[github] Add developer-facing feature PR classification (#17795)

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

@@ -22,11 +22,13 @@ module.exports = {
     'has-tests',
     'needs-tests',
     'needs-docs',
+    'needs-developer-docs',
     'needs-codeowners',
     'too-big',
     'labeller-recheck',
     'bugfix',
     'new-feature',
+    'new-feature-developer',
     'breaking-change',
     'developer-breaking-change',
     'undocumented-api-change',
@@ -40,5 +42,17 @@ module.exports = {
     // Keep matching the old esphome-docs name during the transition period
     /https:\/\/github\.com\/esphome\/esphome-docs\/pull\/\d+/,
     /esphome\/esphome-docs#\d+/
+  ],
+
+  DEVELOPER_DOCS_PR_PATTERNS: [
+    /https:\/\/github\.com\/esphome\/developers\.esphome\.io\/pull\/\d+/,
+    /esphome\/developers\.esphome\.io#\d+/
+  ],
+
+  // Files whose developer-facing changes are documented via Python docstrings
+  // only - developers.esphome.io has no reference page for them yet, so PRs
+  // touching nothing but these files (and tests/) skip needs-developer-docs.
+  DEV_DOCS_EXEMPT_FILES: [
+    'esphome/config_validation.py'
   ]
 };