   const labels = new Set();
-  const { owner, repo } = context.repo;
 
   try {
-    const { data: codeownersFile } = await github.rest.repos.getContent({
-      owner,
-      repo,
-      path: 'CODEOWNERS',
-    });
-
-    const codeownersContent = Buffer.from(codeownersFile.content, 'base64').toString('utf8');
+    const codeownersPatterns = loadCodeowners();
     const prAuthor = context.payload.pull_request.user.login;
 
-    const codeownersLines = codeownersContent.split('\n')
-      .map(line => line.trim())
-      .filter(line => line && !line.startsWith('#'));
-
-    const codeownersRegexes = codeownersLines.map(line => {
-      const parts = line.split(/\s+/);
-      const pattern = parts[0];
-      const owners = parts.slice(1);
-
-      let regex;
-      if (pattern.endsWith('*')) {
-        const dir = pattern.slice(0, -1);
-        regex = new RegExp(`^${dir.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}`);
-      } else if (pattern.includes('*')) {
-        // First escape all regex special chars except *, then replace * with .*
-        const regexPattern = pattern
-          .replace(/[.+?^${}()|[\]\\]/g, '\\$&')
-          .replace(/\*/g, '.*');
-        regex = new RegExp(`^${regexPattern}$`);
-      } else {
-        regex = new RegExp(`^${pattern.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')}$`);
-      }
-
-      return { regex, owners };
-    });
-
-    for (const file of changedFiles) {
-      for (const { regex, owners } of codeownersRegexes) {
-        if (regex.test(file) && owners.some(owner => owner === `@${prAuthor}`)) {
-          labels.add('by-code-owner');
-          return labels;
-        }
-      }
+    // Check if PR author is a codeowner of any changed file
+    const effective = getEffectiveOwners(changedFiles, codeownersPatterns);
+    if (effective.users.has(prAuthor)) {
+      labels.add('by-code-owner');
     }
   } catch (error) {
     console.log('Failed to read or parse CODEOWNERS file:', error.message);
@@ -238,6 +196,7 @@ async function detectPRTemplateCheckboxes(context) {
     { pattern: /- \[x\] New feature \(non-breaking change which adds functionality\)/i, label: 'new-feature' },
     { pattern: /- \[x\] Breaking change \(fix or feature that would cause existing functionality to not work as expected\)/i, label: 'breaking-change' },
     { pattern: /- \[x\] Developer breaking change \(an API change that could break external components\)/i, label: 'developer-breaking-change' },
+    { pattern: /- \[x\] Undocumented C\+\+ API change \(removal or change of undocumented public methods that lambda users may depend on\)/i, label: 'undocumented-api-change' },
     { pattern: /- \[x\] Code quality improvements to existing code or addition of tests/i, label: 'code-quality' }
   ];
 
@@ -258,7 +217,7 @@ async function detectDeprecatedComponents(github, context, changedFiles) {
   const { owner, repo } = context.repo;
 
   // Compile regex once for better performance
-  const componentFileRegex = /^esphome\/components\/([^\/]+)\//;
+  const componentFileRegex = COMPONENT_REGEX;
 
   // Get files that are modified or added in components directory
   const componentFiles = changedFiles.filter(file => componentFileRegex.test(file));

.github/scripts/auto-label-pr/index.js

@@ -35,6 +35,7 @@ async function fetchApiData() {
 module.exports = async ({ github, context }) => {
   // Environment variables
   const SMALL_PR_THRESHOLD = parseInt(process.env.SMALL_PR_THRESHOLD);
+  const MEDIUM_PR_THRESHOLD = parseInt(process.env.MEDIUM_PR_THRESHOLD);
   const MAX_LABELS = parseInt(process.env.MAX_LABELS);
   const TOO_BIG_THRESHOLD = parseInt(process.env.TOO_BIG_THRESHOLD);
   const COMPONENT_LABEL_THRESHOLD = parseInt(process.env.COMPONENT_LABEL_THRESHOLD);
@@ -120,7 +121,7 @@ module.exports = async ({ github, context }) => {
     detectNewComponents(prFiles),
     detectNewPlatforms(prFiles, apiData),
     detectCoreChanges(changedFiles),
-    detectPRSize(prFiles, totalAdditions, totalDeletions, totalChanges, isMegaPR, SMALL_PR_THRESHOLD, TOO_BIG_THRESHOLD),
+    detectPRSize(prFiles, totalAdditions, totalDeletions, totalChanges, isMegaPR, SMALL_PR_THRESHOLD, MEDIUM_PR_THRESHOLD, TOO_BIG_THRESHOLD),
     detectDashboardChanges(changedFiles),
     detectGitHubActionsChanges(changedFiles),
     detectCodeOwner(github, context, changedFiles),

.github/scripts/codeowners.js

@@ -0,0 +1,227 @@
+// Shared CODEOWNERS parsing and matching utilities.
+//
+// Used by:
+//   - codeowner-review-request.yml
+//   - codeowner-approved-label-update.yml
+//   - auto-label-pr/detectors.js (detectCodeOwner)
+
+/**
+ * Convert a CODEOWNERS glob pattern to a RegExp.
+ *
+ * Handles **, *, and ? wildcards after escaping regex-special characters.
+ */
+function globToRegex(pattern) {
+  let regexStr = pattern
+    .replace(/([.+^=!:${}()|[\]\\])/g, '\\$1')
+    .replace(/\*\*/g, '\x00GLOBSTAR\x00')  // protect ** from next replace
+    .replace(/\*/g, '[^/]*')               // single star
+    .replace(/\x00GLOBSTAR\x00/g, '.*')    // restore globstar
+    .replace(/\?/g, '.');
+  return new RegExp('^' + regexStr + '$');
+}
+
+/**
+ * Parse raw CODEOWNERS file content into an array of
+ * { pattern, regex, owners } objects.
+ *
+ * Each `owners` entry is the raw string from the file (e.g. "@user" or
+ * "@esphome/core").
+ */
+function parseCodeowners(content) {
+  const lines = content
+    .split('\n')
+    .map(line => line.trim())
+    .filter(line => line && !line.startsWith('#'));
+
+  const patterns = [];
+  for (const line of lines) {
+    const parts = line.split(/\s+/);
+    if (parts.length < 2) continue;
+
+    const pattern = parts[0];
+    const owners = parts.slice(1);
+    const regex = globToRegex(pattern);
+    patterns.push({ pattern, regex, owners });
+  }
+  return patterns;
+}
+
+/**
+ * Fetch and parse the CODEOWNERS file via the GitHub API.
+ *
+ * @param {object} github  - octokit instance from actions/github-script
+ * @param {string} owner   - repo owner
+ * @param {string} repo    - repo name
+ * @param {string} [ref]   - git ref (SHA / branch) to read from
+ * @returns {Array<{pattern: string, regex: RegExp, owners: string[]}>}
+ */
+async function fetchCodeowners(github, owner, repo, ref) {
+  const params = { owner, repo, path: 'CODEOWNERS' };
+  if (ref) params.ref = ref;
+
+  const { data: file } = await github.rest.repos.getContent(params);
+  const content = Buffer.from(file.content, 'base64').toString('utf8');
+  return parseCodeowners(content);
+}
+
+/**
+ * Classify raw owner strings into individual users and teams.
+ *
+ * @param {string[]} rawOwners - e.g. ["@user1", "@esphome/core"]
+ * @returns {{ users: string[], teams: string[] }}
+ *   users  – login names without "@"
+ *   teams  – team slugs without the "org/" prefix
+ */
+function classifyOwners(rawOwners) {
+  const users = [];
+  const teams = [];
+  for (const o of rawOwners) {
+    const clean = o.startsWith('@') ? o.slice(1) : o;
+    if (clean.includes('/')) {
+      teams.push(clean.split('/')[1]);
+    } else {
+      users.push(clean);
+    }
+  }
+  return { users, teams };
+}
+
+/**
+ * For each file, find its effective codeowners using GitHub's
+ * "last match wins" semantics, then union across all files.
+ *
+ * @param {string[]} files              - list of file paths
+ * @param {Array}    codeownersPatterns  - from parseCodeowners / fetchCodeowners
+ * @returns {{ users: Set<string>, teams: Set<string>, matchedFileCount: number }}
+ */
+function getEffectiveOwners(files, codeownersPatterns) {
+  const users = new Set();
+  const teams = new Set();
+  let matchedFileCount = 0;
+
+  for (const file of files) {
+    // Last matching pattern wins for each file
+    let effectiveOwners = null;
+    for (const { regex, owners } of codeownersPatterns) {
+      if (regex.test(file)) {
+        effectiveOwners = owners;
+      }
+    }
+    if (effectiveOwners) {
+      matchedFileCount++;
+      const classified = classifyOwners(effectiveOwners);
+      for (const u of classified.users) users.add(u);
+      for (const t of classified.teams) teams.add(t);
+    }
+  }
+
+  return { users, teams, matchedFileCount };
+}
+
+/**
+ * Read and parse the CODEOWNERS file from disk.
+ *
+ * Use this when the repo is already checked out (avoids an API call).
+ *
+ * @param {string} [repoRoot='.'] - path to the repo root
+ * @returns {Array<{pattern: string, regex: RegExp, owners: string[]}>}
+ */
+function loadCodeowners(repoRoot = '.') {
+  const fs = require('fs');
+  const path = require('path');
+  const content = fs.readFileSync(path.join(repoRoot, 'CODEOWNERS'), 'utf8');
+  return parseCodeowners(content);
+}
+
+/** Possible label actions returned by determineLabelAction. */
+const LabelAction = Object.freeze({
+  ADD: 'add',
+  REMOVE: 'remove',
+  NONE: 'none',
+});
+
+/**
+ * Determine what label action is needed for a PR based on codeowner approvals.
+ *
+ * Checks changed files against CODEOWNERS patterns, reviews, and current labels
+ * to decide if the label should be added, removed, or left unchanged.
+ *
+ * @param {object} github              - octokit instance from actions/github-script
+ * @param {string} owner               - repo owner
+ * @param {string} repo                - repo name
+ * @param {number} pr_number           - pull request number
+ * @param {Array}  codeownersPatterns   - from loadCodeowners / fetchCodeowners
+ * @param {string} labelName           - label to manage
+ * @returns {Promise<LabelAction>}
+ */
+async function determineLabelAction(github, owner, repo, pr_number, codeownersPatterns, labelName) {
+  // Get the list of changed files in this PR
+  const prFiles = await github.paginate(
+    github.rest.pulls.listFiles,
+    { owner, repo, pull_number: pr_number }
+  );
+
+  const changedFiles = prFiles.map(file => file.filename);
+  console.log(`Found ${changedFiles.length} changed files`);
+
+  if (changedFiles.length === 0) {
+    console.log('No changed files found');
+    return LabelAction.NONE;
+  }
+
+  // Get effective owners using last-match-wins semantics
+  const effective = getEffectiveOwners(changedFiles, codeownersPatterns);
+  const componentCodeowners = effective.users;
+
+  console.log(`Component-specific codeowners: ${Array.from(componentCodeowners).join(', ') || '(none)'}`);
+
+  // Get current labels
+  const { data: currentLabels } = await github.rest.issues.listLabelsOnIssue({
+    owner, repo, issue_number: pr_number
+  });
+  const hasLabel = currentLabels.some(label => label.name === labelName);
+
+  if (componentCodeowners.size === 0) {
+    console.log('No component-specific codeowners found');
+    return hasLabel ? LabelAction.REMOVE : LabelAction.NONE;
+  }
+
+  // Get all reviews and find latest per user
+  const reviews = await github.paginate(
+    github.rest.pulls.listReviews,
+    { owner, repo, pull_number: pr_number }
+  );
+
+  const latestReviewByUser = new Map();
+  for (const review of reviews) {
+    if (!review.user || review.user.type === 'Bot' || review.state === 'COMMENTED') continue;
+    latestReviewByUser.set(review.user.login, review);
+  }
+
+  // Check if any component-specific codeowner has an active approval
+  let hasCodeownerApproval = false;
+  for (const [login, review] of latestReviewByUser) {
+    if (review.state === 'APPROVED' && componentCodeowners.has(login)) {
+      console.log(`Codeowner '${login}' has approved`);
+      hasCodeownerApproval = true;
+      break;
+    }
+  }
+
+  if (hasCodeownerApproval && !hasLabel) return LabelAction.ADD;
+  if (!hasCodeownerApproval && hasLabel) return LabelAction.REMOVE;
+
+  console.log(`Label already ${hasLabel ? 'present' : 'absent'}, no change needed`);
+  return LabelAction.NONE;
+}
+
+module.exports = {
+  globToRegex,
+  parseCodeowners,
+  fetchCodeowners,
+  loadCodeowners,
+  classifyOwners,
+  getEffectiveOwners,
+  LabelAction,
+  determineLabelAction
+};

.github/scripts/detect-tags.js

@@ -0,0 +1,66 @@
+/**
+ * Shared tag detection from changed file paths.
+ * Used by pr-title-check and auto-label-pr workflows.
+ */
+
+const COMPONENT_REGEX = /^esphome\/components\/([^\/]+)\//;
+
+/**
+ * Detect component names from changed files.
+ * @param {string[]} changedFiles - List of changed file paths
+ * @returns {Set<string>} Set of component names
+ */
+function detectComponents(changedFiles) {
+  const components = new Set();
+  for (const file of changedFiles) {
+    const match = file.match(COMPONENT_REGEX);
+    if (match) {
+      components.add(match[1]);
+    }
+  }
+  return components;
+}
+
+/**
+ * Detect if core files were changed.
+ * Core files are in esphome/core/ or top-level esphome/ directory.
+ * @param {string[]} changedFiles - List of changed file paths
+ * @returns {boolean}
+ */
+function hasCoreChanges(changedFiles) {
+  return changedFiles.some(file =>
+    file.startsWith('esphome/core/') ||
+    (file.startsWith('esphome/') && file.split('/').length === 2)
+  );
+}
+
+/**
+ * Detect if dashboard files were changed.
+ * @param {string[]} changedFiles - List of changed file paths
+ * @returns {boolean}
+ */
+function hasDashboardChanges(changedFiles) {
+  return changedFiles.some(file =>
+    file.startsWith('esphome/dashboard/') ||
+    file.startsWith('esphome/components/dashboard_import/')
+  );
+}
+
+/**
+ * Detect if GitHub Actions files were changed.
+ * @param {string[]} changedFiles - List of changed file paths
+ * @returns {boolean}
+ */
+function hasGitHubActionsChanges(changedFiles) {
+  return changedFiles.some(file =>
+    file.startsWith('.github/workflows/')
+  );
+}
+
+module.exports = {
+  COMPONENT_REGEX,
+  detectComponents,
+  hasCoreChanges,
+  hasDashboardChanges,
+  hasGitHubActionsChanges,
+};

.github/workflows/auto-label-pr.yml

@@ -12,6 +12,7 @@ permissions:
 
 env:
   SMALL_PR_THRESHOLD: 30
+  MEDIUM_PR_THRESHOLD: 100
   MAX_LABELS: 15
   TOO_BIG_THRESHOLD: 1000
   COMPONENT_LABEL_THRESHOLD: 10
@@ -26,7 +27,7 @@ jobs:
 
       - name: Generate a token
         id: generate-token
-        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2
+        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v2
         with:
           app-id: ${{ secrets.ESPHOME_GITHUB_APP_ID }}
           private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}

.github/workflows/ci-api-proto.yml

@@ -62,7 +62,7 @@ jobs:
         run: git diff
       - if: failure()
         name: Archive artifacts
-        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: generated-proto-files
           path: |

.github/workflows/ci-clang-tidy-hash.yml

@@ -40,7 +40,7 @@ jobs:
           echo "You have modified clang-tidy configuration but have not updated the hash." | tee -a $GITHUB_STEP_SUMMARY
           echo "Please run 'script/clang_tidy_hash.py --update' and commit the changes." | tee -a $GITHUB_STEP_SUMMARY
 
-      - if: failure()
+      - if: failure() && github.event.pull_request.head.repo.full_name == github.repository
         name: Request changes
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:
@@ -53,7 +53,7 @@ jobs:
               body: 'You have modified clang-tidy configuration but have not updated the hash.\nPlease run `script/clang_tidy_hash.py --update` and commit the changes.'
             })
 
-      - if: success()
+      - if: success() && github.event.pull_request.head.repo.full_name == github.repository
         name: Dismiss review
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:

.github/workflows/ci-docker.yml

@@ -49,7 +49,7 @@ jobs:
         with:
           python-version: "3.11"
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
 
       - name: Set TAG
         run: |

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
       - name: Restore Python virtual environment
         id: cache-venv
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: venv
           # yamllint disable-line rule:line-length
@@ -106,6 +106,7 @@ jobs:
           script/build_codeowners.py --check
           script/build_language_schema.py --check
           script/generate-esp32-boards.py --check
+          script/generate-rp2040-boards.py --check
 
   pytest:
     name: Run pytest
@@ -153,12 +154,12 @@ jobs:
           . venv/bin/activate
           pytest -vv --cov-report=xml --tb=native -n auto tests --ignore=tests/integration/
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@671740ac38dd9b0130fbe1cec585b89eea48d3de # v5.5.2
+        uses: codecov/codecov-action@1af58845a975a7985b0beb0cbe6fbbb71a41dbad # v5.5.3
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
       - name: Save Python virtual environment cache
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache/save@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/save@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: venv
           key: ${{ runner.os }}-${{ steps.restore-python.outputs.python-version }}-venv-${{ needs.common.outputs.cache-key }}
@@ -170,6 +171,8 @@ jobs:
       - common
     outputs:
       integration-tests: ${{ steps.determine.outputs.integration-tests }}
+      integration-tests-run-all: ${{ steps.determine.outputs.integration-tests-run-all }}
+      integration-test-files: ${{ steps.determine.outputs.integration-test-files }}
       clang-tidy: ${{ steps.determine.outputs.clang-tidy }}
       clang-tidy-mode: ${{ steps.determine.outputs.clang-tidy-mode }}
       python-linters: ${{ steps.determine.outputs.python-linters }}
@@ -182,6 +185,7 @@ jobs:
       cpp-unit-tests-run-all: ${{ steps.determine.outputs.cpp-unit-tests-run-all }}
       cpp-unit-tests-components: ${{ steps.determine.outputs.cpp-unit-tests-components }}
       component-test-batches: ${{ steps.determine.outputs.component-test-batches }}
+      benchmarks: ${{ steps.determine.outputs.benchmarks }}
     steps:
       - name: Check out code from GitHub
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -194,7 +198,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
       - name: Restore components graph cache
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: .temp/components_graph.json
           key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}
@@ -210,6 +214,8 @@ jobs:
 
           # Extract individual fields
           echo "integration-tests=$(echo "$output" | jq -r '.integration_tests')" >> $GITHUB_OUTPUT
+          echo "integration-tests-run-all=$(echo "$output" | jq -r '.integration_tests_run_all')" >> $GITHUB_OUTPUT
+          echo "integration-test-files=$(echo "$output" | jq -c '.integration_test_files')" >> $GITHUB_OUTPUT
           echo "clang-tidy=$(echo "$output" | jq -r '.clang_tidy')" >> $GITHUB_OUTPUT
           echo "clang-tidy-mode=$(echo "$output" | jq -r '.clang_tidy_mode')" >> $GITHUB_OUTPUT
           echo "python-linters=$(echo "$output" | jq -r '.python_linters')" >> $GITHUB_OUTPUT
@@ -222,9 +228,10 @@ jobs:
           echo "cpp-unit-tests-run-all=$(echo "$output" | jq -r '.cpp_unit_tests_run_all')" >> $GITHUB_OUTPUT
           echo "cpp-unit-tests-components=$(echo "$output" | jq -c '.cpp_unit_tests_components')" >> $GITHUB_OUTPUT
           echo "component-test-batches=$(echo "$output" | jq -c '.component_test_batches')" >> $GITHUB_OUTPUT
+          echo "benchmarks=$(echo "$output" | jq -r '.benchmarks')" >> $GITHUB_OUTPUT
       - name: Save components graph cache
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache/save@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/save@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: .temp/components_graph.json
           key: components-graph-${{ hashFiles('esphome/components/**/*.py') }}
@@ -246,7 +253,7 @@ jobs:
           python-version: "3.13"
       - name: Restore Python virtual environment
         id: cache-venv
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: venv
           key: ${{ runner.os }}-${{ steps.python.outputs.python-version }}-venv-${{ needs.common.outputs.cache-key }}
@@ -261,9 +268,20 @@ jobs:
       - name: Register matcher
         run: echo "::add-matcher::.github/workflows/matchers/pytest.json"
       - name: Run integration tests
+        env:
+          INTEGRATION_TEST_FILES: ${{ needs.determine-jobs.outputs.integration-test-files }}
+          INTEGRATION_TESTS_RUN_ALL: ${{ needs.determine-jobs.outputs.integration-tests-run-all }}
         run: |
           . venv/bin/activate
-          pytest -vv --no-cov --tb=native -n auto tests/integration/
+          if [[ "$INTEGRATION_TESTS_RUN_ALL" == "true" ]]; then
+            echo "Running all integration tests"
+            pytest -vv --no-cov --tb=native -n auto tests/integration/
+          else
+            # Parse JSON array into bash array to avoid shell expansion issues
+            mapfile -t test_files < <(echo "$INTEGRATION_TEST_FILES" | jq -r '.[]')
+            echo "Running ${#test_files[@]} specific integration tests"
+            pytest -vv --no-cov --tb=native -n auto "${test_files[@]}"
+          fi
 
   cpp-unit-tests:
     name: Run C++ unit tests
@@ -292,6 +310,40 @@ jobs:
             script/cpp_unit_test.py $ARGS
           fi
 
+  benchmarks:
+    name: Run CodSpeed benchmarks
+    runs-on: ubuntu-24.04
+    needs:
+      - common
+      - determine-jobs
+    if: >-
+      (github.event_name == 'push' && github.ref_name == 'dev') ||
+      (github.event_name == 'pull_request' && needs.determine-jobs.outputs.benchmarks == 'true')
+    steps:
+      - name: Check out code from GitHub
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Restore Python
+        uses: ./.github/actions/restore-python
+        with:
+          python-version: ${{ env.DEFAULT_PYTHON }}
+          cache-key: ${{ needs.common.outputs.cache-key }}
+
+      - name: Build benchmarks
+        id: build
+        run: |
+          . venv/bin/activate
+          export BENCHMARK_LIB_CONFIG=$(python script/setup_codspeed_lib.py)
+          # --build-only prints BUILD_BINARY=<path> to stdout
+          BINARY=$(script/cpp_benchmark.py --all --build-only | grep '^BUILD_BINARY=' | tail -1 | cut -d= -f2-)
+          echo "binary=$BINARY" >> $GITHUB_OUTPUT
+
+      - name: Run CodSpeed benchmarks
+        uses: CodSpeedHQ/action@1c8ae4843586d3ba879736b7f6b7b0c990757fab # v4
+        with:
+          run: ${{ steps.build.outputs.binary }}
+          mode: simulation
+
   clang-tidy-single:
     name: ${{ matrix.name }}
     runs-on: ubuntu-24.04
@@ -335,14 +387,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-${{ matrix.pio_cache_key }}-${{ hashFiles('platformio.ini') }}
@@ -414,14 +466,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
@@ -503,14 +555,14 @@ jobs:
 
       - name: Cache platformio
         if: github.ref == 'refs/heads/dev'
-        uses: actions/cache@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
 
       - name: Cache platformio
         if: github.ref != 'refs/heads/dev'
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-tidyesp32-${{ hashFiles('platformio.ini') }}
@@ -686,7 +738,7 @@ jobs:
       ram_usage: ${{ steps.extract.outputs.ram_usage }}
       flash_usage: ${{ steps.extract.outputs.flash_usage }}
       cache_hit: ${{ steps.cache-memory-analysis.outputs.cache-hit }}
-      skip: ${{ steps.check-script.outputs.skip }}
+      skip: ${{ steps.check-script.outputs.skip || steps.check-tests.outputs.skip }}
     steps:
       - name: Check out target branch
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -705,10 +757,39 @@ jobs:
             echo "::warning::ci_memory_impact_extract.py not found on target branch, skipping memory impact analysis"
           fi
 
-      # All remaining steps only run if script exists
+      # Check if test files exist on the target branch for the requested
+      # components and platform. When a PR adds new test files for a platform,
+      # the target branch won't have them yet, so skip instead of failing.
+      # This check must be done here (not in determine-jobs.py) because
+      # determine-jobs runs on the PR branch and cannot see what the target
+      # branch has.
+      - name: Check for test files on target branch
+        id: check-tests
+        if: steps.check-script.outputs.skip != 'true'
+        run: |
+          components='${{ toJSON(fromJSON(needs.determine-jobs.outputs.memory_impact).components) }}'
+          platform="${{ fromJSON(needs.determine-jobs.outputs.memory_impact).platform }}"
+          found=false
+          for component in $(echo "$components" | jq -r '.[]'); do
+            # Check for test files matching the platform (test.platform.yaml or test-*.platform.yaml)
+            for f in tests/components/${component}/test*.${platform}.yaml; do
+              if [ -f "$f" ]; then
+                found=true
+                break 2
+              fi
+            done
+          done
+          if [ "$found" = false ]; then
+            echo "skip=true" >> $GITHUB_OUTPUT
+            echo "::warning::No test files found on target branch for platform ${platform}, skipping memory impact analysis"
+          else
+            echo "skip=false" >> $GITHUB_OUTPUT
+          fi
+
+      # All remaining steps only run if script and tests exist
       - name: Generate cache key
         id: cache-key
-        if: steps.check-script.outputs.skip != 'true'
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true'
         run: |
           # Get the commit SHA of the target branch
           target_sha=$(git rev-parse HEAD)
@@ -735,14 +816,14 @@ jobs:
 
       - name: Restore cached memory analysis
         id: cache-memory-analysis
-        if: steps.check-script.outputs.skip != 'true'
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true'
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: memory-analysis-target.json
           key: ${{ steps.cache-key.outputs.cache-key }}
 
       - name: Cache status
-        if: steps.check-script.outputs.skip != 'true'
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true'
         run: |
           if [ "${{ steps.cache-memory-analysis.outputs.cache-hit }}" == "true" ]; then
             echo "✓ Cache hit! Using cached memory analysis results."
@@ -752,21 +833,21 @@ jobs:
           fi
 
       - name: Restore Python
-        if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
         uses: ./.github/actions/restore-python
         with:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
 
       - name: Cache platformio
-        if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-memory-${{ fromJSON(needs.determine-jobs.outputs.memory_impact).platform }}-${{ hashFiles('platformio.ini') }}
 
       - name: Build, compile, and analyze memory
-        if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true'
         id: build
         run: |
           . venv/bin/activate
@@ -800,15 +881,15 @@ jobs:
             --platform "$platform"
 
       - name: Save memory analysis to cache
-        if: steps.check-script.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true' && steps.build.outcome == 'success'
-        uses: actions/cache/save@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true' && steps.cache-memory-analysis.outputs.cache-hit != 'true' && steps.build.outcome == 'success'
+        uses: actions/cache/save@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: memory-analysis-target.json
           key: ${{ steps.cache-key.outputs.cache-key }}
 
       - name: Extract memory usage for outputs
         id: extract
-        if: steps.check-script.outputs.skip != 'true'
+        if: steps.check-script.outputs.skip != 'true' && steps.check-tests.outputs.skip != 'true'
         run: |
           if [ -f memory-analysis-target.json ]; then
             ram=$(jq -r '.ram_bytes' memory-analysis-target.json)
@@ -822,7 +903,7 @@ jobs:
           fi
 
       - name: Upload memory analysis JSON
-        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: memory-analysis-target
           path: memory-analysis-target.json
@@ -848,7 +929,7 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
       - name: Cache platformio
-        uses: actions/cache/restore@cdf6c1fa76f9f475f3d7449005a359c84ca0f306 # v5.0.3
+        uses: actions/cache/restore@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5.0.4
         with:
           path: ~/.platformio
           key: platformio-memory-${{ fromJSON(needs.determine-jobs.outputs.memory_impact).platform }}-${{ hashFiles('platformio.ini') }}
@@ -886,7 +967,7 @@ jobs:
             --platform "$platform"
 
       - name: Upload memory analysis JSON
-        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: memory-analysis-pr
           path: memory-analysis-pr.json
@@ -916,13 +997,13 @@ jobs:
           python-version: ${{ env.DEFAULT_PYTHON }}
           cache-key: ${{ needs.common.outputs.cache-key }}
       - name: Download target analysis JSON
-        uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7.0.0
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: memory-analysis-target
           path: ./memory-analysis
         continue-on-error: true
       - name: Download PR analysis JSON
-        uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7.0.0
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: memory-analysis-pr
           path: ./memory-analysis

.github/workflows/codeowner-approved-label-update.yml

@@ -0,0 +1,81 @@
+# Adds/removes a 'code-owner-approved' label when a component-specific
+# codeowner approves (or dismisses) a PR.
+#
+# Uses pull_request_target so that fork PRs do not require workflow approval.
+# The label is reconciled on every PR update; for review events specifically,
+# this means the label is applied on the next push after a codeowner review.
+
+name: Codeowner Approved Label
+
+on:
+  pull_request_target:
+    types: [opened, synchronize, reopened, ready_for_review]
+    branches-ignore:
+      - release
+      - beta
+
+permissions:
+  issues: write
+  pull-requests: read
+  contents: read
+
+jobs:
+  codeowner-approved:
+    name: Run
+    if: ${{ github.repository == 'esphome/esphome' }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout base branch
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
+          sparse-checkout: |
+            .github/scripts/codeowners.js
+            CODEOWNERS
+
+      - name: Check codeowner approval and update label
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        env:
+          PR_NUMBER: ${{ github.event.pull_request.number }}
+        with:
+          script: |
+            const { loadCodeowners, determineLabelAction, LabelAction } = require('./.github/scripts/codeowners.js');
+
+            const owner = context.repo.owner;
+            const repo = context.repo.repo;
+            const pr_number = parseInt(process.env.PR_NUMBER, 10);
+            const LABEL_NAME = 'code-owner-approved';
+
+            console.log(`Processing PR #${pr_number} for codeowner approval label`);
+
+            const codeownersPatterns = loadCodeowners();
+            const action = await determineLabelAction(
+              github, owner, repo, pr_number, codeownersPatterns, LABEL_NAME
+            );
+
+            if (action === LabelAction.NONE) {
+              console.log('No label change needed');
+              return;
+            }
+
+            try {
+              if (action === LabelAction.ADD) {
+                await github.rest.issues.addLabels({
+                  owner, repo, issue_number: pr_number, labels: [LABEL_NAME]
+                });
+                console.log(`Added '${LABEL_NAME}' label`);
+              } else if (action === LabelAction.REMOVE) {
+                await github.rest.issues.removeLabel({
+                  owner, repo, issue_number: pr_number, name: LABEL_NAME
+                });
+                console.log(`Removed '${LABEL_NAME}' label`);
+              }
+            } catch (error) {
+              if (error.status === 403) {
+                console.log(`Warning: insufficient permissions to update label (expected for fork PRs)`);
+              } else if (error.status === 404) {
+                console.log(`Label '${LABEL_NAME}' not present, nothing to remove`);
+              } else {
+                throw error;
+              }
+            }

.github/workflows/codeowner-review-request.yml

@@ -13,6 +13,9 @@ on:
   # Needs to be pull_request_target to get write permissions
   pull_request_target:
     types: [opened, reopened, synchronize, ready_for_review]
+    branches-ignore:
+      - release
+      - beta
 
 permissions:
   pull-requests: write
@@ -24,10 +27,17 @@ jobs:
     if: ${{ github.repository == 'esphome/esphome' && !github.event.pull_request.draft }}
     runs-on: ubuntu-latest
     steps:
+      - name: Checkout base branch
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          ref: ${{ github.event.pull_request.base.sha }}
+
       - name: Request reviews from component codeowners
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
         with:
           script: |
+            const { loadCodeowners, getEffectiveOwners } = require('./.github/scripts/codeowners.js');
+
             const owner = context.repo.owner;
             const repo = context.repo.repo;
             const pr_number = context.payload.pull_request.number;
@@ -38,12 +48,15 @@ jobs:
             const BOT_COMMENT_MARKER = '<!-- codeowner-review-request-bot -->';
 
             try {
-              // Get the list of changed files in this PR
-              const { data: files } = await github.rest.pulls.listFiles({
-                owner,
-                repo,
-                pull_number: pr_number
-              });
+              // Get the list of changed files in this PR (with pagination)
+              const files = await github.paginate(
+                github.rest.pulls.listFiles,
+                {
+                  owner,
+                  repo,
+                  pull_number: pr_number
+                }
+              );
 
               const changedFiles = files.map(file => file.filename);
               console.log(`Found ${changedFiles.length} changed files`);
@@ -53,32 +66,10 @@ jobs:
                 return;
               }
 
-              // Fetch CODEOWNERS file from root
-              const { data: codeownersFile } = await github.rest.repos.getContent({
-                owner,
-                repo,
-                path: 'CODEOWNERS',
-                ref: context.payload.pull_request.base.sha
-              });
-              const codeownersContent = Buffer.from(codeownersFile.content, 'base64').toString('utf8');
+              // Parse CODEOWNERS from the checked-out base branch
+              const codeownersPatterns = loadCodeowners();
 
-              // Parse CODEOWNERS file to extract all patterns and their owners
-              const codeownersLines = codeownersContent.split('\n')
-                .map(line => line.trim())
-                .filter(line => line && !line.startsWith('#'));
-
-              const codeownersPatterns = [];
-
-              // Convert CODEOWNERS pattern to regex (robust glob handling)
-              function globToRegex(pattern) {
-                // Escape regex special characters except for glob wildcards
-                let regexStr = pattern
-                  .replace(/([.+^=!:${}()|[\]\\])/g, '\\$1') // escape regex chars
-                  .replace(/\*\*/g, '.*') // globstar
-                  .replace(/\*/g, '[^/]*') // single star
-                  .replace(/\?/g, '.'); // question mark
-                return new RegExp('^' + regexStr + '$');
-              }
+              console.log(`Parsed ${codeownersPatterns.length} codeowner patterns`);
 
               // Helper function to create comment body
               function createCommentBody(reviewersList, teamsList, matchedFileCount, isSuccessful = true) {
@@ -93,50 +84,11 @@ jobs:
                 }
               }
 
-              for (const line of codeownersLines) {
-                const parts = line.split(/\s+/);
-                if (parts.length < 2) continue;
-
-                const pattern = parts[0];
-                const owners = parts.slice(1);
-
-                // Use robust glob-to-regex conversion
-                const regex = globToRegex(pattern);
-                codeownersPatterns.push({ pattern, regex, owners });
-              }
-
-              console.log(`Parsed ${codeownersPatterns.length} codeowner patterns`);
-
-              // Match changed files against CODEOWNERS patterns
-              const matchedOwners = new Set();
-              const matchedTeams = new Set();
-              const fileMatches = new Map(); // Track which files matched which patterns
-
-              for (const file of changedFiles) {
-                for (const { pattern, regex, owners } of codeownersPatterns) {
-                  if (regex.test(file)) {
-                    console.log(`File '${file}' matches pattern '${pattern}' with owners: ${owners.join(', ')}`);
-
-                    if (!fileMatches.has(file)) {
-                      fileMatches.set(file, []);
-                    }
-                    fileMatches.get(file).push({ pattern, owners });
-
-                    // Add owners to the appropriate set (remove @ prefix)
-                    for (const owner of owners) {
-                      const cleanOwner = owner.startsWith('@') ? owner.slice(1) : owner;
-                      if (cleanOwner.includes('/')) {
-                        // Team mention (org/team-name)
-                        const teamName = cleanOwner.split('/')[1];
-                        matchedTeams.add(teamName);
-                      } else {
-                        // Individual user
-                        matchedOwners.add(cleanOwner);
-                      }
-                    }
-                  }
-                }
-              }
+              // Match changed files against CODEOWNERS patterns using last-match-wins semantics
+              const effective = getEffectiveOwners(changedFiles, codeownersPatterns);
+              const matchedOwners = effective.users;
+              const matchedTeams = effective.teams;
+              const matchedFileCount = effective.matchedFileCount;
 
               if (matchedOwners.size === 0 && matchedTeams.size === 0) {
                 console.log('No codeowners found for any changed files');
@@ -170,11 +122,14 @@ jobs:
               }
 
               // Check for completed reviews to avoid re-requesting users who have already reviewed
-              const { data: reviews } = await github.rest.pulls.listReviews({
-                owner,
-                repo,
-                pull_number: pr_number
-              });
+              const reviews = await github.paginate(
+                github.rest.pulls.listReviews,
+                {
+                  owner,
+                  repo,
+                  pull_number: pr_number
+                }
+              );
 
               const reviewedUsers = new Set();
               reviews.forEach(review => {
@@ -247,7 +202,7 @@ jobs:
               }
 
               const totalReviewers = reviewersList.length + teamsList.length;
-              console.log(`Requesting reviews from ${reviewersList.length} users and ${teamsList.length} teams for ${fileMatches.size} matched files`);
+              console.log(`Requesting reviews from ${reviewersList.length} users and ${teamsList.length} teams for ${matchedFileCount} matched files`);
 
               // Request reviews
               try {
@@ -279,7 +234,7 @@ jobs:
 
                 // Only add a comment if there are new codeowners to mention (not previously pinged)
                 if (reviewersList.length > 0 || teamsList.length > 0) {
-                  const commentBody = createCommentBody(reviewersList, teamsList, fileMatches.size, true);
+                  const commentBody = createCommentBody(reviewersList, teamsList, matchedFileCount, true);
 
                   await github.rest.issues.createComment({
                     owner,
@@ -297,7 +252,7 @@ jobs:
 
