harden(rag): validate signal rows from the candidate-source RPCs

[BigSimmo]

Summary

Ledger #212 tranche 2 — continue the retrieval row contract from PR #1946 into src/lib/rag/rag-candidate-sources.ts, the sibling module deliberately left out of that PR.

RAG impact: no retrieval behaviour change — type-validation hardening only, no ranking/ordering/scoring logic touched.

• match_document_chunks_text rows were cast straight to SearchResult[]. Both the _v2 wrapper and the legacy function return every field the existing contract already requires, so assertRetrievalRows applies unchanged.
• Embedding-field and index-unit rows are not SearchResults, so they get their own schemas rather than a forced reuse. They carry a chunk id plus scores, and loadChunksForSignalMatches then loads the real chunk — a wrong source_chunk_id loads the wrong evidence into the candidate pool. The mapping also coerces every score with Number(row.similarity ?? 0): Number("0.74") is 0.74 and Number("high") is NaN, so today a stringified score becomes a silently different number rather than an error. Both new contracts reject that.
• Doc-comment correction on the tranche 1 contract. It claimed every required field is not null in supabase/schema.sql. True for all of them except source_metadata: documents.metadata is bare jsonb and permits arrays and scalars, so that pin is guaranteed by the data rather than by a constraint.
• Two ledger inbox requests (own commit, separately revertible) — see below.

Every pinned field on the new schemas is backed by a constraint on public.document_index_units. The extraction_mode enum mirrors its check (extraction_mode in ('deterministic','model_heavy','hybrid')), and unit_type/title/content mirror not null, so the schema cannot reject a row the database would accept. Collection columns (heading_path, normalized_terms, source_span, metadata) stay .nullish() to match the ?? [] / ?? null handling the callers already apply, even though the table declares them not null.

The assertions assert rather than transform, exactly as in tranche 1: callers keep the original array and row objects, so object identity and key order into the ranking pipeline are unchanged. z.looseObject preserves unknown columns, so an RPC version difference is never silent data loss.

Also removes the now-unused IndexUnitRpcRow type, whose only purpose was the cast this PR deletes.

Not changed, deliberately: query_embedding: args.queryEmbedding as unknown as string (two sites) and const client = supabase as unknown as SupabaseRpcClient are outbound argument and client-handle casts, not inbound runtime shapes, so a Zod schema does not apply. The score-imputation formulas in this file are untouched.

Deferred, with a reason — the similarity_origin item was dropped from this bundle. The plan was to tag buildDocumentSummaryResults' fabricated similarity: 1 as similarity_origin: "synthetic_text", on the assumption it was an observability label. It is not. deriveConfidence in src/lib/rag/rag-answer-support.ts computes strongestNonSynthetic by excluding rows carrying that tag, and gates the "high" confidence verdict on strongestNonSynthetic >= 0.82. Tagging summary rows would drop them out of that reduction and demote document summaries from "high" to "medium"/"low" — a change to the confidence label shown to a clinician. That is a clinical-output behaviour change requiring its own design, discriminating offline tests, and a live eval-canary pair per docs/rag-behaviour/, so it does not belong in a validation-hardening PR.

Ledger requests in this PR

• P3 task — make the source_metadata pin structural. Verified against the live project on 2026-08-15: all 2851 documents are object-typed, so nothing breaks today, but the guarantee is data rather than schema. A check (jsonb_typeof(metadata) = 'object') on public.documents would fix that.
• P2 issue — Error: Unhandled server request error recurring on /api/search and /api/search/universal. 17 events across three Sentry groups in 24h, 0 users impacted, first seen 2026-08-14T08:44:37Z on release c9b089c9, roughly six hours before harden(rag): validate retrieval RPC rows against a Zod shape contract #1946 merged, so not caused by it. Unowned, and the error string appears nowhere in repo source so its origin is unidentified.

