diff --git a/esphome/__main__.py b/esphome/__main__.py
index 6393e4a70e..c4f76fcc99 100644
--- a/esphome/__main__.py
+++ b/esphome/__main__.py
@@ -865,11 +865,8 @@ def compile_program(args: ArgsProtocol, config: ConfigType) -> int:
             RuntimeError,
             ValueError,
         ) as err:
-            # The firmware already built; idedata is a bonus artifact here.
-            # Broad on purpose: a vanished compiler (OSError), a failed
-            # include probe (RuntimeError), or a truncated compile DB
-            # (ValueError/LookupError) must not fail a successful build
-            # either.
+            # Broad on purpose: the firmware already built; an idedata
+            # failure must not fail a successful build.
             _LOGGER.warning("Could not generate idedata: %s", err)
     else:
         from esphome.platformio import toolchain
@@ -2737,12 +2734,8 @@ def run_esphome(argv):
     cache_write_eligible = (
         args.command in ("upload", "logs") and not command_line_substitutions
     )
-    # An explicit CLI toolchain must run the per-platform validators; the
-    # cache was validated under whatever the last compile used. Only the
-    # read is gated: the refresh below still saves the freshly validated
-    # config. The sidecar is only written when none exists; a
-    # compile-written one keeps the compile's toolchain (the firmware on
-    # disk was built by it), which upload/logs then restore.
+    # An explicit --toolchain must re-run the per-platform validators, so
+    # gate only the cache read; the refresh below still saves the result.
     cache_read_eligible = cache_write_eligible and args.toolchain is None
     if cache_read_eligible:
         from esphome.compiled_config import load_compiled_config
@@ -2768,11 +2761,8 @@ def run_esphome(argv):
             return 2
     CORE.config = config
 
-    # Every platform resolves the toolchain during validation now, but the
-    # compiled-config cache fast path skips validation entirely and a
-    # sidecar written before the toolchain field existed restores nothing;
-    # this fallback covers that path. Must run before the cache refresh
-    # below so its sidecar records the same toolchain a compile would.
+    # The cache fast path skips validation, and legacy sidecars lack the
+    # toolchain field. Must run before the cache refresh below.
     if CORE.toolchain is None:
         CORE.toolchain = Toolchain.PLATFORMIO
 
diff --git a/esphome/arduino/library.py b/esphome/arduino/library.py
index 5d7712e4ad..80e7aa0043 100644
--- a/esphome/arduino/library.py
+++ b/esphome/arduino/library.py
@@ -1,25 +1,12 @@
 """Arduino-core backend for the shared PlatformIO library converter.
 
-Turns the libraries registered via ``cg.add_library()`` into build inputs for
-a native Arduino build. Bare names that exist under the framework's bundled
-``libraries/`` directory (ESP8266WiFi, Wire, SPI, ...) are read straight from
-the framework tree; everything else goes through the shared
-resolution/download pipeline in ``esphome.platformio.library``. Nothing here
-is core-specific: the caller names the PlatformIO platform, MCU, and cache
-key of the Arduino core it builds.
+Bundled names build straight from the framework tree; everything else goes
+through ``esphome.platformio.library``. Mirrors ``lib_ldf_mode=off``: each
+library builds its own archive; all include dirs join one global path.
 
-Known deviations: flat-layout (``library.properties``, no ``src/``)
-libraries get the recursive default source filter rather than PlatformIO's
-root-only Arduino-1.0 filter (no bundled library is affected), and the
-Arduino ``dot_a_linkage`` property is honored even though PlatformIO
-ignores it. Bundled libraries never run a manifest ``extraScript`` (a
-warning names the library if one declares it). Manifest ``-I`` build
-flags join the global include path rather than staying private to the
-library's own sources as under PlatformIO.
-
-Mirrors PlatformIO's ``lib_ldf_mode=off`` behavior: each library builds into
-its own static archive and every library's include dir joins one global
-include path.
+Deviations from PlatformIO: flat-layout libraries get the recursive default
+source filter; ``dot_a_linkage`` is honored; bundled libraries never run a
+manifest ``extraScript``; manifest ``-I`` flags join the global include path.
 """
 
 from __future__ import annotations
@@ -101,12 +88,8 @@ def _warn_properties_depends(name: str, data: object) -> None:
 
 
 def _manifest_build(name: str, data: object) -> dict:
-    """The manifest's ``build`` section, validated by name.
-
-    A bare json.load imposes no shape; a malformed manifest must name the
-    library instead of an AttributeError deep in a traceback (and must do so
-    before apply_extra_script dereferences the same section).
-    """
+    """The manifest's ``build`` section; a malformed manifest must fail
+    naming the library, not with an AttributeError."""
     build = data.get("build", {}) if isinstance(data, dict) else None
     if not isinstance(build, dict):
         raise EsphomeError(f"Library {name} has a malformed manifest")
@@ -119,9 +102,8 @@ def _library_info(name: str, read_path: Path, data: dict) -> ArduinoLibrary:
 
     # PIO's source-dir resolution: manifest srcDir, else src/Src, else the root
     if "srcDir" in build:
-        # An explicitly declared srcDir (falsy included) that does not
-        # resolve is unambiguously a manifest/tree error; a silently empty
-        # source set would surface as link errors far from the cause
+        # A declared srcDir (falsy included) that does not resolve is a
+        # manifest error
         src_dir = build["srcDir"]
         if not (
             isinstance(src_dir, str) and src_dir and (read_path / src_dir).is_dir()
@@ -138,11 +120,8 @@ def _library_info(name: str, read_path: Path, data: dict) -> ArduinoLibrary:
     # PlatformIO shell-lexes each build.flags entry
     flag_tokens = lex_build_flags(build.get("flags", []), f"library {name}")
 
-    # build.libArchive is PIO behavior; dot_a_linkage is honored as a
-    # deliberate extra (Arduino IDE's property, which PIO ignores) so
-    # properties-only libraries can opt out of archiving too. Both parse
-    # through the same strict table: bool("false") is True, and a typo'd
-    # value must not silently change link semantics.
+    # dot_a_linkage (Arduino IDE's property, ignored by PIO) is a deliberate
+    # extra. Strict parse: bool("false") is True.
     def _parse_archive(key: str, raw: object) -> bool:
         if isinstance(raw, bool):
             return raw
@@ -233,9 +212,7 @@ def _bundled_library(framework_path: Path, name: str) -> ArduinoLibrary:
         manifest = lib_dir / "library.properties"
         data = parse_library_properties(manifest) if manifest.is_file() else {}
     if isinstance(data, dict):
-        # The dependency walk never runs for bundled libraries (a no-op for
-        # the ESP8266 core, whose bundled manifests declare none); on a core
-        # where one does, the skip must be visible before link errors
+        # Bundled manifest deps are never walked; make the skip visible
         if data.get("dependencies"):
             _LOGGER.warning(
                 "Bundled library %s declares dependencies, which are not "
@@ -296,10 +273,8 @@ def resolve_libraries(
     # PlatformIO's lib_ignore covers framework-bundled libraries too; the
     # shared converter only filters the registry/git ones.
     lib_ignore = lib_ignore_set()
-    # One memoized answer to "does the framework bundle this name?" for the
-    # classification loop, the provides hook, and the dependency walk: the
-    # safety guard and the dir probe must stay fused (path traversal), and
-    # common names (Wire, SPI) are asked repeatedly
+    # Memoized "does the framework bundle this name?"; the safety guard and
+    # dir probe must stay fused (path traversal)
     _provided = functools.cache(
         lambda name: (
             _is_safe_library_name(name)
@@ -309,16 +284,11 @@ def resolve_libraries(
     for library in CORE.platformio_libraries.values():
         if is_lib_ignored(library.name, lib_ignore):
             continue
-        # Only a bare name with a matching framework directory is bundled: a
-        # version pin means a registry package ("pngle@1.1.0"), and a bare
-        # name without the directory resolves from the registry at the
-        # latest version, matching PlatformIO (a typo fails loudly as a
-        # registry lookup error).
+        # Bundled only for a bare name with a matching framework dir; pinned
+        # or unmatched names resolve from the registry, as under PlatformIO.
         if not library.repository and not library.version and _provided(library.name):
-            # A bundled library's own manifest dependencies are not walked.
-            # PlatformIO would walk them even under lib_ldf_mode=off, but no
-            # library bundled with the ESP8266 core declares any, so the walk
-            # is a no-op there; core add_library() calls list what they need.
+            # Bundled libraries' own manifest deps are not walked (none of
+            # the ESP8266 core's declare any; _bundled_library warns if one does)
             bundled.append(_bundled_library(framework_path, library.name))
         else:
             external.append(library)
@@ -328,9 +298,8 @@ def resolve_libraries(
     converted_manifest_names: set[str] = set()
     # Ordered set of bundled dependency names to add once conversion is done
     pending_bundled: dict[str, None] = {}
-    # Short names of the separately-requested externals: a manifest
-    # dependency matching one is already in the build, not a bundled name to
-    # add (a duplicate archive shows up as duplicate-symbol link errors)
+    # Deps matching a separately-requested external are already in the build
+    # (a duplicate archive means duplicate-symbol link errors)
     external_short_names = {
         _external_short_name(lib.name) for lib in external if lib.name
     }
@@ -360,18 +329,14 @@ def resolve_libraries(
             ):
                 continue
             if dep.get("owner") or not _provided(name):
-                # The converter resolves owner-qualified and non-bundled
-                # names from the registry; an owner-less name that exists in
-                # the framework tree prefers the bundled copy ({"Wire": "*"}
-                # normalizes to version="*"), matching PlatformIO's
-                # process_dependencies. The shared walk's post-emit
-                # reconciliation reports any real drops.
+                # Owner-less names in the framework tree prefer the bundled
+                # copy (PIO's process_dependencies); everything else resolves
+                # via the converter, and the walk reports any real drops
                 continue
             if not dependency_is_usable(dep, pio_platform, "arduino", component.name):
                 continue
-            # Deferred: a later-emitted converted library may satisfy this
-            # name (its manifest name is only known at its own emit), and
-            # adding the bundled copy too would double the archive
+            # Deferred: a later-emitted library's manifest name may satisfy
+            # this; adding now could double the archive
             pending_bundled.setdefault(name)
 
     def _emit(component: ConvertedLibrary) -> None:
@@ -388,9 +353,6 @@ def resolve_libraries(
         _add_bundled_dependencies(component)
 
     if external:
-        # Every converter drop path raises (an incompatible top-level is a
-        # RuntimeError, resolution and download failures raise), so the
-        # return needs no re-verification here.
         convert_libraries(
             external,
             LibraryBackend(
@@ -398,10 +360,8 @@ def resolve_libraries(
                 framework="arduino",
                 emit=_emit,
                 cache_key=cache_key,
-                # The graph walk must not resolve a bundled name from the
-                # registry ({"Wire": "*"} in a manifest); the bundled copy
-                # is added by _add_bundled_dependencies after emit. Unsafe
-                # names are simply not provided.
+                # The walk must not resolve bundled names from the registry;
+                # _add_bundled_dependencies adds them after emit
                 provides=_provided,
             ),
         )
diff --git a/esphome/arduino8266/framework.py b/esphome/arduino8266/framework.py
index 5ca305e0ef..f680815c31 100644
--- a/esphome/arduino8266/framework.py
+++ b/esphome/arduino8266/framework.py
@@ -6,14 +6,9 @@ ESP-IDF install in ``esphome.espidf.framework``):
     <cache>/arduino8266/frameworks/<version>/   framework-arduinoespressif8266
     <cache>/arduino8266/toolchains/<version>/   toolchain-xtensa (gcc 10.3)
 