                   // Only try to add a comment if there are new codeowners to mention
                   if (reviewersList.length > 0 || teamsList.length > 0) {
-                    const commentBody = createCommentBody(reviewersList, teamsList, fileMatches.size, false);
+                    const commentBody = createCommentBody(reviewersList, teamsList, matchedFileCount, false);
 
                     try {
                       await github.rest.issues.createComment({

.github/workflows/codeql.yml

@@ -58,7 +58,7 @@ jobs:
 
       # Initializes the CodeQL tools for scanning.
       - name: Initialize CodeQL
-        uses: github/codeql-action/init@45cbd0c69e560cd9e7cd7f8c32362050c9b7ded2 # v4.32.2
+        uses: github/codeql-action/init@38697555549f1db7851b81482ff19f1fa5c4fedc # v4.34.1
         with:
           languages: ${{ matrix.language }}
           build-mode: ${{ matrix.build-mode }}
@@ -86,6 +86,6 @@ jobs:
           exit 1
 
       - name: Perform CodeQL Analysis
-        uses: github/codeql-action/analyze@45cbd0c69e560cd9e7cd7f8c32362050c9b7ded2 # v4.32.2
+        uses: github/codeql-action/analyze@38697555549f1db7851b81482ff19f1fa5c4fedc # v4.34.1
         with:
           category: "/language:${{matrix.language}}"

.github/workflows/pr-title-check.yml

@@ -0,0 +1,93 @@
+name: PR Title Check
+
+on:
+  pull_request:
+    types: [opened, edited, synchronize, reopened]
+
+permissions:
+  contents: read
+  pull-requests: read
+
+jobs:
+  check:
+    name: Validate PR title
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8.0.0
+        with:
+          script: |
+            const {
+              detectComponents,
+              hasCoreChanges,
+              hasDashboardChanges,
+              hasGitHubActionsChanges,
+            } = require('./.github/scripts/detect-tags.js');
+
+            const title = context.payload.pull_request.title;
+            const author = context.payload.pull_request.user.login;
+
+            // Skip bot PRs (e.g. dependabot) - they have their own title format
+            if (author === 'dependabot[bot]') {
+              return;
+            }
+
+            // Block titles starting with "word:" or "word(scope):" patterns
+            const commitStylePattern = /^\w+(\(.*?\))?[!]?\s*:/;
+            if (commitStylePattern.test(title)) {
+              core.setFailed(
+                `PR title should not start with a "prefix:" style format.\n` +
+                `Please use the format: [component] Brief description\n`
+              );
+              return;
+            }
+
+            // Get changed files to detect tags
+            const files = await github.paginate(github.rest.pulls.listFiles, {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: context.issue.number,
+            });
+            const filenames = files.map(f => f.filename);
+
+            // Detect tags from changed files using shared logic
+            const tags = new Set();
+
+            for (const comp of detectComponents(filenames)) {
+              tags.add(comp);
+            }
+            if (hasCoreChanges(filenames)) tags.add('core');
+            if (hasDashboardChanges(filenames)) tags.add('dashboard');
+            if (hasGitHubActionsChanges(filenames)) tags.add('ci');
+
+            if (tags.size === 0) {
+              return;
+            }
+
+            // Check for angle brackets not wrapped in backticks.
+            // Astro docs MDX treats bare < as JSX component opening tags.
+            const stripped = title.replace(/`[^`]*`/g, '');
+            if (/[<>]/.test(stripped)) {
+              core.setFailed(
+                'PR title contains `<` or `>` not wrapped in backticks.\n' +
+                'Astro docs MDX interprets bare `<` as JSX components.\n' +
+                'Please wrap angle brackets with backticks, e.g.: [component] Add `<feature>` support'
+              );
+              return;
+            }
+
+            // Check title starts with [tag] prefix
+            const bracketPattern = /^\[\w+\]/;
+            if (!bracketPattern.test(title)) {
+              const suggestion = [...tags].map(c => `[${c}]`).join('');
+              // Skip if the suggested prefix would be too long for a readable title
+              if (suggestion.length > 40) {
+                return;
+              }
+              core.setFailed(
+                `PR modifies: ${[...tags].join(', ')}\n` +
+                `Title must start with a [tag] prefix.\n` +
+                `Suggested: ${suggestion} <description>`
+              );
+            }

.github/workflows/release.yml

@@ -99,15 +99,15 @@ jobs:
           python-version: "3.11"
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
 
       - name: Log in to docker hub
-        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
+        uses: docker/login-action@b45d80f862d83dbcd57f89517bcf500b2ab88fb2 # v4.0.0
         with:
           username: ${{ secrets.DOCKER_USER }}
           password: ${{ secrets.DOCKER_PASSWORD }}
       - name: Log in to the GitHub container registry
-        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
+        uses: docker/login-action@b45d80f862d83dbcd57f89517bcf500b2ab88fb2 # v4.0.0
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
@@ -138,7 +138,7 @@ jobs:
       #     version: ${{ needs.init.outputs.tag }}
 
       - name: Upload digests
-        uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
+        uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
           name: digests-${{ matrix.platform.arch }}
           path: /tmp/digests
@@ -171,24 +171,24 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - name: Download digests
-        uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7.0.0
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           pattern: digests-*
           path: /tmp/digests
           merge-multiple: true
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3.12.0
+        uses: docker/setup-buildx-action@4d04d5d9486b7bd6fa91e7baf45bbb4f8b9deedd # v4.0.0
 
       - name: Log in to docker hub
         if: matrix.registry == 'dockerhub'
-        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
+        uses: docker/login-action@b45d80f862d83dbcd57f89517bcf500b2ab88fb2 # v4.0.0
         with:
           username: ${{ secrets.DOCKER_USER }}
           password: ${{ secrets.DOCKER_PASSWORD }}
       - name: Log in to the GitHub container registry
         if: matrix.registry == 'ghcr'
-        uses: docker/login-action@c94ce9fb468520275223c153574b00df6fe4bcc9 # v3.7.0
+        uses: docker/login-action@b45d80f862d83dbcd57f89517bcf500b2ab88fb2 # v4.0.0
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
@@ -221,7 +221,7 @@ jobs:
     steps:
       - name: Generate a token
         id: generate-token
-        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
+        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
         with:
           app-id: ${{ secrets.ESPHOME_GITHUB_APP_ID }}
           private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}
@@ -256,7 +256,7 @@ jobs:
     steps:
       - name: Generate a token
         id: generate-token
-        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
+        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
         with:
           app-id: ${{ secrets.ESPHOME_GITHUB_APP_ID }}
           private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}
@@ -287,7 +287,7 @@ jobs:
     steps:
       - name: Generate a token
         id: generate-token
-        uses: actions/create-github-app-token@29824e69f54612133e76f7eaac726eef6c875baf # v2.2.1
+        uses: actions/create-github-app-token@f8d387b68d61c58ab83c6c016672934102569859 # v3.0.0
         with:
           app-id: ${{ secrets.ESPHOME_GITHUB_APP_ID }}
           private-key: ${{ secrets.ESPHOME_GITHUB_APP_PRIVATE_KEY }}

.github/workflows/stale.yml

@@ -19,7 +19,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Stale
-        uses: actions/stale@997185467fa4f803885201cee163a9f38240193d # v10.1.1
+        uses: actions/stale@b5d41d4e1d5dceea10e7104786b73624c18a190f # v10.2.0
         with:
           debug-only: ${{ github.ref != 'refs/heads/dev' }} # Dry-run when not run on dev branch
           remove-stale-when-updated: true

.github/workflows/sync-device-classes.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:
-          python-version: 3.13
+          python-version: "3.14"
 
       - name: Install Home Assistant
         run: |

.pre-commit-config.yaml

@@ -11,7 +11,7 @@ ci:
 repos:
   - repo: https://github.com/astral-sh/ruff-pre-commit
     # Ruff version.
-    rev: v0.15.0
+    rev: v0.15.6
     hooks:
       # Run the linter.
       - id: ruff
@@ -37,7 +37,7 @@ repos:
       - id: end-of-file-fixer
       - id: trailing-whitespace
   - repo: https://github.com/asottile/pyupgrade
-    rev: v3.20.0
+    rev: v3.21.2
     hooks:
       - id: pyupgrade
         args: [--py311-plus]

CODEOWNERS

@@ -54,6 +54,8 @@ esphome/components/atm90e32/* @circuitsetup @descipher
 esphome/components/audio/* @kahrendt
 esphome/components/audio_adc/* @kbx81
 esphome/components/audio_dac/* @kbx81
+esphome/components/audio_file/* @kahrendt
+esphome/components/audio_file/media_source/* @kahrendt
 esphome/components/axs15231/* @clydebarrow
 esphome/components/b_parasite/* @rbaron
 esphome/components/ballu/* @bazuchan
@@ -130,6 +132,7 @@ esphome/components/dashboard_import/* @esphome/core
 esphome/components/datetime/* @jesserockz @rfdarter
 esphome/components/debug/* @esphome/core
 esphome/components/delonghi/* @grob6000
+esphome/components/dew_point/* @CFlix
 esphome/components/dfplayer/* @glmnet
 esphome/components/dfrobot_sen0395/* @niklasweber
 esphome/components/dht/* @OttoWinter
@@ -213,6 +216,7 @@ esphome/components/hbridge/light/* @DotNetDann
 esphome/components/hbridge/switch/* @dwmw2
 esphome/components/hc8/* @omartijn
 esphome/components/hdc2010/* @optimusprimespace @ssieb
+esphome/components/hdc302x/* @joshuasing
 esphome/components/he60r/* @clydebarrow
 esphome/components/heatpumpir/* @rob-deutsch
 esphome/components/hitachi_ac424/* @sourabhjaiswal
@@ -240,7 +244,6 @@ esphome/components/hyt271/* @Philippe12
 esphome/components/i2c/* @esphome/core
 esphome/components/i2c_device/* @gabest11
 esphome/components/i2s_audio/* @jesserockz
-esphome/components/i2s_audio/media_player/* @jesserockz
 esphome/components/i2s_audio/microphone/* @jesserockz
 esphome/components/i2s_audio/speaker/* @jesserockz @kahrendt
 esphome/components/iaqcore/* @yozik04
@@ -315,6 +318,7 @@ esphome/components/mcp9808/* @k7hpn
 esphome/components/md5/* @esphome/core
 esphome/components/mdns/* @esphome/core
 esphome/components/media_player/* @jesserockz
+esphome/components/media_source/* @kahrendt
 esphome/components/micro_wake_word/* @jesserockz @kahrendt
 esphome/components/micronova/* @edenhaus @jorre05
 esphome/components/microphone/* @jesserockz @kahrendt
@@ -406,11 +410,13 @@ esphome/components/restart/* @esphome/core
 esphome/components/rf_bridge/* @jesserockz
 esphome/components/rgbct/* @jesserockz
 esphome/components/rp2040/* @jesserockz
+esphome/components/rp2040_ble/* @bdraco
 esphome/components/rp2040_pio_led_strip/* @Papa-DMan
 esphome/components/rp2040_pwm/* @jesserockz
 esphome/components/rpi_dpi_rgb/* @clydebarrow
 esphome/components/rtl87xx/* @kuba2k2
-esphome/components/rtttl/* @glmnet
+esphome/components/rtttl/* @glmnet @ximex
+esphome/components/runtime_image/* @clydebarrow @guillempages @kahrendt
 esphome/components/runtime_stats/* @bdraco
 esphome/components/rx8130/* @beormund
 esphome/components/safe_mode/* @jsuanet @kbx81 @paulmonigatti
@@ -427,8 +433,10 @@ esphome/components/select/* @esphome/core
 esphome/components/sen0321/* @notjj
 esphome/components/sen21231/* @shreyaskarnik
 esphome/components/sen5x/* @martgras
+esphome/components/sen6x/* @martgras @mebner86 @mikelawrence @tuct
 esphome/components/sensirion_common/* @martgras
 esphome/components/sensor/* @esphome/core
+esphome/components/serial_proxy/* @kbx81
 esphome/components/sfa30/* @ghsensdev
 esphome/components/sgp40/* @SenexCrenshaw
 esphome/components/sgp4x/* @martgras @SenexCrenshaw
@@ -449,8 +457,11 @@ esphome/components/sn74hc165/* @jesserockz
 esphome/components/socket/* @esphome/core
 esphome/components/sonoff_d1/* @anatoly-savchenkov
 esphome/components/sound_level/* @kahrendt
+esphome/components/spa06_base/* @danielkent-net
+esphome/components/spa06_i2c/* @danielkent-net
 esphome/components/speaker/* @jesserockz @kahrendt
 esphome/components/speaker/media_player/* @kahrendt @synesthesiam
+esphome/components/speaker_source/* @kahrendt
 esphome/components/spi/* @clydebarrow @esphome/core
 esphome/components/spi_device/* @clydebarrow
 esphome/components/spi_led_strip/* @clydebarrow
@@ -581,6 +592,7 @@ esphome/components/xl9535/* @mreditor97
 esphome/components/xpt2046/touchscreen/* @nielsnl68 @numo68
 esphome/components/xxtea/* @clydebarrow
 esphome/components/zephyr/* @tomaszduda23
+esphome/components/zephyr_mcumgr/ota/* @tomaszduda23
 esphome/components/zhlt01/* @cfeenstra1024
 esphome/components/zigbee/* @tomaszduda23
 esphome/components/zio_ultrasonic/* @kahrendt

Doxyfile

@@ -48,7 +48,7 @@ PROJECT_NAME           = ESPHome
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 2026.2.1
+PROJECT_NUMBER         = 2026.4.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a

README.md

@@ -1,4 +1,4 @@
-# ESPHome [![Discord Chat](https://img.shields.io/discord/429907082951524364.svg)](https://discord.gg/KhAMKrd) [![GitHub release](https://img.shields.io/github/release/esphome/esphome.svg)](https://GitHub.com/esphome/esphome/releases/)
+# ESPHome [![Discord Chat](https://img.shields.io/discord/429907082951524364.svg)](https://discord.gg/KhAMKrd) [![GitHub release](https://img.shields.io/github/release/esphome/esphome.svg)](https://GitHub.com/esphome/esphome/releases/) [![CodSpeed](https://img.shields.io/endpoint?url=https://codspeed.io/badge.json)](https://codspeed.io/esphome/esphome)
 
 <a href="https://esphome.io/">
   <picture>

esphome/__main__.py

@@ -1,6 +1,7 @@
 # PYTHON_ARGCOMPLETE_OK
 import argparse
 from collections.abc import Callable
+from contextlib import suppress
 from datetime import datetime
 import functools
 import getpass
@@ -9,6 +10,8 @@ import logging
 import os
 from pathlib import Path
 import re
+import shutil
+import subprocess
 import sys
 import time
 from typing import Protocol
@@ -23,6 +26,7 @@ import esphome.codegen as cg
 from esphome.config import iter_component_configs, read_config, strip_default_ids
 from esphome.const import (
     ALLOWED_NAME_CHARS,
+    ARGUMENT_HELP_DEVICE,
     CONF_API,
     CONF_BAUD_RATE,
     CONF_BROKER,
@@ -43,7 +47,9 @@ from esphome.const import (
     CONF_SUBSTITUTIONS,
     CONF_TOPIC,
     ENV_NOGITIGNORE,
+    KEY_CORE,
     KEY_NATIVE_IDF,
+    KEY_TARGET_PLATFORM,
     PLATFORM_ESP32,
     PLATFORM_ESP8266,
     PLATFORM_RP2040,
@@ -55,7 +61,11 @@ from esphome.helpers import get_bool_env, indent, is_ip_address
 from esphome.log import AnsiFore, color, setup_log
 from esphome.types import ConfigType
 from esphome.util import (
+    PICOTOOL_PACKAGE,
+    detect_rp2040_bootsel,
+    get_picotool_path,
     get_serial_ports,
+    is_picotool_usb_permission_error,
     list_yaml_files,
     run_external_command,
     run_external_process,
@@ -64,9 +74,26 @@ from esphome.util import (
 
 _LOGGER = logging.getLogger(__name__)
 
+ESPHOME_COMMAND = [sys.executable, "-m", "esphome"]
+
 # Maximum buffer size for serial log reading to prevent unbounded memory growth
 SERIAL_BUFFER_MAX_SIZE = 65536
 
+_RP2040_BOOTSEL_INSTRUCTIONS = (
+    "To enter BOOTSEL mode:\n"
+    "  1. Unplug the device\n"
+    "  2. Hold the BOOT/BOOTSEL button\n"
+    "  3. Plug in the USB cable while holding the button\n"
+    "  4. Release the button - the device should appear as a USB drive (RPI-RP2)\n"
+    "Then run the upload command again."
+)
+
+_RP2040_UDEV_HINT = (
+    "You may need to add a udev rule for RP2040 devices. "
+    "See: https://github.com/raspberrypi/picotool"
+    "/blob/master/udev/60-picotool.rules"
+)
+
 # Special non-component keys that appear in configs
 _NON_COMPONENT_KEYS = frozenset(
     {
@@ -162,6 +189,7 @@ class PortType(StrEnum):
     NETWORK = "NETWORK"
     MQTT = "MQTT"
     MQTTIP = "MQTTIP"
+    BOOTSEL = "BOOTSEL"
 
 
 # Magic MQTT port types that require special handling
@@ -240,6 +268,19 @@ def choose_upload_log_host(
         (f"{port.path} ({port.description})", port.path) for port in get_serial_ports()
     ]
 
+    # Add RP2040 BOOTSEL device option when uploading
+    bootsel_permission_error = False
+    if (
+        purpose == Purpose.UPLOADING
+        and CORE.data.get(KEY_CORE, {}).get(KEY_TARGET_PLATFORM) == PLATFORM_RP2040
+        and (picotool := _find_picotool()) is not None
+    ):
+        bootsel = detect_rp2040_bootsel(picotool)
+        if bootsel.device_count > 0:
+            options.append(("RP2040 BOOTSEL (via picotool)", "BOOTSEL"))
+        elif bootsel.permission_error:
+            bootsel_permission_error = True
+
     if purpose == Purpose.LOGGING:
         if has_mqtt_logging():
             mqtt_config = CORE.config[CONF_MQTT]
@@ -257,6 +298,25 @@ def choose_upload_log_host(
         if has_mqtt_ip_lookup():
             options.append(("Over The Air (MQTT IP lookup)", "MQTTIP"))
 
+    # Show helpful BOOTSEL instructions for RP2040 when no BOOTSEL device is found
+    if (
+        purpose == Purpose.UPLOADING
+        and CORE.data.get(KEY_CORE, {}).get(KEY_TARGET_PLATFORM) == PLATFORM_RP2040
+        and not any(get_port_type(opt[1]) == PortType.BOOTSEL for opt in options)
+    ):
+        if bootsel_permission_error:
+            _LOGGER.warning(
+                "An RP2040 device in BOOTSEL mode was detected but could "
+                "not be accessed due to USB permissions."
+            )
+            if sys.platform.startswith("linux"):
+                _LOGGER.warning(_RP2040_UDEV_HINT)
+        if not options:
+            raise EsphomeError(
+                f"No RP2040 device found. {_RP2040_BOOTSEL_INSTRUCTIONS}"
+            )
+        _LOGGER.info("Tip: %s", _RP2040_BOOTSEL_INSTRUCTIONS)
+
     if check_default is not None and check_default in [opt[1] for opt in options]:
         return [check_default]
     return [choose_prompt(options, purpose=purpose)]
@@ -403,10 +463,13 @@ def get_port_type(port: str) -> PortType:
 
     Returns:
         PortType.SERIAL for serial ports (/dev/ttyUSB0, COM1, etc.)
+        PortType.BOOTSEL for RP2040 BOOTSEL upload via picotool
         PortType.MQTT for MQTT logging
         PortType.MQTTIP for MQTT IP lookup
         PortType.NETWORK for IP addresses, hostnames, or mDNS names
     """
+    if port == "BOOTSEL":
+        return PortType.BOOTSEL
     if port.startswith("/") or port.startswith("COM"):
         return PortType.SERIAL
     if port == "MQTT":
@@ -431,6 +494,14 @@ def run_miniterm(config: ConfigType, port: str, args) -> int:
         return 1
     _LOGGER.info("Starting log output from %s with baud rate %s", port, baud_rate)
 
+    process_stacktrace = None
+
+    try:
+        module = importlib.import_module("esphome.components." + CORE.target_platform)
+        process_stacktrace = getattr(module, "process_stacktrace")
+    except AttributeError:
+        pass
+
     backtrace_state = False
     ser = serial.Serial()
     ser.baudrate = baud_rate
@@ -472,9 +543,14 @@ def run_miniterm(config: ConfigType, port: str, args) -> int:
                             )
                             safe_print(parser.parse_line(line, time_str))
 
-                            backtrace_state = platformio_api.process_stacktrace(
-                                config, line, backtrace_state=backtrace_state
-                            )
+                            if process_stacktrace:
+                                backtrace_state = process_stacktrace(
+                                    config, line, backtrace_state
+                                )
+                            else:
+                                backtrace_state = platformio_api.process_stacktrace(
+                                    config, line, backtrace_state=backtrace_state
+                                )
                     except serial.SerialException:
                         _LOGGER.error("Serial port closed!")
                         return 0
@@ -614,6 +690,47 @@ def _check_and_emit_build_info() -> None:
     )
 
 
+def _get_configured_xtal_freq() -> int | None:
+    """Read the configured crystal frequency from the sdkconfig file."""
+    sdkconfig_path = CORE.relative_build_path(f"sdkconfig.{CORE.name}")
+    if not sdkconfig_path.is_file():
+        return None
+    with suppress(OSError, ValueError):
+        content = sdkconfig_path.read_text()
+        for line in content.splitlines():
+            if line.startswith("CONFIG_XTAL_FREQ="):
+                return int(line.split("=", 1)[1])
+    return None
+
+
+def _make_crystal_freq_callback(
+    configured_freq: int,
+) -> Callable[[str], str | None]:
+    """Create a callback that checks esptool crystal frequency output."""
+    crystal_re = re.compile(r"Crystal frequency:\s+(\d+)\s*MHz")
+
+    def check_crystal_line(line: str) -> str | None:
+        if not (match := crystal_re.search(line)):
+            return None
+        detected = int(match.group(1))
+        if detected == configured_freq:
+            return None
+        return (
+            f"\n\033[33mWARNING: Crystal frequency mismatch! "
+            f"Device reports {detected}MHz but firmware is configured "
+            f"for {configured_freq}MHz.\n"
+            f"UART logging and other clock-dependent features will not "
+            f"work correctly.\n"
+            f"Set the correct crystal frequency with sdkconfig_options:\n"
+            f"  esp32:\n"
+            f"    framework:\n"
+            f"      sdkconfig_options:\n"
+            f"        CONFIG_XTAL_FREQ_{detected}: 'y'\033[0m\n\n"
+        )
+
+    return check_crystal_line
+
+
 def upload_using_esptool(
     config: ConfigType, port: str, file: str, speed: int
 ) -> str | int:
@@ -642,6 +759,14 @@ def upload_using_esptool(
 
         mcu = get_esp32_variant().lower()
 
+    line_callbacks: list[Callable[[str], str | None]] = []
+    if (
+        CORE.is_esp32
+        and file is None
+        and (configured_freq := _get_configured_xtal_freq()) is not None
+    ):
+        line_callbacks.append(_make_crystal_freq_callback(configured_freq))
+
     def run_esptool(baud_rate):
         cmd = [
             "esptool",
@@ -666,9 +791,13 @@ def upload_using_esptool(
         if os.environ.get("ESPHOME_USE_SUBPROCESS") is None:
             import esptool
 
-            return run_external_command(esptool.main, *cmd)  # pylint: disable=no-member
+            return run_external_command(
+                esptool.main,  # pylint: disable=no-member
+                *cmd,
+                line_callbacks=line_callbacks,
+            )
 
-        return run_external_process(*cmd)
+        return run_external_process(*cmd, line_callbacks=line_callbacks)
 
     rc = run_esptool(first_baudrate)
     if rc == 0 or first_baudrate == 115200:
@@ -681,15 +810,140 @@ def upload_using_esptool(
     return run_esptool(115200)
 
 
-def upload_using_platformio(config: ConfigType, port: str):
+def upload_using_platformio(config: ConfigType, port: str) -> int:
     from esphome import platformio_api
 
+    # RP2040 platform-raspberrypi build recipe expects firmware.bin.signed for
+    # the upload target, but 'nobuild' skips the build phase that creates it.
+    # Create it here so the upload doesn't fail.
+    if CORE.data.get(KEY_CORE, {}).get(KEY_TARGET_PLATFORM) == PLATFORM_RP2040:
+        idedata = platformio_api.get_idedata(config)
+        build_dir = Path(idedata.firmware_elf_path).parent
+        firmware_bin = build_dir / "firmware.bin"
+        signed_bin = build_dir / "firmware.bin.signed"
+        if firmware_bin.is_file() and not signed_bin.is_file():
+            shutil.copy2(firmware_bin, signed_bin)
+
     upload_args = ["-t", "upload", "-t", "nobuild"]
     if port is not None:
         upload_args += ["--upload-port", port]
     return platformio_api.run_platformio_cli_run(config, CORE.verbose, *upload_args)
 
 
+def _find_picotool() -> Path | None:
+    """Find the picotool binary from PlatformIO packages."""
+    from esphome import platformio_api
+
+    try:
+        idedata = platformio_api.get_idedata(CORE.config)
+    except Exception:  # noqa: BLE001  # pylint: disable=broad-except
+        return None
+    return get_picotool_path(idedata.cc_path)
+
+
+def upload_using_picotool(config: ConfigType) -> int:
+    """Upload firmware to RP2040 in BOOTSEL mode using picotool.
+
+    Uses picotool to load the ELF firmware directly via USB, avoiding
+    the mass storage copy approach that causes "disk not ejected properly"
+    warnings on macOS.
+    """
+    from esphome import platformio_api
+
+    idedata = platformio_api.get_idedata(config)
+    firmware_elf = Path(idedata.firmware_elf_path)
+
+    if not firmware_elf.is_file():
+        _LOGGER.error(
+            "Firmware ELF file not found at %s. "
+            "Make sure the project has been compiled first.",
+            firmware_elf,
+        )
+        return 1
+
+    picotool = get_picotool_path(idedata.cc_path)
+    if picotool is None:
+        _LOGGER.error(
+            "picotool not found. Ensure the RP2040 PlatformIO platform "
+            "is installed (%s).",
+            PICOTOOL_PACKAGE,
+        )
+        return 1
+
+    _LOGGER.info("Uploading firmware to RP2040 via picotool...")
+    try:
+        # Don't capture stdout — let picotool write directly to the terminal
+        # so progress bars display in real-time with \r updates.
+        # Capture stderr only so we can detect permission errors.
+        result = subprocess.run(
+            [str(picotool), "load", "-v", "-x", str(firmware_elf)],
+            stderr=subprocess.PIPE,
+            timeout=60,
+            check=False,
+        )
+    except subprocess.TimeoutExpired:
+        _LOGGER.error("picotool upload timed out after 60 seconds.")
+        return 1
+    except OSError as err:
+        _LOGGER.error("Failed to run picotool: %s", err)
+        return 1
+
+    if result.returncode != 0:
+        stderr = result.stderr.decode("utf-8", errors="replace").strip()
+        if stderr:
+            for line in stderr.splitlines():
+                safe_print(line)
+        if is_picotool_usb_permission_error(stderr):
+            msg = "Permission denied accessing USB device."
+            if sys.platform.startswith("linux"):
+                msg += f" {_RP2040_UDEV_HINT}"
+            _LOGGER.error(msg)
+        else:
+            _LOGGER.error("picotool upload failed (exit code %d).", result.returncode)
+        return 1
+
+    return 0
+
+
+def _wait_for_serial_port(
+    port: str | None = None,
+    timeout: float = 30.0,
+    known_ports: set[str] | None = None,
+) -> None:
+    """Wait for a serial port to appear, e.g. after a device reboot.
+
+    USB-CDC devices disappear briefly after flashing while the device
+    reboots and re-enumerates on the USB bus.
+
+    If port is given, wait for that specific path. If known_ports is
+    given, wait for a new port that wasn't in the set. Otherwise wait
+    for any serial port to appear.
+    """
+
+    def _port_found() -> bool:
+        if port is not None:
+            if os.name == "posix":
+                return os.path.exists(port)
+            return any(p.path == port for p in get_serial_ports())
+        ports = get_serial_ports()
+        if known_ports is not None:
+            return any(p.path not in known_ports for p in ports)
+        return bool(ports)
+
+    if _port_found():
+        return
+    if port is not None:
+        _LOGGER.info("Waiting for %s to come online...", port)
+    else:
+        _LOGGER.info("Waiting for device to reboot...")
+    start = time.monotonic()
+    while time.monotonic() - start < timeout:
+        time.sleep(0.05)
+        if _port_found():
+            time.sleep(0.05)
+            return
+
+
 def check_permissions(port: str):
     if os.name == "posix" and get_port_type(port) == PortType.SERIAL:
         # Check if we can open selected serial port
@@ -719,7 +973,15 @@ def upload_program(
     except AttributeError:
         pass
 
-    if get_port_type(host) == PortType.SERIAL:
+    port_type = get_port_type(host)
+
+    if port_type == PortType.BOOTSEL:
+        exit_code = upload_using_picotool(config)
+        # Return None for device - BOOTSEL can't be used for logging,
+        # so command_run will show the interactive chooser for log source
+        return exit_code, None
+
+    if port_type == PortType.SERIAL:
         check_permissions(host)
 
         exit_code = 1
@@ -773,6 +1035,7 @@ def show_logs(config: ConfigType, args: ArgsProtocol, devices: list[str]) -> int
     port_type = get_port_type(port)
 
     if port_type == PortType.SERIAL:
+        _wait_for_serial_port(port)
         check_permissions(port)
         return run_miniterm(config, port, args)
 
@@ -911,6 +1174,9 @@ def command_run(args: ArgsProtocol, config: ConfigType) -> int | None:
         purpose=Purpose.UPLOADING,
     )
 
+    # Snapshot current serial ports before upload so we can detect new ones
+    pre_upload_ports = {p.path for p in get_serial_ports()}
+
     exit_code, successful_device = upload_program(config, args, devices)
     if exit_code == 0:
         _LOGGER.info("Successfully uploaded program.")
@@ -921,6 +1187,19 @@ def command_run(args: ArgsProtocol, config: ConfigType) -> int | None:
     if args.no_logs:
         return 0
 
+    # After BOOTSEL upload, wait for a new serial port to appear
+    # so it shows up in the log chooser
+    if (
+        successful_device is None
+        and CORE.data.get(KEY_CORE, {}).get(KEY_TARGET_PLATFORM) == PLATFORM_RP2040
+    ):
+        _wait_for_serial_port(known_ports=pre_upload_ports)
+        # If exactly one new serial port appeared, use it directly
+        serial_ports = get_serial_ports()
+        new_ports = [p for p in serial_ports if p.path not in pre_upload_ports]
+        if len(new_ports) == 1:
+            successful_device = new_ports[0].path
+
     # For logs, prefer the device we successfully uploaded to
     devices = choose_upload_log_host(
         default=successful_device,
@@ -944,12 +1223,6 @@ def command_clean_all(args: ArgsProtocol) -> int | None:
     return 0
 
 
-def command_mqtt_fingerprint(args: ArgsProtocol, config: ConfigType) -> int | None:
-    from esphome import mqtt
-
-    return mqtt.get_fingerprint(config)
-
-
 def command_version(args: ArgsProtocol) -> int | None:
     safe_print(f"Version: {const.__version__}")
     return 0
@@ -1036,9 +1309,8 @@ def command_update_all(args: ArgsProtocol) -> int | None:
     files = list_yaml_files(args.configuration)
 
     def build_command(f):
-        if CORE.dashboard:
-            return ["esphome", "--dashboard", "run", f, "--no-logs", "--device", "OTA"]
-        return ["esphome", "run", f, "--no-logs", "--device", "OTA"]
+        dashboard = ["--dashboard"] if CORE.dashboard else []
+        return [*ESPHOME_COMMAND, *dashboard, "run", f, "--no-logs", "--device", "OTA"]
 
     return run_multiple_configs(files, build_command)
 
@@ -1187,7 +1459,7 @@ def command_rename(args: ArgsProtocol, config: ConfigType) -> int | None:
 
     new_path.write_text(new_raw, encoding="utf-8")
 
-    rc = run_external_process("esphome", "config", str(new_path))
+    rc = run_external_process(*ESPHOME_COMMAND, "config", str(new_path))
     if rc != 0:
         print(color(AnsiFore.BOLD_RED, "Rename failed. Reverting changes."))
         new_path.unlink()
@@ -1205,7 +1477,7 @@ def command_rename(args: ArgsProtocol, config: ConfigType) -> int | None:
         cli_args.insert(0, "--dashboard")
 
     try:
-        rc = run_external_process("esphome", *cli_args)
+        rc = run_external_process(*ESPHOME_COMMAND, *cli_args)
     except KeyboardInterrupt:
         rc = 1
     if rc != 0:
@@ -1237,7 +1509,6 @@ POST_CONFIG_ACTIONS = {
     "run": command_run,
     "clean": command_clean,
     "clean-mqtt": command_clean_mqtt,
-    "mqtt-fingerprint": command_mqtt_fingerprint,
     "idedata": command_idedata,
     "rename": command_rename,
     "discover": command_discover,
@@ -1361,7 +1632,7 @@ def parse_args(argv):
     parser_upload.add_argument(
         "--device",
         action="append",
-        help="Manually specify the serial port/address to use, for example /dev/ttyUSB0. Can be specified multiple times for fallback addresses.",
+        help=ARGUMENT_HELP_DEVICE,
     )
     parser_upload.add_argument(
         "--upload_speed",
@@ -1384,7 +1655,7 @@ def parse_args(argv):
     parser_logs.add_argument(
         "--device",
         action="append",
-        help="Manually specify the serial port/address to use, for example /dev/ttyUSB0. Can be specified multiple times for fallback addresses.",
+        help=ARGUMENT_HELP_DEVICE,
     )
     parser_logs.add_argument(
         "--reset",
@@ -1414,7 +1685,7 @@ def parse_args(argv):
     parser_run.add_argument(
         "--device",
         action="append",
-        help="Manually specify the serial port/address to use, for example /dev/ttyUSB0. Can be specified multiple times for fallback addresses.",
+        help=ARGUMENT_HELP_DEVICE,
     )
     parser_run.add_argument(
         "--upload_speed",
@@ -1451,13 +1722,6 @@ def parse_args(argv):
     )
     parser_wizard.add_argument("configuration", help="Your YAML configuration file.")
 
-    parser_fingerprint = subparsers.add_parser(
-        "mqtt-fingerprint", help="Get the SSL fingerprint from a MQTT broker."
-    )
-    parser_fingerprint.add_argument(
-        "configuration", help="Your YAML configuration file(s).", nargs="+"
-    )
-
     subparsers.add_parser("version", help="Print the ESPHome version and exit.")
 
     parser_clean = subparsers.add_parser(
@@ -1610,7 +1874,7 @@ def run_esphome(argv):
         # argv[0] is the program path, skip it since we prefix with "esphome"
         def build_command(f):
             return (
-                ["esphome"]
+                [*ESPHOME_COMMAND]
                 + [arg for arg in argv[1:] if arg not in args.configuration]
                 + [str(f)]
             )

esphome/analyze_memory/__init__.py

@@ -1,6 +1,6 @@
 """Memory usage analyzer for ESPHome compiled binaries."""
 
-from collections import defaultdict
+from collections import Counter, defaultdict
 from dataclasses import dataclass, field
 import logging
 from pathlib import Path
@@ -40,6 +40,15 @@ _READELF_SECTION_PATTERN = re.compile(
     r"\s*\[\s*\d+\]\s+([\.\w]+)\s+\w+\s+[\da-fA-F]+\s+[\da-fA-F]+\s+([\da-fA-F]+)"
 )
 
+# Regex for extracting call targets from objdump disassembly
+# Matches direct call instructions across architectures:
+#   Xtensa: call0/call4/call8/call12/callx0/callx4/callx8/callx12 <addr> <symbol>
+#   ARM:    bl/blx <addr> <symbol>
+# Captures the mangled symbol name inside angle brackets.
+_CALL_TARGET_PATTERN = re.compile(
+    r"\t(?:call(?:0|4|8|12)|callx(?:0|4|8|12)|blx?)\s+[\da-fA-F]+ <([^>]+)>"
+)
+
 # Component category prefixes
 _COMPONENT_PREFIX_ESPHOME = "[esphome]"
 _COMPONENT_PREFIX_EXTERNAL = "[external]"
@@ -192,20 +201,27 @@ class MemoryAnalyzer:
         self._cswtch_symbols: list[tuple[str, int, str, str]] = []
         # Library symbol mapping: symbol_name -> library_name
         self._lib_symbol_map: dict[str, str] = {}
+        # Source file symbol mapping: symbol_name -> component_name
+        # Used for extern "C" and other symbols without C++ namespace
+        self._source_symbol_map: dict[str, str] = {}
         # Library dir to name mapping: "lib641" -> "espsoftwareserial",
         # "espressif__mdns" -> "mdns"
         self._lib_hash_to_name: dict[str, str] = {}
         # Heuristic category to library redirect: "mdns_lib" -> "[lib]mdns"
         self._heuristic_to_lib: dict[str, str] = {}
+        # Function call counts: mangled_name -> call_count
+        self._function_call_counts: Counter[str] = Counter()
 
     def analyze(self) -> dict[str, ComponentMemory]:
         """Analyze the ELF file and return component memory usage."""
         self._parse_sections()
         self._parse_symbols()
         self._scan_libraries()
+        self._scan_source_symbols()
         self._categorize_symbols()
         self._analyze_cswtch_symbols()
         self._analyze_sdk_libraries()
+        self._analyze_function_calls()
         return dict(self.components)
 
     def _parse_sections(self) -> None:
@@ -351,6 +367,11 @@ class MemoryAnalyzer:
         if lib_name := self._lib_symbol_map.get(symbol_name):
             return f"{_COMPONENT_PREFIX_LIB}{lib_name}"
 
+        # Check source file mapping (catches extern "C" functions in ESPHome sources)
+        # Must be before heuristic patterns since source attribution is authoritative
+        if component := self._source_symbol_map.get(symbol_name):
+            return component
+
         # Check against symbol patterns
         for component, patterns in SYMBOL_PATTERNS.items():
             if any(pattern in symbol_name for pattern in patterns):
@@ -384,8 +405,9 @@ class MemoryAnalyzer:
             return
 
         _LOGGER.info("Demangling %d symbols", len(symbols))
-        self._demangle_cache = batch_demangle(symbols, objdump_path=self.objdump_path)
-        _LOGGER.info("Successfully demangled %d symbols", len(self._demangle_cache))
+        demangled = batch_demangle(symbols, objdump_path=self.objdump_path)
+        self._demangle_cache.update(demangled)
+        _LOGGER.info("Successfully demangled %d symbols", len(demangled))
 
     def _demangle_symbol(self, symbol: str) -> str:
         """Get demangled C++ symbol name from cache."""
@@ -640,6 +662,7 @@ class MemoryAnalyzer:
             return None
 
         symbol_map: dict[str, str] = {}
+        source_symbol_map: dict[str, str] = {}
         current_symbol: str | None = None
         section_prefixes = (".text.", ".rodata.", ".data.", ".bss.", ".literal.")
 