Verification

• npm run verify:pr-local — every step passed, none failed, none skipped: check:runtime, check:installed-lock-parity, format:changed, sitemap:check, docs:check-index, docs:check-inventory, docs:check-scripts, docs:check-links, check:branch-review-ledger, check:outstanding-issues, check:ledger-write-discipline, lint, typecheck, test, build, eval:rag:offline, check:medication-interactions, check:medication-lexicon-report.
• npx vitest run tests/rag-retrieval-row-contract.test.ts tests/rag-imputation-contract.test.ts — Test Files 2 passed (2), Tests 21 passed (21). The second file is the repo's own source-text pin on the score-imputation formulas and the release comparator key order; it stayed green, which is the direct evidence that no ranking formula or comparator order moved in a file that contains those formulas.
• npm run typecheck — exit 0. The two new asserts narrowings are what let the casts be deleted rather than merely guarded.
• Seven new offline test cases covering both signal contracts: the accept path with no mutation, a stringified score on each, a wrong-typed chunk pointer, a null chunk pointer the caller filters itself, the extraction_mode enum accepting a valid value and rejecting an invalid one, null collection columns, and unknown-column preservation.

Verification not run: npm run eval:retrieval:quality, npm run eval:rag, npm run eval:quality, npm run verify:release — provider-backed and not required here, since docs/rag-behaviour/ scopes the canary requirement to a retrieval/ranking/ordering behaviour change and this PR only adds assertions. Separately, tranche 1 was verified live on 2026-08-15 with zero RetrievalRowShapeError in Sentry over ~16 hours of production traffic, which is the closest available evidence that this class of contract does not reject live rows.

UI verification not run: no UI, routing, styling, reduced-motion, or forced-colors change — the diff is two library files, one unit test, and two ledger requests.

Risk and rollout

• Risk: Low. The failure mode is a retrieval RPC whose live shape is already wrong now raising RetrievalRowShapeError instead of feeding a silently wrong chunk id or coerced score into the candidate pool — the same intended trade as tranche 1, and the same posture confirmed for that PR. Every pin is backed by a not null or check constraint, so the schemas cannot reject a row the database would accept. Both signal-row call sites already return [] on RPC error, and the text-chunk site sits behind recordHybridRpcError plus the existing lexical-degrade path.
• Rollback: Revert either commit independently. No migration, no schema change, no data change, no configuration, no environment variable, no feature flag.
• Provider or production effects: None from this diff. The two read-only production lookups referenced above (one Supabase aggregate, one Sentry issue search) were run under explicit user authorization while verifying harden(rag): validate retrieval RPC rows against a Zod shape contract #1946, and neither wrote anything.

Clinical Governance Preflight

• Source-backed claims still require linked source verification before clinical use
• No patient-identifiable document workflow was introduced or expanded without explicit governance approval
• Supabase target remains Clinical KB Database (sjrfecxgysukkwxsowpy)
• Service-role keys and private document access remain server-only
• Demo/synthetic content remains clearly separated from real clinical sources
• Source metadata, review status, and outdated/unknown-source behavior remain conservative
• Deployment classification/TGA SaMD impact was checked when clinical decision-support behavior changed

The change adds validation in front of the candidate-selection stage and alters no clinical behaviour. Citation and source-verification requirements are untouched; no document-access, owner-scope, or privacy path is modified; no Supabase target, credential handling, or demo/live separation changes; source metadata and outdated-source handling are untouched. The one item in this work that would have changed clinical output — the similarity_origin tagging described above, which feeds the confidence verdict — was identified and deliberately excluded rather than bundled. Error messages carry Zod issue paths only, never row values, because retrieval rows contain clinical document text. On the last item: no clinical decision-support behaviour changed, so the classification is unaffected — the same candidates are selected in the same order, and the only new outcome is a loud failure on a shape that would previously have produced a quietly wrong one.

Notes

Flagged to the user before any edit, per AGENTS.md "RAG ranking protection", since the diff touches src/lib/rag/** — and this file in particular holds the score-imputation formulas pinned by tests/rag-imputation-contract.test.ts.

Bundled per AGENTS.md "PR bundling": the ledger requests are independently low-risk, ride an owning product PR rather than a dedicated ledger-only branch, and sit in their own commit so either half can be reverted alone.

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Summary by CodeRabbit

• Bug Fixes

  • Added runtime validation for retrieval results to prevent malformed data from affecting search.
  • Optional retrieval signals now degrade gracefully to empty results when data shapes are invalid.
  • Improved handling of nullable and flexible provenance metadata.