-ninja itself comes from PATH or the ninja PyPI wheel (a requirements.txt
-dependency), so only the two packages above are downloaded, via the shared
-PlatformIO-registry installer in ``esphome.platformio.registry``.
-
-Sources default to the PlatformIO registry (the exact packages the PlatformIO
-toolchain has always used, so the bits are identical); the
-``ESPHOME_ARDUINO8266_*_MIRRORS`` environment variables override the URLs with
-``{VERSION}`` / ``{SYSTEM}`` substitution.
+Packages come from the PlatformIO registry (identical bits to the PlatformIO
+backend); ``ESPHOME_ARDUINO8266_*_MIRRORS`` overrides the URLs. ninja comes
+from PATH or the ninja PyPI wheel.
 """
 
 from __future__ import annotations
@@ -31,9 +26,8 @@ from esphome.platformio.registry import install_package
 
 FRAMEWORK_PACKAGE = "framework-arduinoespressif8266"
 TOOLCHAIN_PACKAGE = "toolchain-xtensa"
-# gcc 10.3, the toolchain Arduino core 3.x builds with. The compile flags in
-# the build generator are tuned to it; treat version changes as a full
-# reinstall (the install dir is keyed on the version).
+# gcc 10.3, the toolchain Arduino core 3.x builds with; the build
+# generator's compile flags are tuned to it.
 TOOLCHAIN_VERSION = "2.100300.220621"
 
 ESPHOME_ARDUINO8266_FRAMEWORK_MIRRORS = str_to_lst_of_str(
@@ -56,31 +50,20 @@ MIN_FRAMEWORK_VERSION = Version(3, 1, 1)
 
 
 def framework_package_version(ver: Version) -> str:
-    """Map an Arduino core version (e.g. 3.1.2) to its package version.
+    """Map an Arduino core version to its registry package version (3.1.2 ->
+    3.30102.0; the leading 3 is the package major).
 
-    The PlatformIO registry's encoding for cores newer than 2.6.2 (3.1.2 ->
-    3.30102.0, and 2.7.4 -> 3.20704.0: the leading 3 is the package major,
-    not the core major). Exact registry names only from 3.0.2 up: 2.6.3,
-    3.0.0 and 3.0.1 ship as 3.20603.200130 / 3.30000.210519 /
-    3.30001.210627, which this formula cannot produce. Safe for the
-    PlatformIO caller (a ~ range) and for check_and_install (floored at
-    MIN_FRAMEWORK_VERSION); an exact lookup below that floor must not use
-    this helper. A future core 4.x needs its own encoding and toolchain pin
-    rather than a registry lookup for a package that cannot exist.
+    Exact registry names only for cores > 2.6.2 and >= 3.0.2; callers floor
+    at MIN_FRAMEWORK_VERSION.
     """
     if ver.major > 3:
-        # Backend-neutral: this also fires on the PlatformIO validation path
-        # (via _format_framework_arduino_version), where switching toolchains
-        # would not help
         raise EsphomeError(
             f"Arduino core {ver} is not supported yet; "
             "the newest known core series is 3.x"
         )
     if ver <= Version(2, 6, 2):
-        # Same boundary as _format_framework_arduino_version's era guard (a
-        # 2.6.2 pre-release sorts above 2.6.2 and belongs to this encoding).
-        # Older cores use the 1.x/2.x package-major encodings; never encode
-        # them wrongly for a caller that skipped that guard
+        # Cores <= 2.6.2 use the older 1.x/2.x package-major encodings (same
+        # boundary as _format_framework_arduino_version's era guard)
         raise EsphomeError(
             f"Arduino core {ver} uses an older package encoding than this "
             "helper implements (newer than 2.6.2)"
@@ -141,10 +124,7 @@ def check_and_install(framework_version: Version) -> InstalledPaths:
     )
 
 
-# Sentinel: "resolve for me" (None is a real value meaning disabled).
-# The native run_compile (a later PR in the chain) will resolve once and
-# thread the result so one build never pays the PATH scan and runnability
-# probe three times.
+# Sentinel: "resolve for me"; None is a real value meaning disabled.
 CCACHE_UNRESOLVED: Any = object()
 
 
@@ -176,8 +156,7 @@ def get_build_env(
 def ccache_path() -> str | None:
     """The ccache binary to prefix compiles with, or None when disabled.
 
-    Deliberately uncached (matching espidf): the decision reads
-    ESPHOME_CCACHE_ENABLE and PATH, which can change between builds in a
+    Deliberately uncached: env/PATH can change between builds in a
     long-lived host process.
     """
     return resolve_ccache_path()
@@ -186,10 +165,7 @@ def ccache_path() -> str | None:
 def ccache_env(ccache: str | None = CCACHE_UNRESOLVED) -> dict[str, str]:
     """Return ccache settings for the build subprocess (not os.environ).
 
-    Mirrors ``espidf.framework._ccache_env``: cache under the machine-global
-    tools dir, depend mode (gcc emits depfiles via -MMD), and CCACHE_BASEDIR
-    scoped to the build dir so devices share framework cache entries. Values
-    the user already set in the environment are respected.
+    Values the user already set in the environment are respected.
     """
     if ccache is CCACHE_UNRESOLVED:
         ccache = ccache_path()
diff --git a/esphome/build_gen/build_tool.py b/esphome/build_gen/build_tool.py
index 4cdbb88c28..6395f84dd0 100644
--- a/esphome/build_gen/build_tool.py
+++ b/esphome/build_gen/build_tool.py
@@ -21,14 +21,9 @@ def main() -> int:
         # Remove first: ``ar rc`` replaces members but never drops ones whose
         # source was removed from the build, which would leak stale objects.
         Path(archive).unlink(missing_ok=True)
-        # Expand the response file here instead of passing @rspfile: GNU ar
-        # treats backslashes in response files as escapes, corrupting Windows
-        # paths ("sub\a.o" -> "suba.o").
-        # One path per line (rspfile_content = $in_newline). ninja shell-quotes
-        # a path containing specials, so undo a simple surrounding quote per
-        # line. Expanding into argv trades away the OS command-line length
-        # limit rspfiles dodge; the relative object paths here stay far
-        # below it.
+        # GNU ar treats backslashes in response files as escapes (corrupts
+        # Windows paths), so expand the rspfile into argv, stripping the
+        # simple surrounding quote ninja adds to special paths.
         objects = [
             line[1:-1]
             if len(line) >= 2 and line[0] == line[-1] and line[0] in "'\""
diff --git a/esphome/build_helpers/ccache.py b/esphome/build_helpers/ccache.py
index 81bafe874e..8804e5028d 100644
--- a/esphome/build_helpers/ccache.py
+++ b/esphome/build_helpers/ccache.py
@@ -1,13 +1,5 @@
-"""Shared ccache policy for build backends.
-
-``ccache_defaults_env`` serves the backends that export ``CCACHE_*`` into a
-build subprocess (native ESP-IDF and Arduino); ``resolve_ccache_path``
-carries the probe and enable rules (PlatformIO and the native Arduino
-build). The ESP-IDF backend keeps ``IDF_CCACHE_ENABLE`` as a
-higher-precedence override and falls back to the shared resolver (probe
-included) when it is unset; PlatformIO feeds its SCons wrapper script
-through env channels instead of ``CCACHE_*`` defaults.
-"""
+"""Shared ccache policy for build backends: env-knob parsing, binary
+resolution, and default ``CCACHE_*`` values."""
 
 from __future__ import annotations
 
@@ -50,12 +42,8 @@ def parse_enable_env(name: str) -> bool | None:
 def resolve_ccache_path() -> str | None:
     """The ccache binary to wrap compiles with, or None when disabled.
 
-    Shared policy for every backend: on by default when a runnable ccache is
-    on PATH, ``ESPHOME_CCACHE_ENABLE=0`` opts out, and an explicit ``=1``
-    warns when no binary is found and skips the runnability probe;
-    any other value warns and is treated as unset. The
-    Windows extended-length prefix is stripped before probing so the probe
-    validates the exact string the build will execute (#18399).
+    An explicit ``ESPHOME_CCACHE_ENABLE=1`` skips the runnability probe; the
+    Windows extended-length prefix is stripped before probing (#18399).
     """
     import shutil
 
@@ -85,9 +73,8 @@ def ccache_defaults_env(cache_dir: Path) -> dict[str, str]:
     """
     from esphome.core import CORE
 
-    # build_path is set during preload for every config-loading command; unset
-    # means the caller built the environment too early. Fail loudly rather
-    # than silently drop CCACHE_BASEDIR (losing cross-device cache hits).
+    # An unset build_path means the env was built before preload; fail loudly
+    # rather than silently drop CCACHE_BASEDIR.
     if CORE.build_path is None:
         raise ValueError(
             "CORE.build_path must be set before constructing the build environment"
diff --git a/esphome/build_helpers/idedata.py b/esphome/build_helpers/idedata.py
index 31b62df528..00a890e087 100644
--- a/esphome/build_helpers/idedata.py
+++ b/esphome/build_helpers/idedata.py
@@ -123,10 +123,8 @@ def _pick_entry(entries: list[dict]) -> dict:
     raise ValueError("no C++ translation unit found in compile_commands.json")
 
 
-# Compiler launchers that may prefix a compile command. A closed denylist is
-# sturdier than trying to enumerate compiler names: launchers are few and
-# stable, while compilers (cross prefixes, versioned names, icx, armcc, ...)
-# are an open set.
+# Compiler launchers that may prefix a compile command; a closed launcher
+# denylist beats enumerating compiler names, an open set.
 _LAUNCHER_STEMS = frozenset({"ccache", "sccache", "distcc", "icecc", "buildcache"})
 
