Correct the record the second review round measured against

Round 2 found the functional side true and six record/discipline defects.

- D9: the write-path line said "comparison uses secrets.compare_digest" as if
  it covered both tokens. It does not: the operator's plaintext is compared with
  compare_digest (api_auth.py:54, :110), a holder token is SQL equality on its
  sha256 digest (holder_store.verify_token) because no plaintext is stored. The
  boundary is now stated in verify_token's docstring as well as the record.
- D10/D13: three historical numbers were written as if they were current. The
  four-file 59 is pinned to 2ea48d8 (test_trust_quarantine.py was 25 tests there,
  26 from d56996b on), and both 401 gate lines are pinned to the commit they were
  measured on (83dfc14, 89c880f) with the current 406 named next to them.
- D12: the compiler cache-key line overstated one direction. The old key had no
  identity part at all, so whoever compiled first got served to the next caller;
  an empty pack reaching the operator is one direction, not the mechanism.
- D11: the p2-5 acceptance cell's suite count is pinned the same way.
- D14: bench/video_audio_check.py wrote straight into bench/reports/, so a
  reviewer running it in its own worktree would have overwritten frozen
  evidence. It now takes --report/--payload and refuses a destination that
  already holds a frozen report; refuse_frozen_overwrite is tested, along with
  the guards that stop the harness from measuring nothing.

Gates: pytest -q 410 passed; ruff clean; bench.filesize_check OK;
bench.audit --product 33 harness files / 2 reports / 6 set files, clean;
pyright 0 errors on the three touched files; mypy cold cache Success on the same
three.

bench/tests/test_video_audio_check.py

@@ -0,0 +1,56 @@
+"""The video+audio harness must refuse to measure nothing, and must not touch frozen evidence."""
+
+from pathlib import Path
+from typing import Any
+
+import pytest
+
+from bench import video_audio_check
+
+
+def test_a_frozen_report_is_not_overwritten_by_a_harness(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """A reviewer runs harnesses in a worktree of its own; the committed reports stay put."""
+    monkeypatch.setattr(video_audio_check, "PAYLOAD", tmp_path / "video_audio.json")
+    frozen = tmp_path / "VIDEO_AUDIO.md"
+    frozen.write_text("committed evidence", encoding="utf-8")
+    with pytest.raises(SystemExit, match="is a frozen report"):
+        video_audio_check.refuse_frozen_overwrite(frozen)
+    elsewhere = tmp_path / "scratch" / "VIDEO_AUDIO.md"
+    elsewhere.parent.mkdir()
+    elsewhere.write_text("scratch", encoding="utf-8")
+    video_audio_check.refuse_frozen_overwrite(elsewhere)
+
+
+def test_a_missing_speech_snapshot_says_so_before_ranking(tmp_path: Path) -> None:
+    """Without a snapshot every video defers, and the after row would equal the before row."""
+    with pytest.raises(SystemExit, match="no speech snapshot"):
+        video_audio_check.add_speech(tmp_path, [tmp_path / "a.mp4"], tmp_path / "no-snapshot", 0)
+
+
+def test_a_store_without_video_sources_refuses(tmp_path: Path) -> None:
+    """Speech has to join to a video source; a store with none would measure a new corpus."""
+    import sqlite3
+
+    videos = tmp_path / "videomme"
+    videos.mkdir()
+    (videos / "a.mp4").write_bytes(b"\x00")
+    with pytest.raises(SystemExit, match="are not here"):
+        video_audio_check.guard_videos(tmp_path / "nowhere", tmp_path)
+    store = tmp_path / "store"
+    (store / "data").mkdir(parents=True)
+    connection = sqlite3.connect(store / "data" / "ely_eye.sqlite")
+    connection.execute("CREATE TABLE sources (source_id text, kind text)")
+    connection.commit()
+    connection.close()
+    with pytest.raises(SystemExit, match="holds no video sources"):
+        video_audio_check.guard_videos(videos, store)
+
+
+def test_every_measured_video_query_carries_gold() -> None:
+    """An answerable-only set: a query with no gold would score 0 against nothing."""
+    queries: list[Any] = video_audio_check.video_queries()
+    assert queries, "the frozen suite must carry answerable video queries"
+    assert all(query.modality == video_audio_check.VIDEO_MODALITY for query in queries)
+    assert all(query.gold for query in queries)