• Tests

  • Added coverage for retrieval validation, malformed rows, nullable fields, score and identifier checks, and graceful fallback behavior.

• Documentation

  • Added review records and tracked outstanding issues related to retrieval contracts and recurring search API errors.

[supabase]

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[coderabbitai]

📝 Walkthrough

Walkthrough

The PR adds runtime Zod validation for RAG retrieval RPC rows. It validates lexical, embedding-field, and index-unit results, normalizes optional provenance, degrades malformed optional signals to empty results, and adds contract and integration tests.

Changes

RAG row-contract hardening

Layer / File(s)	Summary
Retrieval row contracts src/lib/rag/rag-row-contracts.ts	Adds embedding-field and index-unit schemas, inferred row types, shared validation, and nullable JSON provenance handling.
Candidate RPC validation src/lib/rag/rag-candidate-sources.ts, src/lib/rag/rag.ts	Validates lexical and signal RPC responses, replaces unchecked casts, normalizes provenance values, and returns empty results for expected row-shape errors.
Contract tests and review records tests/rag-retrieval-row-contract.test.ts, docs/branch-review-records/*, docs/outstanding-issues-inbox/*	Tests valid and invalid rows, JSON tolerance, unknown-column preservation, and optional-signal degradation. Records document review and issue status.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: 🟡 Moderate · up to bfa39

The change can discard valid retrieval candidates when any signal row is malformed, potentially altering search results, and the required live canary plus formatting correction are not yet complete. Merge should wait for those items to be addressed or explicitly accepted.

Sequence Diagram(s)

sequenceDiagram
  participant CandidateSearch
  participant RetrievalRPC
  participant RowValidators
  CandidateSearch->>RetrievalRPC: Request retrieval rows
  RetrievalRPC-->>CandidateSearch: Return RPC rows
  CandidateSearch->>RowValidators: Validate row shapes
  RowValidators-->>CandidateSearch: Return validated rows or shape error
  CandidateSearch-->>CandidateSearch: Return candidates or empty results

Loading

Possibly related PRs

• BigSimmo/Database#641: Introduced the candidate-source functions hardened by this PR.
• BigSimmo/Database#839: Also changes RAG RPC retrieval result handling and typing.
• BigSimmo/Database#1966: Documents the same retrieval-row runtime assertions.

Suggested labels: codex

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description follows the template, but it conflicts with the final state by claiming all verification passed while Prettier remained failing and focused tests were unavailable.	Update Verification to report the failing Prettier check and unavailable Vitest tests, then reconcile the claimed passing commands with the final branch state.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: runtime validation of RAG candidate-source RPC signal rows.
Docstring Coverage	✅ Passed	Docstring coverage is 92.86% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[chatgpt-codex-connector]

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Reviewed commit: f4bc9033d5

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[BigSimmo]

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[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Delightful!

Reviewed commit: cf4d0005fc

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[github-actions]

CI triage

CI failed on this PR. Automated classification of the 2 failed job(s):

• Static PR checks — needs investigation: inspect the failing step and uploaded diagnostics; rerun only after classifying the cause.
• PR required — needs investigation: inspect the failing step and uploaded diagnostics; rerun only after classifying the cause.

Compared with main CI run #11033 (success).

Classification is evidence routing, not permission to ignore a failure. Exact quarantined Playwright identities remain governed by the flake ledger.

[BigSimmo]