 
@@ -300,17 +298,14 @@ def idedata_from_build(compile_commands: Path, launcher: str | None = None) -> d
     representative = _pick_entry(entries)
     cxx_path, defines, rep_includes, cxx_flags = parse_entry(representative, launcher)
     if _is_launcher(cxx_path):
-        # Checked before the toolchain probe (which would fail opaquely on
-        # a launcher) so the unusable compile DB is named, and never
-        # cached or conflated with "nothing built yet"
+        # Reject before the toolchain probe, which would fail opaquely on
+        # a launcher; never cache the unusable compile DB
         raise EsphomeError(
             f"compile_commands.json names the launcher {cxx_path} as the "
             "compiler; the compile database is unusable"
         )
 
     # Seed with the representative's includes so it is not parsed twice
-    # (per-file -c/-o arguments make every command distinct, so memoizing
-    # whole commands would never hit)
     build_includes: dict[str, None] = dict.fromkeys(
         rep_includes if _is_esphome_src(representative["file"]) else ()
     )
diff --git a/esphome/build_helpers/ninja.py b/esphome/build_helpers/ninja.py
index 9850dfd828..8c25bc9513 100644
--- a/esphome/build_helpers/ninja.py
+++ b/esphome/build_helpers/ninja.py
@@ -25,11 +25,7 @@ def _ninja_runs(binary: str) -> bool:
 
 def find_ninja() -> Path:
     """Locate the ninja binary: a runnable PATH hit first, else the ninja
-    PyPI wheel.
-
-    The wheel is a requirements.txt dependency, so pip has already
-    integrity-checked it; no download logic is needed here.
-    """
+    PyPI wheel."""
     if binary := shutil.which("ninja"):
         binary = strip_win_long_path_prefix(binary)
         if _ninja_runs(binary):
@@ -58,13 +54,9 @@ def escape(value: Path | str) -> str:
 
 
 def quote_arg(tok: str) -> str:
-    """Wrap a token in double quotes with the Windows argv rule.
-
-    Same escaping rule as ``subprocess.list2cmdline``: a backslash run
-    doubles only immediately before a quote (or the closing quote), and the
-    quote itself is escaped. CreateProcess-only; POSIX sh collapses
-    backslash runs inside double quotes, so shell_token single-quotes
-    there instead. ``$`` must already be doubled for ninja.
+    """Quote with the CreateProcess argv rule (as ``subprocess.list2cmdline``):
+    backslash runs double only before a quote. Windows-only; ``$`` must
+    already be doubled for ninja.
     """
     quoted = re.sub(r'(\\*)"', lambda m: m.group(1) * 2 + '\\"', tok)
     quoted = re.sub(r"(\\+)\Z", lambda m: m.group(1) * 2, quoted)
@@ -78,16 +70,11 @@ _NEEDS_QUOTE = re.compile(r"[^\w@%+=:,./-]")
 
 
 def shell_token(tok: str, force: bool = False) -> str:
-    """Quote a lexed token only when needed; ``force`` always quotes.
+    """Re-quote a lexed token for the platform shell; ``force`` always quotes.
 
-    Lexing strips the quoting a user wrote (``-DX="a b"`` becomes the single
-    token ``-DX=a b``); re-quote on the way out so the compiler receives the
-    same argv element SCons would pass under PlatformIO. Ninja hands POSIX
-    commands to ``/bin/sh -c`` and Windows commands to CreateProcess, so the
-    quoting style is chosen per platform: single quotes on POSIX (sh expands
-    nothing inside them, matching SCons's no-shell spawn) and the argv rule
-    on Windows. ``$`` is doubled first in either case because ninja expands
-    ``$`` before the command reaches the shell.
+    Single quotes on POSIX (/bin/sh), the argv rule on Windows
+    (CreateProcess). ``$`` is doubled first because ninja expands it before
+    the command reaches the shell.
     """
     tok = tok.replace("$", "$$")  # ninja would expand a bare $ to nothing
     if not (force or not tok or _NEEDS_QUOTE.search(tok)):
diff --git a/esphome/build_helpers/size_summary.py b/esphome/build_helpers/size_summary.py
index 72c429d095..b888111044 100644
--- a/esphome/build_helpers/size_summary.py
+++ b/esphome/build_helpers/size_summary.py
@@ -4,11 +4,7 @@ from __future__ import annotations
 
 
 def format_bar(used: int, total: int) -> str:
-    """Match PlatformIO's ``_format_availale_bytes`` (pioupload.py) exactly.
-
-    The upstream helper's name really is spelled that way; keep the citation
-    verbatim so it stays greppable in the PlatformIO source.
-    """
+    """Match PlatformIO's ``_format_availale_bytes`` (sic, pioupload.py) exactly."""
     pct_raw = used / total if total else 0
     blocks = 10
     filled = min(int(round(blocks * pct_raw)), blocks)
diff --git a/esphome/compiled_config.py b/esphome/compiled_config.py
index 066209b184..0d855d71db 100644
--- a/esphome/compiled_config.py
+++ b/esphome/compiled_config.py
@@ -105,10 +105,9 @@ def _refresh_sidecar() -> bool:
                 and CORE.toolchain is not None
                 and old.toolchain != CORE.toolchain.value
             ):
-                # The config was validated under a different toolchain than
-                # the compile's, and platforms normalize toolchain-sensitive
-                # keys (e.g. the esp32 board name) differently; caching it
-                # would disagree with the sidecar until the next compile
+                # Platforms normalize toolchain-sensitive keys differently;
+                # never cache a config validated under a different toolchain
+                # than the compile's
                 _LOGGER.debug(
                     "Not caching: config validated with toolchain %r but the "
                     "last compile used %r",
diff --git a/esphome/components/esp8266/boards.py b/esphome/components/esp8266/boards.py
index 5be8011ba4..d458442dbd 100644
--- a/esphome/components/esp8266/boards.py
+++ b/esphome/components/esp8266/boards.py
@@ -362,14 +362,9 @@ BOARDS = {
 }
 
 
-# Per-board Arduino core build metadata for the native (PlatformIO-free)
-# toolchain: the variant directory (supplies pins_arduino.h) and the
-# board-identity defines the PlatformIO builder passes via build.extra_flags.
-# Valid for platform 4.x only (older tags differ, e.g. esp8285's variant);
-# the native toolchain's validator enforces that pairing by requiring core
-# >= 3.1.1 and rejecting a custom platform_version.
-# -DESP8266 and -DARDUINO_ARCH_ESP8266 are shared by every board and added by
-# the generator; only the per-board defines are listed here.
+# Per-board variant dir + identity defines from platform-espressif8266 4.x
+# build.extra_flags; the shared -DESP8266/-DARDUINO_ARCH_ESP8266 are added
+# by the generator.
 #
 # Regenerate ESP8266_BOARD_BUILD with (v4.2.1 is the platform version the
 # native toolchain mirrors; regenerate against the tag when bumping it):
diff --git a/esphome/components/esp8266/build_surgery.py b/esphome/components/esp8266/build_surgery.py
index 97ce750dd5..2df1d5dbb8 100644
--- a/esphome/components/esp8266/build_surgery.py
+++ b/esphome/components/esp8266/build_surgery.py
@@ -84,8 +84,6 @@ def apply_testing_memory_patches(content: str, segments: Collection[str]) -> str
     """
     for segment in _TESTING_SEGMENT_SIZES:
         if segment not in segments and _segment_line_re(segment).search(content):
-            # A known segment left unpatched would keep its real memory limit
-            # and silently under-provision the testing build
             raise RuntimeError(
                 f"Testing-mode segment {segment} is present in the linker "
                 "script but was not selected for patching"
@@ -111,12 +109,8 @@ def segment_length(content: str, segment_name: str) -> int | None:
 
 
 def surgery_fingerprint() -> str:
-    """Fingerprint of this module's source, covering every behavioral input.
-
-    Linker-script caches include it so an edit here invalidates them; hashing
-    the source over-invalidates on comment edits, which is the safe direction.
-    Native-toolchain-only, like ``segment_length``; no script twin.
-    """
+    """Hash of this module's source; linker-script caches include it so an
+    edit here invalidates them."""
     import inspect
     import sys
 
diff --git a/esphome/config_validation.py b/esphome/config_validation.py
index 102e78b3d9..98001d5d5b 100644
--- a/esphome/config_validation.py
+++ b/esphome/config_validation.py
@@ -2540,12 +2540,8 @@ def platformio_version_constraint(value):
 def _check_supported_toolchain(
     platform_name: str, supported: tuple[Toolchain, ...]
 ) -> None:
-    """Raise when the resolved ``CORE.toolchain`` is not in ``supported``.
-
-    One message shape for every platform, so a ``--toolchain`` a platform
-    cannot serve always fails by name instead of silently building with a
-    different backend.
-    """
+    """Raise when the resolved ``CORE.toolchain`` is not in ``supported``
+    (one message shape for every platform)."""
     toolchain = CORE.toolchain
     if toolchain is None:
         # A caller ran the check before resolving; an ordering bug, not a
@@ -2591,14 +2587,8 @@ def resolve_toolchain(
 def require_platformio_toolchain(
     platform_name: str,
 ) -> Callable[[ConfigType], ConfigType]:
-    """Reject a CLI-selected toolchain other than PlatformIO.
-
-    For platforms with only the PlatformIO backend. Without this a
-    ``--toolchain`` they cannot serve would either build with PlatformIO
-    while claiming another backend, or (for a toolchain another platform
-    owns, like ``esp-idf``) dispatch to a native backend that cannot
-    build this platform at all.
-    """
+    """Reject a CLI-selected toolchain other than PlatformIO, for platforms
+    with only the PlatformIO backend."""
     return resolve_toolchain(
         platform_name, (Toolchain.PLATFORMIO,), Toolchain.PLATFORMIO
     )
diff --git a/esphome/core/__init__.py b/esphome/core/__init__.py
index a20a60e322..a4fd2ced30 100644
--- a/esphome/core/__init__.py
+++ b/esphome/core/__init__.py
@@ -985,12 +985,8 @@ class EsphomeCore:
 
     @property
     def using_toolchain_arduino(self):
-        """The native (PlatformIO-free) ESP8266 Arduino build backend.
-
-        Unlike ``using_arduino`` (the target *framework*, true for any
-        platform compiling Arduino code), this is a build *toolchain*
-        choice, like its ``using_toolchain_*`` siblings.
-        """
+        """The native ESP8266 Arduino build toolchain (unlike
+        ``using_arduino``, which is the target framework)."""
         return self.toolchain == Toolchain.ARDUINO
 
