audit: the port's pass — the scan that could not walk, and the drift a generator ends

--scan's walk was unwalkable on POSIX: probe rates have no termios
B-constant, so the first off-nominal probe raised out of the loop. The port
speaks termios2 BOTHER now (red-proven on a pty at 9984 Bd), the probe's
open lives inside the walk's error handling, an fd no longer leaks on an
unmakeable rate, and the swallowed unknown-signature reply is named at
timeout instead of reported as silence. CMakePresets.json's generator emits
the submodule toolchain path it had drifted from — a hand edit on a
generated file, exactly the class rule 10 exists for — and presets.generated
gates the pair from here on (the  marker CMake rejects at the
presets root stayed out; the check is the guard). The over-slot image guard
the tsb runner gained reaches the pureboot runner too; the GPIO bridge's
delivery comment states the hardware truth (RXC at the stop bit's sampling
point); the hardware suite gains the scan check — the one place the rate
physics is real; and the libavr pin advances over both audit rounds.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tools/make_presets.py

@@ -7,11 +7,14 @@ port's TUs compile identically; the sims prove nothing new there) exist for
 libavr's reflect spot set only, mirroring its rule: the full reflect matrix
 is never built, one chip per hardware class and pack vintage is.
 
-Run from the repo root: tools/make_presets.py
+Run from the repo root: tools/make_presets.py — or with --check, which
+verifies the committed file matches this generator and edits nothing (the
+ctest entry `presets.generated` runs that, so drift reds the gate).
 """
 
 import json
 import os
+import sys
 
 CHIPS = [
     "attiny13", "attiny13a", "attiny25", "attiny45", "attiny85",
@@ -41,7 +44,7 @@ def main():
         "hidden": True,
         "generator": "Ninja",
         "binaryDir": "${sourceDir}/build/${presetName}",
-        "toolchainFile": "$env{LIBAVR_ROOT}/cmake/avr-toolchain.cmake",
+        "toolchainFile": "${sourceDir}/libavr/cmake/avr-toolchain.cmake",
         "cacheVariables": {
             "CMAKE_BUILD_TYPE": "Release",
             "CMAKE_EXPORT_COMPILE_COMMANDS": "ON",
@@ -72,6 +75,9 @@ def main():
     for chip in REFLECT_SPOT:
         add(chip, "reflect")
 
+    # CMake rejects unknown fields in the presets root, $comment included, so
+    # the file cannot carry a generated-file marker; the --check ctest is the
+    # whole of rule 10's guard here.
     presets = {
         "version": 8,
         "configurePresets": configure,
@@ -79,12 +85,19 @@ def main():
         "testPresets": test,
         "workflowPresets": workflows,
     }
+    rendered = json.dumps(presets, indent=1) + "\n"
     path = os.path.join(os.path.dirname(os.path.abspath(__file__)), "..", "CMakePresets.json")
+    if "--check" in sys.argv[1:]:
+        current = open(path).read() if os.path.exists(path) else ""
+        if current != rendered:
+            print("CMakePresets.json does not match its generator — run tools/make_presets.py")
+            return 1
+        return 0
     with open(path, "w") as f:
-        json.dump(presets, f, indent=1)
-        f.write("\n")
+        f.write(rendered)
     print(f"{len(CHIPS)} chips, {len(REFLECT_SPOT)} reflect: {os.path.normpath(path)}")
+    return 0
 
 
 if __name__ == "__main__":
-    main()
+    sys.exit(main())