@@ -675,9 +698,18 @@ class MemoryAnalyzer:
                     if dir_key in source_path:
                         symbol_map[current_symbol] = lib_name
                         break
+                else:
+                    # Map ESPHome source files to components for extern "C"
+                    # and other symbols without C++ namespace
+                    component = self._source_file_to_component(source_path)
+                    if component.startswith(
+                        (_COMPONENT_PREFIX_ESPHOME, _COMPONENT_PREFIX_EXTERNAL)
+                    ):
+                        source_symbol_map[current_symbol] = component
 
             current_symbol = None
 
+        self._source_symbol_map = source_symbol_map
         return symbol_map or None
 
     def _scan_libraries(self) -> None:
@@ -728,6 +760,112 @@ class MemoryAnalyzer:
             len(libraries),
         )
 
+    def _scan_source_symbols(self) -> None:
+        """Scan ESPHome source object files to map extern "C" symbols to components.
+
+        When no linker map file is available, this uses ``nm`` to scan ``.o`` files
+        under ``src/esphome/`` and build a symbol-to-component mapping. This catches
+        ``extern "C"`` functions and other symbols that lack C++ namespace prefixes.
+
+        Skips scanning if ``_source_symbol_map`` was already populated by
+        ``_parse_map_file()``.
+        """
+        if self._source_symbol_map or not self.nm_path:
+            return
+
+        obj_dir = self._find_object_files_dir()
+        if obj_dir is None:
+            return
+
+        # Find ESPHome source object files
+        esphome_src_dir = obj_dir / "src" / "esphome"
+        if not esphome_src_dir.is_dir():
+            return
+
+        obj_files = sorted(esphome_src_dir.rglob("*.o"))
+        if not obj_files:
+            return
+
+        # Run nm with --print-file-name to get file:symbol mapping
+        result = run_tool(
+            [self.nm_path, "--print-file-name", "-g", "--defined-only"]
+            + [str(f) for f in obj_files],
+        )
+        if result is None or result.returncode != 0:
+            _LOGGER.debug("nm scan of source objects failed")
+            return
+
+        self._source_symbol_map = self._parse_nm_source_output(result.stdout, obj_dir)
+        if self._source_symbol_map:
+            _LOGGER.info(
+                "Built source symbol map from nm: %d symbols",
+                len(self._source_symbol_map),
+            )
+
+    def _parse_nm_source_output(self, output: str, base_dir: Path) -> dict[str, str]:
+        """Parse nm output to map non-namespaced symbols to ESPHome components.
+
+        Extracts global defined symbols from ESPHome source object files that
+        don't use C++ namespacing (e.g. ``extern "C"`` functions).
+
+        Args:
+            output: Raw stdout from ``nm --print-file-name -g --defined-only``
+                or ``nm --print-file-name -S``.
+            base_dir: Build directory for computing relative paths.
+
+        Returns:
+            Dict mapping symbol names to component names.
+        """
+        source_map: dict[str, str] = {}
+        for line in output.splitlines():
+            # Format: /path/to/file.o: addr type name
+            #     or: /path/to/file.o: addr size type name (with -S)
+            colon_idx = line.rfind(".o:")
+            if colon_idx == -1:
+                continue
+
+            file_path = line[: colon_idx + 2]
+            fields = line[colon_idx + 3 :].split()
+            if len(fields) < 3:
+                continue
+
+            # With -S flag, format is: addr size type name
+            # Without -S flag: addr type name
+            # type is a single char; size is hex digits
+            # Detect by checking if fields[1] is a single uppercase letter (type)
+            if len(fields[1]) == 1 and fields[1].isalpha():
+                # addr type name
+                sym_type = fields[1]
+                symbol_name = fields[2]
+            elif len(fields) >= 4:
+                # addr size type name
+                sym_type = fields[2]
+                symbol_name = fields[3]
+            else:
+                continue
+
+            # Only global defined symbols (uppercase type)
+            if not sym_type.isupper() or sym_type == "U":
+                continue
+
+            # Skip symbols already in esphome:: namespace
+            if symbol_name.startswith("_ZN7esphome"):
+                continue
+
+            # Make path relative to base_dir for _source_file_to_component
+            try:
+                rel_path = str(Path(file_path).relative_to(base_dir))
+            except ValueError:
+                continue
+
+            component = self._source_file_to_component(rel_path)
+            if component.startswith(
+                (_COMPONENT_PREFIX_ESPHOME, _COMPONENT_PREFIX_EXTERNAL)
+            ):
+                source_map[symbol_name] = component
+
+        return source_map
+
     def _find_object_files_dir(self) -> Path | None:
         """Find the directory containing object files for this build.
 
@@ -1011,6 +1149,43 @@ class MemoryAnalyzer:
             total_size,
         )
 
+    def _analyze_function_calls(self) -> None:
+        """Count function call sites by parsing disassembly output.
+
+        Parses direct call instructions (call0/call8/bl/blx) from objdump -d
+        to count how many times each function is called. This helps identify
+        inlining candidates — frequently called small functions benefit most
+        from inlining.
+        """
+        result = run_tool(
+            [self.objdump_path, "-d", str(self.elf_path)],
+            timeout=60,
+        )
+        if result is None or result.returncode != 0:
+            _LOGGER.debug("Failed to disassemble ELF for function call analysis")
+            return
+
+        self._function_call_counts = Counter(
+            match.group(1)
+            for line in result.stdout.splitlines()
+            if (match := _CALL_TARGET_PATTERN.search(line))
+        )
+
+        # Demangle any call targets not already in the cache
+        missing = [
+            name
+            for name in self._function_call_counts
+            if name not in self._demangle_cache
+        ]
+        if missing:
+            self._batch_demangle_symbols(missing)
+
+        _LOGGER.debug(
+            "Function call analysis: %d unique targets, %d total calls",
+            len(self._function_call_counts),
+            sum(self._function_call_counts.values()),
+        )
+
     def get_unattributed_ram(self) -> tuple[int, int, int]:
         """Get unattributed RAM sizes (SDK/framework overhead).
 

esphome/analyze_memory/cli.py

@@ -231,6 +231,110 @@ class MemoryAnalyzerCLI(MemoryAnalyzer):
                     lines.append(f"    {size:>6,} B  {sym_name}")
             lines.append("")
 
+    # Number of top called functions to show
+    TOP_CALLS_LIMIT: int = 50
+    # Number of inlining candidates to show
+    INLINE_CANDIDATES_LIMIT: int = 25
+    # Maximum function size in bytes to consider for inlining
+    INLINE_SIZE_THRESHOLD: int = 16
+
+    def _build_symbol_sizes(self) -> dict[str, int]:
+        """Build a size lookup from all component symbols: mangled_name -> size."""
+        return {
+            symbol: size
+            for symbols in self._component_symbols.values()
+            for symbol, _, size, _ in symbols
+        }
+
+    def _format_call_row(
+        self, index: int, mangled: str, count: int, symbol_sizes: dict[str, int]
+    ) -> str:
+        """Format a single row for call frequency tables."""
+        demangled = self._demangle_cache.get(mangled, mangled)
+        if len(demangled) > 80:
+            demangled = f"{demangled[:77]}..."
+        size = symbol_sizes.get(mangled)
+        size_str = f"{size:>5,} B" if size is not None else "      ?"
+        return f"{index:>3}  {count:>5}  {size_str}  {demangled}"
+
+    def _add_call_table_header(self, lines: list[str]) -> None:
+        """Add the header row for call frequency tables."""
+        lines.append(f"{'#':>3}  {'Calls':>5}  {'Size':>7}  Function")
+        lines.append(f"{'---':>3}  {'-----':>5}  {'-------':>7}  {'-' * 60}")
+
+    def _add_function_call_analysis(self, lines: list[str]) -> None:
+        """Add function call frequency analysis section.
+
+        Shows the most frequently called functions by call site count.
+        """
+        self._add_section_header(lines, "Top Called Functions")
+
+        symbol_sizes = self._build_symbol_sizes()
+
+        # Sort by call count descending
+        sorted_calls = sorted(
+            self._function_call_counts.items(), key=lambda x: x[1], reverse=True
+        )
+
+        self._add_call_table_header(lines)
+
+        for i, (mangled, count) in enumerate(sorted_calls[: self.TOP_CALLS_LIMIT]):
+            lines.append(self._format_call_row(i + 1, mangled, count, symbol_sizes))
+
+        total_calls = sum(self._function_call_counts.values())
+        lines.append("")
+        lines.append(
+            f"Total: {len(self._function_call_counts)} unique targets, "
+            f"{total_calls:,} call sites"
+        )
+        lines.append("")
+
+    def _add_inline_candidates(self, lines: list[str]) -> None:
+        """Add inlining candidates section.
+
+        Shows frequently called functions that are small enough to benefit
+        from inlining (< 16 bytes). These are the best candidates for
+        reducing call overhead.
+        """
+        self._add_section_header(
+            lines,
+            f"Inlining Candidates (<{self.INLINE_SIZE_THRESHOLD} B, by call count)",
+        )
+
+        symbol_sizes = self._build_symbol_sizes()
+
+        # Filter to small functions with known size, sort by call count
+        candidates = sorted(
+            (
+                (mangled, count)
+                for mangled, count in self._function_call_counts.items()
+                if mangled in symbol_sizes
+                and symbol_sizes[mangled] < self.INLINE_SIZE_THRESHOLD
+            ),
+            key=lambda x: x[1],
+            reverse=True,
+        )
+
+        if not candidates:
+            lines.append("No candidates found.")
+            lines.append("")
+            return
+
+        self._add_call_table_header(lines)
+
+        for i, (mangled, count) in enumerate(
+            candidates[: self.INLINE_CANDIDATES_LIMIT]
+        ):
+            lines.append(self._format_call_row(i + 1, mangled, count, symbol_sizes))
+
+        lines.append("")
+        lines.append(
+            f"Showing top {min(len(candidates), self.INLINE_CANDIDATES_LIMIT)} "
+            f"of {len(candidates)} functions under "
+            f"{self.INLINE_SIZE_THRESHOLD} B"
+        )
+        lines.append("")
+
     def generate_report(self, detailed: bool = False) -> str:
         """Generate a formatted memory report."""
         components = sorted(
@@ -533,6 +637,11 @@ class MemoryAnalyzerCLI(MemoryAnalyzer):
         if self._cswtch_symbols:
             self._add_cswtch_analysis(lines)
 
+        # Function call frequency analysis
+        if self._function_call_counts:
+            self._add_function_call_analysis(lines)
+            self._add_inline_candidates(lines)
+
         lines.append(
             "Note: This analysis covers symbols in the ELF file. Some runtime allocations may not be included."
         )

esphome/analyze_memory/const.py

@@ -256,7 +256,7 @@ SYMBOL_PATTERNS = {
     "ipv6_stack": ["nd6_", "ip6_", "mld6_", "icmp6_", "icmp6_input"],
     # Order matters! More specific categories must come before general ones.
     # mdns must come before bluetooth to avoid "_mdns_disable_pcb" matching "ble_" pattern
-    "mdns_lib": ["mdns"],
+    "mdns_lib": ["mdns", "packet$"],
     # memory_mgmt must come before wifi_stack to catch mmu_hal_* symbols
     "memory_mgmt": [
         "mem_",
@@ -408,7 +408,6 @@ SYMBOL_PATTERNS = {
     ],
     "arduino_core": [
         "pinMode",
-        "resetPins",
         "millis",
         "micros",
         "delay(",  # More specific - Arduino delay function with parenthesis
@@ -794,7 +793,6 @@ SYMBOL_PATTERNS = {
         "s_dp",
         "s_ni",
         "s_reg_dump",
-        "packet$",
         "d_mult_table",
         "K",
         "fcstab",

esphome/automation.py

@@ -1,3 +1,5 @@
+import logging
+
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome.const import (
@@ -57,8 +59,42 @@ def maybe_conf(conf, *validators):
     return validate
 
 
-def register_action(name: str, action_type: MockObjClass, schema: cv.Schema):
-    return ACTION_REGISTRY.register(name, action_type, schema)
+_LOGGER = logging.getLogger(__name__)
+
+
+def register_action(
+    name: str,
+    action_type: MockObjClass,
+    schema: cv.Schema,
+    *,
+    synchronous: bool | None = None,
+):
+    """Register an action type.
+
+    All callers must pass ``synchronous`` explicitly.
+
+    ``synchronous=True`` — the action never defers ``play_next_()`` to a
+    later point (callback, timer, or ``loop()``).  Trigger arguments are
+    only used during the initial call, so string args can use non-owning
+    StringRef for zero-copy access.
+
+    ``synchronous=False`` — the action defers ``play_next_()`` via a
+    callback, timer, or ``Component::loop()``.  Trigger arguments must
+    outlive the initial call, so string args use owning std::string to
+    prevent dangling references.
+    """
+    if synchronous is None:
+        _LOGGER.warning(
+            "register_action('%s', ...) is missing the synchronous= parameter. "
+            "Defaulting to synchronous=False (safe but prevents StringRef "
+            "optimization). Check the C++ class: use synchronous=False if "
+            "play_next_() is deferred to a callback, timer, or loop(); "
+            "use synchronous=True if play_next_() always runs before the "
+            "initial play/play_complex call returns",
+            name,
+        )
+        synchronous = False
+    return ACTION_REGISTRY.register(name, action_type, schema, synchronous=synchronous)
 
 
 def register_condition(name: str, condition_type: MockObjClass, schema: cv.Schema):
@@ -335,7 +371,10 @@ async def component_is_idle_condition_to_code(
 
 
 @register_action(
-    "delay", DelayAction, cv.templatable(cv.positive_time_period_milliseconds)
+    "delay",
+    DelayAction,
+    cv.templatable(cv.positive_time_period_milliseconds),
+    synchronous=False,
 )
 async def delay_action_to_code(
     config: ConfigType,
@@ -366,6 +405,7 @@ async def delay_action_to_code(
         cv.has_at_least_one_key(CONF_THEN, CONF_ELSE),
         cv.has_at_least_one_key(CONF_CONDITION, CONF_ANY, CONF_ALL),
     ),
+    synchronous=True,
 )
 async def if_action_to_code(
     config: ConfigType,
@@ -394,6 +434,7 @@ async def if_action_to_code(
             cv.Required(CONF_THEN): validate_action_list,
         }
     ),
+    synchronous=True,
 )
 async def while_action_to_code(
     config: ConfigType,
@@ -417,6 +458,7 @@ async def while_action_to_code(
             cv.Required(CONF_THEN): validate_action_list,
         }
     ),
+    synchronous=True,
 )
 async def repeat_action_to_code(
     config: ConfigType,
@@ -445,7 +487,7 @@ _validate_wait_until = cv.maybe_simple_value(
 )
 
 
-@register_action("wait_until", WaitUntilAction, _validate_wait_until)
+@register_action("wait_until", WaitUntilAction, _validate_wait_until, synchronous=False)
 async def wait_until_action_to_code(
     config: ConfigType,
     action_id: ID,
@@ -461,7 +503,12 @@ async def wait_until_action_to_code(
     return var
 
 
-@register_action("lambda", LambdaAction, cv.lambda_)
+# Lambda executes user C++ inline and returns — synchronous by execution model.
+# User code could theoretically store the StringRef for deferred use, but StringRef
+# is a view type and storing views beyond their scope is always unsafe regardless
+# of this optimization.  Marking non-synchronous would disable StringRef for nearly
+# all user services since most use lambda.
+@register_action("lambda", LambdaAction, cv.lambda_, synchronous=True)
 async def lambda_action_to_code(
     config: ConfigType,
     action_id: ID,
@@ -480,6 +527,7 @@ async def lambda_action_to_code(
             cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
         }
     ),
+    synchronous=True,
 )
 async def component_update_action_to_code(
     config: ConfigType,
@@ -499,6 +547,7 @@ async def component_update_action_to_code(
             cv.Required(CONF_ID): cv.use_id(cg.PollingComponent),
         }
     ),
+    synchronous=True,
 )
 async def component_suspend_action_to_code(
     config: ConfigType,
@@ -521,6 +570,7 @@ async def component_suspend_action_to_code(
             ),
         }
     ),
+    synchronous=True,
 )
 async def component_resume_action_to_code(
     config: ConfigType,
@@ -578,6 +628,27 @@ async def build_condition_list(
     return conditions
 
 
+def has_non_synchronous_actions(actions: ConfigType) -> bool:
+    """Check if a validated action list contains any non-synchronous actions.
+
+    Non-synchronous actions (delay, wait_until, script.wait, etc.) store
+    trigger args for later execution, making non-owning types like StringRef
+    unsafe.
+    """
+    if isinstance(actions, list):
+        return any(has_non_synchronous_actions(item) for item in actions)
+    if isinstance(actions, dict):
+        for key in actions:
+            if key in ACTION_REGISTRY and not ACTION_REGISTRY[key].synchronous:
+                return True
+        return any(
+            has_non_synchronous_actions(v)
+            for v in actions.values()
+            if isinstance(v, (list, dict))
+        )
+    return False
+
+
 async def build_automation(
     trigger: MockObj, args: TemplateArgsType, config: ConfigType
 ) -> MockObj:

esphome/build_gen/espidf.py

@@ -72,7 +72,7 @@ def get_component_cmakelists(minimal: bool = False) -> str:
 
     # Extract compile definitions from build flags (-DXXX -> XXX)
     compile_defs = [flag[2:] for flag in CORE.build_flags if flag.startswith("-D")]
-    compile_defs_str = "\n    ".join(compile_defs) if compile_defs else ""
+    compile_defs_str = "\n    ".join(sorted(compile_defs)) if compile_defs else ""
 
     # Extract compile options (-W flags, excluding linker flags)
     compile_opts = [
@@ -80,11 +80,11 @@ def get_component_cmakelists(minimal: bool = False) -> str:
         for flag in CORE.build_flags
         if flag.startswith("-W") and not flag.startswith("-Wl,")
     ]
-    compile_opts_str = "\n    ".join(compile_opts) if compile_opts else ""
+    compile_opts_str = "\n    ".join(sorted(compile_opts)) if compile_opts else ""
 
     # Extract linker options (-Wl, flags)
     link_opts = [flag for flag in CORE.build_flags if flag.startswith("-Wl,")]
-    link_opts_str = "\n    ".join(link_opts) if link_opts else ""
+    link_opts_str = "\n    ".join(sorted(link_opts)) if link_opts else ""
 
     return f"""\
 # Auto-generated by ESPHome

esphome/codegen.py

@@ -11,6 +11,7 @@
 from esphome.cpp_generator import (  # noqa: F401
     ArrayInitializer,
     Expression,
+    FlashStringLiteral,
     LineComment,
     LogStringLiteral,
     MockObj,

esphome/components/absolute_humidity/absolute_humidity.cpp

@@ -1,22 +1,29 @@
 #include "esphome/core/log.h"
 #include "absolute_humidity.h"
 
-namespace esphome {
-namespace absolute_humidity {
+namespace esphome::absolute_humidity {
 
-static const char *const TAG = "absolute_humidity.sensor";
+static const char *const TAG{"absolute_humidity.sensor"};
 
 void AbsoluteHumidityComponent::setup() {
+  this->temperature_sensor_->add_on_state_callback([this](float state) {
+    this->temperature_ = state;
+    this->enable_loop();
+  });
   ESP_LOGD(TAG, "  Added callback for temperature '%s'", this->temperature_sensor_->get_name().c_str());
-  this->temperature_sensor_->add_on_state_callback([this](float state) { this->temperature_callback_(state); });
+  // Get initial value
   if (this->temperature_sensor_->has_state()) {
-    this->temperature_callback_(this->temperature_sensor_->get_state());
+    this->temperature_ = this->temperature_sensor_->get_state();
   }
 
+  this->humidity_sensor_->add_on_state_callback([this](float state) {
+    this->humidity_ = state;
+    this->enable_loop();
+  });
   ESP_LOGD(TAG, "  Added callback for relative humidity '%s'", this->humidity_sensor_->get_name().c_str());
-  this->humidity_sensor_->add_on_state_callback([this](float state) { this->humidity_callback_(state); });
+  // Get initial value
   if (this->humidity_sensor_->has_state()) {
-    this->humidity_callback_(this->humidity_sensor_->get_state());
+    this->humidity_ = this->humidity_sensor_->get_state();
   }
 }
 
@@ -46,14 +53,12 @@ void AbsoluteHumidityComponent::dump_config() {
 }
 
 void AbsoluteHumidityComponent::loop() {
-  if (!this->next_update_) {
-    return;
-  }
-  this->next_update_ = false;
+  // Only run once
+  this->disable_loop();
 
   // Ensure we have source data
-  const bool no_temperature = std::isnan(this->temperature_);
-  const bool no_humidity = std::isnan(this->humidity_);
+  const bool no_temperature{std::isnan(this->temperature_)};
+  const bool no_humidity{std::isnan(this->humidity_)};
   if (no_temperature || no_humidity) {
     if (no_temperature) {
       ESP_LOGW(TAG, "No valid state from temperature sensor!");
@@ -67,9 +72,9 @@ void AbsoluteHumidityComponent::loop() {
   }
 
   // Convert to desired units
-  const float temperature_c = this->temperature_;
-  const float temperature_k = temperature_c + 273.15;
-  const float hr = this->humidity_ / 100;
+  const float temperature_c{this->temperature_};
+  const float temperature_k{temperature_c + 273.15f};
+  const float hr{this->humidity_ / 100.0f};
 
   // Calculate saturation vapor pressure
   float es;
@@ -90,12 +95,9 @@ void AbsoluteHumidityComponent::loop() {
   }
 
   // Calculate absolute humidity
-  const float absolute_humidity = vapor_density(es, hr, temperature_k);
+  const float absolute_humidity{vapor_density(es, hr, temperature_k)};
 
-  ESP_LOGD(TAG,
-           "Saturation vapor pressure %f kPa\n"
-           "Publishing absolute humidity %f g/m³",
-           es, absolute_humidity);
+  ESP_LOGD(TAG, "Saturation vapor pressure %f kPa, absolute humidity %f g/m³", es, absolute_humidity);
 
   // Publish absolute humidity
   this->status_clear_warning();
@@ -106,16 +108,16 @@ void AbsoluteHumidityComponent::loop() {
 // More accurate than Tetens in normal meteorologic conditions
 float AbsoluteHumidityComponent::es_buck(float temperature_c) {
   float a, b, c, d;
-  if (temperature_c >= 0) {
-    a = 0.61121;
-    b = 18.678;
-    c = 234.5;
-    d = 257.14;
+  if (temperature_c >= 0.0f) {
+    a = 0.61121f;
+    b = 18.678f;
+    c = 234.5f;
+    d = 257.14f;
   } else {
-    a = 0.61115;
-    b = 18.678;
-    c = 233.7;
-    d = 279.82;
+    a = 0.61115f;
+    b = 18.678f;
+    c = 233.7f;
+    d = 279.82f;
   }
   return a * expf((b - (temperature_c / c)) * (temperature_c / (d + temperature_c)));
 }
@@ -123,14 +125,14 @@ float AbsoluteHumidityComponent::es_buck(float temperature_c) {
 // Tetens equation (https://en.wikipedia.org/wiki/Tetens_equation)
 float AbsoluteHumidityComponent::es_tetens(float temperature_c) {
   float a, b;
-  if (temperature_c >= 0) {
-    a = 17.27;
-    b = 237.3;
+  if (temperature_c >= 0.0f) {
+    a = 17.27f;
+    b = 237.3f;
   } else {
-    a = 21.875;
-    b = 265.5;
+    a = 21.875f;
+    b = 265.5f;
   }
-  return 0.61078 * expf((a * temperature_c) / (temperature_c + b));
+  return 0.61078f * expf((a * temperature_c) / (temperature_c + b));
 }
 
 // Wobus equation
@@ -149,18 +151,18 @@ float AbsoluteHumidityComponent::es_wobus(float t) {
   //
   //     Baker, Schlatter  17-MAY-1982     Original version.
 
-  const float c0 = +0.99999683e00;
-  const float c1 = -0.90826951e-02;
-  const float c2 = +0.78736169e-04;
-  const float c3 = -0.61117958e-06;
-  const float c4 = +0.43884187e-08;
-  const float c5 = -0.29883885e-10;
-  const float c6 = +0.21874425e-12;
-  const float c7 = -0.17892321e-14;
-  const float c8 = +0.11112018e-16;
-  const float c9 = -0.30994571e-19;
-  const float p = c0 + t * (c1 + t * (c2 + t * (c3 + t * (c4 + t * (c5 + t * (c6 + t * (c7 + t * (c8 + t * (c9)))))))));
-  return 0.61078 / pow(p, 8);
+  constexpr float c0{+0.99999683e+00f};
+  constexpr float c1{-0.90826951e-02f};
+  constexpr float c2{+0.78736169e-04f};
+  constexpr float c3{-0.61117958e-06f};
+  constexpr float c4{+0.43884187e-08f};
+  constexpr float c5{-0.29883885e-10f};
+  constexpr float c6{+0.21874425e-12f};
+  constexpr float c7{-0.17892321e-14f};
+  constexpr float c8{+0.11112018e-16f};
+  constexpr float c9{-0.30994571e-19f};
+  const float p{c0 + t * (c1 + t * (c2 + t * (c3 + t * (c4 + t * (c5 + t * (c6 + t * (c7 + t * (c8 + t * (c9)))))))))};
+  return 0.61078f / powf(p, 8.0f);
 }
 
 // From https://www.environmentalbiophysics.org/chalk-talk-how-to-calculate-absolute-humidity/
@@ -171,11 +173,10 @@ float AbsoluteHumidityComponent::vapor_density(float es, float hr, float ta) {
   // hr = relative humidity [0-1]
   // ta = absolute temperature (K)
 
-  const float ea = hr * es * 1000;   // vapor pressure of the air (Pa)
-  const float mw = 18.01528;         // molar mass of water (g⋅mol⁻¹)
-  const float r = 8.31446261815324;  // molar gas constant (J⋅K⁻¹)
+  const float ea{hr * es * 1000.0f};  // vapor pressure of the air (Pa)
+  const float mw{18.01528f};          // molar mass of water (g⋅mol⁻¹)
+  const float r{8.31446261815324f};   // molar gas constant (J⋅K⁻¹)
   return (ea * mw) / (r * ta);
 }
 
-}  // namespace absolute_humidity
-}  // namespace esphome
+}  // namespace esphome::absolute_humidity

esphome/components/absolute_humidity/absolute_humidity.h

@@ -3,8 +3,7 @@
 #include "esphome/core/component.h"
 #include "esphome/components/sensor/sensor.h"
 
-namespace esphome {
-namespace absolute_humidity {
+namespace esphome::absolute_humidity {
 
 /// Enum listing all implemented saturation vapor pressure equations.
 enum SaturationVaporPressureEquation {
@@ -16,8 +15,6 @@ enum SaturationVaporPressureEquation {
 /// This class implements calculation of absolute humidity from temperature and relative humidity.
 class AbsoluteHumidityComponent : public sensor::Sensor, public Component {
  public:
-  AbsoluteHumidityComponent() = default;
-
   void set_temperature_sensor(sensor::Sensor *temperature_sensor) { this->temperature_sensor_ = temperature_sensor; }
   void set_humidity_sensor(sensor::Sensor *humidity_sensor) { this->humidity_sensor_ = humidity_sensor; }
   void set_equation(SaturationVaporPressureEquation equation) { this->equation_ = equation; }
@@ -27,15 +24,6 @@ class AbsoluteHumidityComponent : public sensor::Sensor, public Component {
   void loop() override;
 
  protected:
-  void temperature_callback_(float state) {
-    this->next_update_ = true;
-    this->temperature_ = state;
-  }
-  void humidity_callback_(float state) {
-    this->next_update_ = true;
-    this->humidity_ = state;
-  }
-
   /** Buck equation for saturation vapor pressure in kPa.
    *
    * @param temperature_c Air temperature in °C.
@@ -57,19 +45,15 @@ class AbsoluteHumidityComponent : public sensor::Sensor, public Component {
    * @param es Saturation vapor pressure in kPa.
    * @param hr Relative humidity 0 to 1.
    * @param ta Absolute temperature in K.
-   * @param heater_duration The duration in ms that the heater should turn on for when measuring.
    */
   static float vapor_density(float es, float hr, float ta);
 
   sensor::Sensor *temperature_sensor_{nullptr};
   sensor::Sensor *humidity_sensor_{nullptr};
 
-  bool next_update_{false};
-
   float temperature_{NAN};
   float humidity_{NAN};
   SaturationVaporPressureEquation equation_;
 };
 
-}  // namespace absolute_humidity
-}  // namespace esphome
+}  // namespace esphome::absolute_humidity

esphome/components/ac_dimmer/ac_dimmer.cpp

@@ -199,12 +199,19 @@ void AcDimmer::setup() {
   setTimer1Callback(&timer_interrupt);
 #endif
 #ifdef USE_ESP32
-  dimmer_timer = timer_begin(TIMER_FREQUENCY_HZ);
-  timer_attach_interrupt(dimmer_timer, &AcDimmerDataStore::s_timer_intr);
-  // For ESP32, we can't use dynamic interval calculation because the timerX functions
-  // are not callable from ISR (placed in flash storage).
-  // Here we just use an interrupt firing every 50 µs.
-  timer_alarm(dimmer_timer, TIMER_INTERVAL_US, true, 0);
+  if (dimmer_timer == nullptr) {
+    dimmer_timer = timer_begin(TIMER_FREQUENCY_HZ);
+    if (dimmer_timer == nullptr) {
+      ESP_LOGE(TAG, "Failed to create GPTimer for AC dimmer");
+      this->mark_failed();
+      return;
+    }
+    timer_attach_interrupt(dimmer_timer, &AcDimmerDataStore::s_timer_intr);
+    // For ESP32, we can't use dynamic interval calculation because the timerX functions
+    // are not callable from ISR (placed in flash storage).
+    // Here we just use an interrupt firing every 50 µs.
+    timer_alarm(dimmer_timer, TIMER_INTERVAL_US, true, 0);
+  }
 #endif
 }
 

esphome/components/adc/adc_sensor.h

@@ -22,7 +22,8 @@ namespace adc {
 
 #ifdef USE_ESP32
 // clang-format off
-#if (ESP_IDF_VERSION_MAJOR == 5 && \
+#if ESP_IDF_VERSION_MAJOR >= 6 || \
+    (ESP_IDF_VERSION_MAJOR == 5 && \
      ((ESP_IDF_VERSION_MINOR == 0 && ESP_IDF_VERSION_PATCH >= 5) || \
       (ESP_IDF_VERSION_MINOR == 1 && ESP_IDF_VERSION_PATCH >= 3) || \
       (ESP_IDF_VERSION_MINOR >= 2)) \

esphome/components/adc/adc_sensor_rp2040.cpp

@@ -8,6 +8,13 @@
 #endif  // CYW43_USES_VSYS_PIN
 #include <hardware/adc.h>
 
+// PICO_VSYS_PIN is defined in pico-sdk board headers (e.g. boards/pico2.h),
+// but the Arduino framework's config_autogen.h includes a generic board header
+// that doesn't define it. Provide the standard value (pin 29) as a fallback.
+#ifndef PICO_VSYS_PIN
+#define PICO_VSYS_PIN 29  // NOLINT(cppcoreguidelines-macro-usage)
+#endif
+
 namespace esphome {
 namespace adc {
 

esphome/components/addressable_light/addressable_light_display.cpp

@@ -58,7 +58,10 @@ void HOT AddressableLightDisplay::draw_absolute_pixel_internal(int x, int y, Col
 
   if (this->pixel_mapper_f_.has_value()) {
     // Params are passed by reference, so they may be modified in call.
-    this->addressable_light_buffer_[(*this->pixel_mapper_f_)(x, y)] = color;
+    int index = (*this->pixel_mapper_f_)(x, y);
+    if (index < 0 || static_cast<size_t>(index) >= this->addressable_light_buffer_.size())
+      return;
+    this->addressable_light_buffer_[index] = color;
   } else {
     this->addressable_light_buffer_[y * this->get_width_internal() + x] = color;
   }

esphome/components/addressable_light/addressable_light_display.h

@@ -33,7 +33,7 @@ class AddressableLightDisplay : public display::DisplayBuffer {
         // - Save the current effect index.
         this->last_effect_index_ = light_state_->get_current_effect_index();
         // - Disable any current effect.
-        light_state_->make_call().set_effect(0).perform();
+        light_state_->make_call().set_effect(uint32_t{0}).perform();
       }
     }
     enabled_ = enabled;

esphome/components/ade7880/ade7880.cpp

@@ -121,7 +121,7 @@ void ADE7880::update() {
     this->update_sensor_from_s32_register16_(chan->forward_active_energy, AFWATTHR, [&chan](float val) {
       return chan->forward_active_energy_total += val / 14400.0f;
     });
-    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, AFWATTHR, [&chan](float val) {
+    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, ARWATTHR, [&chan](float val) {
       return chan->reverse_active_energy_total += val / 14400.0f;
     });
   }
@@ -137,7 +137,7 @@ void ADE7880::update() {
     this->update_sensor_from_s32_register16_(chan->forward_active_energy, BFWATTHR, [&chan](float val) {
       return chan->forward_active_energy_total += val / 14400.0f;
     });
-    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, BFWATTHR, [&chan](float val) {
+    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, BRWATTHR, [&chan](float val) {
       return chan->reverse_active_energy_total += val / 14400.0f;
     });
   }
@@ -153,7 +153,7 @@ void ADE7880::update() {
     this->update_sensor_from_s32_register16_(chan->forward_active_energy, CFWATTHR, [&chan](float val) {
       return chan->forward_active_energy_total += val / 14400.0f;
     });
-    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, CFWATTHR, [&chan](float val) {
+    this->update_sensor_from_s32_register16_(chan->reverse_active_energy, CRWATTHR, [&chan](float val) {
       return chan->reverse_active_energy_total += val / 14400.0f;
     });
   }

esphome/components/ade7880/ade7880_registers.h

@@ -85,6 +85,9 @@ constexpr uint16_t CWATTHR = 0xE402;
 constexpr uint16_t AFWATTHR = 0xE403;
 constexpr uint16_t BFWATTHR = 0xE404;
 constexpr uint16_t CFWATTHR = 0xE405;
+constexpr uint16_t ARWATTHR = 0xE406;
+constexpr uint16_t BRWATTHR = 0xE407;
+constexpr uint16_t CRWATTHR = 0xE408;
 constexpr uint16_t AFVARHR = 0xE409;
 constexpr uint16_t BFVARHR = 0xE40A;
 constexpr uint16_t CFVARHR = 0xE40B;

esphome/components/ads1115/ads1115.cpp

@@ -173,19 +173,8 @@ float ADS1115Component::request_measurement(ADS1115Multiplexer multiplexer, ADS1
   }
 
   if (resolution == ADS1015_12_BITS) {
-    bool negative = (raw_conversion >> 15) == 1;
-
-    // shift raw_conversion as it's only 12-bits, left justified
-    raw_conversion = raw_conversion >> (16 - ADS1015_12_BITS);
-
-    // check if number was negative in order to keep the sign
-    if (negative) {
-      // the number was negative
-      // 1) set the negative bit back
-      raw_conversion |= 0x8000;
-      // 2) reset the former (shifted) negative bit
-      raw_conversion &= 0xF7FF;
-    }
+    // ADS1015 returns 12-bit value left-justified in 16 bits; shift right and sign-extend
+    raw_conversion = static_cast<uint16_t>(static_cast<int16_t>(raw_conversion) >> (16 - ADS1015_12_BITS));
   }
 
   auto signed_conversion = static_cast<int16_t>(raw_conversion);

esphome/components/ags10/sensor.py

@@ -92,6 +92,7 @@ AGS10_NEW_I2C_ADDRESS_SCHEMA = cv.maybe_simple_value(
     "ags10.new_i2c_address",
     AGS10NewI2cAddressAction,
     AGS10_NEW_I2C_ADDRESS_SCHEMA,
+    synchronous=True,
 )
 async def ags10newi2caddress_to_code(config, action_id, template_arg, args):
     var = cg.new_Pvariable(action_id, template_arg)
@@ -121,6 +122,7 @@ AGS10_SET_ZERO_POINT_SCHEMA = cv.Schema(
     "ags10.set_zero_point",
     AGS10SetZeroPointAction,
     AGS10_SET_ZERO_POINT_SCHEMA,
+    synchronous=True,
 )
 async def ags10setzeropoint_to_code(config, action_id, template_arg, args):
     var = cg.new_Pvariable(action_id, template_arg)

esphome/components/aic3204/audio_dac.py

@@ -34,7 +34,10 @@ SET_AUTO_MUTE_ACTION_SCHEMA = cv.maybe_simple_value(
 
 
 @automation.register_action(
-    "aic3204.set_auto_mute_mode", SetAutoMuteAction, SET_AUTO_MUTE_ACTION_SCHEMA
+    "aic3204.set_auto_mute_mode",
+    SetAutoMuteAction,
+    SET_AUTO_MUTE_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def aic3204_set_volume_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])

esphome/components/alarm_control_panel/__init__.py

@@ -186,8 +186,8 @@ ALARM_CONTROL_PANEL_CONDITION_SCHEMA = maybe_simple_id(
 )
 