     @property
diff --git a/esphome/core/config.py b/esphome/core/config.py
index cbd36e8924..bade3ba9c4 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -566,11 +566,7 @@ async def _add_platformio_options(pio_options: dict[str, str | list[str]]) -> No
     if CORE.using_native_toolchain:
         # The native builds don't read platformio.ini; honor the options
         # with a native equivalent and warn about the rest, which would
-        # otherwise be silently ignored. Every dispatch site that tests a
-        # specific using_toolchain_* as a stand-in for "native" (project
-        # writing, compile, upload, firmware paths) must agree with this
-        # gate: a toolchain treated as native here must never fall through
-        # to a PlatformIO code path there.
+        # otherwise be silently ignored.
         for key, val in pio_options.items():
             vals = [val] if isinstance(val, str) else val
             if key == CONF_BUILD_FLAGS:
@@ -600,12 +596,8 @@ async def _add_platformio_options(pio_options: dict[str, str | list[str]]) -> No
                 # discovered dependencies
                 cg.add_platformio_option(key, vals)
             elif key in NATIVE_ARDUINO_PIO_OPTIONS and CORE.using_toolchain_arduino:
-                # Real-world knobs many published ESP8266 configs rely on:
-                # f_cpu 160000000L for timing-sensitive integrations, and a
-                # custom ldscript to reserve a filesystem region or correct
-                # a board's flash size. The esp8266 native generator reads
-                # both; other native toolchains have no equivalent and fall
-                # through to the warning.
+                # The esp8266 native generator reads these; other native
+                # toolchains have no equivalent and fall through to the warning.
                 cg.add_platformio_option(key, val)
             elif key != "upload_speed":
                 # upload_speed needs no handling: it is read from the raw
diff --git a/esphome/espidf/component.py b/esphome/espidf/component.py
index d71607714c..4eeaa30e7f 100644
--- a/esphome/espidf/component.py
+++ b/esphome/espidf/component.py
@@ -88,10 +88,8 @@ def generate_cmakelists_txt(component: IDFComponent) -> str:
     build_src_filter = ensure_list(
         component.data.get("build", {}).get("srcFilter", DEFAULT_BUILD_SRC_FILTER)
     )
-    # PlatformIO shell-lexes each build.flags entry, so one entry can carry a
-    # flag and its argument (e.g. "-include cp_custom_alloc.h"); bare
-    # -I/-L/-l/-D tokens re-glue to their argument ("-I foo" -> "-Ifoo") so
-    # prefix classifiers below still route them.
+    # PlatformIO shell-lexes each build.flags entry; bare -I/-L/-l/-D tokens
+    # re-glue to their argument so the prefix classifiers below route them.
     build_flags = lex_build_flags(
         component.data.get("build", {}).get("flags", DEFAULT_BUILD_FLAGS),
         f"library {component.name}",
diff --git a/esphome/espidf/framework.py b/esphome/espidf/framework.py
index 3977c6560c..c6d9ef13f1 100644
--- a/esphome/espidf/framework.py
+++ b/esphome/espidf/framework.py
@@ -1155,11 +1155,8 @@ def _ccache_env() -> dict[str, str]:
     Only values the user has not already set in the environment are returned, so
     a custom ``CCACHE_DIR`` / ``CCACHE_MAXSIZE`` / etc. is respected.
     """
-    # Honor an explicit choice already in the environment (opt-out or opt-in).
-    # IDF_CCACHE_ENABLE (this backend's native knob) wins over the shared
-    # ESPHOME_CCACHE_ENABLE, which resolve_ccache_path parses; without it a
-    # user disabling ccache to debug a miscompile would silently keep it
-    # enabled here.
+    # IDF_CCACHE_ENABLE (the backend-native knob) wins over the shared
+    # ESPHOME_CCACHE_ENABLE.
     idf_knob = parse_enable_env("IDF_CCACHE_ENABLE")
     if idf_knob is False:
         return {}
@@ -1167,8 +1164,6 @@ def _ccache_env() -> dict[str, str]:
         # ESP-IDF silently skips ccache without the binary; don't enable it.
         return {}
 
-    # ccache is enabled past here; the shared helper carries the CCACHE_*
-    # policy (and the fail-loud build_path guard).
     env = ccache_defaults_env(get_idf_tools_path() / "ccache")
     if idf_knob is None:
         # An unparsable IDF_CCACHE_ENABLE must not leak to idf.py as truthy
diff --git a/esphome/framework_helpers.py b/esphome/framework_helpers.py
index 3da8f403ee..d98d9e4982 100644
--- a/esphome/framework_helpers.py
+++ b/esphome/framework_helpers.py
@@ -199,10 +199,8 @@ def run_command(
 def tool_version_runs(binary: str, warning: str) -> bool:
     """Probe ``binary --version``; on failure warn with ``warning`` % binary.
 
-    ``shutil.which`` proves existence, not runnability: on Windows it also
-    matches ``.bat``/``.cmd`` wrappers and stale package-manager shims whose
-    target is gone. Callers probe once and fall back instead of failing
-    every build step with an opaque OS error.
+    ``shutil.which`` proves existence, not runnability (Windows .bat/.cmd
+    shims, stale package-manager shims).
     """
     try:
         subprocess.run(
diff --git a/esphome/platformio/extra_script.py b/esphome/platformio/extra_script.py
index 4a0a0dc7c5..e311e8729b 100644
--- a/esphome/platformio/extra_script.py
+++ b/esphome/platformio/extra_script.py
@@ -141,9 +141,7 @@ class _FakeSConsEnv:
     def Append(self, **kwargs) -> None:  # noqa: N802 (SCons API name)
         for key, value in kwargs.items():
             if key not in _CAPTURED_KEYS:
-                # Diagnosable from the build log when a script configures
-                # something this shim does not translate; once per key so a
-                # loop of Appends cannot spam
+                # Warn once per key so a loop of Appends cannot spam
                 if key not in self._warned_keys:
                     self._warned_keys.add(key)
                     _LOGGER.warning(
@@ -239,9 +237,8 @@ def run_extra_script(
         )
         return ExtraScriptResult()
     except Exception as e:  # noqa: BLE001  # pylint: disable=broad-exception-caught
-        # Discard any partial capture: folding half a script's flags into the
-        # build could produce wrong-output firmware that links cleanly. The
-        # warning plus the resulting loud link error point back here.
+        # Discard any partial capture: half-applied flags could build wrong
+        # firmware that links cleanly.
         _LOGGER.warning(
             "PIO extra-script %s (in %s) raised %r; ignoring its output",
             script_path,
diff --git a/esphome/platformio/library.py b/esphome/platformio/library.py
index 110ab1483e..a37c7fe5bf 100644
--- a/esphome/platformio/library.py
+++ b/esphome/platformio/library.py
@@ -47,11 +47,8 @@ DEFAULT_BUILD_SRC_FILTER = (
 DEFAULT_BUILD_SRC_DIRS = "src"
 DEFAULT_BUILD_INCLUDE_DIR = "include"
 DEFAULT_BUILD_FLAGS = []
-# Source suffix -> compiler kind, PlatformIO's CSUFFIXES/CXXSUFFIXES/ASSUFFIXES
-# split. Native build generators map the kind to their compile rules. "asm"
-# deliberately merges SCons's AS (.s/.asm) and ASPP (.S/.spp/.sx) sets: the
-# ninja rules compile all of them as assembler-with-cpp, whose asm-mode
-# preprocessor passes non-directive text through unchanged.
+# Suffix -> compiler kind (PlatformIO's CSUFFIXES/CXXSUFFIXES/ASSUFFIXES).
+# "asm" merges SCons's AS and ASPP sets: all compile as assembler-with-cpp.
 SOURCE_KIND_FOR_SUFFIX: dict[str, str] = {
     ".c": "c",
     ".cpp": "cxx",
@@ -301,10 +298,9 @@ class LibraryBackend:
     framework: str
     emit: Callable[["ConvertedLibrary"], None]
     cache_key: str
-    # When set, an owner-less manifest dependency this returns True for is
-    # skipped by the graph walk: the backend provides it outside the
-    # registry (e.g. a library bundled with the Arduino core), mirroring
-    # PlatformIO's process_dependencies preference for bundled builders.
+    # Owner-less dependency names this returns True for are skipped by the
+    # walk; the backend supplies them outside the registry (e.g. core-bundled
+    # libraries).
     provides: Callable[[str], bool] | None = None
 
 
@@ -633,13 +629,8 @@ def join_flag_args(tokens: Iterable[str], owner: str) -> list[str]:
 def dependency_is_usable(
     dep: dict, platform: str | None, framework: str, requester: str
 ) -> bool:
-    """Whether a manifest dependency passes the compatibility filter.
-
-    The routine cross-platform skip logs at debug; any other
-    ``InvalidLibrary`` cause is a dropped dependency and warns naming the
-    requester (unreachable from ``check_library_data`` today, which raises
-    only for the platform filter).
-    """
+    """Compatibility filter for a manifest dependency: platform mismatches
+    skip at debug, any other ``InvalidLibrary`` warns naming the requester."""
     try:
         check_library_data(dep, platform, framework)
     except IncompatiblePlatform as e:
@@ -699,9 +690,7 @@ def normalize_dependencies(
                 continue
             normalized.append(entry)
         elif isinstance(entry, str) and entry:
-            # PIO also accepts a bare list of names ("dependencies":
-            # ["Wire"]); dropping them here would hide a real dependency
-            # from every caller's visibility warning
+            # PIO also accepts a bare list of names ("dependencies": ["Wire"])
             normalized.append({"name": entry})
         else:
             _LOGGER.warning(
@@ -1025,10 +1014,8 @@ def convert_libraries(
             component.data.get("dependencies"), component.name
         ):
             if "name" not in dependency or "version" not in dependency:
-                # Version-less deps cannot resolve from the registry.
-                # Deferred: only the final resolution set can tell a real
-                # drop from a name another manifest resolves later, so the
-                # reconciliation after emit owns the warning
+                # Version-less deps cannot resolve from the registry; the
+                # post-emit reconciliation owns the drop warning
                 _LOGGER.debug(
                     "Skip version-less dependency %r of %s",
                     dependency.get("name"),
@@ -1056,9 +1043,8 @@ def convert_libraries(
                 # The backend adds it from its own tree; resolving it here
                 # would fetch a same-named registry package instead
                 if (pin := dependency.get("version")) and pin != "*":
-                    # The declared constraint is discarded for the bundled
-                    # copy; a too-old bundled library must not surface as
-                    # link errors with no stated cause
+                    # The version pin is discarded for the bundled copy; make
+                    # the substitution visible
                     _LOGGER.warning(
                         "Dependency %s pins version %s; using the library "
                         "bundled with the framework instead",
@@ -1126,11 +1112,9 @@ def convert_libraries(
     for component in components.values():
         backend.emit(component)
 
-    # A version-less dependency is satisfied when its request key resolved,
-    # a resolved component's manifest name matches, or the backend provides
-    # it from its own tree (e.g. the arduino bundled libraries, added by the
-    # backend after emit). Anything else is a real drop that would otherwise
-    # surface as link errors far from the cause.
+    # Warn for version-less deps nothing satisfied (request key, manifest
+    # name, or backend provides()); a silent drop surfaces as link errors
+    # far from the cause.
     resolved_manifest_names = {c.data.get("name") for c in components.values()}
     warned: set[str] = set()
     for dep_name, dep_owner, requester in skipped_versionless:
diff --git a/esphome/platformio/registry.py b/esphome/platformio/registry.py
index 09a66e0cf9..99ccbe2334 100644
--- a/esphome/platformio/registry.py
+++ b/esphome/platformio/registry.py
@@ -1,9 +1,5 @@
-"""Install packages from the PlatformIO registry without PlatformIO.
-
-Native toolchains install the exact registry packages the PlatformIO backend
-uses, so the bits are identical, but resolve and verify them with esphome's
-own download machinery instead of importing the platformio package.
-"""
+"""Install packages from the PlatformIO registry without importing the
+platformio package (identical bits, esphome's own download machinery)."""
 
 from __future__ import annotations
 
@@ -33,11 +29,9 @@ _REGISTRY_URL = (
 def get_systype() -> str:
     """The registry system tag for the current host.
 
