Slice B: Orchestrator live-Chroma dimension gatherer for the data-integrity runner

Context

Slice A (the runner-seam) wired the dimension-consistency producer into DataIntegrityDiagnosisService through an OPTIONAL injected dimensionGatherer (pure + unit-tested, no live Chroma). This is Slice B: the live-Chroma binding that injects a real dimension gatherer so the signal goes LIVE on the hourly data-integrity sweep.

The work

A dataIntegrityDimensionGatherer getter on Orchestrator (sibling of the existing dataIntegrityCoverageGatherer) that:

• connects a live Chroma client via ai/services/shared/vector/chromaClientPrimitives.mjs (the dummy embedding fn is needed only for schema hydration; a read-only .get does not call the embedder, so it is not gated by the slow embed-canary),
• resolves the live collection handles for ['neo-agent-memory','neo-agent-sessions'],
• calls auditCollectionVectorDimensions per collection with the vectorDimension SSOT leaf (ai/config.template.mjs:340, default 4096) read at the use-site,
• returns samples: [{collection, expectedDimension, mismatchedVectorCount}],
• and is injected into the runner construction alongside the already-injected coverageGatherer.

The getter MUST return [] on a connection failure (never throw): the runner treats an absent/failing dimension gatherer as "skip dimension this cycle" without suppressing the proven coverage signal (Slice A's gatherDimensionSamples already degrades this way; the getter must not defeat it by throwing).

Acceptance Criteria

• The Orchestrator injects a live dimension gatherer into DataIntegrityDiagnosisService.
• A wrong-dimension vector in a Memory Core collection produces an escalation on the hourly sweep.
• A Chroma connection failure yields empty samples (dimension skipped), never a thrown gather or a suppressed coverage signal.
• The offline-coverage / live-dimension split is documented at the use-site.

Related

Slice A runner-seam (the immediately-preceding ticket), the dimension producer / the gatherer it consumes, #14117 (the live loop), #14039 (v13.1 epic), #14081 (binary-split rebatch — a realistic wrong-dimension source).

Authored by Vega (Claude Opus 4.8, Claude Code).