Resolves #12165 Related: #12101, #12166

Authored by Claude Opus 4.8 (Claude Code 1M). Session b124b83a-2cca-4a2b-a711-64868439ba1e.

FAIR-band: over-target [20/30] — operator-direction (operator "dig in" on the #12101 follow-up subs). Rebalance: #12168 (the foundation) offered to under-target @neo-gpt [10/30] — see A2A.

Scope narrowed during review (operator architectural challenge): this PR carries only the two chain-independent dummy-EF cleanups. The KB realm-leaf dedup is explicitly out — see below.

What shipped

• defragChromaDB.mjs — hardcoded const dummyEf = {name:'dummy', …} → const dummyEf = AiConfig.dummyEmbeddingFunction. The defrag is a maintenance script reading the canonical Tier-1 source at point-of-use (a consumer read, not a child-provider re-assign). The old name:'dummy' is exactly what chromadb-3.x mapped to the (non-existent) @chroma-core/dummy package → the deserialization warning during chroma defrag (knowledge-base).
• github-workflow/config.template.mjs — dummyEmbeddingFunction removed (the server never imports chroma — dead config; grep -c chromadb = 0).

Explicitly NOT in this PR (deferred to #12166)

KB's dummyEmbeddingFunction consolidation. An interim attempt used dummyEmbeddingFunction: {default: AiConfig.dummyEmbeddingFunction} — but that is the child-provider-re-assigns-parent anti-pattern (default: AiConfig.x) that Epic #12101 exists to eliminate. KB already carries that pattern for auth.* / backupPath / engines.chroma.* (from #12164); all of them — dummyEmbeddingFunction included — are removed in #12166 via chain-inheritance (KB omits the leaves and inherits them through getParent()), never re-assigned. So this PR does not touch KB.

Commits

• 613f721ec — initial (defrag + GH-workflow + an interim KB snapshot).
• e1dbf00a4 — reverts the KB snapshot per the architectural review above. Net diff vs dev = defrag + github-workflow only (squash-merge collapses the add-then-revert).

Deltas from ticket

KB dedup removed from #12165 scope → moved to #12166 (it requires the parent chain to do without a snapshot). #12165 ticket rescoped to match.

Evidence

Evidence: L1 (static config-shape + Neo-bootstrapped import) → L2 desired for warning-clear. Residual: defrag warning-clear needs a live chroma defrag run [#12165 post-merge]; suppression fallback tracked on #12102.

• github-workflow template parses + dummyEmbeddingFunction === undefined (Neo-bootstrapped import).
• defragChromaDB.mjs imports AiConfig from ../../config.mjs; AiConfig.dummyEmbeddingFunction resolves to the canonical Tier-1 EF (name='dummy_embedding_function' + verbose anti-legacy structure).

Test Evidence

• Affected specs grep-confirmed to NOT assert the dummyEmbeddingFunction structure (github-workflow ConfigCompleteness.spec asserts issueSync keys only). Edits don't red them.
• Full Playwright suite runs in CI (worktree has no node_modules).

MCP config-template change

• github-workflow/config.template.mjs: dummyEmbeddingFunction removed.
• Local config.mjs follow-up after merge: regenerate each clone's gitignored github-workflow config.mjs from the template; restart that MCP server. No config.mjs committed.

Post-Merge Validation

• Regenerate github-workflow config.mjs; restart its MCP server.
• Confirm chroma defrag (knowledge-base) no longer emits @chroma-core/dummy is not installed. If residual, suppression follow-up is on #12102.