-    A transliteration of ``platformio.util.get_systype()``, honoring the same
-    ``PLATFORMIO_SYSTEM_TYPE`` override, so this module never imports the
-    platformio package. One deviation: windows-arm64 maps straight to
-    ``windows_amd64``: the registry ships no arm64 toolchains and those hosts
-    run x86 binaries via emulation, which upstream leaves to the override.
+    Transliterates ``platformio.util.get_systype()`` (same
+    ``PLATFORMIO_SYSTEM_TYPE`` override). Deviation: windows-arm64 maps to
+    ``windows_amd64`` (no arm64 toolchains; x86 emulation).
     """
     if systype := os.environ.get("PLATFORMIO_SYSTEM_TYPE"):
         return systype
@@ -100,10 +94,8 @@ def registry_download(package: str, version: str) -> tuple[str, str, int | None]
                     f"Unexpected package registry response for {package}: "
                     f"{str(ver)[:200]}"
                 )
-            # Only a MISSING key means "any system"; an explicitly empty
-            # list must not match (a wrong-architecture download would be
-            # cached as a good install). A bare string would make ``in`` a
-            # substring test.
+            # Only a missing key means "any system"; an empty list must not
+            # match, and a bare string would make ``in`` a substring test.
             systems = file.get("system")
             if systems is None:
                 systems = ["*"]
@@ -138,12 +130,8 @@ def registry_download(package: str, version: str) -> tuple[str, str, int | None]
 
 
 def _check_layout(name: str, dest: Path, expect: Collection[str]) -> None:
-    """Raise when an install tree is missing an expected directory.
-
-    Runs on fresh extracts and on marker hits: a marked tree that later
-    lost files (manual deletion, antivirus quarantine) must fail by name
-    instead of surfacing as an opaque toolchain error.
-    """
+    """Raise when an install tree is missing an expected directory (runs on
+    fresh extracts and on marker hits)."""
     for rel in expect:
         if not (dest / rel).is_dir():
             raise EsphomeError(
@@ -177,21 +165,16 @@ def install_package(
         return
     from filelock import FileLock
 
-    # The cache is machine-global; serialize concurrent cold builds so one
-    # process cannot wipe the directory another is extracting into (same
-    # filelock pattern as platformio/toolchain.py and git.py).
+    # Serialize concurrent cold builds (same filelock pattern as git.py).
     dest.parent.mkdir(parents=True, exist_ok=True)
-    # fallback_to_soft would silently degrade to an existence lock on a
-    # flock-less filesystem; a hard-killed run would then hang every later
-    # build forever (same hazard git.py documents).
+    # A soft-lock fallback would turn a hard-killed run into a permanent
+    # hang (see git.py).
     with FileLock(f"{dest}.lock", fallback_to_soft=False):
         if marker.is_file():
             # Another process finished the install while we waited
             return
         rmdir(dest, msg=f"Clean up incomplete {name} install")
-        # A persistent download location (not a temp dir) so an interrupted
-        # download resumes across esphome runs via download_with_resume's
-        # .part file, mirroring the espidf dist/ convention.
+        # Persistent location so an interrupted download resumes across runs.
         downloads_dir.mkdir(parents=True, exist_ok=True)
         archive = downloads_dir / f"{name}-{version}"
         _LOGGER.info("Downloading %s %s ...", name, version)
diff --git a/tests/unit_tests/build_gen/test_build_tool.py b/tests/unit_tests/build_gen/test_build_tool.py
index 875ffcb773..7f56abe9cb 100644
--- a/tests/unit_tests/build_gen/test_build_tool.py
+++ b/tests/unit_tests/build_gen/test_build_tool.py
@@ -3,6 +3,8 @@
 from __future__ import annotations
 
 from pathlib import Path
+import subprocess
+import sys
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -50,8 +52,6 @@ def test_unknown_mode(capsys: pytest.CaptureFixture[str]) -> None:
 
 def test_runs_as_script(tmp_path: Path) -> None:
     """The ninja rules invoke the file as a plain script."""
-    import subprocess
-    import sys
 
     src = tmp_path / "a.bin"
     src.write_text("x")
diff --git a/tests/unit_tests/build_helpers/test_idedata.py b/tests/unit_tests/build_helpers/test_idedata.py
index 7297912955..52ffc88224 100644
--- a/tests/unit_tests/build_helpers/test_idedata.py
+++ b/tests/unit_tests/build_helpers/test_idedata.py
@@ -429,8 +429,7 @@ def test_load_or_build_idedata_corrupted_cache_is_logged(
 
 
 def test_load_or_build_idedata_never_caches_a_launcher(tmp_path: Path) -> None:
-    """A compile DB naming a launcher as the compiler is rejected by name,
-    before the toolchain probe could fail opaquely, and never cached."""
+    """A compile DB naming a launcher as the compiler is rejected, never cached."""
     compile_commands = tmp_path / "compile_commands.json"
     compile_commands.write_text(
         json.dumps(
diff --git a/tests/unit_tests/build_helpers/test_ninja.py b/tests/unit_tests/build_helpers/test_ninja.py
index b1a43bd4af..6f0bbda0b9 100644
--- a/tests/unit_tests/build_helpers/test_ninja.py
+++ b/tests/unit_tests/build_helpers/test_ninja.py
@@ -4,6 +4,7 @@ from __future__ import annotations
 
 import os
 from pathlib import Path
+import subprocess
 import sys
 from unittest.mock import MagicMock, patch
 
@@ -84,7 +85,6 @@ def test_shell_token_quotes_shell_metacharacters() -> None:
 def test_shell_token_posix_roundtrips_through_sh() -> None:
     """Backslash runs, $, backticks, and quotes must reach the compiler
     exactly as lexed once ninja un-doubles $$ and /bin/sh strips quotes."""
-    import subprocess
 
     if sys.platform == "win32":
         pytest.skip("POSIX sh quoting")
diff --git a/tests/unit_tests/components/esp8266/test_build_surgery.py b/tests/unit_tests/components/esp8266/test_build_surgery.py
index b1c3fd7be8..411a35eb96 100644
--- a/tests/unit_tests/components/esp8266/test_build_surgery.py
+++ b/tests/unit_tests/components/esp8266/test_build_surgery.py
@@ -2,8 +2,13 @@
 
 from __future__ import annotations
 
+import importlib.util
+from pathlib import Path
+import sys
+
 import pytest
 
+from esphome.components.esp8266 import build_surgery
 from esphome.components.esp8266.boards import BOARDS, ESP8266_BOARD_BUILD
 from esphome.components.esp8266.build_surgery import (
     RATETABLE_RULE,
@@ -110,11 +115,6 @@ def test_board_build_covers_every_board() -> None:
 def test_surgery_fingerprint_is_stable_and_sensitive(tmp_path) -> None:
     """The properties the linker-script cache depends on: the fingerprint is
     stable across calls and changes when the module's source changes."""
-    import importlib.util
-    from pathlib import Path as _Path
-    import sys
-
-    from esphome.components.esp8266 import build_surgery
 
     first = build_surgery.surgery_fingerprint()
     assert first == build_surgery.surgery_fingerprint()
@@ -124,7 +124,7 @@ def test_surgery_fingerprint_is_stable_and_sensitive(tmp_path) -> None:
     # A modified copy of the module must fingerprint differently
     copy = tmp_path / "build_surgery_variant.py"
     copy.write_text(
-        _Path(build_surgery.__file__).read_text(encoding="utf-8")
+        Path(build_surgery.__file__).read_text(encoding="utf-8")
         + "\nEXTRA_BEHAVIORAL_INPUT = 1\n",
         encoding="utf-8",
     )
diff --git a/tests/unit_tests/test_arduino8266_framework.py b/tests/unit_tests/test_arduino8266_framework.py
index c173fb27f2..2837be1905 100644
--- a/tests/unit_tests/test_arduino8266_framework.py
+++ b/tests/unit_tests/test_arduino8266_framework.py
@@ -26,9 +26,8 @@ def test_framework_package_version() -> None:
     # A future major bump needs its own encoding, not a doomed registry lookup
     with pytest.raises(EsphomeError, match="not supported yet"):
         framework.framework_package_version(cv.Version(4, 0, 0))
-    # Cores up to 2.6.2 use other encodings; the helper is total, not wrong,
-    # and its boundary matches the PlatformIO era guard: a 2.6.2 pre-release
-    # sorts above 2.6.2 and keeps the package-major-3 encoding
+    # The boundary matches the PlatformIO era guard; a 2.6.2 pre-release
+    # keeps this encoding
     with pytest.raises(EsphomeError, match="older package encoding"):
         framework.framework_package_version(cv.Version(2, 6, 2))
     assert framework.framework_package_version(cv.Version(2, 6, 2, "b1")) == "3.20602.0"
@@ -102,9 +101,8 @@ def test_get_build_env_prepends_toolchain_bin(tmp_path: Path) -> None:
 def test_ccache_path_delegates_uncached(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
-    """The wrapper delegates to the shared policy (covered in
-    build_helpers/test_ccache.py) on every call: the env/PATH decision
-    must not freeze for the process lifetime in a long-lived host."""
+    """Delegates on every call; the env/PATH decision must not freeze for
+    the process lifetime."""
     monkeypatch.delenv("ESPHOME_CCACHE_ENABLE", raising=False)
     with patch.object(
         framework, "resolve_ccache_path", return_value="/usr/bin/ccache"
diff --git a/tests/unit_tests/test_arduino_library.py b/tests/unit_tests/test_arduino_library.py
index 42e1bfc1c9..c310c964d9 100644
--- a/tests/unit_tests/test_arduino_library.py
+++ b/tests/unit_tests/test_arduino_library.py
@@ -12,7 +12,13 @@ import pytest
 from esphome.arduino import library as component
 from esphome.const import KEY_CORE, KEY_TARGET_PLATFORM, PLATFORM_ESP8266
 from esphome.core import CORE, EsphomeError, Library
-from esphome.platformio.library import ConvertedLibrary, LibraryBackend
+import esphome.platformio.library as pio_library
+from esphome.platformio.library import (
+    ConvertedLibrary,
+    IncompatiblePlatform,
+    InvalidLibrary,
+    LibraryBackend,
+)
 
