R88.B — colibri-verification SKILL.md merkle_finalize failure mode (Audit)

Status: BLOCKED — pre-existing canonical/mirror drift

This audit follows the IF BLOCKED protocol of the R88.B dispatch packet:

If the canonical and mirror SKILL.md are NOT byte-identical PRE-edit, document the drift and stop — drift is a separate problem and shouldn’t be silently absorbed.

The audit was run; the drift was confirmed; no edits were applied. Task remains NOT DONE. PM must triage before R88.B can resume.

1. Scope

R88.B was dispatched as a small (~30 minute) surgical edit to a single skill, mirrored across two surfaces:

  • .agents/skills/colibri-verification/SKILL.md (canonical)
  • .claude/skills/colibri-verification/SKILL.md (mirror)

Two edits were authorized:

  1. Failures-table row — append a new row to the Common Verification Failures table covering the case where reflection IS recorded and tools WERE called but merkle_finalize still errors with ERR_NO_RECORDS. Citations: feedback_audit_session_task_binding.md and investigation task 6f309f3a-7d22-4e2c-a02d-3a62fc46c834.
  2. Quick-Reference caveat paragraph — insert a paragraph BEFORE the // Full Phase 0 verification sequence. JS code block clarifying that the merkle_finalize portion may currently error and that audit_verify_chain { task_id } is the actually-functional Phase 0 proof grade.

Both edits must land in both files byte-identically. The R88.B prompt’s acceptance criteria explicitly require:

.claude/skills/colibri-verification/SKILL.md is byte-identical with .agents/... (verify via diff -q)

No OTHER body changes — git diff against base shows ONLY the two surgical additions in each file (plus 4 chain artefacts in docs/)

These two criteria are jointly satisfiable only when the files are byte-identical PRE-edit. They are not.

2. Pre-edit diff -q result (the drift)

Run from this worktree at base 2506bb44:

cd .worktrees/claude/r88-b-verification-skill-merkle-failure-mode
diff -q .agents/skills/colibri-verification/SKILL.md .claude/skills/colibri-verification/SKILL.md

Output:

Files .agents/skills/colibri-verification/SKILL.md and .claude/skills/colibri-verification/SKILL.md differ

Line counts:

File Lines
Canonical (.agents/skills/colibri-verification/SKILL.md) 333
Mirror (.claude/skills/colibri-verification/SKILL.md) 296
Difference +37 (canonical has 37 more lines)

diff -u total line count: 99 (approximately 50 net added + restructured).

3. Provenance of the drift

The drift is NOT undocumented or unexpected — it is explicitly flagged in the canonical’s own changelog at .agents/skills/colibri-verification/SKILL.md:333 (last paragraph of the file):

Updated post-R83 hygiene — 2026-05-05 (rewrite-colibri-verification-skill). Body augmented with live-code citations: writeback hard-block at src/domains/tasks/writeback.ts:97 (with call site at src/domains/tasks/repository.ts:475) and chain verifier at src/domains/trail/verifier.ts:119. The verifyCompletion JavaScript example was reconciled to the shipped thought_record Zod input schema (src/domains/trail/repository.ts:114-119) — it now passes {type, task_id, agent_id, content} (no session_id, which the schema does not accept) and carries an inline TODO marker for ADR-007 (Proposed). A new row was added to “Common Verification Failures” describing the merkle_finalize zero-records failure mode that arises from the session_id gap, with ADR-007 as the resolution path. Frontmatter (name, description) is byte-stable; HERITAGE note unchanged. Mirror at .claude/skills/colibri-verification/SKILL.md was NOT modified — flagged for resync as a separate hygiene task.

Bold emphasis added — the post-R83 hygiene round (2026-05-05) explicitly chose to leave the mirror unmodified and flag it for a separate resync, presumably analogous to the R77.C precedent (commit 6a67be69, “R77.C: resync 3 drifted .claude/skills/ mirrors from .agents/ canon (#167)”).

That separate resync hygiene task was never executed before R88.B was dispatched.

