# Semantic result evidence

Google EmbeddingGemma 2 retrieves the closest eligible sources. A closest source
can still be unrelated when the requested content is missing. Similarity and
reciprocal-rank-fusion scores are not probabilities or proof of presence.

The shared hybrid engine now distinguishes primary results from related
suggestions using the [frozen presentation policy](../tools/relevance-eval/policies/evidence-v1.json):
semantic-only primary candidates require raw cosine **at least 0.70** and membership
in the existing leading semantic cluster. Weaker candidates and the separated
tail remain available with a `_related` match-kind suffix. This is a presentation
boundary, not hard deletion or a claim that no matching artifact exists.

Independent filename and keyword results preserve their existing priority and
match kind, even when the same path also occurs among related semantic neighbors.
Primary results precede related suggestions within the caller's total limit.
Strict filters and source validation still run before classification. Raw
`search_semantic` diagnostics are unchanged.

Clients use `searchi_service::is_related_result` to identify suggestions rather
than interpreting fused scores as confidence. Debug tracing records
`hybrid.semantic_shortlist` with `main_candidates`, `related_candidates`,
`candidates_before` and `candidates_after`; no eligible source is silently
discarded by this classification stage.

The policy was frozen before new blind-query inference. Existing development
evidence predicts useful precision/visibility tradeoffs but is not independent
validation: 31/32 text/code positive tops meet the display floor, with 0/16 absent
tops; repeated Code-scope rows are 8/8 and 0/4. Historical mixed-media top-score
promotion is 49/55 positives and 1/6 absent queries, with strongest-file correctness
evaluated separately. Temporal near-misses can remain strong similarities.
Related suggestions preserve access to weak genuine results. These counts do
not justify a universal confidence claim or perfect absence detection.

## Frozen blind evaluation for 0.1.9

The completed [absence-v3 summary](../fixtures/absence-v3/evaluation-summary.json)
records actual Google CPU inference on 36 covered assets and 36 frozen queries:
16 positive, 16 absent and four partial requests. No extraction, semantic or
speech failure removed a required source or channel. The policy was not retuned
after evaluation.

- Absent queries showing primary neighbors fell from **16/16 to 4/16** compared
  with a replay of the previously shipped leading-cluster rule using these same
  actual vectors. This is not a timed run of the old binary.
- All **16/16 positive requests** retained expected sources within five accessible
  results, including related suggestions. Primary first-result correctness was
  **10/16**; primary mean recall@5 was **0.625**, with at least one correct primary
  source for 11/16 requests. Five needed the related group.
- All 16 absent requests still had accessible related neighbors. The remaining
  four primary errors were document/code near-misses, so absence is not solved.

Publisher-based media labels, one independent AI annotator and the small corpus
limit generalization. The report SHA-256 is
`3a032695607a5035016602cbd995d9c4ef028891e5310eb585a9356f2404b628`.
Initial indexing took 894.9 seconds, query startup 1.017 seconds and ordered warm
raw queries a median 94.4 ms on the shared CPU VM. Hybrid queries reused vectors
from the preceding raw calls; these are not cold first-input or UI benchmarks.

The current browser-rendered production UI capture verifies that related items
start collapsed, stay out of arrow-key navigation until expanded, remain
accessible when expanded, and restore a visible primary selection when collapsed.
Its exact source/build hashes are in screenshots/capture-manifest.json. Native
WebView interaction and OS integration are separate, unexecuted checks.
Windows/Linux desktop and headless/CLI 0.1.9 packages passed their actual CPU
startup/search checks. Publication verification is recorded in ROADMAP.md.