 
 @pytest.fixture(autouse=True)
@@ -212,9 +218,7 @@ def test_resolve_libraries_bundled(tmp_path: Path) -> None:
 def test_resolve_libraries_registry_name_is_external(
     tmp_path: Path, version: str | None
 ) -> None:
-    """A name that is not bundled reaches the converter: bare resolves from
-    the registry at the latest version (matching PlatformIO and the
-    documented libraries: key) and a version pin is a registry package."""
+    """A name that is not bundled reaches the converter, bare or pinned."""
     framework = _make_framework(tmp_path)
     _add_library("pngle", version)
     with patch.object(component, "convert_libraries", return_value=[]) as mock_convert:
@@ -410,12 +414,8 @@ def test_bundled_dependency_nonplatform_rejection_warns(
     tmp_path: Path, caplog: pytest.LogCaptureFixture
 ) -> None:
     """An InvalidLibrary whose cause is not the platform filter is visible."""
-    from esphome.platformio.library import InvalidLibrary
-
     framework = _make_framework(tmp_path)
     converted = _webserver(tmp_path, {"build": {}, "dependencies": [{"name": "Wire"}]})
-    import esphome.platformio.library as pio_library
-
     with (
         _emitting_converter(converted),
         patch.object(
@@ -466,9 +466,7 @@ def test_library_info_lib_archive_parse(
 
 
 def test_bundled_dependency_dict_shorthand_prefers_bundled(tmp_path: Path) -> None:
-    """The {"Wire": "*"} dict shorthand (version="*", no owner) must resolve
-    to the bundled library, matching PIO's process_dependencies, instead of
-    being routed to the registry."""
+    """The {"Wire": "*"} dict shorthand resolves to the bundled library."""
     framework = _make_framework(tmp_path)
     converted = _webserver(tmp_path, {"build": {}, "dependencies": {"Wire": "*"}})
     with _emitting_converter(converted):
@@ -481,12 +479,8 @@ def test_bundled_dependency_platform_rejection_is_debug(
 ) -> None:
     """The typed IncompatiblePlatform (the routine cross-platform skip)
     stays at debug regardless of message wording."""
-    from esphome.platformio.library import IncompatiblePlatform
-
     framework = _make_framework(tmp_path)
     converted = _webserver(tmp_path, {"build": {}, "dependencies": [{"name": "Wire"}]})
-    import esphome.platformio.library as pio_library
-
     with (
         _emitting_converter(converted),
         patch.object(
@@ -626,11 +620,8 @@ def test_bundled_library_non_dict_manifest_skips_probes_and_raises(
 def test_dict_shorthand_dependency_skips_registry_through_real_converter(
     tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ) -> None:
-    """{"Wire": "*"} in a real manifest must never reach the registry: the
-    graph walk skips backend-provided names and the bundled copy is added
-    after emit (no converter mock; a registry touch fails the test)."""
-    import esphome.platformio.library as pio_library
-
+    """{"Wire": "*"} resolves to the bundled copy without touching the
+    registry (real converter)."""
     framework = _make_framework(tmp_path)
     _local_lib(tmp_path, {"Wire": "*"})
     # Pin the component cache to tmp_path (data_dir honors an ambient
@@ -702,8 +693,6 @@ def test_pinned_bundled_dependency_substitution_warns(
 ) -> None:
     """A non-* version pin on a backend-provided dependency is discarded
     for the bundled copy; the substitution must be visible."""
-    import esphome.platformio.library as pio_library
-
     framework = _make_framework(tmp_path)
     _local_lib(tmp_path, {"Wire": "^2.0.0"})
     monkeypatch.setenv("ESPHOME_DATA_DIR", str(tmp_path / ".esphome"))
@@ -720,9 +709,7 @@ def test_pinned_bundled_dependency_substitution_warns(
 def test_transitively_resolved_dependency_does_not_warn(
     tmp_path: Path, caplog: pytest.LogCaptureFixture
 ) -> None:
-    """A version-less dependency the walk resolved as another library's
-    registry dependency is present in the build; the skipping warning must
-    stay quiet for it."""
+    """A dependency the walk already resolved does not warn."""
     framework = _make_framework(tmp_path)
     _add_library("ESP32Async/ESPAsyncWebServer", "3.9.6")
     ws, tcp = _ws_tcp_pair(tmp_path)
@@ -754,9 +741,8 @@ def test_external_short_name(spec: str, expected: str) -> None:
 def test_converted_manifest_name_suppresses_bundled_dependency(
     tmp_path: Path,
 ) -> None:
-    """A dependency name a converted library's manifest provides is not
-    also added from the framework tree (a duplicate archive would surface
-    as duplicate-symbol link errors), even when the provider emits later."""
+    """A name a converted library's manifest provides is not also added
+    from the framework tree, even when the provider emits later."""
     framework = _make_framework(tmp_path)
     _add_library("ESP32Async/ESPAsyncWebServer", "3.9.6")
     # Requested under a different short name; only the manifest says "Wire"
@@ -814,8 +800,6 @@ def test_versionless_dependency_with_provider_stays_quiet(
 ) -> None:
     """With a provides backend the version-less skip is routine (debug) and
     the bundled copy is picked up after emit."""
-    import esphome.platformio.library as pio_library
-
     framework = _make_framework(tmp_path)
     _local_lib(tmp_path, [{"name": "Wire"}])
     monkeypatch.setenv("ESPHOME_DATA_DIR", str(tmp_path / ".esphome"))
diff --git a/tests/unit_tests/test_compiled_config.py b/tests/unit_tests/test_compiled_config.py
index 62d043f480..4333420a9e 100644
--- a/tests/unit_tests/test_compiled_config.py
+++ b/tests/unit_tests/test_compiled_config.py
@@ -643,8 +643,7 @@ def test_save_compiled_config_and_sidecar_toolchain_mismatch(
     tmp_path: Path, sidecar_toolchain: str | None, saved: bool
 ) -> None:
     """A config validated under a different toolchain than the compile's
-    must not overwrite the cache: platforms normalize toolchain-sensitive
-    keys differently and the sidecar keeps the compile's toolchain."""
+    must not overwrite the cache."""
     yaml_path = _bare_yaml(tmp_path)
     _prime_core(tmp_path)
     CORE.config = {CONF_ESPHOME: {CONF_NAME: "lite_test"}}
diff --git a/tests/unit_tests/test_config_validation.py b/tests/unit_tests/test_config_validation.py
index 9f8633667e..0f927a6513 100644
--- a/tests/unit_tests/test_config_validation.py
+++ b/tests/unit_tests/test_config_validation.py
@@ -1,3 +1,4 @@
+import importlib
 import json
 import logging
 from pathlib import Path
@@ -48,6 +49,7 @@ from esphome.const import (
     TYPE_GIT,
     TYPE_LOCAL,
     Framework,
+    Toolchain,
 )
 from esphome.core import (
     CORE,
@@ -3169,9 +3171,6 @@ def test_file__remapped_path_is_directory_raises(setup_core: Path) -> None:
 
 def test_require_platformio_toolchain() -> None:
     """Platforms with only the PlatformIO backend reject other toolchains."""
-    from esphome.const import Toolchain
-    from esphome.core import CORE
-
     validator = cv.require_platformio_toolchain("RP2")
     CORE.toolchain = None
     config: dict = {}
@@ -3186,9 +3185,6 @@ def test_require_platformio_toolchain() -> None:
 def test_check_supported_toolchain_unresolved_is_an_ordering_bug() -> None:
     """Calling the check before resolution fails naming the ordering bug,
     not a user-facing unsupported-toolchain error."""
-    from esphome.const import Toolchain
-    from esphome.core import CORE
-
     CORE.toolchain = None
     with pytest.raises(Invalid, match="not resolved before RP2 validation"):
         cv._check_supported_toolchain("RP2", (Toolchain.PLATFORMIO,))
@@ -3209,14 +3205,7 @@ def test_check_supported_toolchain_unresolved_is_an_ordering_bug() -> None:
 def test_every_platformio_only_platform_rejects_arduino_toolchain(
     platform: str, minimal_config: dict
 ) -> None:
-    """The invariant every native-toolchain gate relies on: a platform that
-    cannot serve a CLI toolchain rejects it at validation (esp32, esp8266,
-    and nrf52 pin this in their own suites)."""
-    import importlib
-
-    from esphome.const import Toolchain
-    from esphome.core import CORE
-
+    """A platform that cannot serve a CLI toolchain rejects it at validation."""
     module = importlib.import_module(f"esphome.components.{platform}")
     CORE.toolchain = Toolchain.ARDUINO
     with pytest.raises(Invalid, match="Unsupported toolchain 'arduino'"):
diff --git a/tests/unit_tests/test_espidf_component.py b/tests/unit_tests/test_espidf_component.py
index 1baa22777c..e2884454e5 100644
--- a/tests/unit_tests/test_espidf_component.py
+++ b/tests/unit_tests/test_espidf_component.py
@@ -6,6 +6,7 @@ from unittest.mock import MagicMock
 
 import pytest
 
+from esphome.components import esp32 as esp32_module
 from esphome.const import (
     KEY_CORE,
     KEY_TARGET_FRAMEWORK,
@@ -15,6 +16,7 @@ from esphome.const import (
 )
 from esphome.core import CORE, Library
 from esphome.espidf.component import (
+    _emit_idf_component,
     generate_cmakelists_txt,
     generate_idf_component_yml,
     generate_idf_components,
@@ -1072,8 +1074,6 @@ def test_idf_component_download_passes_salt() -> None:
 def test_emit_idf_component_wires_esp32_target(tmp_path, monkeypatch):
     """Emitting a component resolves the esp32 variant into the shared
     extraScript helper."""
-    from esphome.components import esp32 as esp32_module
-    from esphome.espidf.component import _emit_idf_component
 
     monkeypatch.setattr(esp32_module, "get_esp32_variant", lambda: "ESP32")
     (tmp_path / "src").mkdir()
diff --git a/tests/unit_tests/test_espidf_framework.py b/tests/unit_tests/test_espidf_framework.py
index 32e2d7a3fb..d66f1fc7db 100644
--- a/tests/unit_tests/test_espidf_framework.py
+++ b/tests/unit_tests/test_espidf_framework.py
@@ -1395,8 +1395,6 @@ def test_get_framework_env_without_python_env_uses_os_path(tmp_path: Path) -> No
 