 
+@setup_entity("alarm_control_panel")
 async def setup_alarm_control_panel_core_(var, config):
-    await setup_entity(var, config, "alarm_control_panel")
     for conf in config.get(CONF_ON_STATE, []):
         trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID], var)
         await automation.build_automation(trigger, [], conf)
@@ -243,7 +243,10 @@ async def new_alarm_control_panel(config, *args):
 
 
 @automation.register_action(
-    "alarm_control_panel.arm_away", ArmAwayAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.arm_away",
+    ArmAwayAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_arm_away_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -255,7 +258,10 @@ async def alarm_action_arm_away_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.arm_home", ArmHomeAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.arm_home",
+    ArmHomeAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_arm_home_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -267,7 +273,10 @@ async def alarm_action_arm_home_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.arm_night", ArmNightAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.arm_night",
+    ArmNightAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_arm_night_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -279,7 +288,10 @@ async def alarm_action_arm_night_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.disarm", DisarmAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.disarm",
+    DisarmAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_disarm_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -291,7 +303,10 @@ async def alarm_action_disarm_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.pending", PendingAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.pending",
+    PendingAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_pending_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -299,7 +314,10 @@ async def alarm_action_pending_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.triggered", TriggeredAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.triggered",
+    TriggeredAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_trigger_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -307,7 +325,10 @@ async def alarm_action_trigger_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.chime", ChimeAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.chime",
+    ChimeAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def alarm_action_chime_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
@@ -315,7 +336,10 @@ async def alarm_action_chime_to_code(config, action_id, template_arg, args):
 
 
 @automation.register_action(
-    "alarm_control_panel.ready", ReadyAction, ALARM_CONTROL_PANEL_ACTION_SCHEMA
+    "alarm_control_panel.ready",
+    ReadyAction,
+    ALARM_CONTROL_PANEL_ACTION_SCHEMA,
+    synchronous=True,
 )
 @automation.register_condition(
     "alarm_control_panel.ready",

esphome/components/alarm_control_panel/alarm_control_panel.cpp

@@ -51,22 +51,6 @@ void AlarmControlPanel::publish_state(AlarmControlPanelState state) {
   }
 }
 
-void AlarmControlPanel::add_on_state_callback(std::function<void()> &&callback) {
-  this->state_callback_.add(std::move(callback));
-}
-
-void AlarmControlPanel::add_on_cleared_callback(std::function<void()> &&callback) {
-  this->cleared_callback_.add(std::move(callback));
-}
-
-void AlarmControlPanel::add_on_chime_callback(std::function<void()> &&callback) {
-  this->chime_callback_.add(std::move(callback));
-}
-
-void AlarmControlPanel::add_on_ready_callback(std::function<void()> &&callback) {
-  this->ready_callback_.add(std::move(callback));
-}
-
 void AlarmControlPanel::arm_with_code_(AlarmControlPanelCall &(AlarmControlPanelCall::*arm_method)(),
                                        const char *code) {
   auto call = this->make_call();

esphome/components/alarm_control_panel/alarm_control_panel.h

@@ -37,25 +37,24 @@ class AlarmControlPanel : public EntityBase {
    *
    * @param callback The callback function
    */
-  void add_on_state_callback(std::function<void()> &&callback);
+  template<typename F> void add_on_state_callback(F &&callback) {
+    this->state_callback_.add(std::forward<F>(callback));
+  }
 
-  /** Add a callback for when the state of the alarm_control_panel clears from triggered
-   *
-   * @param callback The callback function
-   */
-  void add_on_cleared_callback(std::function<void()> &&callback);
+  /** Add a callback for when the state of the alarm_control_panel clears from triggered. */
+  template<typename F> void add_on_cleared_callback(F &&callback) {
+    this->cleared_callback_.add(std::forward<F>(callback));
+  }
 
-  /** Add a callback for when a chime zone goes from closed to open
-   *
-   * @param callback The callback function
-   */
-  void add_on_chime_callback(std::function<void()> &&callback);
+  /** Add a callback for when a chime zone goes from closed to open. */
+  template<typename F> void add_on_chime_callback(F &&callback) {
+    this->chime_callback_.add(std::forward<F>(callback));
+  }
 
-  /** Add a callback for when a ready state changes
-   *
-   * @param callback The callback function
-   */
-  void add_on_ready_callback(std::function<void()> &&callback);
+  /** Add a callback for when a ready state changes. */
+  template<typename F> void add_on_ready_callback(F &&callback) {
+    this->ready_callback_.add(std::forward<F>(callback));
+  }
 
   /** A numeric representation of the supported features as per HomeAssistant
    *

esphome/components/alarm_control_panel/alarm_control_panel_call.cpp

@@ -12,7 +12,14 @@ AlarmControlPanelCall::AlarmControlPanelCall(AlarmControlPanel *parent) : parent
 
 AlarmControlPanelCall &AlarmControlPanelCall::set_code(const char *code) {
   if (code != nullptr) {
-    this->code_ = std::string(code);
+    return this->set_code(code, strlen(code));
+  }
+  return *this;
+}
+
+AlarmControlPanelCall &AlarmControlPanelCall::set_code(const char *code, size_t len) {
+  if (code != nullptr) {
+    this->code_ = std::string(code, len);
   }
   return *this;
 }

esphome/components/alarm_control_panel/alarm_control_panel_call.h

@@ -15,7 +15,8 @@ class AlarmControlPanelCall {
   AlarmControlPanelCall(AlarmControlPanel *parent);
 
   AlarmControlPanelCall &set_code(const char *code);
-  AlarmControlPanelCall &set_code(const std::string &code) { return this->set_code(code.c_str()); }
+  AlarmControlPanelCall &set_code(const char *code, size_t len);
+  AlarmControlPanelCall &set_code(const std::string &code) { return this->set_code(code.c_str(), code.size()); }
   AlarmControlPanelCall &arm_away();
   AlarmControlPanelCall &arm_home();
   AlarmControlPanelCall &arm_night();

esphome/components/alpha3/alpha3.cpp

@@ -125,7 +125,7 @@ void Alpha3::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc
         this->current_sensor_->publish_state(NAN);
       if (this->speed_sensor_ != nullptr)
         this->speed_sensor_->publish_state(NAN);
-      if (this->speed_sensor_ != nullptr)
+      if (this->voltage_sensor_ != nullptr)
         this->voltage_sensor_->publish_state(NAN);
       break;
     }

esphome/components/am43/cover/am43_cover.cpp

@@ -63,8 +63,9 @@ void Am43Component::control(const CoverCall &call) {
       ESP_LOGW(TAG, "[%s] Error writing stop command to device, error = %d", this->get_name().c_str(), status);
     }
   }
-  if (call.get_position().has_value()) {
-    auto pos = *call.get_position();
+  auto opt_pos = call.get_position();
+  if (opt_pos.has_value()) {
+    auto pos = *opt_pos;
 
     if (this->invert_position_)
       pos = 1 - pos;

esphome/components/am43/sensor/am43_sensor.h

@@ -35,7 +35,7 @@ class Am43 : public esphome::ble_client::BLEClientNode, public PollingComponent
   uint8_t current_sensor_;
   // The AM43 often gets into a state where it spams loads of battery update
   // notifications. Here we will limit to no more than every 10s.
-  uint8_t last_battery_update_;
+  uint32_t last_battery_update_;
 };
 
 }  // namespace am43

esphome/components/analog_threshold/analog_threshold_binary_sensor.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include "esphome/core/automation.h"
 #include "esphome/core/component.h"
 #include "esphome/components/binary_sensor/binary_sensor.h"
 #include "esphome/components/sensor/sensor.h"

esphome/components/animation/__init__.py

@@ -69,9 +69,15 @@ SET_FRAME_SCHEMA = cv.Schema(
 )
 
 
-@automation.register_action("animation.next_frame", NextFrameAction, NEXT_FRAME_SCHEMA)
-@automation.register_action("animation.prev_frame", PrevFrameAction, PREV_FRAME_SCHEMA)
-@automation.register_action("animation.set_frame", SetFrameAction, SET_FRAME_SCHEMA)
+@automation.register_action(
+    "animation.next_frame", NextFrameAction, NEXT_FRAME_SCHEMA, synchronous=True
+)
+@automation.register_action(
+    "animation.prev_frame", PrevFrameAction, PREV_FRAME_SCHEMA, synchronous=True
+)
+@automation.register_action(
+    "animation.set_frame", SetFrameAction, SET_FRAME_SCHEMA, synchronous=True
+)
 async def animation_action_to_code(config, action_id, template_arg, args):
     paren = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, paren)

esphome/components/anova/anova.cpp

@@ -24,8 +24,9 @@ void Anova::loop() {
 }
 
 void Anova::control(const ClimateCall &call) {
-  if (call.get_mode().has_value()) {
-    ClimateMode mode = *call.get_mode();
+  auto mode_val = call.get_mode();
+  if (mode_val.has_value()) {
+    ClimateMode mode = *mode_val;
     AnovaPacket *pkt;
     switch (mode) {
       case climate::CLIMATE_MODE_OFF:
@@ -45,8 +46,9 @@ void Anova::control(const ClimateCall &call) {
       ESP_LOGW(TAG, "[%s] esp_ble_gattc_write_char failed, status=%d", this->parent_->address_str(), status);
     }
   }
-  if (call.get_target_temperature().has_value()) {
-    auto *pkt = this->codec_->get_set_target_temp_request(*call.get_target_temperature());
+  auto target_temp = call.get_target_temperature();
+  if (target_temp.has_value()) {
+    auto *pkt = this->codec_->get_set_target_temp_request(*target_temp);
     auto status =
         esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
                                  pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);
@@ -67,10 +69,8 @@ void Anova::gattc_event_handler(esp_gattc_cb_event_t event, esp_gatt_if_t gattc_
     case ESP_GATTC_SEARCH_CMPL_EVT: {
       auto *chr = this->parent_->get_characteristic(ANOVA_SERVICE_UUID, ANOVA_CHARACTERISTIC_UUID);
       if (chr == nullptr) {
-        ESP_LOGW(TAG,
-                 "[%s] No control service found at device, not an Anova..?\n"
-                 "[%s] Note, this component does not currently support Anova Nano.",
-                 this->get_name().c_str(), this->get_name().c_str());
+        ESP_LOGW(TAG, "[%s] No control service found at device, not an Anova..?", this->get_name().c_str());
+        ESP_LOGW(TAG, "[%s] Note, this component does not currently support Anova Nano.", this->get_name().c_str());
         break;
       }
       this->char_handle_ = chr->handle;
@@ -144,9 +144,12 @@ void Anova::update() {
     return;
 
   if (this->current_request_ < 2) {
-    auto *pkt = this->codec_->get_read_device_status_request();
-    if (this->current_request_ == 0)
-      this->codec_->get_set_unit_request(this->fahrenheit_ ? 'f' : 'c');
+    AnovaPacket *pkt;
+    if (this->current_request_ == 0) {
+      pkt = this->codec_->get_set_unit_request(this->fahrenheit_ ? 'f' : 'c');
+    } else {
+      pkt = this->codec_->get_read_device_status_request();
+    }
     auto status =
         esp_ble_gattc_write_char(this->parent_->get_gattc_if(), this->parent_->get_conn_id(), this->char_handle_,
                                  pkt->length, pkt->data, ESP_GATT_WRITE_TYPE_NO_RSP, ESP_GATT_AUTH_REQ_NONE);

esphome/components/apds9960/apds9960.cpp

@@ -251,11 +251,11 @@ void APDS9960::read_gesture_data_() {
 
   uint8_t buf[128];
   for (uint8_t pos = 0; pos < fifo_level * 4; pos += 32) {
-    // The ESP's i2c driver has a limited buffer size.
-    // This way of retrieving the data should be wrong according to the datasheet
-    // but it seems to work.
+    // Read in 32-byte chunks due to ESP8266 I2C buffer limit.
+    // Always read from 0xFC — the FIFO auto-increments through 0xFC-0xFF
+    // and advances its internal pointer after every 4th byte.
     uint8_t read = std::min(32, fifo_level * 4 - pos);
-    APDS9960_WARNING_CHECK(this->read_bytes(0xFC + pos, buf + pos, read), "Reading FIFO buffer failed.");
+    APDS9960_WARNING_CHECK(this->read_bytes(0xFC, buf + pos, read), "Reading FIFO buffer failed.");
   }
 
   if (millis() - this->gesture_start_ > 500) {

esphome/components/api/__init__.py

@@ -76,7 +76,7 @@ SERVICE_ARG_NATIVE_TYPES: dict[str, MockObj] = {
     "bool": cg.bool_,
     "int": cg.int32,
     "float": cg.float_,
-    "string": cg.std_string,
+    "string": cg.StringRef,
     "bool[]": cg.FixedVector.template(cg.bool_).operator("const").operator("ref"),
     "int[]": cg.FixedVector.template(cg.int32).operator("const").operator("ref"),
     "float[]": cg.FixedVector.template(cg.float_).operator("const").operator("ref"),
@@ -233,8 +233,8 @@ def _consume_api_sockets(config: ConfigType) -> ConfigType:
 
     # API needs 1 listening socket + typically 3 concurrent client connections
     # (not max_connections, which is the upper limit rarely reached)
-    sockets_needed = 1 + 3
-    socket.consume_sockets(sockets_needed, "api")(config)
+    socket.consume_sockets(3, "api")(config)
+    socket.consume_sockets(1, "api", socket.SocketType.TCP_LISTEN)(config)
     return config
 
 
@@ -301,11 +301,12 @@ CONFIG_SCHEMA = cv.All(
             # Maximum queued send buffers per connection before dropping connection
             # Each buffer uses ~8-12 bytes overhead plus actual message size
             # Platform defaults based on available RAM and typical message rates:
+            # CONF_MAX_SEND_QUEUE defaults are power of 2 for efficient modulo
             cv.SplitDefault(
                 CONF_MAX_SEND_QUEUE,
-                esp8266=5,  # Limited RAM, need to fail fast
+                esp8266=4,  # Limited RAM, need to fail fast
                 esp32=8,  # More RAM, can buffer more
-                rp2040=5,  # Limited RAM
+                rp2040=8,  # Moderate RAM
                 bk72xx=8,  # Moderate RAM
                 nrf52=8,  # Moderate RAM
                 rtl87xx=8,  # Moderate RAM
@@ -380,9 +381,18 @@ async def to_code(config: ConfigType) -> None:
                 if is_optional:
                     func_args.append((cg.bool_, "return_response"))
 
+            # Check if action chain has non-synchronous actions that would make
+            # non-owning StringRef dangle (rx_buf_ reused after delay)
+            has_non_synchronous = automation.has_non_synchronous_actions(
+                conf.get(CONF_THEN, [])
+            )
+
             service_arg_names: list[str] = []
             for name, var_ in conf[CONF_VARIABLES].items():
                 native = SERVICE_ARG_NATIVE_TYPES[var_]
+                # Fall back to std::string for string args if non-synchronous actions exist
+                if has_non_synchronous and native is cg.StringRef:
+                    native = cg.std_string
                 service_template_args.append(native)
                 func_args.append((native, name))
                 service_arg_names.append(name)
@@ -444,7 +454,10 @@ async def to_code(config: ConfigType) -> None:
             # and plaintext disabled. Only a factory reset can remove it.
             cg.add_define("USE_API_PLAINTEXT")
         cg.add_define("USE_API_NOISE")
-        cg.add_library("esphome/noise-c", "0.1.10")
+        cg.add_library("esphome/noise-c", "0.1.11")
+        # Enable optimized memzero/memcmp in libsodium instead of volatile byte loops
+        cg.add_build_flag("-DHAVE_WEAK_SYMBOLS=1")
+        cg.add_build_flag("-DHAVE_INLINE_ASM=1")
     else:
         cg.add_define("USE_API_PLAINTEXT")
 
@@ -509,11 +522,13 @@ HOMEASSISTANT_ACTION_ACTION_SCHEMA = cv.All(
     "homeassistant.action",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_ACTION_ACTION_SCHEMA,
+    synchronous=True,
 )
 @automation.register_action(
     "homeassistant.service",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_ACTION_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_service_to_code(
     config: ConfigType,
@@ -524,24 +539,31 @@ async def homeassistant_service_to_code(
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, False)
-    templ = await cg.templatable(config[CONF_ACTION], args, None)
+    templ = await cg.templatable(config[CONF_ACTION], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     if on_error := config.get(CONF_ON_ERROR):
         cg.add_define("USE_API_HOMEASSISTANT_ACTION_RESPONSES")
@@ -604,29 +626,37 @@ HOMEASSISTANT_EVENT_ACTION_SCHEMA = cv.Schema(
     "homeassistant.event",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_EVENT_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_event_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    templ = await cg.templatable(config[CONF_EVENT], args, None)
+    templ = await cg.templatable(config[CONF_EVENT], args, cg.std_string)
     cg.add(var.set_service(templ))
 
     # Initialize FixedVectors with exact sizes from config
     cg.add(var.init_data(len(config[CONF_DATA])))
     for key, value in config[CONF_DATA].items():
+        # output_type=None because lambdas can return non-string types (int,
+        # float, char*) that TemplatableStringValue converts via to_string.
+        # Static strings are manually wrapped for PROGMEM on ESP8266.
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_data_template(len(config[CONF_DATA_TEMPLATE])))
     for key, value in config[CONF_DATA_TEMPLATE].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_data_template(key, templ))
+        if isinstance(templ, str):
+            templ = cg.FlashStringLiteral(templ)
+        cg.add(var.add_data_template(cg.FlashStringLiteral(key), templ))
 
     cg.add(var.init_variables(len(config[CONF_VARIABLES])))
     for key, value in config[CONF_VARIABLES].items():
         templ = await cg.templatable(value, args, None)
-        cg.add(var.add_variable(key, templ))
+        cg.add(var.add_variable(cg.FlashStringLiteral(key), templ))
 
     return var
 
@@ -644,16 +674,17 @@ HOMEASSISTANT_TAG_SCANNED_ACTION_SCHEMA = cv.maybe_simple_value(
     "homeassistant.tag_scanned",
     HomeAssistantServiceCallAction,
     HOMEASSISTANT_TAG_SCANNED_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def homeassistant_tag_scanned_to_code(config, action_id, template_arg, args):
     cg.add_define("USE_API_HOMEASSISTANT_SERVICES")
     serv = await cg.get_variable(config[CONF_ID])
     var = cg.new_Pvariable(action_id, template_arg, serv, True)
-    cg.add(var.set_service("esphome.tag_scanned"))
+    cg.add(var.set_service(cg.FlashStringLiteral("esphome.tag_scanned")))
     # Initialize FixedVector with exact size (1 data field)
     cg.add(var.init_data(1))
     templ = await cg.templatable(config[CONF_TAG], args, cg.std_string)
-    cg.add(var.add_data("tag_id", templ))
+    cg.add(var.add_data(cg.FlashStringLiteral("tag_id"), templ))
     return var
 
 
@@ -685,6 +716,7 @@ API_RESPOND_ACTION_SCHEMA = cv.All(
     "api.respond",
     APIRespondAction,
     API_RESPOND_ACTION_SCHEMA,
+    synchronous=True,
 )
 async def api_respond_to_code(
     config: ConfigType,

esphome/components/api/api.proto

@@ -58,6 +58,7 @@ service APIConnection {
   rpc subscribe_bluetooth_connections_free(SubscribeBluetoothConnectionsFreeRequest) returns (BluetoothConnectionsFreeResponse) {}
   rpc unsubscribe_bluetooth_le_advertisements(UnsubscribeBluetoothLEAdvertisementsRequest) returns (void) {}
   rpc bluetooth_scanner_set_mode(BluetoothScannerSetModeRequest) returns (void) {}
+  rpc bluetooth_set_connection_params(BluetoothSetConnectionParamsRequest) returns (BluetoothSetConnectionParamsResponse) {}
 
   rpc subscribe_voice_assistant(SubscribeVoiceAssistantRequest) returns (void) {}
   rpc voice_assistant_get_configuration(VoiceAssistantConfigurationRequest) returns (VoiceAssistantConfigurationResponse) {}
@@ -69,6 +70,12 @@ service APIConnection {
   rpc zwave_proxy_request(ZWaveProxyRequest) returns (void) {}
 
   rpc infrared_rf_transmit_raw_timings(InfraredRFTransmitRawTimingsRequest) returns (void) {}
+
+  rpc serial_proxy_configure(SerialProxyConfigureRequest) returns (void) {}
+  rpc serial_proxy_write(SerialProxyWriteRequest) returns (void) {}
+  rpc serial_proxy_set_modem_pins(SerialProxySetModemPinsRequest) returns (void) {}
+  rpc serial_proxy_get_modem_pins(SerialProxyGetModemPinsRequest) returns (void) {}
+  rpc serial_proxy_request(SerialProxyRequest) returns (void) {}
 }
 
 
@@ -198,6 +205,17 @@ message DeviceInfo {
   uint32 area_id = 3;
 }
 
+enum SerialProxyPortType {
+  SERIAL_PROXY_PORT_TYPE_TTL = 0;
+  SERIAL_PROXY_PORT_TYPE_RS232 = 1;
+  SERIAL_PROXY_PORT_TYPE_RS485 = 2;
+}
+
+message SerialProxyInfo {
+  string name = 1;                    // Human-readable port name
+  SerialProxyPortType port_type = 2;  // Port type (RS232, RS485)
+}
+
 message DeviceInfoResponse {
   option (id) = 10;
   option (source) = SOURCE_SERVER;
@@ -260,6 +278,9 @@ message DeviceInfoResponse {
   // Indicates if Z-Wave proxy support is available and features supported
   uint32 zwave_proxy_feature_flags = 23 [(field_ifdef) = "USE_ZWAVE_PROXY"];
   uint32 zwave_home_id = 24 [(field_ifdef) = "USE_ZWAVE_PROXY"];
+
+  // Serial proxy instance metadata
+  repeated SerialProxyInfo serial_proxies = 25 [(field_ifdef) = "USE_SERIAL_PROXY", (fixed_array_size_define) = "SERIAL_PROXY_COUNT"];
 }
 
 message ListEntitiesRequest {
@@ -834,6 +855,33 @@ message GetTimeRequest {
   option (source) = SOURCE_SERVER;
 }
 
+enum DSTRuleType {
+  DST_RULE_TYPE_NONE = 0;
+  DST_RULE_TYPE_MONTH_WEEK_DAY = 1;
+  DST_RULE_TYPE_JULIAN_NO_LEAP = 2;
+  DST_RULE_TYPE_DAY_OF_YEAR = 3;
+}
+
+message DSTRule {
+  option (source) = SOURCE_CLIENT;
+
+  sint32 time_seconds = 1;
+  uint32 day = 2;
+  DSTRuleType type = 3;
+  uint32 month = 4;
+  uint32 week = 5;
+  uint32 day_of_week = 6;
+}
+
+message ParsedTimezone {
+  option (source) = SOURCE_CLIENT;
+
+  sint32 std_offset_seconds = 1;
+  sint32 dst_offset_seconds = 2;
+  DSTRule dst_start = 3;
+  DSTRule dst_end = 4;
+}
+
 message GetTimeResponse {
   option (id) = 37;
   option (source) = SOURCE_CLIENT;
@@ -841,6 +889,7 @@ message GetTimeResponse {
 
   fixed32 epoch_seconds = 1;
   string timezone = 2;
+  ParsedTimezone parsed_timezone = 3;
 }
 
 // ==================== USER-DEFINES SERVICES ====================
@@ -989,6 +1038,7 @@ enum ClimateAction {
   CLIMATE_ACTION_IDLE = 4;
   CLIMATE_ACTION_DRYING = 5;
   CLIMATE_ACTION_FAN = 6;
+  CLIMATE_ACTION_DEFROSTING = 7;
 }
 enum ClimatePreset {
   CLIMATE_PRESET_NONE = 0;
@@ -1554,11 +1604,11 @@ message BluetoothLEAdvertisementResponse {
 }
 
 message BluetoothLERawAdvertisement {
-  uint64 address = 1;
-  sint32 rssi = 2;
+  uint64 address = 1 [(force) = true];
+  sint32 rssi = 2 [(force) = true];
   uint32 address_type = 3;
 
-  bytes data = 4 [(fixed_array_size) = 62];
+  bytes data = 4 [(fixed_array_size) = 62, (force) = true];
 }
 
 message BluetoothLERawAdvertisementsResponse {
@@ -2488,3 +2538,134 @@ message InfraredRFReceiveEvent {
   fixed32 key = 2;                                    // Key identifying the receiver instance
   repeated sint32 timings = 3 [packed = true, (container_pointer_no_template) = "std::vector<int32_t>"];  // Raw timings in microseconds (zigzag-encoded): alternating mark/space periods
 }
+
+// ==================== SERIAL PROXY ====================
+
+enum SerialProxyParity {
+  SERIAL_PROXY_PARITY_NONE = 0;
+  SERIAL_PROXY_PARITY_EVEN = 1;
+  SERIAL_PROXY_PARITY_ODD = 2;
+}
+
+// Configure UART parameters for a serial proxy instance
+message SerialProxyConfigureRequest {
+  option (id) = 138;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  uint32 baudrate = 2;          // Baud rate in bits per second
+  bool flow_control = 3;        // Enable hardware flow control
+  SerialProxyParity parity = 4; // Parity setting
+  uint32 stop_bits = 5;         // Number of stop bits (1 or 2)
+  uint32 data_size = 6;         // Number of data bits (5-8)
+}
+
+// Data received from a serial device, forwarded to clients
+message SerialProxyDataReceived {
+  option (id) = 139;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+  option (no_delay) = true;
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bytes data = 2;               // Raw data received from the serial device
+}
+
+// Write data to a serial device
+message SerialProxyWriteRequest {
+  option (id) = 140;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+  option (no_delay) = true;
+
+  uint32 instance = 1;          // Instance index (0-based)
+  bytes data = 2;               // Raw data to write to the serial device
+}
+
+// Set modem control pin states (RTS and DTR)
+message SerialProxySetModemPinsRequest {
+  option (id) = 141;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  uint32 line_states = 2;       // Bitmask of SerialProxyLineStateFlags
+}
+
+// Request current modem control pin states
+message SerialProxyGetModemPinsRequest {
+  option (id) = 142;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+}
+
+// Response with current modem control pin states
+message SerialProxyGetModemPinsResponse {
+  option (id) = 143;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;          // Instance index (0-based)
+  uint32 line_states = 2;       // Bitmask of SerialProxyLineStateFlags
+}
+
+enum SerialProxyRequestType {
+  SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE = 0;   // Subscribe to receive data from this serial proxy instance
+  SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE = 1; // Unsubscribe from this serial proxy instance
+  SERIAL_PROXY_REQUEST_TYPE_FLUSH = 2;       // Flush the serial port (block until all TX data is sent)
+}
+
+enum SerialProxyStatus {
+  SERIAL_PROXY_STATUS_OK = 0;              // Completed successfully; TX drain confirmed
+  SERIAL_PROXY_STATUS_ASSUMED_SUCCESS = 1; // Platform cannot confirm TX drain; success assumed
+  SERIAL_PROXY_STATUS_ERROR = 2;           // Driver or hardware error
+  SERIAL_PROXY_STATUS_TIMEOUT = 3;         // Timed out before TX completed
+  SERIAL_PROXY_STATUS_NOT_SUPPORTED = 4;   // Request type not supported by this instance
+}
+
+// Generic request message for simple serial proxy operations
+message SerialProxyRequest {
+  option (id) = 144;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;                  // Instance index (0-based)
+  SerialProxyRequestType type = 2;      // Request type
+}
+
+// Response to a SerialProxyRequest (e.g. flush completion or failure)
+message SerialProxyRequestResponse {
+  option (id) = 147;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_SERIAL_PROXY";
+
+  uint32 instance = 1;                  // Instance index (0-based)
+  SerialProxyRequestType type = 2;      // Which request type this responds to
+  SerialProxyStatus status = 3;         // Result status
+  string error_message = 4;            // Additional detail on failure (optional)
+}
+
+// ==================== BLUETOOTH CONNECTION PARAMS ====================
+message BluetoothSetConnectionParamsRequest {
+  option (id) = 145;
+  option (source) = SOURCE_CLIENT;
+  option (ifdef) = "USE_BLUETOOTH_PROXY";
+
+  uint64 address = 1;
+  uint32 min_interval = 2;  // units of 1.25ms
+  uint32 max_interval = 3;  // units of 1.25ms
+  uint32 latency = 4;
+  uint32 timeout = 5;       // units of 10ms
+}
+
+message BluetoothSetConnectionParamsResponse {
+  option (id) = 146;
+  option (source) = SOURCE_SERVER;
+  option (ifdef) = "USE_BLUETOOTH_PROXY";
+
+  uint64 address = 1;
+  int32 error = 2;
+}

esphome/components/api/api_buffer.cpp

@@ -0,0 +1,13 @@
+#include "api_buffer.h"
+
+namespace esphome::api {
+
+void APIBuffer::grow_(size_t n) {
+  auto new_data = make_buffer(n);
+  if (this->size_)
+    std::memcpy(new_data.get(), this->data_.get(), this->size_);
+  this->data_ = std::move(new_data);
+  this->capacity_ = n;
+}
+
+}  // namespace esphome::api

esphome/components/api/api_buffer.h

@@ -0,0 +1,73 @@
+#pragma once
+
+#include <cstdint>
+#include <cstring>
+#include <memory>
+
+#include "esphome/core/defines.h"
+#include "esphome/core/helpers.h"
+
+namespace esphome::api {
+
+/// Helper to use make_unique_for_overwrite where available (skips zero-fill),
+/// falling back to make_unique on older GCC (ESP8266, LibreTiny).
+inline std::unique_ptr<uint8_t[]> make_buffer(size_t n) {
+#if defined(USE_ESP8266) || defined(USE_LIBRETINY)
+  return std::make_unique<uint8_t[]>(n);
+#else
+  return std::make_unique_for_overwrite<uint8_t[]>(n);
+#endif
+}
+
+/// Byte buffer that skips zero-initialization on resize().
+///
+/// std::vector<uint8_t>::resize() zero-fills new bytes via memset. For the
+/// shared protobuf write buffer, every byte is overwritten by the encoder,
+/// making the zero-fill pure waste. For the receive buffer, bytes are
+/// overwritten by socket reads.
+///
+/// Designed for bulk clear/resize/overwrite patterns. grow_() allocates
+/// exactly the requested size (no growth factor) since callers resize to
+/// known sizes rather than appending incrementally.
+///
+/// Safe because: callers always write exactly the number of bytes they
+/// resize for. In the protobuf write path, debug_check_bounds_ validates
+/// writes in debug builds.
+class APIBuffer {
+ public:
+  void clear() { this->size_ = 0; }
+  inline void reserve(size_t n) ESPHOME_ALWAYS_INLINE {
+    if (n > this->capacity_)
+      this->grow_(n);
+  }
+  inline void resize(size_t n) ESPHOME_ALWAYS_INLINE {
+    this->reserve(n);
+    this->size_ = n;  // no zero-fill
+  }
+  /// Reserve capacity for max(reserve_size, new_size) bytes, then set size to new_size.
+  /// Single grow_ check regardless of argument order.
+  inline void reserve_and_resize(size_t reserve_size, size_t new_size) ESPHOME_ALWAYS_INLINE {
+    this->reserve(std::max(reserve_size, new_size));
+    this->size_ = new_size;
+  }
+  uint8_t *data() { return this->data_.get(); }
+  const uint8_t *data() const { return this->data_.get(); }
+  size_t size() const { return this->size_; }
+  bool empty() const { return this->size_ == 0; }
+  uint8_t &operator[](size_t i) { return this->data_[i]; }
+  const uint8_t &operator[](size_t i) const { return this->data_[i]; }
+  /// Release all memory (equivalent to std::vector swap trick).
+  void release() {
+    this->data_.reset();
+    this->size_ = 0;
+    this->capacity_ = 0;
+  }
+
+ protected:
+  void grow_(size_t n);
+  std::unique_ptr<uint8_t[]> data_;
+  size_t size_{0};
+  size_t capacity_{0};
+};
+
+}  // namespace esphome::api

esphome/components/api/api_connection.h

@@ -3,11 +3,23 @@
 #include "esphome/core/defines.h"
 #ifdef USE_API
 #include "api_frame_helper.h"
+#ifdef USE_API_NOISE
+#include "api_frame_helper_noise.h"
+#endif
+#ifdef USE_API_PLAINTEXT
+#include "api_frame_helper_plaintext.h"
+#endif
 #include "api_pb2.h"
 #include "api_pb2_service.h"
 #include "api_server.h"
 #include "esphome/core/application.h"
 #include "esphome/core/component.h"
+#ifdef USE_ESP32_CRASH_HANDLER
+#include "esphome/components/esp32/crash_handler.h"
+#endif
+#ifdef USE_RP2040_CRASH_HANDLER
+#include "esphome/components/rp2040/crash_handler.h"
+#endif
 #include "esphome/core/entity_base.h"
 #include "esphome/core/string_ref.h"
 
@@ -123,7 +135,7 @@ class APIConnection final : public APIServerConnectionBase {
   void send_homeassistant_action(const HomeassistantActionRequest &call) {
     if (!this->flags_.service_call_subscription)
       return;
-    this->send_message(call, HomeassistantActionRequest::MESSAGE_TYPE);
+    this->send_message(call);
   }
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   void on_homeassistant_action_response(const HomeassistantActionResponse &msg) override;
@@ -142,12 +154,13 @@ class APIConnection final : public APIServerConnectionBase {
   void on_bluetooth_gatt_notify_request(const BluetoothGATTNotifyRequest &msg) override;
   void on_subscribe_bluetooth_connections_free_request() override;
   void on_bluetooth_scanner_set_mode_request(const BluetoothScannerSetModeRequest &msg) override;
+  void on_bluetooth_set_connection_params_request(const BluetoothSetConnectionParamsRequest &msg) override;
 
 #endif
 #ifdef USE_HOMEASSISTANT_TIME
   void send_time_request() {
     GetTimeRequest req;
-    this->send_message(req, GetTimeRequest::MESSAGE_TYPE);
+    this->send_message(req);
   }
 #endif
 
@@ -182,6 +195,15 @@ class APIConnection final : public APIServerConnectionBase {
   void send_infrared_rf_receive_event(const InfraredRFReceiveEvent &msg);
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  void on_serial_proxy_configure_request(const SerialProxyConfigureRequest &msg) override;
+  void on_serial_proxy_write_request(const SerialProxyWriteRequest &msg) override;
+  void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &msg) override;
+  void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &msg) override;
+  void on_serial_proxy_request(const SerialProxyRequest &msg) override;
+  void send_serial_proxy_data(const SerialProxyDataReceived &msg);
+#endif
+
 #ifdef USE_EVENT
   void send_event(event::Event *event);
 #endif
@@ -219,6 +241,12 @@ class APIConnection final : public APIServerConnectionBase {
     this->flags_.log_subscription = msg.level;
     if (msg.dump_config)
       App.schedule_dump_config();
+#ifdef USE_ESP32_CRASH_HANDLER
+    esp32::crash_handler_log();
+#endif
+#ifdef USE_RP2040_CRASH_HANDLER
+    rp2040::crash_handler_log();
+#endif
   }
 #ifdef USE_API_HOMEASSISTANT_SERVICES
   void on_subscribe_homeassistant_services_request() override { this->flags_.service_call_subscription = true; }
@@ -247,6 +275,7 @@ class APIConnection final : public APIServerConnectionBase {
     return static_cast<ConnectionState>(this->flags_.connection_state) == ConnectionState::CONNECTED ||
            this->is_authenticated();
   }
+  bool is_marked_for_removal() const { return this->flags_.remove; }
   uint8_t get_log_subscription_level() const { return this->flags_.log_subscription; }
 
   // Get client API version for feature detection
@@ -257,26 +286,44 @@ class APIConnection final : public APIServerConnectionBase {
 
   void on_fatal_error() override;
   void on_no_setup_connection() override;
-  bool send_message_impl(const ProtoMessage &msg, uint8_t message_type) override;
 
