fix(conformance): the harness contradicted itself in two places

1. auditability-proofs-producible rejected any proven ledger row without a
   sentinel, with no layer exemption — while record_run.py DELIBERATELY records
   L0/L1 rows sentinel-less via its own SENTINEL_EXEMPT_LAYERS, because
   run_l1_offline.py renders skips as JUnit <skipped/> and those layers have no
   pass token to attribute. So ANY `--record` run touching L0 or L1 wrote a row
   this gate then rejected. Consequence: a requirement whose verifier set includes
   an L1 check could never be both PROVEN and L0-green — R-NET-06 is exactly such
   a requirement, and hit it the moment it was re-proven on prod. The check now
   honours the same constant instead of restating the policy, so the two halves
   cannot drift apart again.

2. git_sha() marked the tree dirty from tracked files, but conformance/runs/
   ledger.jsonl IS tracked — so the FIRST `--record` run of a session dirtied the
   tree and every LATER run was stamped `-dirty`, which check.sh then refuses to
   honour. Recording one test poisoned the next, and that cost a second live
   fault-injection run against prod to work around. Its docstring already stated
   the intent for the untracked runs/<id>/ half of the same artifact; the ledger is
   the tracked half. Now excluded via pathspec, mirroring status.py's
   IMPL_EXCLUDE_PREFIXES which already lists this path for the same reason.

Neither change weakens an assertion: (1) applies an exemption that already existed
and was already documented, (2) stops the recorder invalidating its own output.

Co-Authored-By: Claude Opus 5 <[email protected]>

conformance/lib/record_run.py

@@ -467,7 +467,14 @@ def git_sha(repo: Path) -> str:
                              capture_output=True, text=True, check=True).stdout.strip()
     except (subprocess.CalledProcessError, OSError):
         return "unknown"
-    dirty = subprocess.run(["git", "-C", str(repo), "diff", "--quiet", "HEAD", "--"],
+    # EXCLUDE conformance/runs/. It is TRACKED, so `--record` writing ledger.jsonl dirtied the
+    # tree and every LATER run in the same session was stamped `-dirty` — recording one test
+    # poisoned the next, and check.sh refuses to honour a dirty proven row. That cost a second
+    # live fault-injection run on prod to work around. The docstring above already states the
+    # intent for the untracked runs/<id>/ half of this same artifact; the ledger is the tracked
+    # half. Mirrors status.py's IMPL_EXCLUDE_PREFIXES, which lists this path for the same reason.
+    dirty = subprocess.run(["git", "-C", str(repo), "diff", "--quiet", "HEAD", "--",
+                            ".", ":(exclude)conformance/runs/"],
                            capture_output=True).returncode != 0
     return f"{sha}-dirty" if dirty else sha