chore(baseline-205): tighten excluded-libs scan to file field only

The previous scan globbed every needle (FNET / Snooze / RadioHead /
mbedtls) against the entire compile_commands.json entry — file +
directory + command + arguments. That caught the framework-wide
`-I.../libraries/<lib>` header search-path flag on every TU, so the
report read "FNET: 68 entries" on teensylc just because the include
path was on every translation unit. The actual AC#1 question — "did
any FNET source file get compiled?" — was masked.

Switch to a path-segment match against the `file` field only:
`/libraries/<needle>/` in the normalized POSIX form. Now the count is
"TUs whose `file` is a `<needle>/...` source file", which is the
question AC#1 asks.

With the fix, all four boards (teensylc, teensy30, teensy41,
stm32f103c8) report `0 (not compiled)` for every excluded library —
AC#1 is met cleanly across the matrix, no hand-reading required.

Also reworded the report line from "Excluded library hits in
compile_commands.json" → "Excluded-library source files compiled
(AC#1 must be 0 for all)" so the report header itself states the
contract.

Refs: #205 AC#1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: zackees

ci/measure_baseline_205.py

@@ -16,8 +16,11 @@
 3. Probes the resulting firmware.elf for ``.text`` / ``.data`` / ``.bss`` /
    ``.dmabuffers`` section sizes via ``arm-none-eabi-size`` (preferred for
    ARM targets) or ``llvm-size``.
-4. Scans compile_commands.json for FNET / Snooze / RadioHead / mbedtls
-   entries (the libraries that #204 root-caused as wrongly-selected).
+4. Scans compile_commands.json for compiled FNET / Snooze / RadioHead /
+   mbedtls source files (the libraries that #204 root-caused as
+   wrongly-selected). Counts are by ``file`` field only — never by the
+   ``-I.../libraries/<lib>`` header search-path flag, which is on every
+   TU regardless of which sources were compiled.
 
 Skipping behaviour:
 
@@ -207,7 +210,20 @@ def generate_compdb(project: Path, env: str) -> tuple[bool, str]:
 
 # ── Parsers ──────────────────────────────────────────────────────────────────
 def parse_compile_commands(path: Path) -> tuple[Optional[int], dict]:
-    """Return (tu_count, excluded_lib_hits)."""
+    """Return (tu_count, excluded_lib_hits).
+
+    ``excluded_lib_hits[lib]`` counts TUs whose ``file`` field is under
+    ``.../libraries/<lib>/`` — i.e. the library actually had a source
+    file compiled. We deliberately do NOT scan the ``arguments`` /
+    ``command`` fields: the framework's full ``-I.../libraries/<lib>``
+    flag is propagated to every TU as a header search path, so a naive
+    substring match would report counts equal to the TU count even
+    when zero ``<lib>/*.c`` files were compiled.
+
+    AC#1 from FastLED/fbuild#205 is "FNET / Snooze / RadioHead /
+    mbedtls are not compiled" — that question is answered by the
+    ``file`` field alone.
+    """
     try:
         with path.open(encoding="utf-8") as fh:
             entries = json.load(fh)
@@ -222,11 +238,13 @@ def parse_compile_commands(path: Path) -> tuple[Optional[int], dict]:
     for entry in entries:
         if not isinstance(entry, dict):
             continue
-        haystack = " ".join(
-            str(entry.get(key, "")) for key in ("file", "directory", "command", "arguments")
-        )
+        file_field = entry.get("file")
+        if not isinstance(file_field, str):
+            continue
+        # Normalize separators so the same check works on Windows + Unix.
+        normalized = file_field.replace("\\", "/")
         for needle in EXCLUDED_LIB_NEEDLES:
-            if needle.lower() in haystack.lower():
+            if f"/libraries/{needle}/" in normalized:
                 hits[needle] += 1
     return tu_count, hits
 