-  void prepare_first_message_buffer(std::vector<uint8_t> &shared_buf, size_t header_padding, size_t total_size) {
+  // Function pointer type for type-erased message encoding
+  using MessageEncodeFn = void (*)(const void *, ProtoWriteBuffer &);
+  // Function pointer type for type-erased size calculation
+  using CalculateSizeFn = uint32_t (*)(const void *);
+
+  template<typename T> bool send_message(const T &msg) {
+    if constexpr (T::ESTIMATED_SIZE == 0) {
+      return this->send_message_(0, T::MESSAGE_TYPE, &encode_msg_noop, &msg);
+    } else {
+      return this->send_message_(msg.calculate_size(), T::MESSAGE_TYPE, &proto_encode_msg<T>, &msg);
+    }
+  }
+
+  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t header_padding, size_t total_size) {
     shared_buf.clear();
     // Reserve space for header padding + message + footer
     // - Header padding: space for protocol headers (7 bytes for Noise, 6 for Plaintext)
     // - Footer: space for MAC (16 bytes for Noise, 0 for Plaintext)
-    shared_buf.reserve(total_size);
-    // Resize to add header padding so message encoding starts at the correct position
-    shared_buf.resize(header_padding);
+    // Reserve full size but only set initial size to header padding
+    // so message encoding starts at the correct position
+    shared_buf.reserve_and_resize(total_size, header_padding);
   }
 
   // Convenience overload - computes frame overhead internally
-  void prepare_first_message_buffer(std::vector<uint8_t> &shared_buf, size_t payload_size) {
+  void prepare_first_message_buffer(APIBuffer &shared_buf, size_t payload_size) {
     const uint8_t header_padding = this->helper_->frame_header_padding();
     const uint8_t footer_size = this->helper_->frame_footer_size();
     this->prepare_first_message_buffer(shared_buf, header_padding, payload_size + header_padding + footer_size);
   }
 
-  bool try_to_clear_buffer(bool log_out_of_space);
+  bool try_to_clear_buffer(bool log_out_of_space) {
+    if (this->flags_.remove)
+      return false;
+    if (this->helper_->can_write_without_blocking())
+      return true;
+    return this->try_to_clear_buffer_slow_(log_out_of_space);
+  }
   bool send_buffer(ProtoWriteBuffer buffer, uint8_t message_type) override;
 
   const char *get_name() const { return this->helper_->get_client_name(); }
@@ -286,6 +333,8 @@ class APIConnection final : public APIServerConnectionBase {
   }
 
  protected:
+  bool try_to_clear_buffer_slow_(bool log_out_of_space);
+
   // Helper function to handle authentication completion
   void complete_authentication_();
 
@@ -312,50 +361,67 @@ class APIConnection final : public APIServerConnectionBase {
   void process_state_subscriptions_();
 #endif
 
-  // Non-template helper to encode any ProtoMessage
-  static uint16_t encode_message_to_buffer(ProtoMessage &msg, uint8_t message_type, APIConnection *conn,
-                                           uint32_t remaining_size);
-
-  // Helper to fill entity state base and encode message
-  static uint16_t fill_and_encode_entity_state(EntityBase *entity, StateResponseProtoMessage &msg, uint8_t message_type,
-                                               APIConnection *conn, uint32_t remaining_size) {
-    msg.key = entity->get_object_id_hash();
-#ifdef USE_DEVICES
-    msg.device_id = entity->get_device_id();
-#endif
-    return encode_message_to_buffer(msg, message_type, conn, remaining_size);
+  // Size thunk — converts void* back to concrete type for direct calculate_size() call
+  template<typename T> static uint32_t calc_size(const void *msg) {
+    return static_cast<const T *>(msg)->calculate_size();
   }
 
-  // Helper to fill entity info base and encode message
-  static uint16_t fill_and_encode_entity_info(EntityBase *entity, InfoResponseProtoMessage &msg, uint8_t message_type,
-                                              APIConnection *conn, uint32_t remaining_size) {
-    // Set common fields that are shared by all entity types
-    msg.key = entity->get_object_id_hash();
+  // Shared no-op encode thunk for empty messages (ESTIMATED_SIZE == 0)
+  static void encode_msg_noop(const void *, ProtoWriteBuffer &) {}
 
-    // API 1.14+ clients compute object_id client-side from the entity name
-    // For older clients, we must send object_id for backward compatibility
-    // See: https://github.com/esphome/backlog/issues/76
-    // TODO: Remove this backward compat code before 2026.7.0 - all clients should support API 1.14 by then
-    // Buffer must remain in scope until encode_message_to_buffer is called
-    char object_id_buf[OBJECT_ID_MAX_LEN];
-    if (!conn->client_supports_api_version(1, 14)) {
-      msg.object_id = entity->get_object_id_to(object_id_buf);
+  // Non-template buffer management for send_message
+  bool send_message_(uint32_t payload_size, uint8_t message_type, MessageEncodeFn encode_fn, const void *msg);
+
+  // Non-template buffer management for batch encoding
+  static uint16_t encode_to_buffer(uint32_t calculated_size, MessageEncodeFn encode_fn, const void *msg,
+                                   APIConnection *conn, uint32_t remaining_size);
+
+  // Thin template wrapper — computes size, delegates buffer work to non-template helper
+  template<typename T> static uint16_t encode_message_to_buffer(T &msg, APIConnection *conn, uint32_t remaining_size) {
+    if constexpr (T::ESTIMATED_SIZE == 0) {
+      return encode_to_buffer(0, &encode_msg_noop, &msg, conn, remaining_size);
+    } else {
+      return encode_to_buffer(msg.calculate_size(), &proto_encode_msg<T>, &msg, conn, remaining_size);
     }
+  }
 
-    if (entity->has_own_name()) {
-      msg.name = entity->get_name();
-    }
+  // Non-template core — fills state fields and encodes
+  static uint16_t fill_and_encode_entity_state(EntityBase *entity, StateResponseProtoMessage &msg,
+                                               CalculateSizeFn size_fn, MessageEncodeFn encode_fn, APIConnection *conn,
+                                               uint32_t remaining_size);
 
-    // Set common EntityBase properties
-#ifdef USE_ENTITY_ICON
-    msg.icon = entity->get_icon_ref();
-#endif
-    msg.disabled_by_default = entity->is_disabled_by_default();
-    msg.entity_category = static_cast<enums::EntityCategory>(entity->get_entity_category());
-#ifdef USE_DEVICES
-    msg.device_id = entity->get_device_id();
-#endif
-    return encode_message_to_buffer(msg, message_type, conn, remaining_size);
+  // Thin template wrapper
+  template<typename T>
+  static uint16_t fill_and_encode_entity_state(EntityBase *entity, T &msg, APIConnection *conn,
+                                               uint32_t remaining_size) {
+    return fill_and_encode_entity_state(entity, msg, &calc_size<T>, &proto_encode_msg<T>, conn, remaining_size);
+  }
+
+  // Non-template core — fills info fields, allocates buffers, and encodes
+  static uint16_t fill_and_encode_entity_info(EntityBase *entity, InfoResponseProtoMessage &msg,
+                                              CalculateSizeFn size_fn, MessageEncodeFn encode_fn, APIConnection *conn,
+                                              uint32_t remaining_size);
+
+  // Thin template wrapper
+  template<typename T>
+  static uint16_t fill_and_encode_entity_info(EntityBase *entity, T &msg, APIConnection *conn,
+                                              uint32_t remaining_size) {
+    return fill_and_encode_entity_info(entity, msg, &calc_size<T>, &proto_encode_msg<T>, conn, remaining_size);
+  }
+
+  // Non-template core — fills device_class, then delegates to fill_and_encode_entity_info
+  static uint16_t fill_and_encode_entity_info_with_device_class(EntityBase *entity, InfoResponseProtoMessage &msg,
+                                                                StringRef &device_class_field, CalculateSizeFn size_fn,
+                                                                MessageEncodeFn encode_fn, APIConnection *conn,
+                                                                uint32_t remaining_size);
+
+  // Thin template wrapper
+  template<typename T>
+  static uint16_t fill_and_encode_entity_info_with_device_class(EntityBase *entity, T &msg,
+                                                                StringRef &device_class_field, APIConnection *conn,
+                                                                uint32_t remaining_size) {
+    return fill_and_encode_entity_info_with_device_class(entity, msg, device_class_field, &calc_size<T>,
+                                                         &proto_encode_msg<T>, conn, remaining_size);
   }
 
 #ifdef USE_VOICE_ASSISTANT
@@ -370,6 +436,10 @@ class APIConnection final : public APIServerConnectionBase {
     return this->client_supports_api_version(1, 14) ? MAX_INITIAL_PER_BATCH : MAX_INITIAL_PER_BATCH_LEGACY;
   }
 
+  // Send keepalive ping or disconnect unresponsive client.
+  // Cold path — extracted from loop() to reduce instruction cache pressure.
+  void __attribute__((noinline)) check_keepalive_(uint32_t now);
+
   // Process active iterator (list_entities/initial_state) during connection setup.
   // Extracted from loop() — only runs during initial handshake, NONE in steady state.
   void __attribute__((noinline)) process_active_iterator_();
@@ -485,7 +555,13 @@ class APIConnection final : public APIServerConnectionBase {
   // === Optimal member ordering for 32-bit systems ===
 
   // Group 1: Pointers (4 bytes each on 32-bit)
+#if defined(USE_API_NOISE) && defined(USE_API_PLAINTEXT)
   std::unique_ptr<APIFrameHelper> helper_;
+#elif defined(USE_API_NOISE)
+  std::unique_ptr<APINoiseFrameHelper> helper_;
+#elif defined(USE_API_PLAINTEXT)
+  std::unique_ptr<APIPlaintextFrameHelper> helper_;
+#endif
   APIServer *parent_;
 
   // Group 2: Iterator union (saves ~16 bytes vs separate iterators)
@@ -541,6 +617,8 @@ class APIConnection final : public APIServerConnectionBase {
                   uint8_t aux_data_index = AUX_DATA_UNUSED);
     // Add item to the front of the batch (for high priority messages like ping)
     void add_item_front(EntityBase *entity, uint8_t message_type, uint8_t estimated_size);
+    // Single push_back site to avoid duplicate _M_realloc_insert instantiation
+    void push_item(const BatchItem &item);
 
     // Clear all items
     void clear() {
@@ -621,8 +699,8 @@ class APIConnection final : public APIServerConnectionBase {
 
   bool schedule_batch_();
   void process_batch_();
-  void process_batch_multi_(std::vector<uint8_t> &shared_buf, size_t num_items, uint8_t header_padding,
-                            uint8_t footer_size) __attribute__((noinline));
+  void process_batch_multi_(APIBuffer &shared_buf, size_t num_items, uint8_t header_padding, uint8_t footer_size)
+      __attribute__((noinline));
   void clear_batch_() {
     this->deferred_batch_.clear();
     this->flags_.batch_scheduled = false;

esphome/components/api/api_frame_helper.cpp

@@ -100,149 +100,61 @@ const LogString *api_error_to_logstr(APIError err) {
   return LOG_STR("UNKNOWN");
 }
 
-// Default implementation for loop - handles sending buffered data
-APIError APIFrameHelper::loop() {
-  if (this->tx_buf_count_ > 0) {
-    APIError err = try_send_tx_buf_();
-    if (err != APIError::OK && err != APIError::WOULD_BLOCK) {
-      return err;
+APIError APIFrameHelper::drain_overflow_and_handle_errors_() {
+  if (this->overflow_buf_.try_drain(this->socket_.get()) == -1) {
+    int err = errno;
+    if (this->check_socket_write_err_(err) != APIError::WOULD_BLOCK) {
+      HELPER_LOG("Socket write failed with errno %d", err);
+      return APIError::SOCKET_WRITE_FAILED;
     }
   }
-  return APIError::OK;  // Convert WOULD_BLOCK to OK to avoid connection termination
+  return APIError::OK;
 }
 
-// Common socket write error handling
-APIError APIFrameHelper::handle_socket_write_error_() {
-  if (errno == EWOULDBLOCK || errno == EAGAIN) {
-    return APIError::WOULD_BLOCK;
-  }
-  HELPER_LOG("Socket write failed with errno %d", errno);
-  this->state_ = State::FAILED;
-  return APIError::SOCKET_WRITE_FAILED;
-}
-
-// Helper method to buffer data from IOVs
-void APIFrameHelper::buffer_data_from_iov_(const struct iovec *iov, int iovcnt, uint16_t total_write_len,
-                                           uint16_t offset) {
-  // Check if queue is full
-  if (this->tx_buf_count_ >= API_MAX_SEND_QUEUE) {
-    HELPER_LOG("Send queue full (%u buffers), dropping connection", this->tx_buf_count_);
-    this->state_ = State::FAILED;
-    return;
-  }
-
-  uint16_t buffer_size = total_write_len - offset;
-  auto &buffer = this->tx_buf_[this->tx_buf_tail_];
-  buffer = std::make_unique<SendBuffer>(SendBuffer{
-      .data = std::make_unique<uint8_t[]>(buffer_size),
-      .size = buffer_size,
-      .offset = 0,
-  });
-
-  uint16_t to_skip = offset;
-  uint16_t write_pos = 0;
-
-  for (int i = 0; i < iovcnt; i++) {
-    if (to_skip >= iov[i].iov_len) {
-      // Skip this entire segment
-      to_skip -= static_cast<uint16_t>(iov[i].iov_len);
-    } else {
-      // Include this segment (partially or fully)
-      const uint8_t *src = reinterpret_cast<uint8_t *>(iov[i].iov_base) + to_skip;
-      uint16_t len = static_cast<uint16_t>(iov[i].iov_len) - to_skip;
-      std::memcpy(buffer->data.get() + write_pos, src, len);
-      write_pos += len;
-      to_skip = 0;
-    }
-  }
-
-  // Update circular buffer tracking
-  this->tx_buf_tail_ = (this->tx_buf_tail_ + 1) % API_MAX_SEND_QUEUE;
-  this->tx_buf_count_++;
-}
-
-// This method writes data to socket or buffers it
+// Write data to socket, overflow to backlog buffer if LWIP TCP send buffer is full.
+// Returns OK if all data was sent or successfully queued.
+// Returns SOCKET_WRITE_FAILED on hard error (sets state to FAILED).
 APIError APIFrameHelper::write_raw_(const struct iovec *iov, int iovcnt, uint16_t total_write_len) {
-  // Returns APIError::OK if successful (or would block, but data has been buffered)
-  // Returns APIError::SOCKET_WRITE_FAILED if socket write failed, and sets state to FAILED
-
-  if (iovcnt == 0)
-    return APIError::OK;  // Nothing to do, success
-
 #ifdef HELPER_LOG_PACKETS
   for (int i = 0; i < iovcnt; i++) {
     LOG_PACKET_SENDING(reinterpret_cast<uint8_t *>(iov[i].iov_base), iov[i].iov_len);
   }
 #endif
 
-  // Try to send any existing buffered data first if there is any
-  if (this->tx_buf_count_ > 0) {
-    APIError send_result = try_send_tx_buf_();
-    // If real error occurred (not just WOULD_BLOCK), return it
-    if (send_result != APIError::OK && send_result != APIError::WOULD_BLOCK) {
-      return send_result;
-    }
+  uint16_t skip = 0;
 
-    // If there is still data in the buffer, we can't send, buffer
-    // the new data and return
-    if (this->tx_buf_count_ > 0) {
-      this->buffer_data_from_iov_(iov, iovcnt, total_write_len, 0);
-      return APIError::OK;  // Success, data buffered
-    }
+  // Drain any existing backlog first
+  if (!this->overflow_buf_.empty()) [[unlikely]] {
+    APIError err = this->drain_overflow_and_handle_errors_();
+    if (err != APIError::OK)
+      return err;
   }
 
-  // Try to send directly if no buffered data
-  // Optimize for single iovec case (common for plaintext API)
-  ssize_t sent =
-      (iovcnt == 1) ? this->socket_->write(iov[0].iov_base, iov[0].iov_len) : this->socket_->writev(iov, iovcnt);
+  // If backlog is clear, try direct send
+  if (this->overflow_buf_.empty()) [[likely]] {
+    ssize_t sent =
+        (iovcnt == 1) ? this->socket_->write(iov[0].iov_base, iov[0].iov_len) : this->socket_->writev(iov, iovcnt);
 
-  if (sent == -1) {
-    APIError err = this->handle_socket_write_error_();
-    if (err == APIError::WOULD_BLOCK) {
-      // Socket would block, buffer the data
-      this->buffer_data_from_iov_(iov, iovcnt, total_write_len, 0);
-      return APIError::OK;  // Success, data buffered
-    }
-    return err;  // Socket write failed
-  } else if (static_cast<uint16_t>(sent) < total_write_len) {
-    // Partially sent, buffer the remaining data
-    this->buffer_data_from_iov_(iov, iovcnt, total_write_len, static_cast<uint16_t>(sent));
-  }
-
-  return APIError::OK;  // Success, all data sent or buffered
-}
-
-// Common implementation for trying to send buffered data
-// IMPORTANT: Caller MUST ensure tx_buf_count_ > 0 before calling this method
-APIError APIFrameHelper::try_send_tx_buf_() {
-  // Try to send from tx_buf - we assume it's not empty as it's the caller's responsibility to check
-  while (this->tx_buf_count_ > 0) {
-    // Get the first buffer in the queue
-    SendBuffer *front_buffer = this->tx_buf_[this->tx_buf_head_].get();
-
-    // Try to send the remaining data in this buffer
-    ssize_t sent = this->socket_->write(front_buffer->current_data(), front_buffer->remaining());
-
-    if (sent == -1) {
-      return this->handle_socket_write_error_();
-    } else if (sent == 0) {
-      // Nothing sent but not an error
-      return APIError::WOULD_BLOCK;
-    } else if (static_cast<uint16_t>(sent) < front_buffer->remaining()) {
-      // Partially sent, update offset
-      // Cast to ensure no overflow issues with uint16_t
-      front_buffer->offset += static_cast<uint16_t>(sent);
-      return APIError::WOULD_BLOCK;  // Stop processing more buffers if we couldn't send a complete buffer
+    if (sent == -1) [[unlikely]] {
+      int err = errno;
+      if (this->check_socket_write_err_(err) != APIError::WOULD_BLOCK) {
+        HELPER_LOG("Socket write failed with errno %d", err);
+        return APIError::SOCKET_WRITE_FAILED;
+      }
+    } else if (static_cast<uint16_t>(sent) >= total_write_len) [[likely]] {
+      return APIError::OK;
     } else {
-      // Buffer completely sent, remove it from the queue
-      this->tx_buf_[this->tx_buf_head_].reset();
-      this->tx_buf_head_ = (this->tx_buf_head_ + 1) % API_MAX_SEND_QUEUE;
-      this->tx_buf_count_--;
-      // Continue loop to try sending the next buffer
+      skip = static_cast<uint16_t>(sent);
     }
   }
 
-  return APIError::OK;  // All buffers sent successfully
+  // Queue unsent data into overflow buffer
+  if (!this->overflow_buf_.enqueue_iov(iov, iovcnt, total_write_len, skip)) {
+    HELPER_LOG("Overflow buffer full, dropping connection");
+    this->state_ = State::FAILED;
+    return APIError::SOCKET_WRITE_FAILED;
+  }
+  return APIError::OK;
 }
 
 const char *APIFrameHelper::get_peername_to(std::span<char, socket::SOCKADDR_STR_LEN> buf) const {
@@ -278,11 +190,12 @@ APIError APIFrameHelper::init_common_() {
 
 APIError APIFrameHelper::handle_socket_read_result_(ssize_t received) {
   if (received == -1) {
-    if (errno == EWOULDBLOCK || errno == EAGAIN) {
+    const int err = errno;
+    if (err == EWOULDBLOCK || err == EAGAIN) {
       return APIError::WOULD_BLOCK;
     }
     state_ = State::FAILED;
-    HELPER_LOG("Socket read failed with errno %d", errno);
+    HELPER_LOG("Socket read failed with errno %d", err);
     return APIError::SOCKET_READ_FAILED;
   } else if (received == 0) {
     state_ = State::FAILED;

esphome/components/api/api_frame_helper.h

@@ -5,13 +5,15 @@
 #include <memory>
 #include <span>
 #include <utility>
-#include <vector>
 
 #include "esphome/core/defines.h"
 #ifdef USE_API
+#include "esphome/components/api/api_buffer.h"
+#include "esphome/components/api/api_overflow_buffer.h"
 #include "esphome/components/socket/socket.h"
 #include "esphome/core/application.h"
 #include "esphome/core/log.h"
+#include "proto.h"
 
 namespace esphome::api {
 
@@ -29,12 +31,14 @@ static constexpr uint16_t MAX_MESSAGE_SIZE = 8192;  // 8 KiB for ESP8266
 static constexpr uint16_t MAX_MESSAGE_SIZE = 32768;  // 32 KiB for ESP32 and other platforms
 #endif
 
+// Extra byte reserved in rx_buf_ beyond the message size so protobuf
+// StringRef fields can be null-terminated in-place after decode.
+static constexpr uint16_t RX_BUF_NULL_TERMINATOR = 1;
+
 // Maximum number of messages to batch in a single write operation
 // Must be >= MAX_INITIAL_PER_BATCH in api_connection.h (enforced by static_assert there)
 static constexpr size_t MAX_MESSAGES_PER_BATCH = 34;
 
-class ProtoWriteBuffer;
-
 // Max client name length (e.g., "Home Assistant 2026.1.0.dev0" = 28 chars)
 static constexpr size_t CLIENT_INFO_NAME_MAX_LEN = 32;
 
@@ -101,9 +105,9 @@ class APIFrameHelper {
   }
   virtual ~APIFrameHelper() = default;
   virtual APIError init() = 0;
-  virtual APIError loop();
+  virtual APIError loop() = 0;
   virtual APIError read_packet(ReadPacketBuffer *buffer) = 0;
-  bool can_write_without_blocking() { return this->state_ == State::DATA && this->tx_buf_count_ == 0; }
+  bool can_write_without_blocking() { return this->state_ == State::DATA && this->overflow_buf_.empty(); }
   int getpeername(struct sockaddr *addr, socklen_t *addrlen) { return socket_->getpeername(addr, addrlen); }
   APIError close() {
     if (state_ == State::CLOSED)
@@ -130,34 +134,41 @@ class APIFrameHelper {
   //
   // For log messages: Use Nagle to coalesce multiple small log packets into
   // fewer larger packets, reducing WiFi overhead. However, we limit batching
-  // to 3 messages to avoid excessive LWIP buffer pressure on memory-constrained
-  // devices like ESP8266. LWIP's TCP_OVERSIZE option coalesces the data into
-  // shared pbufs, but holding data too long waiting for Nagle's timer causes
-  // buffer exhaustion and dropped messages.
+  // to avoid excessive LWIP buffer pressure on memory-constrained devices.
+  // LWIP's TCP_OVERSIZE option coalesces the data into shared pbufs, but
+  // holding data too long waiting for Nagle's timer causes buffer exhaustion
+  // and dropped messages.
   //
-  // Flow: Log 1 (Nagle on) -> Log 2 (Nagle on) -> Log 3 (NODELAY, flush all)
+  // ESP32 (TCP_SND_BUF=4×MSS+) / RP2040 (8×MSS) / LibreTiny (4×MSS): 4 logs per cycle
+  // ESP8266 (2×MSS): 3 logs per cycle (tightest buffers)
+  //
+  // Flow (ESP32/RP2040/LT): Log 1 (Nagle on) -> Log 2 -> Log 3 -> Log 4 (NODELAY, flush)
+  // Flow (ESP8266):         Log 1 (Nagle on) -> Log 2 -> Log 3 (NODELAY, flush all)
   //
   void set_nodelay_for_message(bool is_log_message) {
     if (!is_log_message) {
-      if (this->nodelay_state_ != NODELAY_ON) {
+      if (this->nodelay_counter_) {
         this->set_nodelay_raw_(true);
-        this->nodelay_state_ = NODELAY_ON;
+        this->nodelay_counter_ = 0;
       }
       return;
     }
-
-    // Log messages 1-3: state transitions -1 -> 1 -> 2 -> -1 (flush on 3rd)
-    if (this->nodelay_state_ == NODELAY_ON) {
+    // Log message: enable Nagle on first, flush after LOG_NAGLE_COUNT
+    if (!this->nodelay_counter_)
       this->set_nodelay_raw_(false);
-      this->nodelay_state_ = 1;
-    } else if (this->nodelay_state_ >= LOG_NAGLE_COUNT) {
+    if (++this->nodelay_counter_ > LOG_NAGLE_COUNT) {
       this->set_nodelay_raw_(true);
-      this->nodelay_state_ = NODELAY_ON;
-    } else {
-      this->nodelay_state_++;
+      this->nodelay_counter_ = 0;
     }
   }
-  virtual APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) = 0;
+  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
+    // Resize buffer to include footer space if needed (e.g. Noise MAC)
+    if (frame_footer_size_)
+      buffer.get_buffer()->resize(buffer.get_buffer()->size() + frame_footer_size_);
+    MessageInfo msg{type, 0,
+                    static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_ - frame_footer_size_)};
+    return write_protobuf_messages(buffer, std::span<const MessageInfo>(&msg, 1));
+  }
   // Write multiple protobuf messages in a single operation
   // messages contains (message_type, offset, length) for each message in the buffer
   // The buffer contains all messages with appropriate padding before each
@@ -174,37 +185,28 @@ class APIFrameHelper {
     // rx_buf_len_ tracks bytes read so far; if non-zero, we're mid-frame
     // and clearing would lose partially received data.
     if (this->rx_buf_len_ == 0) {
-      // Use swap trick since shrink_to_fit() is non-binding and may be ignored
-      std::vector<uint8_t>().swap(this->rx_buf_);
+      this->rx_buf_.release();
     }
   }
 
  protected:
-  // Buffer containing data to be sent
-  struct SendBuffer {
-    std::unique_ptr<uint8_t[]> data;
-    uint16_t size{0};    // Total size of the buffer
-    uint16_t offset{0};  // Current offset within the buffer
-
-    // Using uint16_t reduces memory usage since ESPHome API messages are limited to UINT16_MAX (65535) bytes
-    uint16_t remaining() const { return size - offset; }
-    const uint8_t *current_data() const { return data.get() + offset; }
-  };
+  // Drain backlogged overflow data to the socket and handle errors.
+  // Called when overflow_buf_.empty() is false. Out-of-line to keep the
+  // fast path (empty check) inline at call sites.
+  // Returns OK for transient errors (WOULD_BLOCK), SOCKET_WRITE_FAILED for hard errors.
+  APIError drain_overflow_and_handle_errors_();
 
   // Common implementation for writing raw data to socket
   APIError write_raw_(const struct iovec *iov, int iovcnt, uint16_t total_write_len);
 
-  // Try to send data from the tx buffer
-  APIError try_send_tx_buf_();
-
-  // Helper method to buffer data from IOVs
-  void buffer_data_from_iov_(const struct iovec *iov, int iovcnt, uint16_t total_write_len, uint16_t offset);
-
-  // Common socket write error handling
-  APIError handle_socket_write_error_();
-  template<typename StateEnum>
-  APIError write_raw_(const struct iovec *iov, int iovcnt, socket::Socket *socket, std::vector<uint8_t> &tx_buf,
-                      const std::string &info, StateEnum &state, StateEnum failed_state);
+  // Check if a socket write errno is a hard error (not WOULD_BLOCK/EAGAIN).
+  // Returns WOULD_BLOCK for transient errors, SOCKET_WRITE_FAILED for hard errors.
+  APIError check_socket_write_err_(int err) {
+    if (err == EWOULDBLOCK || err == EAGAIN)
+      return APIError::WOULD_BLOCK;
+    this->state_ = State::FAILED;
+    return APIError::SOCKET_WRITE_FAILED;
+  }
 
   // Socket ownership (4 bytes on 32-bit, 8 bytes on 64-bit)
   std::unique_ptr<socket::Socket> socket_;
@@ -228,9 +230,20 @@ class APIFrameHelper {
     EXPLICIT_REJECT = 8,  // Noise only
   };
 
-  // Containers (size varies, but typically 12+ bytes on 32-bit)
-  std::array<std::unique_ptr<SendBuffer>, API_MAX_SEND_QUEUE> tx_buf_;
-  std::vector<uint8_t> rx_buf_;
+  // Fast inline state check for read_packet/write_protobuf_messages hot path.
+  // Returns OK only in DATA state; maps CLOSED/FAILED to BAD_STATE and any
+  // other intermediate state to WOULD_BLOCK.
+  inline APIError ESPHOME_ALWAYS_INLINE check_data_state_() const {
+    if (this->state_ == State::DATA)
+      return APIError::OK;
+    if (this->state_ == State::CLOSED || this->state_ == State::FAILED)
+      return APIError::BAD_STATE;
+    return APIError::WOULD_BLOCK;
+  }
+
+  // Backlog for unsent data when TCP send buffer is full (rarely used in production)
+  APIOverflowBuffer overflow_buf_;
+  APIBuffer rx_buf_;
 
   // Client name buffer - stores name from Hello message or initial peername
   char client_name_[CLIENT_INFO_NAME_MAX_LEN]{};
@@ -240,15 +253,17 @@ class APIFrameHelper {
   State state_{State::INITIALIZE};
   uint8_t frame_header_padding_{0};
   uint8_t frame_footer_size_{0};
-  uint8_t tx_buf_head_{0};
-  uint8_t tx_buf_tail_{0};
-  uint8_t tx_buf_count_{0};
-  // Nagle batching state for log messages. NODELAY_ON (-1) means NODELAY is enabled
-  // (immediate send). Values 1-2 count log messages in the current Nagle batch.
-  // After LOG_NAGLE_COUNT logs, we switch to NODELAY to flush and reset.
-  static constexpr int8_t NODELAY_ON = -1;
-  static constexpr int8_t LOG_NAGLE_COUNT = 2;
-  int8_t nodelay_state_{NODELAY_ON};
+  // Nagle batching counter for log messages. 0 means NODELAY is enabled (immediate send).
+  // Values 1..LOG_NAGLE_COUNT count log messages in the current Nagle batch.
+  // After LOG_NAGLE_COUNT logs, we flush by re-enabling NODELAY and resetting to 0.
+  // ESP8266 has the tightest TCP send buffer (2×MSS) and needs conservative batching.
+  // ESP32 (4×MSS+), RP2040 (8×MSS), and LibreTiny (4×MSS) can coalesce more.
+#ifdef USE_ESP8266
+  static constexpr uint8_t LOG_NAGLE_COUNT = 2;
+#else
+  static constexpr uint8_t LOG_NAGLE_COUNT = 3;
+#endif
+  uint8_t nodelay_counter_{0};
 
   // Internal helper to set TCP_NODELAY socket option
   void set_nodelay_raw_(bool enable) {

esphome/components/api/api_frame_helper_noise.cpp

@@ -19,7 +19,7 @@ namespace esphome::api {
 
 static const char *const TAG = "api.noise";
 #ifdef USE_ESP8266
-static const char PROLOGUE_INIT[] PROGMEM = "NoiseAPIInit";
+static constexpr char PROLOGUE_INIT[] PROGMEM = "NoiseAPIInit";
 #else
 static const char *const PROLOGUE_INIT = "NoiseAPIInit";
 #endif
@@ -153,8 +153,10 @@ APIError APINoiseFrameHelper::loop() {
     }
   }
 
-  // Use base class implementation for buffer sending
-  return APIFrameHelper::loop();
+  if (!this->overflow_buf_.empty()) [[unlikely]] {
+    return this->drain_overflow_and_handle_errors_();
+  }
+  return APIError::OK;
 }
 
 /** Read a packet into the rx_buf_.
@@ -194,17 +196,20 @@ APIError APINoiseFrameHelper::try_read_frame_() {
   uint16_t msg_size = (((uint16_t) rx_header_buf_[1]) << 8) | rx_header_buf_[2];
 
   // Check against size limits to prevent OOM: MAX_HANDSHAKE_SIZE for handshake, MAX_MESSAGE_SIZE for data
-  uint16_t limit = (state_ == State::DATA) ? MAX_MESSAGE_SIZE : MAX_HANDSHAKE_SIZE;
+  bool is_data = (state_ == State::DATA);
+  uint16_t limit = is_data ? MAX_MESSAGE_SIZE : MAX_HANDSHAKE_SIZE;
   if (msg_size > limit) {
     state_ = State::FAILED;
     HELPER_LOG("Bad packet: message size %u exceeds maximum %u", msg_size, limit);
-    return (state_ == State::DATA) ? APIError::BAD_DATA_PACKET : APIError::BAD_HANDSHAKE_PACKET_LEN;
+    return is_data ? APIError::BAD_DATA_PACKET : APIError::BAD_HANDSHAKE_PACKET_LEN;
   }
 
-  // Reserve space for body
-  if (this->rx_buf_.size() != msg_size) {
-    this->rx_buf_.resize(msg_size);
-  }
+  // Reserve space for body (+ null terminator in DATA state so protobuf
+  // StringRef fields can be safely null-terminated in-place after decode.
+  // During handshake, rx_buf_.size() is used in prologue construction, so
+  // the buffer must be exactly msg_size to avoid prologue mismatch.)
+  uint16_t alloc_size = msg_size + (is_data ? RX_BUF_NULL_TERMINATOR : 0);
+  this->rx_buf_.resize(alloc_size);
 
   if (rx_buf_len_ < msg_size) {
     // more data to read
@@ -255,16 +260,19 @@ APIError APINoiseFrameHelper::state_action_() {
     // ignore contents, may be used in future for flags
     // Resize for: existing prologue + 2 size bytes + frame data
     size_t old_size = this->prologue_.size();
-    this->prologue_.resize(old_size + 2 + this->rx_buf_.size());
-    this->prologue_[old_size] = (uint8_t) (this->rx_buf_.size() >> 8);
-    this->prologue_[old_size + 1] = (uint8_t) this->rx_buf_.size();
-    std::memcpy(this->prologue_.data() + old_size + 2, this->rx_buf_.data(), this->rx_buf_.size());
+    size_t rx_size = this->rx_buf_.size();
+    this->prologue_.resize(old_size + 2 + rx_size);
+    this->prologue_[old_size] = (uint8_t) (rx_size >> 8);
+    this->prologue_[old_size + 1] = (uint8_t) rx_size;
+    if (rx_size > 0) {
+      std::memcpy(this->prologue_.data() + old_size + 2, this->rx_buf_.data(), rx_size);
+    }
 
     state_ = State::SERVER_HELLO;
   }
   if (state_ == State::SERVER_HELLO) {
     // send server hello
-    const std::string &name = App.get_name();
+    const auto &name = App.get_name();
     char mac[MAC_ADDRESS_BUFFER_SIZE];
     get_mac_address_into_buffer(mac);
 
@@ -370,6 +378,7 @@ void APINoiseFrameHelper::send_explicit_handshake_reject_(const LogString *reaso
 #ifdef USE_STORE_LOG_STR_IN_FLASH
   // On ESP8266 with flash strings, we need to use PROGMEM-aware functions
   size_t reason_len = strlen_P(reinterpret_cast<PGM_P>(reason));
+  reason_len = std::min(reason_len, sizeof(data) - 1);
   if (reason_len > 0) {
     memcpy_P(data + 1, reinterpret_cast<PGM_P>(reason), reason_len);
   }
@@ -377,6 +386,7 @@ void APINoiseFrameHelper::send_explicit_handshake_reject_(const LogString *reaso
   // Normal memory access
   const char *reason_str = LOG_STR_ARG(reason);
   size_t reason_len = strlen(reason_str);
+  reason_len = std::min(reason_len, sizeof(data) - 1);
   if (reason_len > 0) {
     // NOLINTNEXTLINE(bugprone-not-null-terminated-result) - binary protocol, not a C string
     std::memcpy(data + 1, reason_str, reason_len);
@@ -392,14 +402,9 @@ void APINoiseFrameHelper::send_explicit_handshake_reject_(const LogString *reaso
   state_ = orig_state;
 }
 APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
-  APIError aerr = this->state_action_();
-  if (aerr != APIError::OK) {
+  APIError aerr = this->check_data_state_();
+  if (aerr != APIError::OK)
     return aerr;
-  }
-
-  if (this->state_ != State::DATA) {
-    return APIError::WOULD_BLOCK;
-  }
 
   aerr = this->try_read_frame_();
   if (aerr != APIError::OK)
@@ -407,7 +412,18 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
 
   NoiseBuffer mbuf;
   noise_buffer_init(mbuf);
-  noise_buffer_set_inout(mbuf, this->rx_buf_.data(), this->rx_buf_.size(), this->rx_buf_.size());
+  // read_packet() must only be called in DATA state; the extra
+  // RX_BUF_NULL_TERMINATOR byte is only allocated in DATA state
+  // (see try_read_frame_), so calling this during handshake would
+  // underflow the size calculation below.
+#ifdef ESPHOME_DEBUG_API
+  assert(this->state_ == State::DATA);
+#endif
+  // rx_buf_ has RX_BUF_NULL_TERMINATOR extra byte for null termination
+  // (only added in DATA state — see try_read_frame_), so subtract it
+  // to get the actual encrypted data size for decryption.
+  size_t encrypted_size = this->rx_buf_.size() - RX_BUF_NULL_TERMINATOR;
+  noise_buffer_set_inout(mbuf, this->rx_buf_.data(), encrypted_size, encrypted_size);
   int err = noise_cipherstate_decrypt(this->recv_cipher_, &mbuf);
   APIError decrypt_err =
       handle_noise_error_(err, LOG_STR("noise_cipherstate_decrypt"), APIError::CIPHERSTATE_DECRYPT_FAILED);
@@ -436,23 +452,10 @@ APIError APINoiseFrameHelper::read_packet(ReadPacketBuffer *buffer) {
   buffer->type = type;
   return APIError::OK;
 }
-APIError APINoiseFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
-  // Resize to include MAC space (required for Noise encryption)
-  buffer.get_buffer()->resize(buffer.get_buffer()->size() + frame_footer_size_);
-  MessageInfo msg{type, 0,
-                  static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_ - frame_footer_size_)};
-  return write_protobuf_messages(buffer, std::span<const MessageInfo>(&msg, 1));
-}
-
 APIError APINoiseFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) {
-  APIError aerr = state_action_();
-  if (aerr != APIError::OK) {
+  APIError aerr = this->check_data_state_();
+  if (aerr != APIError::OK)
     return aerr;
-  }
-
-  if (state_ != State::DATA) {
-    return APIError::WOULD_BLOCK;
-  }
 
   if (messages.empty()) {
     return APIError::OK;
@@ -474,7 +477,7 @@ APIError APINoiseFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffer, s
     // buf_start[1], buf_start[2] to be set after encryption
 
