Bug: vault_search ranks tangentially-related notes above the directly on-topic note

[raphasouthall]

Summary

For sharp queries that map cleanly to a single canonical note, vault_search sometimes ranks that canonical note below tangentially-related ones — by 2–4 positions and ~0.1+ score gap.

Example shape (anonymised)

Query targeting a specific environment/topic. Workspace scoped. top_k=5, depth=full.

Returned order by score:

1. 0.59 — Note about an unrelated audit that links to the canonical note in its ## Related section
2. 0.51 — Investigation note in a different subdirectory
3. 0.51 — Architecture note for an unrelated system
4. 0.47 — The canonical note that explicitly contains the queried fact in a top-level section, with the entities in question listed verbatim in a table
5. 0.46 — A peripheral ops note

The canonical note's ## Environments section verbatim contains the queried entities; the regenerated summary already mentions them. Yet three lower-relevance notes score higher.

Hypothesis

The ## Related section in note #1 contains a dense block of [[wiki-links]] matching the query terms, which may be inflating its hybrid score. Backlink / link-density / co-occurrence signals may be over-weighted relative to actual section-level body matches.

Suggested investigation

• Surface (in debug) the per-component score breakdown — semantic vs keyword vs co-occurrence vs context-boost — for the top 5 results in a repro case.
• Consider down-weighting matches that occur only in ## Related / link-list / index sections vs body content.
• Verify the context= re-rank boost is being applied as documented; results that should be in-context appear to be losing to out-of-context neighbours.

Workaround

Don't trust rank #1 alone — scan the full top-5/top-8 and re-rank by visually checking which note's section header matches the query topic.