R89.A verification — test evidence

1. Gate results

All three required gates green at HEAD 2d15d678.

1.1 npm run build 

> colibri@0.0.1 build
> tsc

> colibri@0.0.1 postbuild
> node scripts/copy-migrations.mjs

copy-migrations: copied 6 migration(s) E:\AMS\.worktrees\claude\r89-a-merkle-session-binding\src\db\migrations -> E:\AMS\.worktrees\claude\r89-a-merkle-session-binding\dist\db\migrations

Zero TypeScript errors. The cast at repository.ts:418 bridges exactOptionalPropertyTypes: true (Zod’s optional() infers session_id: string | undefined but CreateThoughtRecordInput uses session_id?: string). The cast follows the same pattern as the existing audit_session_start handler at src/tools/merkle.ts:429.

1.2 npm run lint 

> colibri@0.0.1 lint
> eslint src

Zero lint findings.

1.3 npm test 

Test Suites: 47 passed, 47 total
Tests:       2421 passed, 2421 total
Snapshots:   0 total
Time:        30.08 s

Delta vs. base (fab4bf57): 2406 → 2421 = +15 new tests.

Source Suite Pre-R89.A Post-R89.A Delta
src/__tests__/domains/trail/repository.test.ts trail repository 48 58 +10
src/__tests__/tools/merkle.test.ts merkle tools 43 48 +5
All other suites (unchanged) 2315 2315 0
Total   2406 2421 +15

No pre-existing test regressed. The pinned-hash snapshot at repository.test.ts:186-196 continues to assert 6a2f9597f563d5515cfa69891a51806d0f93bfbe222997d3ba37c365ceee3f1a — proving that adding session_id to the input/persist path does NOT change the 6-field hash subset.

2. New test coverage — acceptance proof

2.1 repository.test.ts — 10 new tests 

createThoughtRecord — session_id binding (R89.A)
  √ persists session_id when supplied (SQL readback)
  √ returns session_id on the created record
  √ writes NULL session_id when omitted (donor-era default)
  √ rejects empty-string session_id via Zod
  √ does NOT change the pinned hash (session_id is out of band)
  √ chain linkage (prev_hash) is unchanged by session_id (per-task_id, not per-session)

getThoughtRecord — session_id round-trip (R89.A)
  √ returns session_id when row has one
  √ returns null session_id when row has none

listThoughtRecords — session_id round-trip (R89.A)
  √ returns session_id on every listed record
  √ returns null session_id alongside bound records (mixed list)

2.2 merkle.test.ts — 5 new tests 

finalizeMerkleRoot — end-to-end session_id binding (R89.A)
  √ audit_session_start → createThoughtRecord({session_id}) → finalizeMerkleRoot returns a root (no ERR_NO_RECORDS)
  √ records bound to a different session_id are NOT counted (cross-session isolation)
  √ thought records created WITHOUT session_id are NOT collected for any session
  √ record_count equals exactly the number of bound thought_records
  √ Merkle root over bound records equals manual buildMerkleTree(hashes) computation

The first test is the load-bearing acceptance: it runs the canonical CLAUDE.md §7 chain WITHOUT bypassing the repository (no insertRecord SQL helper). Pre-R89.A this chain threw NoThoughtRecordsError; post-R89.A it returns a real root.

3. Invariants from the contract — verified

# Invariant Verification
I1 Hash subset stays 6-field {id, type, task_id, content, timestamp, prev_hash}. schema.ts unchanged; pinned-hash test green.
I2 Pinned-hash snapshot at repository.test.ts:186-196 returns 6a2f9597…. Green (test ran in the 58/58 suite).
I3 audit_verify_chain continues to ignore session_id. verifier.ts unchanged; verifier.test.ts 26/26 green.
I4 Per-task_id chain linkage unchanged. New test “chain linkage (prev_hash) is unchanged by session_id (per-task_id, not per-session)” — green.
I5 Pre-existing NULL rows not migrated. 006_eta.sql is unmodified; ALTER stays nullable; no backfill.
I6 MCP envelope shape is additive. Handler return type widened to ThoughtRecordWithSession; envelope structure unchanged.
I7 task_update writeback gate continues to function. writeback.test.ts unchanged-by-shape; 100% pass after fixture update.