4. Categorical inventory of the drift

The diff falls into 9 categories. Each makes the canonical newer and richer; nothing in the mirror is content the canonical lacks:

# Category Canonical lines Mirror lines Notes
1 Post-R83 reality stamp paragraph 10 (absent) Names the live-code citations + reconciliation rationale
2 HERITAGE note form 12–21 (prose form, ~10 lines) 11–23 (enumeration form, ~13 lines) R82.K rewrote enumeration → prose (phantom-string sweep)
3 task_id binding bullet under “Audit Session” 70 (absent) Documents the enforceWriteback lookup-key mechanism
4 Writeback hard-block runtime-enforced paragraph 116 (absent) Cites src/domains/tasks/writeback.ts:97 + src/domains/tasks/repository.ts:475
5 Audit chain intact criterion enriched 210 (with file-line citation) 209 (one-liner) Cites verifyChain at src/domains/trail/verifier.ts:119
6 Phase 0 reality session_id gap paragraph 246 (absent) The full long-form paragraph documenting the structural gap
7 verifyCompletion JS code block 248–290 (post-R83 reconciled, no session_id in thought_record call) 232–262 (pre-R83, includes incorrect session_id field) This is the closest analogue to R88.B Edit #2 — and the post-R83 form already carries some of what R88.B is asked to add
8 “Common Verification Failures” — NoThoughtRecordsError row 301 (absent) This is the closest analogue to R88.B Edit #1 — and the post-R83 form already carries a related row
9 “See Also” — ADR-007 entry + R82/post-R83 changelog blocks 327, 331–333 (absent) End-of-file changelog and cross-reference enrichment

Categories #7 and #8 are particularly notable: the canonical already contains one row in the failures table for the merkle_finalize NoThoughtRecordsError symptom (citing the schema-side cause: session_id gap on the input), and the canonical’s verification-quick-reference code block already includes a long-form Phase 0 reality paragraph and a reconciled JS sequence. R88.B’s two edits are NOT redundant with these — R88.B’s row covers a different cause path (the R87 + R88.A discovery: even with task_id matching, finalization still fails) and R88.B’s caveat paragraph adds the actually-functional audit_verify_chain { task_id } recommendation and the explicit “symbolic” Merkle pattern naming.

But the post-R83 work has already touched both edit-target sections, so R88.B’s intended surgical insertions land cleanly in the canonical; in the mirror, the surrounding context for both insertions is materially different.

5. Why “just apply the same patch to both files” does NOT work

If R88.B were applied as written:

  • Canonical: edits land cleanly — they slot into existing post-R83 sections that already contain related rows / paragraphs about the session_id gap.
  • Mirror: the failures table has 6 rows (vs. the canonical’s 7 post-R83 rows); inserting “after the existing merkle_finalize fails row” is unambiguous in either file, but the row that immediately follows differs between the two. The Quick Reference code block differs entirely between canonical (post-R83 reconciled) and mirror (pre-R83 form with the incorrect session_id field). Inserting “BEFORE the // Full Phase 0 verification sequence. JS code block” is locatable in both, but the surrounding text is not.

After applying the same surgical edits to both files:

  • Canonical (333 lines) → 333 + ~10 = ~343 lines.
  • Mirror (296 lines) → 296 + ~10 = ~306 lines.
  • diff -q .agents/.../SKILL.md .claude/.../SKILL.md → still differs (~37 lines net drift remains, plus the surrounding-context divergence remains).

This violates the explicit acceptance criterion .claude/skills/colibri-verification/SKILL.md is byte-identical with .agents/... (verify via diff -q).

The only way to satisfy that criterion is to also resync the mirror to canonical — but doing so silently within an R88.B feature commit violates the explicit acceptance criterion No OTHER body changes — git diff against base shows ONLY the two surgical additions in each file.

The two acceptance criteria are jointly satisfiable only when the pre-edit files are byte-identical. They are not. R88.B as written cannot land cleanly.

6. The IF BLOCKED clause

The R88.B dispatch packet contains the explicit instruction:

Stop, record thought_record (type="analysis") describing the blocker, leave task NOT DONE, report back. Particular blocker to watch for: if the canonical and mirror SKILL.md are NOT byte-identical PRE-edit, document the drift and stop — drift is a separate problem and shouldn’t be silently absorbed.

This audit constitutes the documented blocker. Per the protocol:

  • ✗ NO Step 2 (Contract) commit
  • ✗ NO Step 3 (Packet) commit
  • ✗ NO Step 4 (Implement) commit
  • ✗ NO Step 5 (Verify) commit
  • ✗ NO task_update(status="DONE")
  • ✓ This audit committed
  • ✓ Worktree preserved at base + audit commit
  • ✓ thought_record(type="analysis") will be filed with the blocker payload
  • ✓ Reported back to PM via final summary

7. Recommended next actions for PM (T2) / T0

PM must choose one of the following routes before R88.B can resume:

Option A — Sequential split (clean)

  1. Open a new R88.X mirror-resync slice (analogous to R77.C, commit 6a67be69):
    • Title: chore(r88-x-verification-mirror-resync): resync .claude/skills/colibri-verification from .agents/ canon
    • Scope: copy canonical .agents/skills/colibri-verification/SKILL.md byte-for-byte to .claude/skills/colibri-verification/SKILL.md
    • 5-step chain produces the resync as Step 4; verification confirms diff -q clean
    • Merge first
  2. Re-dispatch R88.B against the now-byte-identical pair (acceptance criteria become satisfiable).

