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id17037
titleReduce the vector-generation substrate after its replacement safety contract graduates
stateOpen
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enhancementdesignairefactoringarchitectureneeds-re-triage
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createdAtAug 12, 2026, 9:57 PM
updatedAtAug 24, 2026, 9:26 PM
githubUrlhttps://github.com/neomjs/neo/issues/17037
authorneo-opus-vega
commentsCount5
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Reduce the vector-generation substrate after its replacement safety contract graduates

Open Backlog/active-chunk-15 enhancementdesignairefactoringarchitectureneeds-re-triage
neo-opus-vega
neo-opus-vega commented on Aug 12, 2026, 9:57 PM

[PROVISIONAL_UNGRADUATED: D#17084]

This reduction is not code-ready until the successor discussion converges on the smaller vector-generation safety authority and records the ADR-0014 §8 disposition. No implementation assignment should be taken from this ticket meanwhile.

The same standard the merge gate applied to PR #17031 (2,753-line runner → #17036), applied to the vector-generation substrate from PR #17029: keep only complexity that has a named production authority, while preserving Neo's no-mixed-generation invariant.

Current evidence

  • #17026 closed NOT_PLANNED / superseded, and PR #17040 was Drop+Supersede; the fixed-profile deployment replaced the {1,2,4} provider-resource election.
  • Both audited planes reported vectorGeneration: {status: "missing"} after cutover.
  • The Aug 1 recovery did not execute restore-empty-target: it used ai:restore --mode merge before the restore election hooks existed (receipt).
  • Current source still carries 2,391 lines across generationElectionStore.mjs, electionGatedPromote.mjs, and their dedicated specs.
  • The write lifecycle and generic promote helper have zero non-test consumers. Read-only health/path projection and createEmbeddingGenerationId() remain live.

Why this is provisional

Accepted ADR-0014 §8 and D#17015 AC-C require any embedding-coordinate change to create one coordinated KB + all-MC vector generation: every collection validates before the commit barrier, partial promotion is never advertised, and the complete prior generation remains rollback authority.

Retiring the provider-resource election did not retire that corpus-safety contract. Zero production writers proves the current implementation is unintegrated or oversized; it does not authorize deleting the contract without replacement.

D#17084 now owns divergence between:

  1. retaining the hot coordinated runtime election;
  2. compressing it to one cold in-place rebuild authority;
  3. immutable whole-plane/volume replacement; and
  4. a smaller immediate deletion that cannot weaken the future transition contract.

Mechanism disposition — evidence, not yet implementation authority

Bucket Surface Current evidence Decision dependency
Retain projectVectorGenerationHealth, strict legacy reader/path, createEmbeddingGenerationId Live KB/MC health and poison-store consumers. Legacy observability/migration decision in D#17084.
Candidate for removal baseline/candidate/receipt/commit/renew/admissibility/rollback/unpark/accept mutators Zero production writer roots. Replacement transition authority + ADR wording.
Candidate for removal electionGatedPromote.mjs and captured promote-view seams No production helper consumer; restore hooks have no production receipt. Prove removal preserves the converged transition class.
Preserve independently KB shadow swap; ADR-0027 restore writer fence, ordered promotion, reconciliation, strict ledger, committed-only eligibility Existing production owners and tests independent of the election overlay. None; these are not debt targets.

Contract Ledger

Target Surface Source of Authority Required Behavior Fallback / Edge Case Evidence
Generation identity ADR-0014 §8 + D#17015 One immutable coordinate tuple identifies one vector generation across KB and every MC embedding collection. Any coordinate change must not reuse or partially advertise the prior live set. Exact ADR/D#17015 contract.
Transition authority D#17084 (ungraduated) One explicit operational authority builds, validates, commits, and retains rollback for the complete set. Failure before commit leaves the prior complete generation authoritative. Graduation must name the receipt and failure matrix.
Legacy health Existing KB/MC health consumers Preserve strict missing / valid projection / unavailable behavior until migration disposition says otherwise. Legacy partial records remain observable but must not silently gain authority. Current consumer census + focused reader fixtures.
Embedding generation ID Poison-store join-key contract Preserve byte-identical SHA-256 derivation. Invalid/incomplete coordinates remain rejected. Existing equivalence matrix.
KB/MC promotion and restore Existing service owners + ADR-0027 Preserve independent shadow, writer-fence, ordered-promotion, reconciliation, and ledger guarantees. Existing contained failure/resume behavior stays authoritative. Existing service and restore suites.

Acceptance Criteria

  • Mechanism-vs-receipt census completed.
  • Restore-path Bucket D closed as not production-exercised.
  • Successor-risk audit identified the binding ADR-0014 §8 contract.
  • D#17084 graduates with a named transition authority and explicit ADR disposition.
  • This body is re-folded to that converged contract before assignment or code work.
  • The implementation removes/collapses only surfaces proven unnecessary under the converged authority.
  • Retained health/path/ID behavior and independent KB/ADR-0027 guarantees remain exact.
  • The PR reports net production/test LOC removed and exact-head evidence.

Out of Scope

  • Inventing a second transition framework before D#17084 converges.
  • Weakening ADR-0027 restore ordering, fences, crash containment, or eligibility.
  • Treating the retired {1,2,4} resource election as proof that corpus-generation safety was retired.
  • Reopening tickets already closed by resolving PRs.

Decision Record impact

Challenges/amends ADR-0014 §8, depending on D#17084 convergence. Aligned with ADR-0027: its target-set restore contract remains independent and binding.

Related

D#17015 · D#17084 · #17018 · #17023 · #17035 · #17036 · #17081 · ADR-0014 §8 · ADR-0027

Origin Session ID: 8637b4b9-b852-45d9-b057-de34184aae8b

Retrieval Hint: "right-size vector generation safety hot election cold rebuild immutable plane replacement"