 def _ccache_patches(tmp_path: Path, which: str | None, build_path: Path | None):
     return (
-        # The gate defers to the shared resolver (which carries the PATH
-        # lookup, ESPHOME_CCACHE_ENABLE parse, and runnability probe)
         patch("esphome.espidf.framework.resolve_ccache_path", return_value=which),
         patch(
             "esphome.espidf.framework.get_idf_tools_path",
diff --git a/tests/unit_tests/test_main.py b/tests/unit_tests/test_main.py
index b991c9900e..b820f6b551 100644
--- a/tests/unit_tests/test_main.py
+++ b/tests/unit_tests/test_main.py
@@ -101,6 +101,7 @@ from esphome.const import (
     CONF_WEB_SERVER,
     CONF_WIFI,
     KEY_CORE,
+    KEY_TARGET_FRAMEWORK,
     KEY_TARGET_PLATFORM,
     PLATFORM_BK72XX,
     PLATFORM_ESP32,
@@ -7139,7 +7140,7 @@ def test_warn_source_tree_mismatch_falls_back_when_stat_fails(
         RuntimeError("Could not query builtin include dirs"),
         ValueError("no C++ translation unit found"),
         KeyError("command"),
-        None,  # replaced with EsphomeError inside (import is function-local)
+        None,  # replaced with EsphomeError inside
     ],
 )
 def test_compile_program_espidf_idedata_failure_does_not_fail_build(
@@ -7147,14 +7148,6 @@ def test_compile_program_espidf_idedata_failure_does_not_fail_build(
     caplog: pytest.LogCaptureFixture,
 ) -> None:
     """A post-compile idedata error is a warning: the firmware already built."""
-    from esphome.const import (
-        KEY_CORE,
-        KEY_TARGET_FRAMEWORK,
-        KEY_TARGET_PLATFORM,
-        Toolchain,
-    )
-    from esphome.core import CORE, EsphomeError
-
     if error is None:
         error = EsphomeError("compile database is unusable")
     CORE.toolchain = Toolchain.ESP_IDF
@@ -7178,14 +7171,6 @@ def test_compile_program_espidf_idedata_success_is_silent(
     caplog: pytest.LogCaptureFixture,
 ) -> None:
     """The healthy path: idedata generated, nothing to warn about."""
-    from esphome.const import (
-        KEY_CORE,
-        KEY_TARGET_FRAMEWORK,
-        KEY_TARGET_PLATFORM,
-        Toolchain,
-    )
-    from esphome.core import CORE
-
     CORE.toolchain = Toolchain.ESP_IDF
     CORE.data[KEY_CORE] = {
         KEY_TARGET_PLATFORM: "esp32",
@@ -7207,14 +7192,6 @@ def test_compile_program_espidf_idedata_none_warns(
     caplog: pytest.LogCaptureFixture,
 ) -> None:
     """A silent None from the post-compile idedata refresh is made visible."""
-    from esphome.const import (
-        KEY_CORE,
-        KEY_TARGET_FRAMEWORK,
-        KEY_TARGET_PLATFORM,
-        Toolchain,
-    )
-    from esphome.core import CORE
-
     CORE.toolchain = Toolchain.ESP_IDF
     CORE.data[KEY_CORE] = {
         KEY_TARGET_PLATFORM: "esp32",
@@ -7235,8 +7212,6 @@ def test_compile_program_espidf_idedata_none_warns(
 def test_cli_toolchain_skips_the_validated_config_cache(tmp_path: Path) -> None:
     """An explicit --toolchain must run the per-platform validators, so the
     upload/logs fast path becomes a cache miss."""
-    from esphome.__main__ import run_esphome
-
     conf = tmp_path / "device.yaml"
     conf.write_text("esphome:\n  name: t\n")
     argv = ["esphome", "--toolchain", "arduino", "logs", str(conf)]
@@ -7255,8 +7230,6 @@ def test_cli_toolchain_still_refreshes_the_validated_config_cache(
     """An explicit --toolchain gates only the cache read; the freshly
     validated config is still saved so a later plain run keeps the fast
     path (an existing compile-written sidecar keeps its toolchain)."""
-    from esphome.__main__ import run_esphome
-
     conf = tmp_path / "device.yaml"
     conf.write_text("esphome:\n  name: t\n")
     argv = ["esphome", "--toolchain", "platformio", "logs", str(conf)]
diff --git a/tests/unit_tests/test_nrf52_framework.py b/tests/unit_tests/test_nrf52_framework.py
index b5f6b5794f..65b73e37fe 100644
--- a/tests/unit_tests/test_nrf52_framework.py
+++ b/tests/unit_tests/test_nrf52_framework.py
@@ -7,8 +7,10 @@ import sys
 from types import SimpleNamespace
 from unittest.mock import patch
 
+import platformdirs
 import pytest
 
+from esphome.components.nrf52 import _resolve_toolchain
 from esphome.components.nrf52.framework import (
     _PLATFORMIO_PENV_REQUIREMENTS,
     _REQUIREMENTS,
@@ -22,8 +24,9 @@ from esphome.components.nrf52.framework import (
     get_sdk_nrf_tools_path,
     setup_platformio_python_env,
 )
+import esphome.config_validation as cv
 from esphome.config_validation import Version
-from esphome.const import KEY_CORE, KEY_FRAMEWORK_VERSION
+from esphome.const import KEY_CORE, KEY_FRAMEWORK_VERSION, Toolchain
 from esphome.core import CORE, EsphomeError
 from esphome.framework_helpers import get_python_env_executable_path
 
@@ -558,7 +561,6 @@ def testget_tools_path_blank_env_falls_back_to_default(
     Path("") would resolve to the working directory, which clean-all could
     then delete by accident.
     """
-    import platformdirs
 
     monkeypatch.setenv("ESPHOME_SDK_NRF_PREFIX", value)
     expected = (
@@ -570,7 +572,6 @@ def testget_tools_path_blank_env_falls_back_to_default(
 def testget_tools_path_default_is_global_cache(
     monkeypatch: pytest.MonkeyPatch,
 ) -> None:
-    import platformdirs
 
     monkeypatch.delenv("ESPHOME_SDK_NRF_PREFIX", raising=False)
     expected = (
@@ -623,9 +624,6 @@ def test_needs_venv_rebuild_on_dangling_interpreter_symlink(tmp_path: Path) -> N
 
 def test_resolve_toolchain_rejects_unsupported() -> None:
     """A --toolchain nRF52 cannot serve fails instead of degrading silently."""
-    from esphome.components.nrf52 import _resolve_toolchain
-    import esphome.config_validation as cv
-    from esphome.const import Toolchain
 
     CORE.toolchain = Toolchain.ARDUINO
     with pytest.raises(cv.Invalid, match="Unsupported toolchain 'arduino'"):
diff --git a/tests/unit_tests/test_platformio_extra_script.py b/tests/unit_tests/test_platformio_extra_script.py
index 7e904183f1..d09f02d95f 100644
--- a/tests/unit_tests/test_platformio_extra_script.py
+++ b/tests/unit_tests/test_platformio_extra_script.py
@@ -2,19 +2,25 @@
 
 from __future__ import annotations
 
+import logging
 import os
 from pathlib import Path
+from unittest.mock import patch
 
 import pytest
 
+from esphome.core import EsphomeError
+from esphome.platformio.extra_script import (
+    ExtraScriptResult,
+    _FakeSConsEnv,
+    apply_extra_script,
+    captured_as_build_flags,
+    run_extra_script,
+)
 from esphome.platformio.library import ConvertedLibrary as IDFComponent, URLSource
 
 
 def test_extra_script_captures_libpath_libs_and_defines(tmp_path):
-    from esphome.platformio.extra_script import (
-        captured_as_build_flags,
-        run_extra_script,
-    )
 
     (tmp_path / "src" / "esp32").mkdir(parents=True)
     script = tmp_path / "extra_script.py"
@@ -58,10 +64,6 @@ def test_extra_script_libpath_relative_resolves_against_library_dir(
     """Relative LIBPATH entries must resolve against ``library_dir``, not the
     caller's CWD (the shim restores CWD before ``captured_as_build_flags``
     runs)."""
-    from esphome.platformio.extra_script import (
-        ExtraScriptResult,
-        captured_as_build_flags,
-    )
 
     (tmp_path / "lib" / "esp32").mkdir(parents=True)
     elsewhere = tmp_path.parent / "not_the_library_dir"
@@ -76,10 +78,6 @@ def test_extra_script_libpath_relative_resolves_against_library_dir(
 
 
 def test_extra_script_libpath_absolute_outside_library_dir(tmp_path):
-    from esphome.platformio.extra_script import (
-        ExtraScriptResult,
-        captured_as_build_flags,
-    )
 
     outside = tmp_path.parent / "system_lib"
     outside.mkdir(exist_ok=True)
@@ -90,7 +88,6 @@ def test_extra_script_libpath_absolute_outside_library_dir(tmp_path):
 
 
 def test_extra_script_failure_returns_empty_result(tmp_path, caplog):
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "broken.py"
     script.write_text("raise RuntimeError('boom')\n")
@@ -106,7 +103,6 @@ def test_extra_script_failure_returns_empty_result(tmp_path, caplog):
 
 
 def test_apply_extra_script_path_traversal_is_rejected(tmp_path):
-    from esphome.platformio.extra_script import apply_extra_script
 
     library_dir = tmp_path / "lib"
     library_dir.mkdir()
@@ -117,8 +113,6 @@ def test_apply_extra_script_path_traversal_is_rejected(tmp_path):
     c.path = library_dir
     c.data = {"build": {"extraScript": "../evil.py"}}
 
-    from esphome.core import EsphomeError
-
     with pytest.raises(EsphomeError, match="escapes the library directory"):
         apply_extra_script(c, board_mcu=lambda: "esp32", pio_platform="espressif32")
     # Nothing was folded into flags: the traversal was rejected before
@@ -127,7 +121,6 @@ def test_apply_extra_script_path_traversal_is_rejected(tmp_path):
 
 
 def test_apply_extra_script_merges_into_existing_flags(tmp_path):
-    from esphome.platformio.extra_script import apply_extra_script
 
     (tmp_path / "src").mkdir()
     script = tmp_path / "extra.py"
@@ -146,8 +139,6 @@ def test_apply_extra_script_merges_into_existing_flags(tmp_path):
 def test_apply_extra_script_malformed_flags_raises(tmp_path) -> None:
     """A null/dict build.flags fails naming the library instead of injecting
     a non-string into the compiler command line."""
-    from esphome.core import EsphomeError
-    from esphome.platformio.extra_script import apply_extra_script
 