     // Write message header (to be encrypted)
-    const uint8_t msg_offset = 3;
+    constexpr uint8_t msg_offset = 3;
     buf_start[msg_offset] = static_cast<uint8_t>(msg.message_type >> 8);      // type high byte
     buf_start[msg_offset + 1] = static_cast<uint8_t>(msg.message_type);       // type low byte
     buf_start[msg_offset + 2] = static_cast<uint8_t>(msg.payload_size >> 8);  // data_len high byte
@@ -563,8 +566,7 @@ APIError APINoiseFrameHelper::init_handshake_() {
   if (aerr != APIError::OK)
     return aerr;
   // set_prologue copies it into handshakestate, so we can get rid of it now
-  // Use swap idiom to actually release memory (= {} only clears size, not capacity)
-  std::vector<uint8_t>().swap(prologue_);
+  prologue_.release();
 
   err = noise_handshakestate_start(handshake_);
   aerr = handle_noise_error_(err, LOG_STR("noise_handshakestate_start"), APIError::HANDSHAKESTATE_SETUP_FAILED);
@@ -574,7 +576,9 @@ APIError APINoiseFrameHelper::init_handshake_() {
 }
 
 APIError APINoiseFrameHelper::check_handshake_finished_() {
+#ifdef ESPHOME_DEBUG_API
   assert(state_ == State::HANDSHAKE);
+#endif
 
   int action = noise_handshakestate_get_action(handshake_);
   if (action == NOISE_ACTION_READ_MESSAGE || action == NOISE_ACTION_WRITE_MESSAGE)

esphome/components/api/api_frame_helper_noise.h

@@ -22,7 +22,6 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   APIError init() override;
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
  protected:
@@ -43,8 +42,8 @@ class APINoiseFrameHelper final : public APIFrameHelper {
   // Reference to noise context (4 bytes on 32-bit)
   APINoiseContext &ctx_;
 
-  // Vector (12 bytes on 32-bit)
-  std::vector<uint8_t> prologue_;
+  // Buffer for noise handshake prologue (released after handshake)
+  APIBuffer prologue_;
 
   // NoiseProtocolId (size depends on implementation)
   NoiseProtocolId nid_;

esphome/components/api/api_frame_helper_plaintext.cpp

@@ -64,8 +64,10 @@ APIError APIPlaintextFrameHelper::loop() {
   if (state_ != State::DATA) {
     return APIError::BAD_STATE;
   }
-  // Use base class implementation for buffer sending
-  return APIFrameHelper::loop();
+  if (!this->overflow_buf_.empty()) [[unlikely]] {
+    return this->drain_overflow_and_handle_errors_();
+  }
+  return APIError::OK;
 }
 
 /** Read a packet into the rx_buf_.
@@ -128,45 +130,44 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
 
     // Skip indicator byte at position 0
     uint8_t varint_pos = 1;
-    uint32_t consumed = 0;
 
-    auto msg_size_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos, &consumed);
+    // rx_header_buf_pos_ >= 3 and varint_pos == 1, so len >= 2
+    auto msg_size_varint = ProtoVarInt::parse_non_empty(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos);
     if (!msg_size_varint.has_value()) {
       // not enough data there yet
       continue;
     }
 
-    if (msg_size_varint->as_uint32() > MAX_MESSAGE_SIZE) {
+    if (msg_size_varint.value > MAX_MESSAGE_SIZE) {
       state_ = State::FAILED;
-      HELPER_LOG("Bad packet: message size %" PRIu32 " exceeds maximum %u", msg_size_varint->as_uint32(),
-                 MAX_MESSAGE_SIZE);
+      HELPER_LOG("Bad packet: message size %" PRIu32 " exceeds maximum %u",
+                 static_cast<uint32_t>(msg_size_varint.value), MAX_MESSAGE_SIZE);
       return APIError::BAD_DATA_PACKET;
     }
-    rx_header_parsed_len_ = msg_size_varint->as_uint16();
+    rx_header_parsed_len_ = static_cast<uint16_t>(msg_size_varint.value);
 
     // Move to next varint position
-    varint_pos += consumed;
+    varint_pos += msg_size_varint.consumed;
 
-    auto msg_type_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos, &consumed);
+    auto msg_type_varint = ProtoVarInt::parse(&rx_header_buf_[varint_pos], rx_header_buf_pos_ - varint_pos);
     if (!msg_type_varint.has_value()) {
       // not enough data there yet
       continue;
     }
-    if (msg_type_varint->as_uint32() > std::numeric_limits<uint16_t>::max()) {
+    if (msg_type_varint.value > std::numeric_limits<uint16_t>::max()) {
       state_ = State::FAILED;
-      HELPER_LOG("Bad packet: message type %" PRIu32 " exceeds maximum %u", msg_type_varint->as_uint32(),
-                 std::numeric_limits<uint16_t>::max());
+      HELPER_LOG("Bad packet: message type %" PRIu32 " exceeds maximum %u",
+                 static_cast<uint32_t>(msg_type_varint.value), std::numeric_limits<uint16_t>::max());
       return APIError::BAD_DATA_PACKET;
     }
-    rx_header_parsed_type_ = msg_type_varint->as_uint16();
+    rx_header_parsed_type_ = static_cast<uint16_t>(msg_type_varint.value);
     rx_header_parsed_ = true;
   }
   // header reading done
 
-  // Reserve space for body
-  if (this->rx_buf_.size() != this->rx_header_parsed_len_) {
-    this->rx_buf_.resize(this->rx_header_parsed_len_);
-  }
+  // Reserve space for body (+ null terminator so protobuf StringRef fields
+  // can be safely null-terminated in-place after decode)
+  this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR);
 
   if (rx_buf_len_ < rx_header_parsed_len_) {
     // more data to read
@@ -194,11 +195,11 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
 }
 
 APIError APIPlaintextFrameHelper::read_packet(ReadPacketBuffer *buffer) {
-  if (this->state_ != State::DATA) {
-    return APIError::WOULD_BLOCK;
-  }
+  APIError aerr = this->check_data_state_();
+  if (aerr != APIError::OK)
+    return aerr;
 
-  APIError aerr = this->try_read_frame_();
+  aerr = this->try_read_frame_();
   if (aerr != APIError::OK) {
     if (aerr == APIError::BAD_INDICATOR) {
       // Make sure to tell the remote that we don't
@@ -236,16 +237,11 @@ APIError APIPlaintextFrameHelper::read_packet(ReadPacketBuffer *buffer) {
   buffer->type = this->rx_header_parsed_type_;
   return APIError::OK;
 }
-APIError APIPlaintextFrameHelper::write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) {
-  MessageInfo msg{type, 0, static_cast<uint16_t>(buffer.get_buffer()->size() - frame_header_padding_)};
-  return write_protobuf_messages(buffer, std::span<const MessageInfo>(&msg, 1));
-}
-
 APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffer,
                                                           std::span<const MessageInfo> messages) {
-  if (state_ != State::DATA) {
-    return APIError::BAD_STATE;
-  }
+  APIError aerr = this->check_data_state_();
+  if (aerr != APIError::OK)
+    return aerr;
 
   if (messages.empty()) {
     return APIError::OK;
@@ -258,9 +254,11 @@ APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffe
   uint16_t total_write_len = 0;
 
   for (const auto &msg : messages) {
-    // Calculate varint sizes for header layout
-    uint8_t size_varint_len = api::ProtoSize::varint(static_cast<uint32_t>(msg.payload_size));
-    uint8_t type_varint_len = api::ProtoSize::varint(static_cast<uint32_t>(msg.message_type));
+    // Calculate varint sizes for header layout using inline ternary to avoid varint_slow call overhead
+    uint8_t size_varint_len = msg.payload_size < ProtoSize::VARINT_THRESHOLD_1_BYTE
+                                  ? 1
+                                  : (msg.payload_size < ProtoSize::VARINT_THRESHOLD_2_BYTE ? 2 : 3);
+    uint8_t type_varint_len = msg.message_type < ProtoSize::VARINT_THRESHOLD_1_BYTE ? 1 : 2;
     uint8_t total_header_len = 1 + size_varint_len + type_varint_len;
 
     // Calculate where to start writing the header
@@ -282,8 +280,8 @@ APIError APIPlaintextFrameHelper::write_protobuf_messages(ProtoWriteBuffer buffe
     //
     // Example 3 (large values): total_header_len = 6, header_offset = 6 - 6 = 0
     // [0]    - 0x00 indicator byte
-    // [1-3]  - Payload size varint (3 bytes, for sizes 16384-2097151)
-    // [4-5]  - Message type varint (2 bytes, for types 128-32767)
+    // [1-3]  - Payload size varint (3 bytes, for sizes 16384-65535)
+    // [4-5]  - Message type varint (2 bytes, for types 128-16383)
     // [6...] - Actual payload data
     //
     // The message starts at offset + frame_header_padding_

esphome/components/api/api_frame_helper_plaintext.h

@@ -19,7 +19,6 @@ class APIPlaintextFrameHelper final : public APIFrameHelper {
   APIError init() override;
   APIError loop() override;
   APIError read_packet(ReadPacketBuffer *buffer) override;
-  APIError write_protobuf_packet(uint8_t type, ProtoWriteBuffer buffer) override;
   APIError write_protobuf_messages(ProtoWriteBuffer buffer, std::span<const MessageInfo> messages) override;
 
  protected:

esphome/components/api/api_options.proto

@@ -90,4 +90,10 @@ extend google.protobuf.FieldOptions {
     //   - uint16_t <field>_length_{0};
     //   - uint16_t <field>_count_{0};
     optional bool packed_buffer = 50015 [default=false];
+
+    // force: Always encode this field, even when its value equals the proto3 default.
+    // Skips the zero/empty check in calculate_size() and encode(), using the _force
+    // variant of the calc_ method. Use on fields that are almost always non-default
+    // to eliminate dead branches on hot paths.
+    optional bool force = 50016 [default=false];
 }

esphome/components/api/api_overflow_buffer.cpp

@@ -0,0 +1,73 @@
+#include "api_overflow_buffer.h"
+#ifdef USE_API
+#include <cstring>
+
+namespace esphome::api {
+
+APIOverflowBuffer::~APIOverflowBuffer() {
+  for (auto *entry : this->queue_) {
+    if (entry != nullptr)
+      Entry::destroy(entry);
+  }
+}
+
+ssize_t APIOverflowBuffer::try_drain(socket::Socket *socket) {
+  while (this->count_ > 0) {
+    Entry *front = this->queue_[this->head_];
+
+    ssize_t sent = socket->write(front->current_data(), front->remaining());
+
+    if (sent <= 0) {
+      // -1 = error (caller checks errno for EWOULDBLOCK vs hard error)
+      // 0 = nothing sent (treat as no progress)
+      return sent;
+    }
+
+    if (static_cast<uint16_t>(sent) < front->remaining()) {
+      // Partially sent, update offset and stop
+      front->offset += static_cast<uint16_t>(sent);
+      return sent;
+    }
+
+    // Entry fully sent — free it and advance
+    Entry::destroy(front);
+    this->queue_[this->head_] = nullptr;
+    this->head_ = (this->head_ + 1) % API_MAX_SEND_QUEUE;
+    this->count_--;
+  }
+
+  return 0;  // All drained
+}
+
+bool APIOverflowBuffer::enqueue_iov(const struct iovec *iov, int iovcnt, uint16_t total_len, uint16_t skip) {
+  if (this->count_ >= API_MAX_SEND_QUEUE)
+    return false;
+
+  uint16_t buffer_size = total_len - skip;
+  // NOLINTNEXTLINE(cppcoreguidelines-owning-memory)
+  auto *entry = new Entry{new uint8_t[buffer_size], buffer_size, 0};
+  this->queue_[this->tail_] = entry;
+
+  uint16_t to_skip = skip;
+  uint16_t write_pos = 0;
+
+  for (int i = 0; i < iovcnt; i++) {
+    if (to_skip >= iov[i].iov_len) {
+      to_skip -= static_cast<uint16_t>(iov[i].iov_len);
+    } else {
+      const uint8_t *src = reinterpret_cast<uint8_t *>(iov[i].iov_base) + to_skip;
+      uint16_t len = static_cast<uint16_t>(iov[i].iov_len) - to_skip;
+      std::memcpy(entry->data + write_pos, src, len);
+      write_pos += len;
+      to_skip = 0;
+    }
+  }
+
+  this->tail_ = (this->tail_ + 1) % API_MAX_SEND_QUEUE;
+  this->count_++;
+  return true;
+}
+
+}  // namespace esphome::api
+
+#endif  // USE_API

esphome/components/api/api_overflow_buffer.h

@@ -0,0 +1,76 @@
+#pragma once
+#include <array>
+#include <cstdint>
+#include <sys/types.h>
+
+#include "esphome/core/defines.h"
+#ifdef USE_API
+
+#include "esphome/components/socket/headers.h"
+#include "esphome/components/socket/socket.h"
+#include "esphome/core/helpers.h"
+
+namespace esphome::api {
+
+/// Circular queue of heap-allocated byte buffers used as a TCP send backlog.
+///
+/// Under normal operation this buffer is **never used** — data goes straight
+/// from the frame helper to the socket.  It only fills when the LWIP TCP
+/// send buffer is full (slow client, congested network, heavy logging).
+/// The queue drains automatically on subsequent write/loop calls once the
+/// socket becomes writable again.
+///
+/// Capacity is compile-time-fixed via API_MAX_SEND_QUEUE (set from Python
+/// config).  If the queue fills completely the connection is marked failed.
+class APIOverflowBuffer {
+ public:
+  /// A single heap-allocated send-backlog entry.
+  /// Lifetime is manually managed — see destroy().
+  struct Entry {
+    uint8_t *data;
+    uint16_t size;    // Total size of the buffer
+    uint16_t offset;  // Current send offset within the buffer
+
+    uint16_t remaining() const { return this->size - this->offset; }
+    const uint8_t *current_data() const { return this->data + this->offset; }
+
+    /// Free this entry and its data buffer.
+    static ESPHOME_ALWAYS_INLINE void destroy(Entry *entry) {
+      delete[] entry->data;
+      delete entry;  // NOLINT(cppcoreguidelines-owning-memory)
+    }
+  };
+
+  ~APIOverflowBuffer();
+
+  /// True when no backlogged data is waiting.
+  bool empty() const { return this->count_ == 0; }
+
+  /// True when the queue has no room for another entry.
+  bool full() const { return this->count_ >= API_MAX_SEND_QUEUE; }
+
+  /// Number of entries currently queued.
+  uint8_t count() const { return this->count_; }
+
+  /// Try to drain queued data to the socket.
+  /// Returns bytes-written > 0 on success/partial, 0 if all drained or no progress,
+  /// -1 on error (caller must check errno to distinguish EWOULDBLOCK from hard errors).
+  /// Callers only need to act on -1; 0 and positive values both mean "no error".
+  /// Frees entries as they are fully sent.
+  ssize_t try_drain(socket::Socket *socket);
+
+  /// Enqueue unsent IOV data into the backlog.
+  /// Copies iov data starting at byte offset `skip` into a new entry.
+  /// Returns false if the queue is full (caller should fail the connection).
+  bool enqueue_iov(const struct iovec *iov, int iovcnt, uint16_t total_len, uint16_t skip);
+
+ protected:
+  std::array<Entry *, API_MAX_SEND_QUEUE> queue_{};
+  uint8_t head_{0};
+  uint8_t tail_{0};
+  uint8_t count_{0};
+};
+
+}  // namespace esphome::api
+
+#endif  // USE_API

esphome/components/api/api_pb2_defines.h

@@ -0,0 +1,12 @@
+// This file was automatically generated with a tool.
+// See script/api_protobuf/api_protobuf.py
+#pragma once
+
+#include "esphome/core/defines.h"
+#ifdef USE_BLUETOOTH_PROXY
+#ifndef USE_API_VARINT64
+#define USE_API_VARINT64
+#endif
+#endif
+
+namespace esphome::api {}  // namespace esphome::api

esphome/components/api/api_pb2_dump.cpp

@@ -13,7 +13,7 @@ namespace esphome::api {
 static inline void append_quoted_string(DumpBuffer &out, const StringRef &ref) {
   out.append("'");
   if (!ref.empty()) {
-    out.append(ref.c_str());
+    out.append(ref.c_str(), ref.size());
   }
   out.append("'");
 }
@@ -100,6 +100,18 @@ static void dump_bytes_field(DumpBuffer &out, const char *field_name, const uint
   out.append(hex_buf).append("\n");
 }
 
+template<> const char *proto_enum_to_string<enums::SerialProxyPortType>(enums::SerialProxyPortType value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_PORT_TYPE_TTL:
+      return "SERIAL_PROXY_PORT_TYPE_TTL";
+    case enums::SERIAL_PROXY_PORT_TYPE_RS232:
+      return "SERIAL_PROXY_PORT_TYPE_RS232";
+    case enums::SERIAL_PROXY_PORT_TYPE_RS485:
+      return "SERIAL_PROXY_PORT_TYPE_RS485";
+    default:
+      return "UNKNOWN";
+  }
+}
 template<> const char *proto_enum_to_string<enums::EntityCategory>(enums::EntityCategory value) {
   switch (value) {
     case enums::ENTITY_CATEGORY_NONE:
@@ -208,6 +220,20 @@ template<> const char *proto_enum_to_string<enums::LogLevel>(enums::LogLevel val
       return "UNKNOWN";
   }
 }
+template<> const char *proto_enum_to_string<enums::DSTRuleType>(enums::DSTRuleType value) {
+  switch (value) {
+    case enums::DST_RULE_TYPE_NONE:
+      return "DST_RULE_TYPE_NONE";
+    case enums::DST_RULE_TYPE_MONTH_WEEK_DAY:
+      return "DST_RULE_TYPE_MONTH_WEEK_DAY";
+    case enums::DST_RULE_TYPE_JULIAN_NO_LEAP:
+      return "DST_RULE_TYPE_JULIAN_NO_LEAP";
+    case enums::DST_RULE_TYPE_DAY_OF_YEAR:
+      return "DST_RULE_TYPE_DAY_OF_YEAR";
+    default:
+      return "UNKNOWN";
+  }
+}
 #ifdef USE_API_USER_DEFINED_ACTIONS
 template<> const char *proto_enum_to_string<enums::ServiceArgType>(enums::ServiceArgType value) {
   switch (value) {
@@ -321,6 +347,8 @@ template<> const char *proto_enum_to_string<enums::ClimateAction>(enums::Climate
       return "CLIMATE_ACTION_DRYING";
     case enums::CLIMATE_ACTION_FAN:
       return "CLIMATE_ACTION_FAN";
+    case enums::CLIMATE_ACTION_DEFROSTING:
+      return "CLIMATE_ACTION_DEFROSTING";
     default:
       return "UNKNOWN";
   }
@@ -736,6 +764,48 @@ template<> const char *proto_enum_to_string<enums::ZWaveProxyRequestType>(enums:
   }
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+template<> const char *proto_enum_to_string<enums::SerialProxyParity>(enums::SerialProxyParity value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_PARITY_NONE:
+      return "SERIAL_PROXY_PARITY_NONE";
+    case enums::SERIAL_PROXY_PARITY_EVEN:
+      return "SERIAL_PROXY_PARITY_EVEN";
+    case enums::SERIAL_PROXY_PARITY_ODD:
+      return "SERIAL_PROXY_PARITY_ODD";
+    default:
+      return "UNKNOWN";
+  }
+}
+template<> const char *proto_enum_to_string<enums::SerialProxyRequestType>(enums::SerialProxyRequestType value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE:
+      return "SERIAL_PROXY_REQUEST_TYPE_SUBSCRIBE";
+    case enums::SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE:
+      return "SERIAL_PROXY_REQUEST_TYPE_UNSUBSCRIBE";
+    case enums::SERIAL_PROXY_REQUEST_TYPE_FLUSH:
+      return "SERIAL_PROXY_REQUEST_TYPE_FLUSH";
+    default:
+      return "UNKNOWN";
+  }
+}
+template<> const char *proto_enum_to_string<enums::SerialProxyStatus>(enums::SerialProxyStatus value) {
+  switch (value) {
+    case enums::SERIAL_PROXY_STATUS_OK:
+      return "SERIAL_PROXY_STATUS_OK";
+    case enums::SERIAL_PROXY_STATUS_ASSUMED_SUCCESS:
+      return "SERIAL_PROXY_STATUS_ASSUMED_SUCCESS";
+    case enums::SERIAL_PROXY_STATUS_ERROR:
+      return "SERIAL_PROXY_STATUS_ERROR";
+    case enums::SERIAL_PROXY_STATUS_TIMEOUT:
+      return "SERIAL_PROXY_STATUS_TIMEOUT";
+    case enums::SERIAL_PROXY_STATUS_NOT_SUPPORTED:
+      return "SERIAL_PROXY_STATUS_NOT_SUPPORTED";
+    default:
+      return "UNKNOWN";
+  }
+}
+#endif
 
 const char *HelloRequest::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "HelloRequest");
@@ -785,6 +855,14 @@ const char *DeviceInfo::dump_to(DumpBuffer &out) const {
   return out.c_str();
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+const char *SerialProxyInfo::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyInfo");
+  dump_field(out, "name", this->name);
+  dump_field(out, "port_type", static_cast<enums::SerialProxyPortType>(this->port_type));
+  return out.c_str();
+}
+#endif
 const char *DeviceInfoResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "DeviceInfoResponse");
   dump_field(out, "name", this->name);
@@ -845,6 +923,13 @@ const char *DeviceInfoResponse::dump_to(DumpBuffer &out) const {
 #endif
 #ifdef USE_ZWAVE_PROXY
   dump_field(out, "zwave_home_id", this->zwave_home_id);
+#endif
+#ifdef USE_SERIAL_PROXY
+  for (const auto &it : this->serial_proxies) {
+    out.append("  serial_proxies: ");
+    it.dump_to(out);
+    out.append("\n");
+  }
 #endif
   return out.c_str();
 }
@@ -1252,10 +1337,35 @@ const char *GetTimeRequest::dump_to(DumpBuffer &out) const {
   out.append("GetTimeRequest {}");
   return out.c_str();
 }
+const char *DSTRule::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "DSTRule");
+  dump_field(out, "time_seconds", this->time_seconds);
+  dump_field(out, "day", this->day);
+  dump_field(out, "type", static_cast<enums::DSTRuleType>(this->type));
+  dump_field(out, "month", this->month);
+  dump_field(out, "week", this->week);
+  dump_field(out, "day_of_week", this->day_of_week);
+  return out.c_str();
+}
+const char *ParsedTimezone::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "ParsedTimezone");
+  dump_field(out, "std_offset_seconds", this->std_offset_seconds);
+  dump_field(out, "dst_offset_seconds", this->dst_offset_seconds);
+  out.append("  dst_start: ");
+  this->dst_start.dump_to(out);
+  out.append("\n");
+  out.append("  dst_end: ");
+  this->dst_end.dump_to(out);
+  out.append("\n");
+  return out.c_str();
+}
 const char *GetTimeResponse::dump_to(DumpBuffer &out) const {
   MessageDumpHelper helper(out, "GetTimeResponse");
   dump_field(out, "epoch_seconds", this->epoch_seconds);
   dump_field(out, "timezone", this->timezone);
+  out.append("  parsed_timezone: ");
+  this->parsed_timezone.dump_to(out);
+  out.append("\n");
   return out.c_str();
 }
 #ifdef USE_API_USER_DEFINED_ACTIONS
@@ -2469,6 +2579,78 @@ const char *InfraredRFReceiveEvent::dump_to(DumpBuffer &out) const {
   return out.c_str();
 }
 #endif
+#ifdef USE_SERIAL_PROXY
+const char *SerialProxyConfigureRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyConfigureRequest");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "baudrate", this->baudrate);
+  dump_field(out, "flow_control", this->flow_control);
+  dump_field(out, "parity", static_cast<enums::SerialProxyParity>(this->parity));
+  dump_field(out, "stop_bits", this->stop_bits);
+  dump_field(out, "data_size", this->data_size);
+  return out.c_str();
+}
+const char *SerialProxyDataReceived::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyDataReceived");
+  dump_field(out, "instance", this->instance);
+  dump_bytes_field(out, "data", this->data_ptr_, this->data_len_);
+  return out.c_str();
+}
+const char *SerialProxyWriteRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyWriteRequest");
+  dump_field(out, "instance", this->instance);
+  dump_bytes_field(out, "data", this->data, this->data_len);
+  return out.c_str();
+}
+const char *SerialProxySetModemPinsRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxySetModemPinsRequest");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "line_states", this->line_states);
+  return out.c_str();
+}
+const char *SerialProxyGetModemPinsRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyGetModemPinsRequest");
+  dump_field(out, "instance", this->instance);
+  return out.c_str();
+}
+const char *SerialProxyGetModemPinsResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyGetModemPinsResponse");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "line_states", this->line_states);
+  return out.c_str();
+}
+const char *SerialProxyRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyRequest");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "type", static_cast<enums::SerialProxyRequestType>(this->type));
+  return out.c_str();
+}
+const char *SerialProxyRequestResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "SerialProxyRequestResponse");
+  dump_field(out, "instance", this->instance);
+  dump_field(out, "type", static_cast<enums::SerialProxyRequestType>(this->type));
+  dump_field(out, "status", static_cast<enums::SerialProxyStatus>(this->status));
+  dump_field(out, "error_message", this->error_message);
+  return out.c_str();
+}
+#endif
+#ifdef USE_BLUETOOTH_PROXY
+const char *BluetoothSetConnectionParamsRequest::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "BluetoothSetConnectionParamsRequest");
+  dump_field(out, "address", this->address);
+  dump_field(out, "min_interval", this->min_interval);
+  dump_field(out, "max_interval", this->max_interval);
+  dump_field(out, "latency", this->latency);
+  dump_field(out, "timeout", this->timeout);
+  return out.c_str();
+}
+const char *BluetoothSetConnectionParamsResponse::dump_to(DumpBuffer &out) const {
+  MessageDumpHelper helper(out, "BluetoothSetConnectionParamsResponse");
+  dump_field(out, "address", this->address);
+  dump_field(out, "error", this->error);
+  return out.c_str();
+}
+#endif
 
 }  // namespace esphome::api
 

esphome/components/api/api_pb2_service.cpp

@@ -634,6 +634,72 @@ void APIServerConnectionBase::read_message(uint32_t msg_size, uint32_t msg_type,
       this->on_infrared_rf_transmit_raw_timings_request(msg);
       break;
     }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyConfigureRequest::MESSAGE_TYPE: {
+      SerialProxyConfigureRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_configure_request"), msg);
+#endif
+      this->on_serial_proxy_configure_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyWriteRequest::MESSAGE_TYPE: {
+      SerialProxyWriteRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_write_request"), msg);
+#endif
+      this->on_serial_proxy_write_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxySetModemPinsRequest::MESSAGE_TYPE: {
+      SerialProxySetModemPinsRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_set_modem_pins_request"), msg);
+#endif
+      this->on_serial_proxy_set_modem_pins_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyGetModemPinsRequest::MESSAGE_TYPE: {
+      SerialProxyGetModemPinsRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_get_modem_pins_request"), msg);
+#endif
+      this->on_serial_proxy_get_modem_pins_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_SERIAL_PROXY
+    case SerialProxyRequest::MESSAGE_TYPE: {
+      SerialProxyRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_serial_proxy_request"), msg);
+#endif
+      this->on_serial_proxy_request(msg);
+      break;
+    }
+#endif
+#ifdef USE_BLUETOOTH_PROXY
+    case BluetoothSetConnectionParamsRequest::MESSAGE_TYPE: {
+      BluetoothSetConnectionParamsRequest msg;
+      msg.decode(msg_data, msg_size);
+#ifdef HAS_PROTO_MESSAGE_DUMP
+      this->log_receive_message_(LOG_STR("on_bluetooth_set_connection_params_request"), msg);
+#endif
+      this->on_bluetooth_set_connection_params_request(msg);
+      break;
+    }
 #endif
     default:
       break;

esphome/components/api/api_pb2_service.h

@@ -19,14 +19,6 @@ class APIServerConnectionBase : public ProtoService {
  public:
 #endif
 
-  bool send_message(const ProtoMessage &msg, uint8_t message_type) {
-#ifdef HAS_PROTO_MESSAGE_DUMP
-    DumpBuffer dump_buf;
-    this->log_send_message_(msg.message_name(), msg.dump_to(dump_buf));
-#endif
-    return this->send_message_impl(msg, message_type);
-  }
-
   virtual void on_hello_request(const HelloRequest &value){};
 
   virtual void on_disconnect_request(){};
@@ -224,6 +216,28 @@ class APIServerConnectionBase : public ProtoService {
   virtual void on_infrared_rf_transmit_raw_timings_request(const InfraredRFTransmitRawTimingsRequest &value){};
 #endif
 
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_configure_request(const SerialProxyConfigureRequest &value){};
+#endif
+
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_write_request(const SerialProxyWriteRequest &value){};
+#endif
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_set_modem_pins_request(const SerialProxySetModemPinsRequest &value){};
+#endif
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_get_modem_pins_request(const SerialProxyGetModemPinsRequest &value){};
+#endif
+
+#ifdef USE_SERIAL_PROXY
+  virtual void on_serial_proxy_request(const SerialProxyRequest &value){};
+#endif
+
+#ifdef USE_BLUETOOTH_PROXY
+  virtual void on_bluetooth_set_connection_params_request(const BluetoothSetConnectionParamsRequest &value){};
+#endif
+
  protected:
   void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) override;
 };

esphome/components/api/api_server.cpp

@@ -28,10 +28,12 @@ static const char *const TAG = "api";
 // APIServer
 APIServer *global_api_server = nullptr;  // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
 
-APIServer::APIServer() {
-  global_api_server = this;
-  // Pre-allocate shared write buffer
-  shared_write_buffer_.reserve(64);
+APIServer::APIServer() { global_api_server = this; }
+
+void APIServer::socket_failed_(const LogString *msg) {
+  ESP_LOGW(TAG, "Socket %s: errno %d", LOG_STR_ARG(msg), errno);
+  this->destroy_socket_();
+  this->mark_failed();
 }
 
 void APIServer::setup() {
@@ -52,22 +54,20 @@ void APIServer::setup() {
 #endif
 #endif
 
-  this->socket_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0);  // monitored for incoming connections
+  this->socket_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0).release();  // monitored for incoming connections
   if (this->socket_ == nullptr) {
-    ESP_LOGW(TAG, "Could not create socket");
-    this->mark_failed();
+    this->socket_failed_(LOG_STR("creation"));
     return;
   }
   int enable = 1;
   int err = this->socket_->setsockopt(SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int));
   if (err != 0) {
-    ESP_LOGW(TAG, "Socket unable to set reuseaddr: errno %d", err);
+    ESP_LOGW(TAG, "Socket reuseaddr: errno %d", errno);
     // we can still continue
   }
   err = this->socket_->setblocking(false);
   if (err != 0) {
-    ESP_LOGW(TAG, "Socket unable to set nonblocking mode: errno %d", err);
-    this->mark_failed();
+    this->socket_failed_(LOG_STR("nonblocking"));
     return;
   }
 
@@ -75,28 +75,28 @@ void APIServer::setup() {
 
   socklen_t sl = socket::set_sockaddr_any((struct sockaddr *) &server, sizeof(server), this->port_);
   if (sl == 0) {
-    ESP_LOGW(TAG, "Socket unable to set sockaddr: errno %d", errno);
-    this->mark_failed();
+    this->socket_failed_(LOG_STR("set sockaddr"));
     return;
   }
 
   err = this->socket_->bind((struct sockaddr *) &server, sl);
   if (err != 0) {
-    ESP_LOGW(TAG, "Socket unable to bind: errno %d", errno);
-    this->mark_failed();
+    this->socket_failed_(LOG_STR("bind"));
     return;
   }
 
   err = this->socket_->listen(this->listen_backlog_);
   if (err != 0) {
-    ESP_LOGW(TAG, "Socket unable to listen: errno %d", errno);
-    this->mark_failed();
+    this->socket_failed_(LOG_STR("listen"));
     return;
   }
 
 #ifdef USE_LOGGER
   if (logger::global_logger != nullptr) {
-    logger::global_logger->add_log_listener(this);
+    logger::global_logger->add_log_callback(
+        this, [](void *self, uint8_t level, const char *tag, const char *message, size_t message_len) {
+          static_cast<APIServer *>(self)->on_log(level, tag, message, message_len);
+        });
   }
 #endif
 
@@ -199,7 +199,7 @@ void APIServer::remove_client_(size_t client_index) {
 #endif
 }
 
-void APIServer::accept_new_connections_() {
+void __attribute__((flatten)) APIServer::accept_new_connections_() {
   while (true) {
     struct sockaddr_storage source_addr;
     socklen_t addr_len = sizeof(source_addr);
@@ -359,11 +359,11 @@ void APIServer::on_update(update::UpdateEntity *obj) {
 #endif
 
 #ifdef USE_ZWAVE_PROXY
-void APIServer::on_zwave_proxy_request(const esphome::api::ProtoMessage &msg) {
+void APIServer::on_zwave_proxy_request(const ZWaveProxyRequest &msg) {
   // We could add code to manage a second subscription type, but, since this message type is
   //  very infrequent and small, we simply send it to all clients
   for (auto &c : this->clients_)
-    c->send_message(msg, api::ZWaveProxyRequest::MESSAGE_TYPE);
+    c->send_message(msg);
 }
 #endif
 
@@ -433,8 +433,8 @@ void APIServer::handle_action_response(uint32_t call_id, bool success, StringRef
 
 #ifdef USE_API_HOMEASSISTANT_STATES
 // Helper to add subscription (reduces duplication)
-void APIServer::add_state_subscription_(const char *entity_id, const char *attribute, std::function<void(StringRef)> f,
-                                        bool once) {
+void APIServer::add_state_subscription_(const char *entity_id, const char *attribute,
+                                        std::function<void(StringRef)> &&f, bool once) {
   this->state_subs_.push_back(HomeAssistantStateSubscription{
       .entity_id = entity_id, .attribute = attribute, .callback = std::move(f), .once = once,
       // entity_id_dynamic_storage and attribute_dynamic_storage remain nullptr (no heap allocation)
@@ -443,7 +443,7 @@ void APIServer::add_state_subscription_(const char *entity_id, const char *attri
 
 // Helper to add subscription with heap-allocated strings (reduces duplication)
 void APIServer::add_state_subscription_(std::string entity_id, optional<std::string> attribute,
-                                        std::function<void(StringRef)> f, bool once) {
+                                        std::function<void(StringRef)> &&f, bool once) {
   HomeAssistantStateSubscription sub;
   // Allocate heap storage for the strings
   sub.entity_id_dynamic_storage = std::make_unique<std::string>(std::move(entity_id));
@@ -463,29 +463,29 @@ void APIServer::add_state_subscription_(std::string entity_id, optional<std::str
 
 // New const char* overload (for internal components - zero allocation)
 void APIServer::subscribe_home_assistant_state(const char *entity_id, const char *attribute,
-                                               std::function<void(StringRef)> f) {
+                                               std::function<void(StringRef)> &&f) {
   this->add_state_subscription_(entity_id, attribute, std::move(f), false);
 }
 
 void APIServer::get_home_assistant_state(const char *entity_id, const char *attribute,
-                                         std::function<void(StringRef)> f) {
+                                         std::function<void(StringRef)> &&f) {
   this->add_state_subscription_(entity_id, attribute, std::move(f), true);
 }
 
 // std::string overload with StringRef callback (zero-allocation callback)
 void APIServer::subscribe_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                               std::function<void(StringRef)> f) {
+                                               std::function<void(StringRef)> &&f) {
   this->add_state_subscription_(std::move(entity_id), std::move(attribute), std::move(f), false);
 }
 
 void APIServer::get_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                         std::function<void(StringRef)> f) {
+                                         std::function<void(StringRef)> &&f) {
   this->add_state_subscription_(std::move(entity_id), std::move(attribute), std::move(f), true);
 }
 
 // Legacy helper: wraps std::string callback and delegates to StringRef version
 void APIServer::add_state_subscription_(std::string entity_id, optional<std::string> attribute,
-                                        std::function<void(const std::string &)> f, bool once) {
+                                        std::function<void(const std::string &)> &&f, bool once) {
   // Wrap callback to convert StringRef -> std::string, then delegate
   this->add_state_subscription_(std::move(entity_id), std::move(attribute),
                                 std::function<void(StringRef)>([f = std::move(f)](StringRef state) { f(state.str()); }),
@@ -494,12 +494,12 @@ void APIServer::add_state_subscription_(std::string entity_id, optional<std::str
 
 // Legacy std::string overload (for custom_api_device.h - converts StringRef to std::string)
 void APIServer::subscribe_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                               std::function<void(const std::string &)> f) {
+                                               std::function<void(const std::string &)> &&f) {
   this->add_state_subscription_(std::move(entity_id), std::move(attribute), std::move(f), false);
 }
 
 void APIServer::get_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                         std::function<void(const std::string &)> f) {
+                                         std::function<void(const std::string &)> &&f) {
   this->add_state_subscription_(std::move(entity_id), std::move(attribute), std::move(f), true);
 }
 