@@ -332,10 +350,12 @@ def render_markdown(results: List[TargetResult], git_sha: str, branch: str, carg
                 lines.append(f"- {section}: section absent or size tool unavailable")
             else:
                 lines.append(f"- {section}: {value:,} bytes")
-        lines.append("- Excluded library hits in compile_commands.json:")
+        lines.append(
+            "- Excluded-library source files compiled (AC#1 must be 0 for all):"
+        )
         for needle in EXCLUDED_LIB_NEEDLES:
             count = r.excluded_lib_hits.get(needle, 0)
-            label = "not present" if count == 0 else f"{count} entries"
+            label = "0 (not compiled)" if count == 0 else f"{count} TU(s) compiled"
             lines.append(f"  - {needle}: {label}")
         if r.notes:
             lines.append(f"- Notes: {r.notes}")

tasks/baseline-205.md

@@ -1,8 +1,8 @@
 # Baseline measurements for #205
 
-Captured: 2026-05-10T15:14:08Z
-Git SHA: fffb1b4cc6389942bf63cc2ae0f01e65484e10fe
-Branch: chore/fix-baseline-205-teensylc-env
+Captured: 2026-05-10T15:40:43Z
+Git SHA: 52b517511baeba28344e8cb7630aa4772e8420ac
+Branch: chore/baseline-205-tighten-excluded-libs-scan
 Tooling: cargo 1.94.1 (29ea6fb6a 2026-03-24), size tool: arm-none-eabi-size.exe
 
 Generated by `uv run python ci/measure_baseline_205.py`. See module docstring for methodology.
@@ -16,11 +16,11 @@ Generated by `uv run python ci/measure_baseline_205.py`. See module docstring fo
 - .data: 380 bytes
 - .bss: 1,068 bytes
 - .dmabuffers: 192 bytes
-- Excluded library hits in compile_commands.json:
-  - FNET: 68 entries
-  - Snooze: 68 entries
-  - RadioHead: 68 entries
-  - mbedtls: not present
+- Excluded-library source files compiled (AC#1 must be 0 for all):
+  - FNET: 0 (not compiled)
+  - Snooze: 0 (not compiled)
+  - RadioHead: 0 (not compiled)
+  - mbedtls: 0 (not compiled)
 
 ## teensy30 / Blink
 
@@ -31,11 +31,11 @@ Generated by `uv run python ci/measure_baseline_205.py`. See module docstring fo
 - .data: 272 bytes
 - .bss: 1,120 bytes
 - .dmabuffers: 248 bytes
-- Excluded library hits in compile_commands.json:
-  - FNET: 68 entries
-  - Snooze: 68 entries
-  - RadioHead: 68 entries
-  - mbedtls: not present
+- Excluded-library source files compiled (AC#1 must be 0 for all):
+  - FNET: 0 (not compiled)
+  - Snooze: 0 (not compiled)
+  - RadioHead: 0 (not compiled)
+  - mbedtls: 0 (not compiled)
 
 ## teensy41 / Blink
 
@@ -46,11 +46,11 @@ Generated by `uv run python ci/measure_baseline_205.py`. See module docstring fo
 - .data: 3,776 bytes
 - .bss: 1,664 bytes
 - .dmabuffers: section absent or size tool unavailable
-- Excluded library hits in compile_commands.json:
-  - FNET: 85 entries
-  - Snooze: 85 entries
-  - RadioHead: 85 entries
-  - mbedtls: not present
+- Excluded-library source files compiled (AC#1 must be 0 for all):
+  - FNET: 0 (not compiled)
+  - Snooze: 0 (not compiled)
+  - RadioHead: 0 (not compiled)
+  - mbedtls: 0 (not compiled)
 
 ## stm32f103c8 / Blink
 
@@ -60,11 +60,11 @@ Generated by `uv run python ci/measure_baseline_205.py`. See module docstring fo
 - .text: 12,192 bytes
 - .data: 240 bytes
 - .bss: 1,012 bytes
-- Excluded library hits in compile_commands.json:
-  - FNET: not present
-  - Snooze: not present
-  - RadioHead: not present
-  - mbedtls: not present
+- Excluded-library source files compiled (AC#1 must be 0 for all):
+  - FNET: 0 (not compiled)
+  - Snooze: 0 (not compiled)
+  - RadioHead: 0 (not compiled)
+  - mbedtls: 0 (not compiled)
 
 ## Build status