Memory query include omits distances → re-ranker loses semantic signal

Context

query_summaries and query_raw_memories (MCP) report distance: 0 / relevanceScore: 1 on every result — even when the underlying ranking is demonstrably correct (topically-relevant raw-memory results all came back at a perfect 1). Surfaced as one half of #12450 (the "swallowed errors" axis); my 2026-06-10 V-B-A on #12450 split it into two distinct bugs and flagged this score-reporting half as "a pure query-service reporting bug independent of the vector corruption — split it into its own leaf." This is that leaf.

Verified post-v13 (v13 shipped 2026-06-13); #12450 was dispositioned WAIVE→post-v13, so this is now in-scope.

The Problem

Both query paths pass an explicit chroma include array that omits 'distances':

• ai/services/memory-core/MemoryService.mjs:1105 → include: ['metadatas']
• ai/services/memory-core/SummaryService.mjs:374 → include: ['metadatas', 'documents']

ChromaDB returns only the fields named in include (ids always; distances only if 'distances' ∈ include). So the query ranks internally (correct order) but the response carries no distance values → searchResult.distances is undefined.

The impact is larger than mis-reported scores. The Dual-Pass Re-Ranking Middleware (StorageRouter.injectQueryReRanker) consumes those distances as its Pass-1 semantic component:

• StorageRouter.mjs:181 const distances = searchResult.distances?.[0] || [] → []
• :187 const vectorDist = Number(distances[index] ?? 0) → 0 for every candidate
• :189 const semanticScore = 1 / (1 + vectorDist) → 1 (constant)
• :209 compositeScore = semanticScore * topologyMultiplier → topology-only (gravity + frontier weights); the semantic signal is silently eliminated

The re-ranker then re-packs distances: [topK.map(r => r.distance)] (:222) with the zeroed values, so the caller (MemoryService.mjs:1186 / SummaryService.mjs:452) computes distance:0 → relevanceScore:1 for every result.

Net: semantic search across the memory system silently degraded to topology-only ranking, with the perfect-1 score masking it as a healthy match.

The Architectural Reality

• MemoryService.queryMemories (:1091) + SummaryService.querySummaries (:360) build queryArgs.include then call the re-ranked collection.query.
• The re-ranker (StorageRouter.injectQueryReRanker, :126) wraps the chroma proxy's query, reads searchResult.distances?.[0], computes the composite score, and re-packs the chroma envelope.
• Reference precedent: the watermark probe (StorageRouter.mjs:90) calls query() with no explicit include (chroma's default returns distances), confirming the explicit include is what suppresses them.

The Fix

Add 'distances' to both include arrays:

• MemoryService.mjs:1105: ['metadatas'] → ['metadatas', 'distances']
• SummaryService.mjs:374: ['metadatas', 'documents'] → ['metadatas', 'documents', 'distances']

Restores real vector distances end-to-end: Pass-1 distances → real semanticScore → real composite ranking → real re-packed distances → correct relevanceScore.

Contract Ledger Matrix

Decision Record impact

none — no ADR governs the chroma include params; this is a service-layer correctness fix.

Acceptance Criteria

• MemoryService.queryMemories and SummaryService.querySummaries include 'distances' in the chroma include.
• A regression test asserts real (non-constant) relevance: distinct embeddings → at least one result with distance > 0 / relevanceScore < 1 (the current bug yields a constant 1). The pre-existing relevanceScore > 0 assertion is insufficient — 1 > 0 passes the bug.
• Re-ranker semantic signal restored (non-zero distances feed semanticScore), not topology-only.

Out of Scope

• Bug (a) — summary-vector corruption / query_summaries recency-fallback (#12450's other half): if the neo-agent-sessions summary vectors are independently corrupt/missing, this distances-fix restores score reporting but the summary ranking may still be wrong. That couples to #12828 (scheduler/backfill) + #12830 (corrupt-vector root-cause). Post-merge validation will determine whether this leaf also resolves the summary symptom or only the reporting.
• Any change to the re-ranker's topology weighting or the embedding provider.

Related

• Parent: #12450 (this is the bug-(b) leaf, split out per my 2026-06-10 analysis).
• Sibling (bug-a coupling): #12828, #12830.

Release classification: post-release (memory-core query correctness; v13 already shipped 2026-06-13 — not v13.x-blocking).

Origin Session ID: 0f5d9f1d-0683-452d-aac1-f467297186ac

Retrieval Hint: "chroma query include omits distances re-ranker semantic score relevanceScore 1"

Authored by Claude Opus 4.8 (Claude Code), @neo-opus-grace (Grace).