@@ -531,7 +531,7 @@ bool APIServer::update_noise_psk_(const SavedNoisePsk &new_psk, const LogString
       this->set_noise_psk(active_psk);
       for (auto &c : this->clients_) {
         DisconnectRequest req;
-        c->send_message(req, DisconnectRequest::MESSAGE_TYPE);
+        c->send_message(req);
       }
     });
   }
@@ -582,11 +582,7 @@ void APIServer::request_time() {
 }
 #endif
 
-bool APIServer::is_connected(bool state_subscription_only) const {
-  if (!state_subscription_only) {
-    return !this->clients_.empty();
-  }
-
+bool APIServer::is_connected_with_state_subscription() const {
   for (const auto &client : this->clients_) {
     if (client->flags_.state_subscription) {
       return true;
@@ -623,10 +619,7 @@ void APIServer::on_shutdown() {
   this->shutting_down_ = true;
 
   // Close the listening socket to prevent new connections
-  if (this->socket_) {
-    this->socket_->close();
-    this->socket_ = nullptr;
-  }
+  this->destroy_socket_();
 
   // Change batch delay to 5ms for quick flushing during shutdown
   this->batch_delay_ = 5;
@@ -634,7 +627,7 @@ void APIServer::on_shutdown() {
   // Send disconnect requests to all connected clients
   for (auto &c : this->clients_) {
     DisconnectRequest req;
-    if (!c->send_message(req, DisconnectRequest::MESSAGE_TYPE)) {
+    if (!c->send_message(req)) {
       // If we can't send the disconnect request directly (tx_buffer full),
       // schedule it at the front of the batch so it will be sent with priority
       c->schedule_message_front_(nullptr, DisconnectRequest::MESSAGE_TYPE, DisconnectRequest::ESTIMATED_SIZE);

esphome/components/api/api_server.h

@@ -2,6 +2,7 @@
 
 #include "esphome/core/defines.h"
 #ifdef USE_API
+#include "api_buffer.h"
 #include "api_noise_context.h"
 #include "api_pb2.h"
 #include "api_pb2_service.h"
@@ -35,15 +36,11 @@ struct SavedNoisePsk {
 } PACKED;  // NOLINT
 #endif
 
-class APIServer : public Component,
-                  public Controller
-#ifdef USE_LOGGER
-    ,
-                  public logger::LogListener
-#endif
+class APIServer final : public Component,
+                        public Controller
 #ifdef USE_CAMERA
     ,
-                  public camera::CameraListener
+                        public camera::CameraListener
 #endif
 {
  public:
@@ -56,7 +53,7 @@ class APIServer : public Component,
   void on_shutdown() override;
   bool teardown() override;
 #ifdef USE_LOGGER
-  void on_log(uint8_t level, const char *tag, const char *message, size_t message_len) override;
+  void on_log(uint8_t level, const char *tag, const char *message, size_t message_len);
 #endif
 #ifdef USE_CAMERA
   void on_camera_image(const std::shared_ptr<camera::CameraImage> &image) override;
@@ -69,7 +66,7 @@ class APIServer : public Component,
   void set_max_connections(uint8_t max_connections) { this->max_connections_ = max_connections; }
 
   // Get reference to shared buffer for API connections
-  std::vector<uint8_t> &get_shared_buffer_ref() { return shared_write_buffer_; }
+  APIBuffer &get_shared_buffer_ref() { return shared_write_buffer_; }
 
 #ifdef USE_API_NOISE
   bool save_noise_psk(psk_t psk, bool make_active = true);
@@ -183,13 +180,14 @@ class APIServer : public Component,
   void on_update(update::UpdateEntity *obj) override;
 #endif
 #ifdef USE_ZWAVE_PROXY
-  void on_zwave_proxy_request(const esphome::api::ProtoMessage &msg);
+  void on_zwave_proxy_request(const ZWaveProxyRequest &msg);
 #endif
 #ifdef USE_IR_RF
   void send_infrared_rf_receive_event(uint32_t device_id, uint32_t key, const std::vector<int32_t> *timings);
 #endif
 
-  bool is_connected(bool state_subscription_only = false) const;
+  bool is_connected() const { return !this->clients_.empty(); }
+  bool is_connected_with_state_subscription() const;
 
 #ifdef USE_API_HOMEASSISTANT_STATES
   struct HomeAssistantStateSubscription {
@@ -205,20 +203,20 @@ class APIServer : public Component,
   };
 
   // New const char* overload (for internal components - zero allocation)
-  void subscribe_home_assistant_state(const char *entity_id, const char *attribute, std::function<void(StringRef)> f);
-  void get_home_assistant_state(const char *entity_id, const char *attribute, std::function<void(StringRef)> f);
+  void subscribe_home_assistant_state(const char *entity_id, const char *attribute, std::function<void(StringRef)> &&f);
+  void get_home_assistant_state(const char *entity_id, const char *attribute, std::function<void(StringRef)> &&f);
 
   // std::string overload with StringRef callback (for custom_api_device.h with zero-allocation callback)
   void subscribe_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                      std::function<void(StringRef)> f);
+                                      std::function<void(StringRef)> &&f);
   void get_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                std::function<void(StringRef)> f);
+                                std::function<void(StringRef)> &&f);
 
   // Legacy std::string overload (for custom_api_device.h - converts StringRef to std::string for callback)
   void subscribe_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                      std::function<void(const std::string &)> f);
+                                      std::function<void(const std::string &)> &&f);
   void get_home_assistant_state(std::string entity_id, optional<std::string> attribute,
-                                std::function<void(const std::string &)> f);
+                                std::function<void(const std::string &)> &&f);
 
   const std::vector<HomeAssistantStateSubscription> &get_state_subs() const;
 #endif
@@ -245,16 +243,23 @@ class APIServer : public Component,
 #endif  // USE_API_NOISE
 #ifdef USE_API_HOMEASSISTANT_STATES
   // Helper methods to reduce code duplication
-  void add_state_subscription_(const char *entity_id, const char *attribute, std::function<void(StringRef)> f,
-                               bool once);
-  void add_state_subscription_(std::string entity_id, optional<std::string> attribute, std::function<void(StringRef)> f,
+  void add_state_subscription_(const char *entity_id, const char *attribute, std::function<void(StringRef)> &&f,
                                bool once);
+  void add_state_subscription_(std::string entity_id, optional<std::string> attribute,
+                               std::function<void(StringRef)> &&f, bool once);
   // Legacy helper: wraps std::string callback and delegates to StringRef version
   void add_state_subscription_(std::string entity_id, optional<std::string> attribute,
-                               std::function<void(const std::string &)> f, bool once);
+                               std::function<void(const std::string &)> &&f, bool once);
 #endif  // USE_API_HOMEASSISTANT_STATES
+  // No explicit close() needed — listen sockets have no active connections on
+  // failure/shutdown. Destructor handles fd cleanup (close or abort per platform).
+  inline void destroy_socket_() {
+    delete this->socket_;
+    this->socket_ = nullptr;
+  }
+  void socket_failed_(const LogString *msg);
   // Pointers and pointer-like types first (4 bytes each)
-  std::unique_ptr<socket::Socket> socket_ = nullptr;
+  socket::ListenSocket *socket_{nullptr};
 #ifdef USE_API_CLIENT_CONNECTED_TRIGGER
   Trigger<std::string, std::string> client_connected_trigger_;
 #endif
@@ -268,7 +273,11 @@ class APIServer : public Component,
 
   // Vectors and strings (12 bytes each on 32-bit)
   std::vector<std::unique_ptr<APIConnection>> clients_;
-  std::vector<uint8_t> shared_write_buffer_;  // Shared proto write buffer for all connections
+  // Shared proto write buffer for all connections.
+  // Not pre-allocated: all send paths call prepare_first_message_buffer() which
+  // reserves the exact needed size. Pre-allocating here would cause heap fragmentation
+  // since the buffer would almost always reallocate on first use.
+  APIBuffer shared_write_buffer_;
 #ifdef USE_API_HOMEASSISTANT_STATES
   std::vector<HomeAssistantStateSubscription> state_subs_;
 #endif
@@ -316,7 +325,10 @@ template<typename... Ts> class APIConnectedCondition : public Condition<Ts...> {
   TEMPLATABLE_VALUE(bool, state_subscription_only)
  public:
   bool check(const Ts &...x) override {
-    return global_api_server->is_connected(this->state_subscription_only_.value(x...));
+    if (this->state_subscription_only_.value(x...)) {
+      return global_api_server->is_connected_with_state_subscription();
+    }
+    return global_api_server->is_connected();
   }
 };
 

esphome/components/api/client.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import asyncio
 from datetime import datetime
+import importlib
 import logging
 from typing import TYPE_CHECKING, Any
 import warnings
@@ -18,6 +19,7 @@ import contextlib
 
 from esphome.const import CONF_KEY, CONF_PORT, __version__
 from esphome.core import CORE
+from esphome.platformio_api import process_stacktrace
 
 from . import CONF_ENCRYPTION
 
@@ -55,9 +57,19 @@ async def async_run_logs(config: dict[str, Any], addresses: list[str]) -> None:
         addresses=addresses,  # Pass all addresses for automatic retry
     )
     dashboard = CORE.dashboard
+    backtrace_state = False
+
+    # Try platform-specific stacktrace handler first, fall back to generic
+    platform_process_stacktrace = None
+    try:
+        module = importlib.import_module("esphome.components." + CORE.target_platform)
+        platform_process_stacktrace = getattr(module, "process_stacktrace")
+    except (AttributeError, ImportError):
+        pass
 
     def on_log(msg: SubscribeLogsResponse) -> None:
         """Handle a new log message."""
+        nonlocal backtrace_state
         time_ = datetime.now()
         message: bytes = msg.message
         text = message.decode("utf8", "backslashreplace")
@@ -67,6 +79,15 @@ async def async_run_logs(config: dict[str, Any], addresses: list[str]) -> None:
         )
         for parsed_msg in parse_log_message(text, timestamp):
             print(parsed_msg.replace("\033", "\\033") if dashboard else parsed_msg)
+        for raw_line in text.splitlines():
+            if platform_process_stacktrace:
+                backtrace_state = platform_process_stacktrace(
+                    config, raw_line, backtrace_state
+                )
+            else:
+                backtrace_state = process_stacktrace(
+                    config, raw_line, backtrace_state=backtrace_state
+                )
 
     stop = await async_run(cli, on_log, name=name)
     try:

esphome/components/api/custom_api_device.h

@@ -136,8 +136,9 @@ class CustomAPIDevice {
   template<typename T>
   void subscribe_homeassistant_state(void (T::*callback)(StringRef), const std::string &entity_id,
                                      const std::string &attribute = "") {
-    auto f = std::bind(callback, (T *) this, std::placeholders::_1);
-    global_api_server->subscribe_home_assistant_state(entity_id, optional<std::string>(attribute), std::move(f));
+    auto *obj = static_cast<T *>(this);
+    global_api_server->subscribe_home_assistant_state(entity_id, optional<std::string>(attribute),
+                                                      [obj, callback](StringRef state) { (obj->*callback)(state); });
   }
 
   /** Subscribe to the state (or attribute state) of an entity from Home Assistant (legacy std::string version).
@@ -148,10 +149,12 @@ class CustomAPIDevice {
   ESPDEPRECATED("Use void callback(StringRef) instead. Will be removed in 2027.1.0.", "2026.1.0")
   void subscribe_homeassistant_state(void (T::*callback)(std::string), const std::string &entity_id,
                                      const std::string &attribute = "") {
-    auto f = std::bind(callback, (T *) this, std::placeholders::_1);
+    auto *obj = static_cast<T *>(this);
     // Explicit type to disambiguate overload resolution
-    global_api_server->subscribe_home_assistant_state(entity_id, optional<std::string>(attribute),
-                                                      std::function<void(const std::string &)>(f));
+    global_api_server->subscribe_home_assistant_state(
+        entity_id, optional<std::string>(attribute),
+        std::function<void(const std::string &)>(
+            [obj, callback](const std::string &state) { (obj->*callback)(state); }));
   }
 
   /** Subscribe to the state (or attribute state) of an entity from Home Assistant.
@@ -176,8 +179,10 @@ class CustomAPIDevice {
   template<typename T>
   void subscribe_homeassistant_state(void (T::*callback)(const std::string &, StringRef), const std::string &entity_id,
                                      const std::string &attribute = "") {
-    auto f = std::bind(callback, (T *) this, entity_id, std::placeholders::_1);
-    global_api_server->subscribe_home_assistant_state(entity_id, optional<std::string>(attribute), std::move(f));
+    auto *obj = static_cast<T *>(this);
+    global_api_server->subscribe_home_assistant_state(
+        entity_id, optional<std::string>(attribute),
+        [obj, callback, entity_id](StringRef state) { (obj->*callback)(entity_id, state); });
   }
 
   /** Subscribe to the state (or attribute state) of an entity from Home Assistant (legacy std::string version).
@@ -188,10 +193,12 @@ class CustomAPIDevice {
   ESPDEPRECATED("Use void callback(const std::string &, StringRef) instead. Will be removed in 2027.1.0.", "2026.1.0")
   void subscribe_homeassistant_state(void (T::*callback)(std::string, std::string), const std::string &entity_id,
                                      const std::string &attribute = "") {
-    auto f = std::bind(callback, (T *) this, entity_id, std::placeholders::_1);
+    auto *obj = static_cast<T *>(this);
     // Explicit type to disambiguate overload resolution
-    global_api_server->subscribe_home_assistant_state(entity_id, optional<std::string>(attribute),
-                                                      std::function<void(const std::string &)>(f));
+    global_api_server->subscribe_home_assistant_state(
+        entity_id, optional<std::string>(attribute),
+        std::function<void(const std::string &)>(
+            [obj, callback, entity_id](const std::string &state) { (obj->*callback)(entity_id, state); }));
   }
 #else
   template<typename T>

esphome/components/api/homeassistant_service.h

@@ -36,6 +36,8 @@ template<typename... X> class TemplatableStringValue : public TemplatableValue<s
   static std::string value_to_string(const char *val) { return std::string(val); }  // For lambdas returning .c_str()
   static std::string value_to_string(const std::string &val) { return val; }
   static std::string value_to_string(std::string &&val) { return std::move(val); }
+  static std::string value_to_string(const StringRef &val) { return val.str(); }
+  static std::string value_to_string(StringRef &&val) { return val.str(); }
 
  public:
   TemplatableStringValue() : TemplatableValue<std::string, X...>() {}
@@ -128,6 +130,20 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
     this->add_kv_(this->variables_, key, std::forward<V>(value));
   }
 
+#ifdef USE_ESP8266
+  // On ESP8266, ESPHOME_F() returns __FlashStringHelper* (PROGMEM pointer).
+  // Store as const char* — populate_service_map copies from PROGMEM at play() time.
+  template<typename V> void add_data(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_data_template(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->data_template_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+  template<typename V> void add_variable(const __FlashStringHelper *key, V &&value) {
+    this->add_kv_(this->variables_, reinterpret_cast<const char *>(key), std::forward<V>(value));
+  }
+#endif
+
 #ifdef USE_API_HOMEASSISTANT_ACTION_RESPONSES
   template<typename T> void set_response_template(T response_template) {
     this->response_template_ = response_template;
@@ -219,7 +235,32 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
                                    Ts... x) {
     dest.init(source.size());
 
-    // Count non-static strings to allocate exact storage needed
+#ifdef USE_ESP8266
+    // On ESP8266, all static strings from codegen are FLASH_STRING (PROGMEM),
+    // so is_static_string() is always false — the zero-copy STATIC_STRING fast
+    // path from the non-ESP8266 branch cannot trigger. We copy all keys and
+    // values unconditionally: keys via _P functions (may be in PROGMEM), values
+    // via value() which handles FLASH_STRING internally.
+    value_storage.init(source.size() * 2);
+
+    for (auto &it : source) {
+      auto &kv = dest.emplace_back();
+
+      // Key: copy from possible PROGMEM
+      {
+        size_t key_len = strlen_P(it.key);
+        value_storage.push_back(std::string(key_len, '\0'));
+        memcpy_P(value_storage.back().data(), it.key, key_len);
+        kv.key = StringRef(value_storage.back());
+      }
+
+      // Value: value() handles FLASH_STRING via _P functions internally
+      value_storage.push_back(it.value.value(x...));
+      kv.value = StringRef(value_storage.back());
+    }
+#else
+    // On non-ESP8266, strings are directly readable from flash-mapped memory.
+    // Count non-static strings to allocate exact storage needed.
     size_t lambda_count = 0;
     for (const auto &it : source) {
       if (!it.value.is_static_string()) {
@@ -233,14 +274,15 @@ template<typename... Ts> class HomeAssistantServiceCallAction : public Action<Ts
       kv.key = StringRef(it.key);
 
       if (it.value.is_static_string()) {
-        // Static string from YAML - zero allocation
+        // Static string — pointer directly readable, zero allocation
         kv.value = StringRef(it.value.get_static_string());
       } else {
-        // Lambda evaluation - store result, reference it
+        // Lambda — evaluate and store result
         value_storage.push_back(it.value.value(x...));
         kv.value = StringRef(value_storage.back());
       }
     }
+#endif
   }
 
   APIServer *parent_;

esphome/components/api/list_entities.cpp

@@ -94,7 +94,7 @@ ListEntitiesIterator::ListEntitiesIterator(APIConnection *client) : client_(clie
 #ifdef USE_API_USER_DEFINED_ACTIONS
 bool ListEntitiesIterator::on_service(UserServiceDescriptor *service) {
   auto resp = service->encode_list_service_response();
-  return this->client_->send_message(resp, ListEntitiesServicesResponse::MESSAGE_TYPE);
+  return this->client_->send_message(resp);
 }
 #endif
 

esphome/components/api/list_entities.h

@@ -15,7 +15,7 @@ class APIConnection;
     return this->client_->schedule_message_(entity, ResponseType::MESSAGE_TYPE, ResponseType::ESTIMATED_SIZE); \
   }
 
-class ListEntitiesIterator : public ComponentIterator {
+class ListEntitiesIterator final : public ComponentIterator {
  public:
   ListEntitiesIterator(APIConnection *client);
 #ifdef USE_BINARY_SENSOR

esphome/components/api/proto.cpp

@@ -1,5 +1,6 @@
 #include "proto.h"
 #include <cinttypes>
+#include <cstring>
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 
@@ -7,24 +8,71 @@ namespace esphome::api {
 
 static const char *const TAG = "api.proto";
 
+uint32_t ProtoSize::varint_slow(uint32_t value) { return varint_wide(value); }
+
+void ProtoWriteBuffer::encode_varint_raw_slow_(uint32_t value) {
+  do {
+    this->debug_check_bounds_(1);
+    *this->pos_++ = static_cast<uint8_t>(value | 0x80);
+    value >>= 7;
+  } while (value > 0x7F);
+  this->debug_check_bounds_(1);
+  *this->pos_++ = static_cast<uint8_t>(value);
+}
+
+ProtoVarIntResult ProtoVarInt::parse_slow(const uint8_t *buffer, uint32_t len) {
+  // Multi-byte varint: first byte already checked to have high bit set
+  uint32_t result32 = buffer[0] & 0x7F;
+#ifdef USE_API_VARINT64
+  uint32_t limit = std::min(len, uint32_t(4));
+#else
+  uint32_t limit = std::min(len, uint32_t(5));
+#endif
+  for (uint32_t i = 1; i < limit; i++) {
+    uint8_t val = buffer[i];
+    result32 |= uint32_t(val & 0x7F) << (i * 7);
+    if ((val & 0x80) == 0) {
+      return {result32, i + 1};
+    }
+  }
+#ifdef USE_API_VARINT64
+  return parse_wide(buffer, len, result32);
+#else
+  return {0, PROTO_VARINT_PARSE_FAILED};
+#endif
+}
+
+#ifdef USE_API_VARINT64
+ProtoVarIntResult ProtoVarInt::parse_wide(const uint8_t *buffer, uint32_t len, uint32_t result32) {
+  uint64_t result64 = result32;
+  uint32_t limit = std::min(len, uint32_t(10));
+  for (uint32_t i = 4; i < limit; i++) {
+    uint8_t val = buffer[i];
+    result64 |= uint64_t(val & 0x7F) << (i * 7);
+    if ((val & 0x80) == 0) {
+      return {result64, i + 1};
+    }
+  }
+  return {0, PROTO_VARINT_PARSE_FAILED};
+}
+#endif
+
 uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id) {
   uint32_t count = 0;
   const uint8_t *ptr = buffer;
   const uint8_t *end = buffer + length;
 
   while (ptr < end) {
-    uint32_t consumed;
-
-    // Parse field header (tag)
-    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+    // Parse field header (tag) - ptr < end guarantees len >= 1
+    auto res = ProtoVarInt::parse_non_empty(ptr, end - ptr);
     if (!res.has_value()) {
       break;  // Invalid data, stop counting
     }
 
-    uint32_t tag = res->as_uint32();
+    uint32_t tag = static_cast<uint32_t>(res.value);
     uint32_t field_type = tag & WIRE_TYPE_MASK;
     uint32_t field_id = tag >> 3;
-    ptr += consumed;
+    ptr += res.consumed;
 
     // Count if this is the target field
     if (field_id == target_field_id) {
@@ -34,20 +82,20 @@ uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size
     // Skip field data based on wire type
     switch (field_type) {
       case WIRE_TYPE_VARINT: {  // VarInt - parse and skip
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           return count;  // Invalid data, return what we have
         }
-        ptr += consumed;
+        ptr += res.consumed;
         break;
       }
       case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited - parse length and skip data
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           return count;
         }
-        uint32_t field_length = res->as_uint32();
-        ptr += consumed;
+        uint32_t field_length = static_cast<uint32_t>(res.value);
+        ptr += res.consumed;
         if (field_length > static_cast<size_t>(end - ptr)) {
           return count;  // Out of bounds
         }
@@ -70,46 +118,130 @@ uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size
   return count;
 }
 
+// Single-pass encode for repeated submessage elements (non-template core).
+// Writes field tag, reserves 1 byte for length varint, encodes the submessage body,
+// then backpatches the actual length. For the common case (body < 128 bytes), this is
+// just a single byte write with no memmove — all current repeated submessage types
+// (BLE advertisements at ~47B, GATT descriptors at ~24B, service args, etc.) take
+// this fast path.
+//
+// The memmove fallback for body >= 128 bytes exists only for correctness (e.g., a GATT
+// characteristic with many descriptors). It is safe because calculate_size() already
+// reserved space for the full multi-byte varint — the shift fills that reserved space:
+//
+//   calculate_size() allocates per element: tag + varint_size(body) + body_size
+//
+//   After encode, before memmove (1 byte reserved, body written):
+//   [tag][__][body ..... body][??]
+//         ^                   ^-- unused byte (v2 space from calculate_size)
+//         len_pos
+//
+//   After memmove(body_start+1, body_start, body_size):
+//   [tag][__][__][body ..... body]
+//         ^       ^-- body shifted forward, fills v2 space exactly
+//         len_pos
+//
+//   After writing 2-byte varint at len_pos:
+//   [tag][v1][v2][body ..... body]
+//                                ^-- pos_ = element end, within buffer
+void ProtoWriteBuffer::encode_sub_message(uint32_t field_id, const void *value,
+                                          void (*encode_fn)(const void *, ProtoWriteBuffer &)) {
+  this->encode_field_raw(field_id, 2);
+  // Reserve 1 byte for length varint (optimistic: submessage < 128 bytes)
+  uint8_t *len_pos = this->pos_;
+  this->debug_check_bounds_(1);
+  this->pos_++;
+  uint8_t *body_start = this->pos_;
+  encode_fn(value, *this);
+  uint32_t body_size = static_cast<uint32_t>(this->pos_ - body_start);
+  if (body_size < 128) [[likely]] {
+    // Common case: 1-byte varint, just backpatch
+    *len_pos = static_cast<uint8_t>(body_size);
+    return;
+  }
+  // Compute extra bytes needed for varint beyond the 1 already reserved
+  uint8_t extra = ProtoSize::varint(body_size) - 1;
+  // Shift body forward to make room for the extra varint bytes
+  this->debug_check_bounds_(extra);
+  std::memmove(body_start + extra, body_start, body_size);
+  uint8_t *end = this->pos_ + extra;
+  // Write the full varint at len_pos
+  this->pos_ = len_pos;
+  this->encode_varint_raw(body_size);
+  this->pos_ = end;
+}
+
+// Non-template core for encode_optional_sub_message.
+void ProtoWriteBuffer::encode_optional_sub_message(uint32_t field_id, uint32_t nested_size, const void *value,
+                                                   void (*encode_fn)(const void *, ProtoWriteBuffer &)) {
+  if (nested_size == 0)
+    return;
+  this->encode_field_raw(field_id, 2);
+  this->encode_varint_raw(nested_size);
+#ifdef ESPHOME_DEBUG_API
+  uint8_t *start = this->pos_;
+  encode_fn(value, *this);
+  if (static_cast<uint32_t>(this->pos_ - start) != nested_size)
+    this->debug_check_encode_size_(field_id, nested_size, this->pos_ - start);
+#else
+  encode_fn(value, *this);
+#endif
+}
+
+#ifdef ESPHOME_DEBUG_API
+void ProtoWriteBuffer::debug_check_bounds_(size_t bytes, const char *caller) {
+  if (this->pos_ + bytes > this->buffer_->data() + this->buffer_->size()) {
+    ESP_LOGE(TAG, "ProtoWriteBuffer bounds check failed in %s: bytes=%zu offset=%td buf_size=%zu", caller, bytes,
+             this->pos_ - this->buffer_->data(), this->buffer_->size());
+    abort();
+  }
+}
+void ProtoWriteBuffer::debug_check_encode_size_(uint32_t field_id, uint32_t expected, ptrdiff_t actual) {
+  ESP_LOGE(TAG, "encode_message: size mismatch for field %" PRIu32 ": calculated=%" PRIu32 " actual=%td", field_id,
+           expected, actual);
+  abort();
+}
+#endif
+
 void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
   const uint8_t *ptr = buffer;
   const uint8_t *end = buffer + length;
 
   while (ptr < end) {
-    uint32_t consumed;
-
-    // Parse field header
-    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+    // Parse field header - ptr < end guarantees len >= 1
+    auto res = ProtoVarInt::parse_non_empty(ptr, end - ptr);
     if (!res.has_value()) {
       ESP_LOGV(TAG, "Invalid field start at offset %ld", (long) (ptr - buffer));
       return;
     }
 
-    uint32_t tag = res->as_uint32();
+    uint32_t tag = static_cast<uint32_t>(res.value);
     uint32_t field_type = tag & WIRE_TYPE_MASK;
     uint32_t field_id = tag >> 3;
-    ptr += consumed;
+    ptr += res.consumed;
 
     switch (field_type) {
       case WIRE_TYPE_VARINT: {  // VarInt
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           ESP_LOGV(TAG, "Invalid VarInt at offset %ld", (long) (ptr - buffer));
           return;
         }
-        if (!this->decode_varint(field_id, *res)) {
-          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu32 "!", field_id, res->as_uint32());
+        if (!this->decode_varint(field_id, res.value)) {
+          ESP_LOGV(TAG, "Cannot decode VarInt field %" PRIu32 " with value %" PRIu64 "!", field_id,
+                   static_cast<uint64_t>(res.value));
         }
-        ptr += consumed;
+        ptr += res.consumed;
         break;
       }
       case WIRE_TYPE_LENGTH_DELIMITED: {  // Length-delimited
-        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        res = ProtoVarInt::parse(ptr, end - ptr);
         if (!res.has_value()) {
           ESP_LOGV(TAG, "Invalid Length Delimited at offset %ld", (long) (ptr - buffer));
           return;
         }
-        uint32_t field_length = res->as_uint32();
-        ptr += consumed;
+        uint32_t field_length = static_cast<uint32_t>(res.value);
+        ptr += res.consumed;
         if (field_length > static_cast<size_t>(end - ptr)) {
           ESP_LOGV(TAG, "Out-of-bounds Length Delimited at offset %ld", (long) (ptr - buffer));
           return;

esphome/components/api/proto.h

@@ -1,5 +1,7 @@
 #pragma once
 
+#include "api_pb2_defines.h"
+#include "api_buffer.h"
 #include "esphome/core/component.h"
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
@@ -97,75 +99,60 @@ inline void encode_varint_to_buffer(uint32_t val, uint8_t *buffer) {
  * within the same function scope where temporaries are created.
  */
 
-/// Representation of a VarInt - in ProtoBuf should be 64bit but we only use 32bit
+/// Type used for decoded varint values - uint64_t when BLE needs 64-bit addresses, uint32_t otherwise
+#ifdef USE_API_VARINT64
+using proto_varint_value_t = uint64_t;
+#else
+using proto_varint_value_t = uint32_t;
+#endif
+
+/// Sentinel value for consumed field indicating parse failure
+inline constexpr uint32_t PROTO_VARINT_PARSE_FAILED = 0;
+
+/// Result of parsing a varint: value + number of bytes consumed.
+/// consumed == PROTO_VARINT_PARSE_FAILED indicates parse failure (not enough data or invalid).
+struct ProtoVarIntResult {
+  proto_varint_value_t value;
+  uint32_t consumed;  // PROTO_VARINT_PARSE_FAILED = parse failed
+
+  constexpr bool has_value() const { return this->consumed != PROTO_VARINT_PARSE_FAILED; }
+};
+
+/// Static varint parsing methods for the protobuf wire format.
 class ProtoVarInt {
  public:
-  ProtoVarInt() : value_(0) {}
-  explicit ProtoVarInt(uint64_t value) : value_(value) {}
-
-  /// Parse a varint from buffer. consumed must be a valid pointer (not null).
-  static optional<ProtoVarInt> parse(const uint8_t *buffer, uint32_t len, uint32_t *consumed) {
+  /// Parse a varint from buffer. Caller must ensure len >= 1.
+  /// Returns result with consumed=0 on failure (truncated multi-byte varint).
+  static inline ProtoVarIntResult ESPHOME_ALWAYS_INLINE parse_non_empty(const uint8_t *buffer, uint32_t len) {
 #ifdef ESPHOME_DEBUG_API
-    assert(consumed != nullptr);
+    assert(len > 0);
 #endif
+    // Fast path: single-byte varints (0-127) are the most common case
+    // (booleans, small enums, field tags, small message sizes/types).
+    if ((buffer[0] & 0x80) == 0) [[likely]]
+      return {buffer[0], 1};
+    return parse_slow(buffer, len);
+  }
+
+  /// Parse a varint from buffer (safe for empty buffers).
+  /// Returns result with consumed=0 on failure (empty buffer or truncated varint).
+  static inline ProtoVarIntResult ESPHOME_ALWAYS_INLINE parse(const uint8_t *buffer, uint32_t len) {
     if (len == 0)
-      return {};
-
-    // Most common case: single-byte varint (values 0-127)
-    if ((buffer[0] & 0x80) == 0) {
-      *consumed = 1;
-      return ProtoVarInt(buffer[0]);
-    }
-
-    // General case for multi-byte varints
-    // Since we know buffer[0]'s high bit is set, initialize with its value
-    uint64_t result = buffer[0] & 0x7F;
-    uint8_t bitpos = 7;
-
-    // A 64-bit varint is at most 10 bytes (ceil(64/7)). Reject overlong encodings
-    // to avoid undefined behavior from shifting uint64_t by >= 64 bits.
-    uint32_t max_len = std::min(len, uint32_t(10));
-
-    // Start from the second byte since we've already processed the first
-    for (uint32_t i = 1; i < max_len; i++) {
-      uint8_t val = buffer[i];
-      result |= uint64_t(val & 0x7F) << uint64_t(bitpos);
-      bitpos += 7;
-      if ((val & 0x80) == 0) {
-        *consumed = i + 1;
-        return ProtoVarInt(result);
-      }
-    }
-
-    return {};  // Incomplete or invalid varint
-  }
-
-  constexpr uint16_t as_uint16() const { return this->value_; }
-  constexpr uint32_t as_uint32() const { return this->value_; }
-  constexpr uint64_t as_uint64() const { return this->value_; }
-  constexpr bool as_bool() const { return this->value_; }
-  constexpr int32_t as_int32() const {
-    // Not ZigZag encoded
-    return static_cast<int32_t>(this->as_int64());
-  }
-  constexpr int64_t as_int64() const {
-    // Not ZigZag encoded
-    return static_cast<int64_t>(this->value_);
-  }
-  constexpr int32_t as_sint32() const {
-    // with ZigZag encoding
-    return decode_zigzag32(static_cast<uint32_t>(this->value_));
-  }
-  constexpr int64_t as_sint64() const {
-    // with ZigZag encoding
-    return decode_zigzag64(this->value_);
+      return {0, PROTO_VARINT_PARSE_FAILED};
+    return parse_non_empty(buffer, len);
   }
 
  protected:
-  uint64_t value_;
+  // Slow path for multi-byte varints (>= 128), outlined to keep fast path small
+  static ProtoVarIntResult parse_slow(const uint8_t *buffer, uint32_t len) __attribute__((noinline));
+
+#ifdef USE_API_VARINT64
+  /// Continue parsing varint bytes 4-9 with 64-bit arithmetic.
+  static ProtoVarIntResult parse_wide(const uint8_t *buffer, uint32_t len, uint32_t result32) __attribute__((noinline));
+#endif
 };
 
-// Forward declarations for decode_to_message, encode_message and encode_packed_sint32
+// Forward declarations for decode_to_message and related encoding helpers
 class ProtoDecodableMessage;
 class ProtoMessage;
 class ProtoSize;
@@ -217,21 +204,24 @@ class Proto32Bit {
 
 class ProtoWriteBuffer {
  public:
-  ProtoWriteBuffer(std::vector<uint8_t> *buffer) : buffer_(buffer) {}
-  void write(uint8_t value) { this->buffer_->push_back(value); }
-  void encode_varint_raw(uint32_t value) {
-    while (value > 0x7F) {
-      this->buffer_->push_back(static_cast<uint8_t>(value | 0x80));
-      value >>= 7;
+  ProtoWriteBuffer(APIBuffer *buffer) : buffer_(buffer), pos_(buffer->data() + buffer->size()) {}
+  ProtoWriteBuffer(APIBuffer *buffer, size_t write_pos) : buffer_(buffer), pos_(buffer->data() + write_pos) {}
+  inline void ESPHOME_ALWAYS_INLINE encode_varint_raw(uint32_t value) {
+    if (value < 128) [[likely]] {
+      this->debug_check_bounds_(1);
+      *this->pos_++ = static_cast<uint8_t>(value);
+      return;
     }
-    this->buffer_->push_back(static_cast<uint8_t>(value));
+    this->encode_varint_raw_slow_(value);
   }
   void encode_varint_raw_64(uint64_t value) {
     while (value > 0x7F) {
-      this->buffer_->push_back(static_cast<uint8_t>(value | 0x80));
+      this->debug_check_bounds_(1);
+      *this->pos_++ = static_cast<uint8_t>(value | 0x80);
       value >>= 7;
     }
-    this->buffer_->push_back(static_cast<uint8_t>(value));
+    this->debug_check_bounds_(1);
+    *this->pos_++ = static_cast<uint8_t>(value);
   }
   /**
    * Encode a field key (tag/wire type combination).
@@ -245,23 +235,18 @@ class ProtoWriteBuffer {
    *
    * Following https://protobuf.dev/programming-guides/encoding/#structure
    */
-  void encode_field_raw(uint32_t field_id, uint32_t type) {
-    uint32_t val = (field_id << 3) | (type & WIRE_TYPE_MASK);
-    this->encode_varint_raw(val);
-  }
+  void encode_field_raw(uint32_t field_id, uint32_t type) { this->encode_varint_raw((field_id << 3) | type); }
   void encode_string(uint32_t field_id, const char *string, size_t len, bool force = false) {
     if (len == 0 && !force)
       return;
 
     this->encode_field_raw(field_id, 2);  // type 2: Length-delimited string
     this->encode_varint_raw(len);
-
-    // Using resize + memcpy instead of insert provides significant performance improvement:
-    // ~10-11x faster for 16-32 byte strings, ~3x faster for 64-byte strings
-    // as it avoids iterator checks and potential element moves that insert performs
-    size_t old_size = this->buffer_->size();
-    this->buffer_->resize(old_size + len);
-    std::memcpy(this->buffer_->data() + old_size, string, len);
+    // Direct memcpy into pre-sized buffer — avoids push_back() per-byte capacity checks
+    // and vector::insert() iterator overhead. ~10-11x faster for 16-32 byte strings.
+    this->debug_check_bounds_(len);
+    std::memcpy(this->pos_, string, len);
+    this->pos_ += len;
   }
   void encode_string(uint32_t field_id, const std::string &value, bool force = false) {
     this->encode_string(field_id, value.data(), value.size(), force);
@@ -288,17 +273,26 @@ class ProtoWriteBuffer {
     if (!value && !force)
       return;
     this->encode_field_raw(field_id, 0);  // type 0: Varint - bool
-    this->buffer_->push_back(value ? 0x01 : 0x00);
+    this->debug_check_bounds_(1);
+    *this->pos_++ = value ? 0x01 : 0x00;
   }
-  void encode_fixed32(uint32_t field_id, uint32_t value, bool force = false) {
+  // noinline: 51 call sites; inlining causes net code growth vs a single out-of-line copy
+  __attribute__((noinline)) void encode_fixed32(uint32_t field_id, uint32_t value, bool force = false) {
     if (value == 0 && !force)
       return;
 
     this->encode_field_raw(field_id, 5);  // type 5: 32-bit fixed32
-    this->write((value >> 0) & 0xFF);
-    this->write((value >> 8) & 0xFF);
-    this->write((value >> 16) & 0xFF);
-    this->write((value >> 24) & 0xFF);
+    this->debug_check_bounds_(4);
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    // Protobuf fixed32 is little-endian, so direct copy works
+    std::memcpy(this->pos_, &value, 4);
+    this->pos_ += 4;
+#else
+    *this->pos_++ = (value >> 0) & 0xFF;
+    *this->pos_++ = (value >> 8) & 0xFF;
+    *this->pos_++ = (value >> 16) & 0xFF;
+    *this->pos_++ = (value >> 24) & 0xFF;
+#endif
   }
   // NOTE: Wire type 1 (64-bit fixed: double, fixed64, sfixed64) is intentionally
   // not supported to reduce overhead on embedded systems. All ESPHome devices are
@@ -334,11 +328,33 @@ class ProtoWriteBuffer {
   }
   /// Encode a packed repeated sint32 field (zero-copy from vector)
   void encode_packed_sint32(uint32_t field_id, const std::vector<int32_t> &values);
-  void encode_message(uint32_t field_id, const ProtoMessage &value);
-  std::vector<uint8_t> *get_buffer() const { return buffer_; }
+  /// Single-pass encode for repeated submessage elements.
+  /// Thin template wrapper; all buffer work is in the non-template core.
+  template<typename T> void encode_sub_message(uint32_t field_id, const T &value);
+  /// Encode an optional singular submessage field — skips if empty.
+  /// Thin template wrapper; all buffer work is in the non-template core.
+  template<typename T> void encode_optional_sub_message(uint32_t field_id, const T &value);
+
+  // Non-template core for encode_sub_message — backpatch approach.
+  void encode_sub_message(uint32_t field_id, const void *value, void (*encode_fn)(const void *, ProtoWriteBuffer &));
+  // Non-template core for encode_optional_sub_message.
+  void encode_optional_sub_message(uint32_t field_id, uint32_t nested_size, const void *value,
+                                   void (*encode_fn)(const void *, ProtoWriteBuffer &));
+  APIBuffer *get_buffer() const { return buffer_; }
 
  protected:
-  std::vector<uint8_t> *buffer_;
+  // Slow path for encode_varint_raw values >= 128, outlined to keep fast path small
+  void encode_varint_raw_slow_(uint32_t value) __attribute__((noinline));
+
+#ifdef ESPHOME_DEBUG_API
+  void debug_check_bounds_(size_t bytes, const char *caller = __builtin_FUNCTION());
+  void debug_check_encode_size_(uint32_t field_id, uint32_t expected, ptrdiff_t actual);
+#else
+  void debug_check_bounds_([[maybe_unused]] size_t bytes) {}
+#endif
+
+  APIBuffer *buffer_;
+  uint8_t *pos_;
 };
 