4. New invariants — proven

# Invariant Test that proves it
N1 When supplied, session_id is persisted. persists session_id when supplied (SQL readback).
N2 When omitted, session_id is NULL. writes NULL session_id when omitted (donor-era default).
N3 Empty string rejected. rejects empty-string session_id via Zod.
N4 merkle_finalize returns a root, no ERR_NO_RECORDS. audit_session_start → createThoughtRecord({session_id}) → finalizeMerkleRoot returns a root.
N5 record_count matches the supplied count. record_count equals exactly the number of bound thought_records.
N6 Cross-session isolation. records bound to a different session_id are NOT counted (cross-session isolation).

Plus an extra invariant not enumerated in the contract but verified here:

# Invariant Test
Extra Merkle root computed by merkle_finalize equals buildMerkleTree(hashes) over the same hashes. Merkle root over bound records equals manual buildMerkleTree(hashes) computation.

5. Files changed

File LOC added LOC removed Notes
src/domains/trail/repository.ts ~50 ~12 Public types, Zod, 4× SELECT widening, 10-column INSERT, handler return types.
src/__tests__/domains/trail/repository.test.ts ~140 ~12 New describe blocks + fixture update.
src/__tests__/domains/trail/verifier.test.ts ~12 ~12 Fixture update only.
src/__tests__/domains/tasks/writeback.test.ts ~14 ~3 Fixture update only.
src/__tests__/domains/proof/retention.test.ts ~6 ~1 Fixture update only.
src/__tests__/tools/merkle.test.ts ~155 ~1 New describe block.
docs/audits/r89-a-merkle-session-binding-audit.md 150 0 Step 1.
docs/contracts/r89-a-merkle-session-binding-contract.md 140 0 Step 2.
docs/packets/r89-a-merkle-session-binding-packet.md 212 0 Step 3.
docs/verification/r89-a-merkle-session-binding-verification.md (this file) 0 Step 5.

6. Commit chain

Step SHA Subject
1 c2a6d124 audit(r89-a-merkle-session-binding): inventory surface
2 bba94a62 contract(r89-a-merkle-session-binding): behavioral contract
3 041fecbe packet(r89-a-merkle-session-binding): execution plan
4 2d15d678 feat(r89-a-merkle-session-binding): thread session_id through createThoughtRecord
5 (this commit) verify(r89-a-merkle-session-binding): test evidence

Base: fab4bf57 (main).

7. Acceptance summary

All five contract acceptance criteria met:

  • A1 ✓ createThoughtRecord accepts optional session_id, persists when supplied, writes NULL otherwise.
  • A2 ✓ All seven I-invariants hold (pinned-hash + verifier suite green).
  • A3 ✓ All six N-invariants proven by new tests.
  • A4 ✓ npm run build, npm run lint, npm test all green.
  • A5 ✓ Test count strictly increased: 2406 → 2421.

The canonical CLAUDE.md §7 proof-grade chain now returns a Merkle root rather than ERR_NO_RECORDS. The R88.B failure-mode row in the colibri-verification SKILL.md remains correct as a historical documentation artifact; a separate hygiene task may close it once R89.A is observed green in a live MCP session.

8. Out-of-scope (not done in R89.A)

  • No backfill of pre-existing NULL session_id rows.
  • No documentation update to colibri-verification SKILL.md (separate hygiene task — would supersede the R88.B failure-mode row).
  • No change to audit_verify_chain (the chain is per-task_id and remains so).
  • No new MCP tool. The thought_record tool signature gains an optional field; existing clients ignore it.
  • No reverse-index from session_id to task_id (the two scopes stay independent).

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