     (tmp_path / "src").mkdir()
     script = tmp_path / "extra.py"
@@ -164,7 +155,6 @@ def test_apply_extra_script_malformed_flags_raises(tmp_path) -> None:
 def test_apply_extra_script_callable_target_and_str_flags(tmp_path) -> None:
     """The shared helper resolves the board_mcu callable lazily and normalizes
     a string ``build.flags`` value into a list before extending it."""
-    from esphome.platformio.extra_script import apply_extra_script
 
     (tmp_path / "src").mkdir()
     script = tmp_path / "extra.py"
@@ -180,7 +170,6 @@ def test_apply_extra_script_callable_target_and_str_flags(tmp_path) -> None:
 
 
 def test_apply_extra_script_no_script_and_no_flags(tmp_path) -> None:
-    from esphome.platformio.extra_script import apply_extra_script
 
     # No extraScript declared: nothing happens, the target is never resolved
     c = IDFComponent("owner/name", "1.0", source=URLSource("http://dummy"))
@@ -203,9 +192,6 @@ def test_apply_extra_script_no_script_and_no_flags(tmp_path) -> None:
 def test_apply_extra_script_ignores_uncaptured_env_calls(tmp_path, caplog) -> None:
     """Un-captured env vars and unsupported env methods are skipped but
     diagnosable from the build log."""
-    import logging
-
-    from esphome.platformio.extra_script import apply_extra_script
 
     caplog.set_level(logging.DEBUG)
     script = tmp_path / "extra.py"
@@ -223,7 +209,6 @@ def test_apply_extra_script_ignores_uncaptured_env_calls(tmp_path, caplog) -> No
 
 def test_apply_extra_script_swallows_script_errors(tmp_path, caplog) -> None:
     """A raising extra-script is best-effort: logged and skipped."""
-    from esphome.platformio.extra_script import apply_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("raise RuntimeError('boom')\n")
@@ -237,7 +222,6 @@ def test_apply_extra_script_swallows_script_errors(tmp_path, caplog) -> None:
 
 def test_apply_extra_script_pio_platform(tmp_path) -> None:
     """The backend's platform token is exposed to the script as PIOPLATFORM."""
-    from esphome.platformio.extra_script import apply_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("env.Append(LIBS=[env.get('PIOPLATFORM')])\n")
@@ -251,8 +235,6 @@ def test_apply_extra_script_pio_platform(tmp_path) -> None:
 def test_apply_extra_script_missing_script_raises(tmp_path) -> None:
     """A declared but absent extraScript is a broken package and fails by
     name, as it would under PlatformIO."""
-    from esphome.core import EsphomeError
-    from esphome.platformio.extra_script import apply_extra_script
 
     c = IDFComponent("owner/name", "1.0", source=URLSource("http://dummy"))
     c.path = tmp_path
@@ -264,7 +246,6 @@ def test_apply_extra_script_missing_script_raises(tmp_path) -> None:
 def test_run_extra_script_failure_discards_partial_capture(tmp_path, caplog) -> None:
     """A crashed script yields an empty result: half-applied flags could
     build wrong-output firmware that links cleanly."""
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("env.Append(LIBS=['algobsec'])\nraise RuntimeError('boom')\n")
@@ -278,7 +259,6 @@ def test_run_extra_script_failure_discards_partial_capture(tmp_path, caplog) ->
 def test_run_extra_script_syntax_error_is_best_effort(tmp_path, caplog) -> None:
     """A vendored script that does not even compile warns and skips instead
     of aborting the build."""
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("def broken(:\n")
@@ -291,7 +271,6 @@ def test_run_extra_script_syntax_error_is_best_effort(tmp_path, caplog) -> None:
 
 def test_unsupported_env_method_warns_once(caplog) -> None:
     """Repeated calls to the same unsupported method warn only once."""
-    from esphome.platformio.extra_script import _FakeSConsEnv
 
     env = _FakeSConsEnv(
         board_mcu="esp8266", pio_env="esphome_esp8266", pio_platform="espressif8266"
@@ -304,7 +283,6 @@ def test_unsupported_env_method_warns_once(caplog) -> None:
 def test_run_extra_script_sys_exit_is_best_effort(tmp_path, caplog) -> None:
     """A nonzero sys.exit() in a vendored script must not kill the esphome
     run, and its output is discarded."""
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("import sys\nenv.Append(LIBS=['x'])\nsys.exit(3)\n")
@@ -317,7 +295,6 @@ def test_run_extra_script_sys_exit_is_best_effort(tmp_path, caplog) -> None:
 
 def test_run_extra_script_sys_exit_zero_is_success(tmp_path, caplog) -> None:
     """sys.exit(0) is a normal PlatformIO script ending: the capture is kept."""
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("import sys\nenv.Append(LIBS=['algobsec'])\nsys.exit(0)\n")
@@ -330,10 +307,6 @@ def test_run_extra_script_sys_exit_zero_is_success(tmp_path, caplog) -> None:
 
 def test_run_extra_script_unreadable_raises(tmp_path) -> None:
     """An unreadable declared script is a broken package, like a missing one."""
-    from unittest.mock import patch
-
-    from esphome.core import EsphomeError
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_text("")
@@ -348,7 +321,6 @@ def test_run_extra_script_unreadable_raises(tmp_path) -> None:
 
 def test_run_extra_script_bad_encoding_is_best_effort(tmp_path, caplog) -> None:
     """Undecodable content warns and skips, like a SyntaxError."""
-    from esphome.platformio.extra_script import run_extra_script
 
     script = tmp_path / "extra.py"
     script.write_bytes(b"\xff\xfe\x00bad")
@@ -361,7 +333,6 @@ def test_run_extra_script_bad_encoding_is_best_effort(tmp_path, caplog) -> None:
 
 def test_uncaptured_append_key_warns_once(caplog) -> None:
     """A loop of Appends to the same uncaptured key warns once."""
-    from esphome.platformio.extra_script import _FakeSConsEnv
 
     env = _FakeSConsEnv(
         board_mcu="esp8266", pio_env="esphome_esp8266", pio_platform="espressif8266"
diff --git a/tests/unit_tests/test_platformio_library.py b/tests/unit_tests/test_platformio_library.py
index 67acebe505..febaf830a5 100644
--- a/tests/unit_tests/test_platformio_library.py
+++ b/tests/unit_tests/test_platformio_library.py
@@ -13,6 +13,7 @@ import pytest
 from esphome.core import EsphomeError, Library
 import esphome.platformio.library as lib
 from esphome.platformio.library import (
+    SOURCE_KIND_FOR_SUFFIX,
     ConvertedLibrary,
     GitSource,
     InvalidLibrary,
@@ -23,6 +24,8 @@ from esphome.platformio.library import (
     _resolve_registry_version,
     check_library_data,
     convert_libraries,
+    join_flag_args,
+    split_flag_entry,
 )
 
 
@@ -539,7 +542,6 @@ def test_convert_libraries_skips_incompatible_dependency(tmp_path, monkeypatch):
 
 def test_split_flag_entry_unbalanced_quote_is_clean() -> None:
     """A malformed flags entry raises EsphomeError, not a raw ValueError."""
-    from esphome.platformio.library import split_flag_entry
 
     assert split_flag_entry('-DX="a b"', "library x") == ["-DX=a b"]
     with pytest.raises(EsphomeError, match=r"Malformed build flag.*library x"):
@@ -548,7 +550,6 @@ def test_split_flag_entry_unbalanced_quote_is_clean() -> None:
 
 def test_join_flag_args_reglues_spaced_define() -> None:
     """A spaced -D re-glues to its argument, as ParseFlags does."""
-    from esphome.platformio.library import join_flag_args
 
     assert join_flag_args(["-D", "FOO=1", "-Os"], "x") == ["-DFOO=1", "-Os"]
 
@@ -556,7 +557,6 @@ def test_join_flag_args_reglues_spaced_define() -> None:
 def test_join_flag_args_trailing_bare_flag_warns(
     caplog: pytest.LogCaptureFixture,
 ) -> None:
-    from esphome.platformio.library import join_flag_args
 
     assert join_flag_args(["-Os", "-l"], "library x") == ["-Os"]
     assert "Ignoring trailing '-l'" in caplog.text
@@ -576,7 +576,6 @@ def test_lex_build_flags_dangling_flag_does_not_cross_entries(
 def test_split_flag_entry_non_string_is_clean() -> None:
     """A dict or number from a third-party manifest fails naming the entry,
     not with an opaque shlex traceback."""
-    from esphome.platformio.library import split_flag_entry
 
     with pytest.raises(EsphomeError, match="Malformed build flag"):
         split_flag_entry({"esp32": ["-DX"]}, "lib x")
@@ -587,7 +586,6 @@ def test_split_flag_entry_non_string_is_clean() -> None:
 def test_source_kind_map_shape() -> None:
     """The kind values the native compile rules key on, and the deliberate
     AS/ASPP merge (.s and .S both map to asm)."""
-    from esphome.platformio.library import SOURCE_KIND_FOR_SUFFIX
 
     assert set(SOURCE_KIND_FOR_SUFFIX.values()) == {"c", "cxx", "asm"}
     assert SOURCE_KIND_FOR_SUFFIX[".s"] == "asm"
@@ -681,9 +679,8 @@ def test_walk_warns_for_nonplatform_invalid_library(
 def test_versionless_owner_qualified_dependency_warns_despite_provides(
     tmp_path, monkeypatch, caplog: pytest.LogCaptureFixture
 ) -> None:
-    """The backend's provides() only covers owner-less names (the walk's
-    backend-provided skip has the same guard), so an owner-qualified
-    version-less dependency that nobody adds must still warn."""
+    """An owner-qualified version-less dependency is not satisfied by
+    provides(); it must still warn."""
     _patch_download_with_manifests(
         monkeypatch,
         tmp_path,
@@ -758,9 +755,8 @@ def test_versionless_url_ish_dependency_name_warns_cleanly(
 def test_versionless_dependency_matching_resolved_manifest_name_stays_quiet(
     tmp_path, monkeypatch, caplog: pytest.LogCaptureFixture
 ) -> None:
-    """A bare dependency name satisfied by a component requested under an
-    owner-qualified spec (manifest names match) is not a drop; a nameless
-    entry is skipped without a reconciliation warning."""
+    """A bare name satisfied by an owner-qualified component's manifest
+    name is not a drop."""
     _patch_download_with_manifests(
         monkeypatch,
         tmp_path,
diff --git a/tests/unit_tests/test_writer.py b/tests/unit_tests/test_writer.py
index 6c05fc330b..9ccfc4f4ab 100644
--- a/tests/unit_tests/test_writer.py
+++ b/tests/unit_tests/test_writer.py
@@ -1051,8 +1051,6 @@ def test_clean_all_removes_global_arduino8266_install(
     config_dir = tmp_path / "config"
     config_dir.mkdir()
 
-    from esphome.writer import clean_all
-
     with caplog.at_level("INFO"):
         clean_all([str(config_dir)])