Record full Google CPU routing regression with independently verified scores

docs/MIXED-QUALITY-0.1.4.md

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+# Mixed retrieval regression on the 0.1.4 engine
+
+The unchanged frozen 32-file/91-query diagnostic completed on Windows 11 VM
+using actual Google EmbeddingGemma 2, the normal runtime forced to CPU, and one
+inference thread. The release CLI was built from shared engine source `ac90ce7`;
+the earlier baseline used a debug CLI. No labels, rejection threshold, model,
+worker or ranking parameters were tuned from this rerun.
+
+| Hybrid retrieval | Preserved baseline | Current run |
+| --- | ---: | ---: |
+| All-files positive queries: correct first file | 73/80 | 74/80 |
+| All-files positive queries: recall in first five | 79/80 | 80/80 |
+| Code intents in All files: correct first file | 10/14 | 11/14 |
+| Code intents in All files: recall in first five | 13/14 | 14/14 |
+| Explicit Code scope: correct first file | 14/14 | 14/14 |
+| No-answer queries returning candidates (failure) | 10/10 | 10/10 |
+| Queries with labelled hard negatives in first five | 18 | 18 |
+
+Only one scored row changed: `code-audio-en`, asking for code choosing audio
+search for speech queries, previously omitted its implementation from all 20
+results; the intended source is now rank one. Independent read-only review
+recomputed all stored scores from ordered hits and labels: no scored regression
+across 208 executed rows. There are 210 unique rows including two unsupported
+temporal-filter requests, which remain unexecuted rather than counted as passes.
+
+Document top-1 remains 7/8, images 24/24, video file identity 22/22, music 2/4,
+sounds 4/4 and exact metadata/filter positives 4/4. This fixes the known routing
+failure without regression on this diagnostic. It does not establish general
+relevance, precise playback timestamps or calibrated rejection of unrelated files.
+
+## Matching inputs and execution
+
+Fixture/model-manifest/worker hashes and model fingerprint match the preserved
+baseline. Both runs indexed 32 files with zero extraction/media failures,
+62 passages, 182 chunks and identical 62 document, 99 image/frame and 19 audio
+inference calls. Neither reused completed source tasks. The fixture and media
+labels were previously examined; this is not untouched held-out evidence.
+
+Indexing took 2.33 s lexical and 1018.50 s semantic. Across 90 fixed-order hybrid
+All-files requests, MCP roundtrip median/p95 were 96.27/119.15 ms and native
+basic-search median/p95 were 94.14/117.08 ms. First hybrid
+request was 113.39 ms roundtrip and 109.81 ms native. These exclude initialization,
+use retained sessions/caches, and are not first desktop input or large-library
+benchmarks. Different CLI build profiles mean timing differences are not an
+isolated measurement of the routing change.
+
+Ignored raw report `.searchi/qa/mixed-v1-current-014.json`: 638814 bytes, SHA-256
+`b45e096f6f73c7f9669a129384f8b218edceb079891c069e02eb967ab118c17d`.
+Preserved baseline SHA-256 remains
+`c6619d4a66332f0378d42b9ec4f108349ce095aeb2dbcccd535de6095438b37a`.
+Current CLI SHA-256 is
+`e473a59ba0d027263be196cf13fcd764723cad0ecbe077d2e49344d32dde92a6`.
+Normal worker SHA-256 is
+`c01cb3ec13cfca722ee768e8350e1399a8b9a4d14a24a35adc3473a5cfc82a73`.
+The report contains indexing diagnostics; this evaluator does not retain the
+separate MCP session stderr stream. No complete MCP-warning capture is claimed.
+
+## What still matters
+
+Independent repositories/customer files, German speech, music hard negatives,
+speech localization, no-answer calibration and native UI/GPU checks remain open.
+The experimental media rating remains 4/10 under [the existing rubric](MEDIA-QUALITY.md).
+The failed earlier held-out cutoff must not be retuned on these known results.
+Continue with independent calibration evidence before changing retrieval policy.