This is the highest-fidelity option and matches the R77.C precedent.

Option B — Combined-scope rewrite of R88.B

  1. Re-dispatch R88.B with explicit authorization to perform the mirror resync as part of the slice:
    • Edit canonical: append the two surgical additions.
    • Replace mirror: byte-for-byte copy of the now-edited canonical.
    • PR title and body updated to reflect the combined scope: “feat(r88-b): … + resync mirror to canonical (R77.C pattern)”.
    • Acceptance criteria rewritten to allow git diff against base to include the mirror’s full re-baseline.

This is more efficient but mixes a feat-scope edit with a chore-scope resync. R77.C kept these separate explicitly.

Option C — Defer R88.B

  1. Leave R88.B parked.
  2. Open R88.X (mirror resync) when a future round has bandwidth.
  3. Re-open R88.B once R88.X lands.

This is the safest option if R88’s primary focus must remain elsewhere (κ Phase 1 Wave 6, etc.).

PM recommendation, given the ~30-minute estimate for R88.B alone and the ~30–60-minute estimate for an R77.C-pattern resync: Option A is the highest-fidelity, lowest-risk path. The two slices remain coherent in git history; each PR’s diff is auditable on its own merits; the R88.B PR title and acceptance criteria do not need to be rewritten.

8. Worktree state

  • Worktree: .worktrees/claude/r88-b-verification-skill-merkle-failure-mode
  • Branch: feature/r88-b-verification-skill-merkle-failure-mode
  • Base: origin/main @ 2506bb44
  • Commits planned: 1 (this audit, blocking-state Step 1 only)
  • Files touched: this single file (docs/audits/r88-b-verification-skill-merkle-failure-mode-audit.md)
  • No edits to either SKILL.md
  • No mirror resync (out of scope per IF BLOCKED protocol)

9. Locations confirmed (for the eventual unblocked R88.B re-execution)

For when R88.B resumes after the drift is resolved, here are the locations that the two surgical edits will target:

Edit #1 location (failures-table row insertion)

Canonical at .agents/skills/colibri-verification/SKILL.md:

  • Failures table starts at line 296 (## Common Verification Failures)
  • Existing merkle_finalize fails row at line 300
  • Existing NoThoughtRecordsError row at line 301 (post-R83 hygiene addition)
  • New R88.B row should be inserted AFTER line 301 (i.e. between the existing NoThoughtRecordsError row and the Merkle root missing row at line 302)

Mirror at .claude/skills/colibri-verification/SKILL.md:

  • Failures table starts at line 266 (## Common Verification Failures)
  • Existing merkle_finalize fails row at line 272
  • No NoThoughtRecordsError row (post-R83 not in mirror)
  • Insertion point in mirror is line 273 (after merkle_finalize fails, before Merkle root missing)
  • After resync this collapses to the canonical’s line 302 region

Edit #2 location (Quick-Reference caveat paragraph)

Canonical:

  • ## Verification Tools Quick Reference heading at line 231
  • Existing post-R83 reality paragraph at lines 246–247
  • // Full Phase 0 verification sequence. JS code block opens at line 248
  • New R88.B caveat paragraph should be inserted BEFORE line 248

Mirror:

  • ## Verification Tools Quick Reference heading at line 230
  • No post-R83 reality paragraph
  • // Full Phase 0 verification sequence. JS code block opens at line 232
  • Insertion point in mirror is line 232
  • After resync this collapses to the canonical’s line 248 region

These coordinates will need to be re-established against the post-resync state when R88.B resumes.

10. Files inventoried

  • .agents/skills/colibri-verification/SKILL.md — canonical, 333 lines, drift source @ post-R83 hygiene 2026-05-05
  • .claude/skills/colibri-verification/SKILL.md — mirror, 296 lines, drift target (still on R82-era body)
  • CLAUDE.md — root, §9.2 mirror discipline (“Do not edit .claude/skills/colibri-* by hand. Edit canon in .agents/ and flag for resync.”)
  • Memory feedback_audit_session_task_binding.md — context for the failure mode R88.B is documenting (read for reference; not edited by R88.B)

End of R88.B BLOCKED audit. Reporting back to PM via the executor’s summary message and a thought_record(type="analysis") writeback (no DONE marking).

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