 #ifdef HAS_PROTO_MESSAGE_DUMP
@@ -414,15 +430,25 @@ class DumpBuffer {
 
 class ProtoMessage {
  public:
-  virtual ~ProtoMessage() = default;
-  // Default implementation for messages with no fields
-  virtual void encode(ProtoWriteBuffer buffer) const {}
-  // Default implementation for messages with no fields
-  virtual void calculate_size(ProtoSize &size) const {}
+  // Non-virtual defaults for messages with no fields.
+  // Concrete message classes hide these with their own implementations.
+  // All call sites use templates to preserve the concrete type, so virtual
+  // dispatch is not needed. This eliminates per-message vtable entries for
+  // encode/calculate_size, saving ~1.3 KB of flash across all message types.
+  void encode(ProtoWriteBuffer &buffer) const {}
+  uint32_t calculate_size() const { return 0; }
 #ifdef HAS_PROTO_MESSAGE_DUMP
   virtual const char *dump_to(DumpBuffer &out) const = 0;
   virtual const char *message_name() const { return "unknown"; }
 #endif
+
+#ifndef USE_HOST
+ protected:
+#endif
+  // Non-virtual destructor is protected to prevent polymorphic deletion.
+  // On host platform, made public to allow value-initialization of std::array
+  // members (e.g. DeviceInfoResponse::devices) without clang errors.
+  ~ProtoMessage() = default;
 };
 
 // Base class for messages that support decoding
@@ -442,38 +468,20 @@ class ProtoDecodableMessage : public ProtoMessage {
   static uint32_t count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id);
 
  protected:
-  virtual bool decode_varint(uint32_t field_id, ProtoVarInt value) { return false; }
+  ~ProtoDecodableMessage() = default;
+  virtual bool decode_varint(uint32_t field_id, proto_varint_value_t value) { return false; }
   virtual bool decode_length(uint32_t field_id, ProtoLengthDelimited value) { return false; }
   virtual bool decode_32bit(uint32_t field_id, Proto32Bit value) { return false; }
   // NOTE: decode_64bit removed - wire type 1 not supported
 };
 
 class ProtoSize {
- private:
-  uint32_t total_size_ = 0;
-
  public:
-  /**
-   * @brief ProtoSize class for Protocol Buffer serialization size calculation
-   *
-   * This class provides methods to calculate the exact byte counts needed
-   * for encoding various Protocol Buffer field types. The class now uses an
-   * object-based approach to reduce parameter passing overhead while keeping
-   * varint calculation methods static for external use.
-   *
-   * Implements Protocol Buffer encoding size calculation according to:
-   * https://protobuf.dev/programming-guides/encoding/
-   *
-   * Key features:
-   * - Object-based approach reduces flash usage by eliminating parameter passing
-   * - Early-return optimization for zero/default values
-   * - Static varint methods for external callers
-   * - Specialized handling for different field types according to protobuf spec
-   */
-
-  ProtoSize() = default;
-
-  uint32_t get_size() const { return total_size_; }
+  // Varint encoding thresholds: values below each threshold fit in N bytes
+  static constexpr uint32_t VARINT_THRESHOLD_1_BYTE = 1 << 7;   // 128
+  static constexpr uint32_t VARINT_THRESHOLD_2_BYTE = 1 << 14;  // 16384
+  static constexpr uint32_t VARINT_THRESHOLD_3_BYTE = 1 << 21;  // 2097152
+  static constexpr uint32_t VARINT_THRESHOLD_4_BYTE = 1 << 28;  // 268435456
 
   /**
    * @brief Calculates the size in bytes needed to encode a uint32_t value as a varint
@@ -481,24 +489,29 @@ class ProtoSize {
    * @param value The uint32_t value to calculate size for
    * @return The number of bytes needed to encode the value
    */
-  static constexpr uint32_t varint(uint32_t value) {
-    // Optimized varint size calculation using leading zeros
-    // Each 7 bits requires one byte in the varint encoding
-    if (value < 128)
-      return 1;  // 7 bits, common case for small values
-
-    // For larger values, count bytes needed based on the position of the highest bit set
-    if (value < 16384) {
-      return 2;  // 14 bits
-    } else if (value < 2097152) {
-      return 3;  // 21 bits
-    } else if (value < 268435456) {
-      return 4;  // 28 bits
-    } else {
-      return 5;  // 32 bits (maximum for uint32_t)
-    }
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE varint(uint32_t value) {
+    if (value < VARINT_THRESHOLD_1_BYTE) [[likely]]
+      return 1;  // Fast path: 7 bits, most common case
+    if (__builtin_is_constant_evaluated())
+      return varint_wide(value);
+    return varint_slow(value);
   }
 
+ private:
+  // Slow path for varint >= 128, outlined to keep fast path small
+  static uint32_t varint_slow(uint32_t value) __attribute__((noinline));
+  // Shared cascade for values >= 128 (used by both constexpr and noinline paths)
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE varint_wide(uint32_t value) {
+    if (value < VARINT_THRESHOLD_2_BYTE)
+      return 2;
+    if (value < VARINT_THRESHOLD_3_BYTE)
+      return 3;
+    if (value < VARINT_THRESHOLD_4_BYTE)
+      return 4;
+    return 5;
+  }
+
+ public:
   /**
    * @brief Calculates the size in bytes needed to encode a uint64_t value as a varint
    *
@@ -571,312 +584,78 @@ class ProtoSize {
     return varint(tag);
   }
 
-  /**
-   * @brief Common parameters for all add_*_field methods
-   *
-   * All add_*_field methods follow these common patterns:
-   *   * @param field_id_size Pre-calculated size of the field ID in bytes
-   * @param value The value to calculate size for (type varies)
-   * @param force Whether to calculate size even if the value is default/zero/empty
-   *
-   * Each method follows this implementation pattern:
-   * 1. Skip calculation if value is default (0, false, empty) and not forced
-   * 2. Calculate the size based on the field's encoding rules
-   * 3. Add the field_id_size + calculated value size to total_size
-   */
-
-  /**
-   * @brief Calculates and adds the size of an int32 field to the total message size
-   */
-  inline void add_int32(uint32_t field_id_size, int32_t value) {
-    if (value != 0) {
-      add_int32_force(field_id_size, value);
-    }
+  // Static methods that RETURN size contribution (no ProtoSize object needed).
+  // Used by generated calculate_size() methods to accumulate into a plain uint32_t register.
+  static constexpr uint32_t calc_int32(uint32_t field_id_size, int32_t value) {
+    return value ? field_id_size + (value < 0 ? 10 : varint(static_cast<uint32_t>(value))) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of an int32 field to the total message size (force version)
-   */
-  inline void add_int32_force(uint32_t field_id_size, int32_t value) {
-    // Always calculate size when forced
-    // Negative values are encoded as 10-byte varints in protobuf
-    total_size_ += field_id_size + (value < 0 ? 10 : varint(static_cast<uint32_t>(value)));
+  static constexpr uint32_t calc_int32_force(uint32_t field_id_size, int32_t value) {
+    return field_id_size + (value < 0 ? 10 : varint(static_cast<uint32_t>(value)));
   }
-
-  /**
-   * @brief Calculates and adds the size of a uint32 field to the total message size
-   */
-  inline void add_uint32(uint32_t field_id_size, uint32_t value) {
-    if (value != 0) {
-      add_uint32_force(field_id_size, value);
-    }
+  static constexpr uint32_t calc_uint32(uint32_t field_id_size, uint32_t value) {
+    return value ? field_id_size + varint(value) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a uint32 field to the total message size (force version)
-   */
-  inline void add_uint32_force(uint32_t field_id_size, uint32_t value) {
-    // Always calculate size when force is true
-    total_size_ += field_id_size + varint(value);
+  static constexpr uint32_t calc_uint32_force(uint32_t field_id_size, uint32_t value) {
+    return field_id_size + varint(value);
   }
-
-  /**
-   * @brief Calculates and adds the size of a boolean field to the total message size
-   */
-  inline void add_bool(uint32_t field_id_size, bool value) {
-    if (value) {
-      // Boolean fields always use 1 byte when true
-      total_size_ += field_id_size + 1;
-    }
+  static constexpr uint32_t calc_bool(uint32_t field_id_size, bool value) { return value ? field_id_size + 1 : 0; }
+  static constexpr uint32_t calc_bool_force(uint32_t field_id_size) { return field_id_size + 1; }
+  static constexpr uint32_t calc_float(uint32_t field_id_size, float value) {
+    return value != 0.0f ? field_id_size + 4 : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a boolean field to the total message size (force version)
-   */
-  inline void add_bool_force(uint32_t field_id_size, bool value) {
-    // Always calculate size when force is true
-    // Boolean fields always use 1 byte
-    total_size_ += field_id_size + 1;
+  static constexpr uint32_t calc_fixed32(uint32_t field_id_size, uint32_t value) {
+    return value ? field_id_size + 4 : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a float field to the total message size
-   */
-  inline void add_float(uint32_t field_id_size, float value) {
-    if (value != 0.0f) {
-      total_size_ += field_id_size + 4;
-    }
+  static constexpr uint32_t calc_sfixed32(uint32_t field_id_size, int32_t value) {
+    return value ? field_id_size + 4 : 0;
   }
-
-  // NOTE: add_double_field removed - wire type 1 (64-bit: double) not supported
-  // to reduce overhead on embedded systems
-
-  /**
-   * @brief Calculates and adds the size of a fixed32 field to the total message size
-   */
-  inline void add_fixed32(uint32_t field_id_size, uint32_t value) {
-    if (value != 0) {
-      total_size_ += field_id_size + 4;
-    }
+  static constexpr uint32_t calc_sint32(uint32_t field_id_size, int32_t value) {
+    return value ? field_id_size + varint(encode_zigzag32(value)) : 0;
   }
-
-  // NOTE: add_fixed64_field removed - wire type 1 (64-bit: fixed64) not supported
-  // to reduce overhead on embedded systems
-
-  /**
-   * @brief Calculates and adds the size of a sfixed32 field to the total message size
-   */
-  inline void add_sfixed32(uint32_t field_id_size, int32_t value) {
-    if (value != 0) {
-      total_size_ += field_id_size + 4;
-    }
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE calc_sint32_force(uint32_t field_id_size, int32_t value) {
+    return field_id_size + varint(encode_zigzag32(value));
   }
-
-  // NOTE: add_sfixed64_field removed - wire type 1 (64-bit: sfixed64) not supported
-  // to reduce overhead on embedded systems
-
-  /**
-   * @brief Calculates and adds the size of a sint32 field to the total message size
-   *
-   * Sint32 fields use ZigZag encoding, which is more efficient for negative values.
-   */
-  inline void add_sint32(uint32_t field_id_size, int32_t value) {
-    if (value != 0) {
-      add_sint32_force(field_id_size, value);
-    }
+  static constexpr uint32_t calc_int64(uint32_t field_id_size, int64_t value) {
+    return value ? field_id_size + varint(value) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a sint32 field to the total message size (force version)
-   *
-   * Sint32 fields use ZigZag encoding, which is more efficient for negative values.
-   */
-  inline void add_sint32_force(uint32_t field_id_size, int32_t value) {
-    // Always calculate size when force is true
-    // ZigZag encoding for sint32
-    total_size_ += field_id_size + varint(encode_zigzag32(value));
+  static constexpr uint32_t calc_int64_force(uint32_t field_id_size, int64_t value) {
+    return field_id_size + varint(value);
   }
-
-  /**
-   * @brief Calculates and adds the size of an int64 field to the total message size
-   */
-  inline void add_int64(uint32_t field_id_size, int64_t value) {
-    if (value != 0) {
-      add_int64_force(field_id_size, value);
-    }
+  static constexpr uint32_t calc_uint64(uint32_t field_id_size, uint64_t value) {
+    return value ? field_id_size + varint(value) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of an int64 field to the total message size (force version)
-   */
-  inline void add_int64_force(uint32_t field_id_size, int64_t value) {
-    // Always calculate size when force is true
-    total_size_ += field_id_size + varint(value);
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE calc_uint64_force(uint32_t field_id_size, uint64_t value) {
+    return field_id_size + varint(value);
   }
-
-  /**
-   * @brief Calculates and adds the size of a uint64 field to the total message size
-   */
-  inline void add_uint64(uint32_t field_id_size, uint64_t value) {
-    if (value != 0) {
-      add_uint64_force(field_id_size, value);
-    }
+  static constexpr uint32_t calc_length(uint32_t field_id_size, size_t len) {
+    return len ? field_id_size + varint(static_cast<uint32_t>(len)) + static_cast<uint32_t>(len) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a uint64 field to the total message size (force version)
-   */
-  inline void add_uint64_force(uint32_t field_id_size, uint64_t value) {
-    // Always calculate size when force is true
-    total_size_ += field_id_size + varint(value);
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE calc_length_force(uint32_t field_id_size, size_t len) {
+    return field_id_size + varint(static_cast<uint32_t>(len)) + static_cast<uint32_t>(len);
   }
-
-  // NOTE: sint64 support functions (add_sint64_field, add_sint64_field_force) removed
-  // sint64 type is not supported by ESPHome API to reduce overhead on embedded systems
-
-  /**
-   * @brief Calculates and adds the size of a length-delimited field (string/bytes) to the total message size
-   */
-  inline void add_length(uint32_t field_id_size, size_t len) {
-    if (len != 0) {
-      add_length_force(field_id_size, len);
-    }
+  static constexpr uint32_t calc_sint64(uint32_t field_id_size, int64_t value) {
+    return value ? field_id_size + varint(encode_zigzag64(value)) : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a length-delimited field (string/bytes) to the total message size (repeated
-   * field version)
-   */
-  inline void add_length_force(uint32_t field_id_size, size_t len) {
-    // Always calculate size when force is true
-    // Field ID + length varint + data bytes
-    total_size_ += field_id_size + varint(static_cast<uint32_t>(len)) + static_cast<uint32_t>(len);
+  static constexpr uint32_t calc_sint64_force(uint32_t field_id_size, int64_t value) {
+    return field_id_size + varint(encode_zigzag64(value));
   }
-
-  /**
-   * @brief Adds a pre-calculated size directly to the total
-   *
-   * This is used when we can calculate the total size by multiplying the number
-   * of elements by the bytes per element (for repeated fixed-size types like float, fixed32, etc.)
-   *
-   * @param size The pre-calculated total size to add
-   */
-  inline void add_precalculated_size(uint32_t size) { total_size_ += size; }
-
-  /**
-   * @brief Calculates and adds the size of a nested message field to the total message size
-   *
-   * This helper function directly updates the total_size reference if the nested size
-   * is greater than zero.
-   *
-   * @param nested_size The pre-calculated size of the nested message
-   */
-  inline void add_message_field(uint32_t field_id_size, uint32_t nested_size) {
-    if (nested_size != 0) {
-      add_message_field_force(field_id_size, nested_size);
-    }
+  static constexpr uint32_t calc_fixed64(uint32_t field_id_size, uint64_t value) {
+    return value ? field_id_size + 8 : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a nested message field to the total message size (force version)
-   *
-   * @param nested_size The pre-calculated size of the nested message
-   */
-  inline void add_message_field_force(uint32_t field_id_size, uint32_t nested_size) {
-    // Always calculate size when force is true
-    // Field ID + length varint + nested message content
-    total_size_ += field_id_size + varint(nested_size) + nested_size;
+  static constexpr uint32_t calc_sfixed64(uint32_t field_id_size, int64_t value) {
+    return value ? field_id_size + 8 : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a nested message field to the total message size
-   *
-   * This version takes a ProtoMessage object, calculates its size internally,
-   * and updates the total_size reference. This eliminates the need for a temporary variable
-   * at the call site.
-   *
-   * @param message The nested message object
-   */
-  inline void add_message_object(uint32_t field_id_size, const ProtoMessage &message) {
-    // Calculate nested message size by creating a temporary ProtoSize
-    ProtoSize nested_calc;
-    message.calculate_size(nested_calc);
-    uint32_t nested_size = nested_calc.get_size();
-
-    // Use the base implementation with the calculated nested_size
-    add_message_field(field_id_size, nested_size);
+  static constexpr uint32_t calc_message(uint32_t field_id_size, uint32_t nested_size) {
+    return nested_size ? field_id_size + varint(nested_size) + nested_size : 0;
   }
-
-  /**
-   * @brief Calculates and adds the size of a nested message field to the total message size (force version)
-   *
-   * @param message The nested message object
-   */
-  inline void add_message_object_force(uint32_t field_id_size, const ProtoMessage &message) {
-    // Calculate nested message size by creating a temporary ProtoSize
-    ProtoSize nested_calc;
-    message.calculate_size(nested_calc);
-    uint32_t nested_size = nested_calc.get_size();
-
-    // Use the base implementation with the calculated nested_size
-    add_message_field_force(field_id_size, nested_size);
-  }
-
-  /**
-   * @brief Calculates and adds the sizes of all messages in a repeated field to the total message size
-   *
-   * This helper processes a vector of message objects, calculating the size for each message
-   * and adding it to the total size.
-   *
-   * @tparam MessageType The type of the nested messages in the vector
-   * @param messages Vector of message objects
-   */
-  template<typename MessageType>
-  inline void add_repeated_message(uint32_t field_id_size, const std::vector<MessageType> &messages) {
-    // Skip if the vector is empty
-    if (!messages.empty()) {
-      // Use the force version for all messages in the repeated field
-      for (const auto &message : messages) {
-        add_message_object_force(field_id_size, message);
-      }
-    }
-  }
-
-  /**
-   * @brief Calculates and adds the sizes of all messages in a repeated field to the total message size (FixedVector
-   * version)
-   *
-   * @tparam MessageType The type of the nested messages in the FixedVector
-   * @param messages FixedVector of message objects
-   */
-  template<typename MessageType>
-  inline void add_repeated_message(uint32_t field_id_size, const FixedVector<MessageType> &messages) {
-    // Skip if the fixed vector is empty
-    if (!messages.empty()) {
-      // Use the force version for all messages in the repeated field
-      for (const auto &message : messages) {
-        add_message_object_force(field_id_size, message);
-      }
-    }
-  }
-
-  /**
-   * @brief Calculate size of a packed repeated sint32 field
-   */
-  inline void add_packed_sint32(uint32_t field_id_size, const std::vector<int32_t> &values) {
-    if (values.empty())
-      return;
-
-    size_t packed_size = 0;
-    for (int value : values) {
-      packed_size += varint(encode_zigzag32(value));
-    }
-
-    // field_id + length varint + packed data
-    total_size_ += field_id_size + varint(static_cast<uint32_t>(packed_size)) + static_cast<uint32_t>(packed_size);
+  static constexpr inline uint32_t ESPHOME_ALWAYS_INLINE calc_message_force(uint32_t field_id_size,
+                                                                            uint32_t nested_size) {
+    return field_id_size + varint(nested_size) + nested_size;
   }
 };
 
+// Implementation of methods that depend on ProtoSize being fully defined
+
 // Implementation of encode_packed_sint32 - must be after ProtoSize is defined
 inline void ProtoWriteBuffer::encode_packed_sint32(uint32_t field_id, const std::vector<int32_t> &values) {
   if (values.empty())
@@ -896,32 +675,19 @@ inline void ProtoWriteBuffer::encode_packed_sint32(uint32_t field_id, const std:
   }
 }
 
-// Implementation of encode_message - must be after ProtoMessage is defined
-inline void ProtoWriteBuffer::encode_message(uint32_t field_id, const ProtoMessage &value) {
-  this->encode_field_raw(field_id, 2);  // type 2: Length-delimited message
+// Encode thunk — converts void* back to concrete type for direct encode() call
+template<typename T> void proto_encode_msg(const void *msg, ProtoWriteBuffer &buf) {
+  static_cast<const T *>(msg)->encode(buf);
+}
 
-  // Calculate the message size first
-  ProtoSize msg_size;
-  value.calculate_size(msg_size);
-  uint32_t msg_length_bytes = msg_size.get_size();
+// Thin template wrapper; delegates to non-template core in proto.cpp.
+template<typename T> inline void ProtoWriteBuffer::encode_sub_message(uint32_t field_id, const T &value) {
+  this->encode_sub_message(field_id, &value, &proto_encode_msg<T>);
+}
 
-  // Calculate how many bytes the length varint needs
-  uint32_t varint_length_bytes = ProtoSize::varint(msg_length_bytes);
-
-  // Reserve exact space for the length varint
-  size_t begin = this->buffer_->size();
-  this->buffer_->resize(this->buffer_->size() + varint_length_bytes);
-
-  // Write the length varint directly
-  encode_varint_to_buffer(msg_length_bytes, this->buffer_->data() + begin);
-
-  // Now encode the message content - it will append to the buffer
-  value.encode(*this);
-
-#ifdef ESPHOME_DEBUG_API
-  // Verify that the encoded size matches what we calculated
-  assert(this->buffer_->size() == begin + varint_length_bytes + msg_length_bytes);
-#endif
+// Thin template wrapper; delegates to non-template core.
+template<typename T> inline void ProtoWriteBuffer::encode_optional_sub_message(uint32_t field_id, const T &value) {
+  this->encode_optional_sub_message(field_id, value.calculate_size(), &value, &proto_encode_msg<T>);
 }
 
 // Implementation of decode_to_message - must be after ProtoDecodableMessage is defined
@@ -940,14 +706,6 @@ class ProtoService {
   virtual void on_no_setup_connection() = 0;
   virtual bool send_buffer(ProtoWriteBuffer buffer, uint8_t message_type) = 0;
   virtual void read_message(uint32_t msg_size, uint32_t msg_type, const uint8_t *msg_data) = 0;
-  /**
-   * Send a protobuf message by calculating its size, allocating a buffer, encoding, and sending.
-   * This is the implementation method - callers should use send_message() which adds logging.
-   * @param msg The protobuf message to send.
-   * @param message_type The message type identifier.
-   * @return True if the message was sent successfully, false otherwise.
-   */
-  virtual bool send_message_impl(const ProtoMessage &msg, uint8_t message_type) = 0;
 
   // Authentication helper methods
   inline bool check_connection_setup_() {

esphome/components/api/subscribe_state.h

@@ -16,7 +16,7 @@ class APIConnection;
     return this->client_->send_##entity_type##_state(entity); \
   }
 
-class InitialStateIterator : public ComponentIterator {
+class InitialStateIterator final : public ComponentIterator {
  public:
   InitialStateIterator(APIConnection *client);
 #ifdef USE_BINARY_SENSOR

esphome/components/api/user_services.cpp

@@ -1,5 +1,6 @@
 #include "user_services.h"
 #include "esphome/core/log.h"
+#include "esphome/core/string_ref.h"
 
 namespace esphome::api {
 
@@ -11,6 +12,8 @@ template<> int32_t get_execute_arg_value<int32_t>(const ExecuteServiceArgument &
 }
 template<> float get_execute_arg_value<float>(const ExecuteServiceArgument &arg) { return arg.float_; }
 template<> std::string get_execute_arg_value<std::string>(const ExecuteServiceArgument &arg) { return arg.string_; }
+// Zero-copy StringRef version for YAML-generated services (string_ is null-terminated after decode)
+template<> StringRef get_execute_arg_value<StringRef>(const ExecuteServiceArgument &arg) { return arg.string_; }
 
 // Legacy std::vector versions for external components using custom_api_device.h - optimized with reserve
 template<> std::vector<bool> get_execute_arg_value<std::vector<bool>>(const ExecuteServiceArgument &arg) {
@@ -61,6 +64,8 @@ template<> enums::ServiceArgType to_service_arg_type<bool>() { return enums::SER
 template<> enums::ServiceArgType to_service_arg_type<int32_t>() { return enums::SERVICE_ARG_TYPE_INT; }
 template<> enums::ServiceArgType to_service_arg_type<float>() { return enums::SERVICE_ARG_TYPE_FLOAT; }
 template<> enums::ServiceArgType to_service_arg_type<std::string>() { return enums::SERVICE_ARG_TYPE_STRING; }
+// Zero-copy StringRef version for YAML-generated services
+template<> enums::ServiceArgType to_service_arg_type<StringRef>() { return enums::SERVICE_ARG_TYPE_STRING; }
 
 // Legacy std::vector versions for external components using custom_api_device.h
 template<> enums::ServiceArgType to_service_arg_type<std::vector<bool>>() { return enums::SERVICE_ARG_TYPE_BOOL_ARRAY; }

esphome/components/api/user_services.h

@@ -230,7 +230,7 @@ template<typename... Ts> class APIRespondAction : public Action<Ts...> {
   void set_is_optional_mode(bool is_optional) { this->is_optional_mode_ = is_optional; }
 
 #ifdef USE_API_USER_DEFINED_ACTION_RESPONSES_JSON
-  void set_data(std::function<void(Ts..., JsonObject)> func) {
+  void set_data(std::function<void(Ts..., JsonObject)> &&func) {
     this->json_builder_ = std::move(func);
     this->has_data_ = true;
   }
@@ -264,9 +264,9 @@ template<typename... Ts> class APIRespondAction : public Action<Ts...> {
       // Build and send JSON response
       json::JsonBuilder builder;
       this->json_builder_(x..., builder.root());
-      std::string json_str = builder.serialize();
+      auto json_buf = builder.serialize();
       this->parent_->send_action_response(call_id, success, StringRef(error_message),
-                                          reinterpret_cast<const uint8_t *>(json_str.data()), json_str.size());
+                                          reinterpret_cast<const uint8_t *>(json_buf.data()), json_buf.size());
       return;
     }
 #endif

esphome/components/as3935/as3935.cpp

@@ -307,9 +307,9 @@ void AS3935Component::tune_antenna() {
   uint8_t tune_val = this->read_capacitance();
   ESP_LOGI(TAG,
            "Starting antenna tuning\n"
-           "Division Ratio is set to: %d\n"
-           "Internal Capacitor is set to: %d\n"
-           "Displaying oscillator on INT pin. Measure its frequency - multiply value by Division Ratio",
+           "  Division Ratio is set to: %d\n"
+           "  Internal Capacitor is set to: %d\n"
+           "  Displaying oscillator on INT pin. Measure its frequency - multiply value by Division Ratio",
            div_ratio, tune_val);
   this->display_oscillator(true, ANTFREQ);
 }

esphome/components/as3935/as3935.h

@@ -41,7 +41,7 @@ enum AS3935RegisterMasks {
   INT_MASK = 0xF0,
   THRESH_MASK = 0x0F,
   R_SPIKE_MASK = 0xF0,
-  ENERGY_MASK = 0xF0,
+  ENERGY_MASK = 0xE0,
   CAP_MASK = 0xF0,
   LIGHT_MASK = 0xCF,
   DISTURB_MASK = 0xDF,

esphome/components/as5600/__init__.py

@@ -9,6 +9,7 @@ from esphome.const import (
     CONF_ID,
     CONF_POWER_MODE,
     CONF_RANGE,
+    CONF_WATCHDOG,
 )
 
 CODEOWNERS = ["@ammmze"]
@@ -57,7 +58,6 @@ FAST_FILTER = {
 
 CONF_RAW_ANGLE = "raw_angle"
 CONF_RAW_POSITION = "raw_position"
-CONF_WATCHDOG = "watchdog"
 CONF_SLOW_FILTER = "slow_filter"
 CONF_FAST_FILTER = "fast_filter"
 CONF_START_POSITION = "start_position"

esphome/components/as5600/sensor/__init__.py

@@ -23,7 +23,6 @@ AS5600Sensor = as5600_ns.class_("AS5600Sensor", sensor.Sensor, cg.PollingCompone
 
 CONF_RAW_ANGLE = "raw_angle"
 CONF_RAW_POSITION = "raw_position"
-CONF_WATCHDOG = "watchdog"
 CONF_SLOW_FILTER = "slow_filter"
 CONF_FAST_FILTER = "fast_filter"
 CONF_PWM_FREQUENCY = "pwm_frequency"

esphome/components/async_tcp/async_tcp_socket.cpp

@@ -52,11 +52,12 @@ bool AsyncClient::connect(const char *host, uint16_t port) {
       connect_cb_(connect_arg_, this);
     return true;
   }
-  if (errno != EINPROGRESS) {
-    ESP_LOGE(TAG, "Connect failed: %d", errno);
+  const int saved_errno = errno;
+  if (saved_errno != EINPROGRESS) {
+    ESP_LOGE(TAG, "Connect failed: %d", saved_errno);
     close();
     if (error_cb_)
-      error_cb_(error_arg_, this, errno);
+      error_cb_(error_arg_, this, saved_errno);
     return false;
   }
 
@@ -79,11 +80,12 @@ size_t AsyncClient::write(const char *data, size_t len) {
 
   ssize_t sent = socket_->write(data, len);
   if (sent < 0) {
-    if (errno != EAGAIN && errno != EWOULDBLOCK) {
-      ESP_LOGE(TAG, "Write error: %d", errno);
+    const int err = errno;
+    if (err != EAGAIN && err != EWOULDBLOCK) {
+      ESP_LOGE(TAG, "Write error: %d", err);
       close();
       if (error_cb_)
-        error_cb_(error_arg_, this, errno);
+        error_cb_(error_arg_, this, err);
     }
     return 0;
   }
@@ -129,10 +131,11 @@ void AsyncClient::loop() {
           error_cb_(error_arg_, this, error);
       }
     } else if (ret < 0) {
-      ESP_LOGE(TAG, "Select error: %d", errno);
+      const int err = errno;
+      ESP_LOGE(TAG, "Select error: %d", err);
       close();
       if (error_cb_)
-        error_cb_(error_arg_, this, errno);
+        error_cb_(error_arg_, this, err);
     }
   } else if (connected_) {
     // For connected sockets, use the Application's select() results
@@ -148,11 +151,14 @@ void AsyncClient::loop() {
     } else if (len > 0) {
       if (data_cb_)
         data_cb_(data_arg_, this, buf, len);
-    } else if (errno != EAGAIN && errno != EWOULDBLOCK) {
-      ESP_LOGW(TAG, "Read error: %d", errno);
-      close();
-      if (error_cb_)
-        error_cb_(error_arg_, this, errno);
+    } else {
+      const int err = errno;
+      if (err != EAGAIN && err != EWOULDBLOCK) {
+        ESP_LOGW(TAG, "Read error: %d", err);
+        close();
+        if (error_cb_)
+          error_cb_(error_arg_, this, err);
+      }
     }
   }
 }

esphome/components/at581x/__init__.py

@@ -89,6 +89,7 @@ AT581XSettingsAction = at581x_ns.class_("AT581XSettingsAction", automation.Actio
             cv.Required(CONF_ID): cv.use_id(AT581XComponent),
         }
     ),
+    synchronous=True,
 )
 async def at581x_reset_to_code(config, action_id, template_arg, args):
     var = cg.new_Pvariable(action_id, template_arg)
@@ -160,6 +161,7 @@ RADAR_SETTINGS_SCHEMA = cv.Schema(
     "at581x.settings",
     AT581XSettingsAction,
     RADAR_SETTINGS_SCHEMA,
+    synchronous=True,
 )
 async def at581x_settings_to_code(config, action_id, template_arg, args):
     var = cg.new_Pvariable(action_id, template_arg)

esphome/components/at581x/at581x.cpp

@@ -77,14 +77,14 @@ void AT581XComponent::dump_config() { LOG_I2C_DEVICE(this); }
 bool AT581XComponent::i2c_write_config() {
   ESP_LOGCONFIG(TAG,
                 "Writing new config for AT581X\n"
-                "Frequency: %dMHz\n"
-                "Sensing distance: %d\n"
-                "Power: %dµA\n"
-                "Gain: %d\n"
-                "Trigger base time: %dms\n"
-                "Trigger keep time: %dms\n"
-                "Protect time: %dms\n"
-                "Self check time: %dms",
+                "  Frequency: %dMHz\n"
+                "  Sensing distance: %d\n"
+                "  Power: %dµA\n"
+                "  Gain: %d\n"
+                "  Trigger base time: %dms\n"
+                "  Trigger keep time: %dms\n"
+                "  Protect time: %dms\n"
+                "  Self check time: %dms",
                 this->freq_, this->delta_, this->power_, this->gain_, this->trigger_base_time_ms_,
                 this->trigger_keep_time_ms_, this->protect_time_ms_, this->self_check_time_ms_);
 
@@ -135,6 +135,11 @@ bool AT581XComponent::i2c_write_config() {
   }
 
   // Set gain
+  if (this->gain_ < 0 || static_cast<size_t>(this->gain_) >= ARRAY_SIZE(GAIN5C_TABLE) ||
+      static_cast<size_t>(this->gain_ >> 1) >= ARRAY_SIZE(GAIN63_TABLE)) {
+    ESP_LOGE(TAG, "AT581X gain index out of range: %d", this->gain_);
+    return false;
+  }
   if (!this->i2c_write_reg(GAIN_ADDR_TABLE[0], GAIN5C_TABLE[this->gain_]) ||
       !this->i2c_write_reg(GAIN_ADDR_TABLE[1], GAIN63_TABLE[this->gain_ >> 1])) {
     ESP_LOGE(TAG, "Failed to write AT581X gain registers");

esphome/components/atc_mithermometer/atc_mithermometer.cpp

@@ -61,6 +61,10 @@ optional<ParseResult> ATCMiThermometer::parse_header_(const esp32_ble_tracker::S
   }
 
   auto raw = service_data.data;
+  if (raw.size() < 13) {
+    ESP_LOGVV(TAG, "parse_header_(): service data too short (%zu).", raw.size());
+    return {};
+  }
 
   static uint8_t last_frame_count = 0;
   if (last_frame_count == raw[12]) {

esphome/components/atm90e26/atm90e26.cpp

@@ -197,7 +197,7 @@ float ATM90E26Component::get_reactive_power_() {
 float ATM90E26Component::get_power_factor_() {
   const uint16_t val = this->read16_(ATM90E26_REGISTER_POWERF);  // signed
   if (val & 0x8000) {
-    return -(val & 0x7FF) / 1000.0f;
+    return -(val & 0x7FFF) / 1000.0f;
   } else {
     return val / 1000.0f;
   }

esphome/components/atm90e32/atm90e32.cpp

@@ -619,7 +619,7 @@ void ATM90E32Component::run_gain_calibrations() {
       ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Skipping voltage calibration: measured voltage is 0.", cs,
                phase_labels[phase]);
     } else {
-      uint32_t new_voltage_gain = static_cast<uint16_t>((ref_voltage / measured_voltage) * current_voltage_gain);
+      uint32_t new_voltage_gain = static_cast<uint32_t>((ref_voltage / measured_voltage) * current_voltage_gain);
       if (new_voltage_gain == 0) {
         ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Voltage gain would be 0. Check reference and measured voltage.", cs,
                  phase_labels[phase]);
@@ -644,7 +644,7 @@ void ATM90E32Component::run_gain_calibrations() {
       ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Skipping current calibration: measured current is 0.", cs,
                phase_labels[phase]);
     } else {
-      uint32_t new_current_gain = static_cast<uint16_t>((ref_current / measured_current) * current_current_gain);
+      uint32_t new_current_gain = static_cast<uint32_t>((ref_current / measured_current) * current_current_gain);
       if (new_current_gain == 0) {
         ESP_LOGW(TAG, "[CALIBRATION][%s] Phase %s - Current gain would be 0. Check reference and measured current.", cs,
                  phase_labels[phase]);