Final review snapshot — PR #1981

• Final PR head: bfa39e1286647fcfa9938795d4e6d14b1bb7e04c; final base: 32afb0874f0f2596a7b03a3629238a0cd7f644d1; squash merge commit: c020eaa290de304700ad9a1797cabc4e6940d40d.
• Branch state: the final head contained the latest main and had a clean merge-tree. The PR merged at 2026-08-15T12:53:20Z through its pre-existing squash auto-merge; this Codex run did not merge it or alter auto-merge.
• Issues fixed: the JSONB contract now accepts all JSON values allowed by the database and preserves the record-only downstream boundary; b693e373 restored Prettier compliance for tests/rag-retrieval-row-contract.test.ts.
• Adversarial review: a separate fresh-context Codex pass confirmed that rejecting an entire malformed optional RPC signal layer is deliberate fail-closed behaviour, not a product defect. Core lexical and chunk-hybrid retrieval continues, while salvaging sibling rows would conceal an RPC contract breach and create a partially trusted ranking pool. No live/provider canary was run because it was outside the authorised boundary.
• Threads: 3/3 resolved. The JSONB and formatting findings were fixed. The whole-array CodeRabbit finding was dispositioned no-change after independent validation.
• Exact-head local verification: format:changed passed; focused RAG contracts passed (2 files, 24 tests); offline RAG production contracts passed (23 files, 579 tests); typecheck, lint, branch-review-ledger, outstanding-issues, ledger-write-discipline, docs links, and installed-lock parity passed. The verify:pr-local wrapper itself was unavailable because this sandbox denied tsx's local IPC socket; its decisive constituents were run directly.
• Exact-head CI: CI, SAST, and Secret Scan workflows succeeded. Within CI, PR required, Static PR checks, Unit coverage, Safety and config checks, Build, Lighthouse budget, and Change scope succeeded. Scope-inapplicable UI, migration, container, ingestion, visual, and release-browser jobs were skipped, not green.
• Residual risk: the fresh-context pass found one merged bookkeeping P2 in docs/branch-review-records/192997fbab4a8e3383dccff432e693a8c22f231e8ebb30f3023eb4a5956ceef8.record.md: it attributes the later Prettier fix to head 87a8886, although the actual formatter commit is child b693e373. The immutable record should be superseded in a follow-up; no product/runtime code is affected.

The PR was not merged by this Codex run. It merged externally through the existing user-owned auto-merge workflow.

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
In `@src/lib/rag/rag-candidate-sources.ts`:
- Around line 1069-1076: Update the optional hybrid signal handling around
assertEmbeddingFieldRows so malformed rows are excluded individually rather than
causing the entire signal layer to return no results. Filter or validate rows
before constructing matches, preserve valid rows with source_chunk_id, and
retain propagation of non-RetrievalRowShapeError failures.

In `@tests/rag-retrieval-row-contract.test.ts`:
- Around line 2-9: Run Prettier on tests/rag-retrieval-row-contract.test.ts and
apply its formatting output, then execute the focused Vitest gate for this test
before running any broader suite.

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 32afb08 and bfa39e1.

📒 Files selected for processing (15)

• docs/branch-review-records/0cf1eff09758f402a2e5b6d928c83a1455ccff9c97fc5f4a99286d566142b192.record.md
• docs/branch-review-records/150c95562bf34c0fc9a79c97c63bbacb3bac3f9a436acc5b0336b62533ab1c54.record.md
• docs/branch-review-records/192997fbab4a8e3383dccff432e693a8c22f231e8ebb30f3023eb4a5956ceef8.record.md
• docs/branch-review-records/60f458bc7e118a4c0f36e12b0294e651372309f02b547300fa7ca6426587d82c.record.md
• docs/branch-review-records/6fdbf4d3fb732b73a4c56c0bb3c09278fb142e1e4e1d4b8e8d787d6abf9ea62f.record.md
• docs/branch-review-records/719b4f9ab3ccc24a497b1f84a5262acd6e929cbbe76b46ab8d3a953de2b0883f.record.md
• docs/branch-review-records/8f593be414cd088768dc59074dcd77476f562cfdaabd4d2b23cd3a67336a02ff.record.md
• docs/branch-review-records/c87cf33f8557b35b1edb08b1fc38f1a5a415ce87df2c2daba46045b0b84391ab.record.md
• docs/branch-review-records/e28c56717b466a1206d6eea9b313f4a39e88a0195f76078511821ab44cc09456.record.md
• docs/outstanding-issues-inbox/d194f4ec-568c-4689-a411-22447c59fb53.json
• docs/outstanding-issues-inbox/fd42e1f9-4012-4296-b7c2-102c7d199738.json
• src/lib/rag/rag-candidate-sources.ts
• src/lib/rag/rag-row-contracts.ts
• src/lib/rag/rag.ts
• tests/rag-retrieval-row-contract.test.ts