Validate gated Google retrieval and record unchanged localization quality

docs/SPEECH-VAD.md

@@ -243,11 +243,44 @@ segments versus nineteen; segment count does not prove transcript accuracy.
 Music/sound ASR text vanished through explicit no-speech decisions, not manual
 phrase filtering. Original Google audio retrieval remains independent.
 
-The next gate is genuine Google retrieval on all eight unchanged queries and
-independent speech recall/alignment assessment. Do not select a production
+Genuine Google retrieval on all eight unchanged queries is now measured below;
+independent speech recall/alignment assessment remains open. Do not select a production
 policy from timing or this tiny corpus alone. A future persistent ASR session
 could reduce model-start overhead but must be measured independently.
 
+## Genuine Google comparison result
+
+The updated Rust diagnostic verifies the exact embedded frozen VAD bytes,
+reconstructs every source interval window and requires explicit no-speech status
+for the four empty competitors. The original ungated coverage contract remains
+strict. Six Rust tests passed, including omission/tampering rejection; the
+agent also ran strict Clippy and built the release executable. Its recorded
+SHA-256 matches the current executable:
+`5a8ecb9e2ff571610cfe9f0dcd4876953d8975ff4a84972d321cd91636ceaf84`.
+
+Actual Google EmbeddingGemma 2 CPU document/query inference completed using the
+normal auto-capable worker with CPU forced. All twenty recognized segments
+entered retrieval without relevance-label filtering; all five original source
+identities remained verified. The complete, eligible ranking report is ignored
+`.searchi/speech/gated-base-google-ranks-v2.json`, SHA-256
+`1647cf5826dbeaf43f8c47209ca40af6bc2b68cd56f0c5f44eda36ed2eab8a30`.
+The scorer report SHA-256 is
+`3d15e72764cf2329b31caf9020af9182a91acb7229b13d7dec1b24464351c0dc`.
+An initial run used a nonexistent worker path and retained its incomplete
+verification checkpoint; it performed no successful inference and was not scored.
+
+| Fixed eight-query metric | Ungated base | VAD-gated base |
+| --- | ---: | ---: |
+| Correct top file | 8/8 | 8/8 |
+| Top start point within labelled interval | 4/8 | 4/8 |
+| Top interval overlaps labelled interval | 6/8 | 6/8 |
+
+The speech gate removed incidental music/sound transcripts and reduced this
+pool's processing cost, but did **not** improve these localization metrics.
+It is not selected as a production default. More independent speech coverage,
+recognition and alignment work is needed before adding transcription enrichment.
+The original Google media embeddings remain the product's media search path.
+
 Open gates: actual one-thread audit, detection/recognition
 comparison, ordinary and DTW timestamp regression, independent held-out quality,
 background starvation/cancellation/crash recovery, packaging/license review,