ZAKON Phase A FU-1: Evidence Field Migration (approver → agent)

MC: #100390 (Subtask 3)
Date: 2026-05-16
Status: COMPLETE
Owner: Skillforge

Executive Summary

This document records the migration of evidence verification files from legacy approver field to ZAKON #29-compliant agent field. This follow-up closes a schema debt introduced in ZAKON Phase A B2 (MC #100385) when the agent field contract was introduced with a grandfather exemption for pre-existing files.

Migration Scope:

33 evidence directories scanned in /tmp/evidence-*
14 verification.json files inspected
2 files migrated (100346, 100348)
5 files already compliant (had "agent" field)
7 files with different schema (neither approver nor agent)

Validation: Both migrated files accepted by B2 hook (exit 0). Proveo confirmed agent='proveo' in approved allowlist.

Secondary Finding: date -r returning epoch 0 on these files triggers grandfather exemption before Python schema validation — partial bypass of ZAKON #29 full schema enforcement. Hook validates ONLY agent field allowlist membership, NOT mc/timestamp/verdict/evidence_files presence. Follow-up recommendation: MC for hook enhancement to enforce full schema or explicit schema-version tagging.

Schema Before/After

Legacy Schema (pre-ZAKON Phase A B2)

{
  "verified": true,
  "superseded_by": 100385,
  "approver": "proveo",
  "evidence": [
    "/tmp/evidence-100346/screenshot.png",
    "/tmp/evidence-100346/curl-output.txt"
  ]
}

Current Schema (ZAKON #29 compliant)

{
  "verified": true,
  "superseded_by": 100385,
  "agent": "proveo",
  "evidence": [
    "/tmp/evidence-100346/screenshot.png",
    "/tmp/evidence-100346/curl-output.txt"
  ]
}

Change: Key "approver" renamed to "agent". Value preserved: "proveo".

Note: Full ZAKON #29 canonical schema includes additional required fields:

mc (string) — MC task ID
timestamp (string) — ISO 8601 UTC timestamp
verdict (string) — PASS/FAIL/PARTIAL/BLOCKED
evidence_files (array) — List of artifact paths

The migrated files from MC #100346 and #100348 carry only the legacy four fields (verified, superseded_by, agent, evidence) because they predate the ZAKON Phase A B2 contract. The B2 hook enforcement accepts them under grandfather exemption (file mtime < 1747051700).

Migration Execution

Agent: Codecraft (Subtask 1)

Evidence Path: /tmp/evidence-100390/verification.json
Agent: codecraft
Timestamp: 2026-05-16T17:01:00Z
Verdict: PASS
SHA256 (session ID): a60fc0b4c7217fa65

Actions:

Scanned 33 directories matching /tmp/evidence-[0-9]*
Identified 14 files with verification.json
Filtered for files containing "approver" key
Found 2 candidates:
- /tmp/evidence-100346/verification.json
- /tmp/evidence-100348/verification.json

Performed in-place atomic replacement:

jq '.agent = .approver | del(.approver)' < old.json > new.json
mv new.json verification.json

Verified field presence via grep -r '"agent"' /tmp/evidence-*

Evidence Files:

migration-log.txt — Full scan output
grep-after.txt — Post-migration verification

Agent: Proveo / Angie Jones (Subtask 2)

Evidence Path: /tmp/evidence-100390/proveo-validation.json
Agent: angie-jones
Timestamp: 2026-05-16T17:04:00Z
Verdict: PASS
SHA256 (session ID): a6476b789f9bf4409

Validation Method:

Invoked ~/.claude/hooks/lib/evidence-agent-check.sh check_evidence_dir_agent for both directories
Verified exit code 0 (ACCEPT) for:
- /tmp/evidence-100346/
- /tmp/evidence-100348/
Confirmed agent='proveo' present in both files
Cross-referenced against EVIDENCE_AGENT_ALLOWLIST (line 14 of evidence-agent-check.sh)
Result: Both files carry agent field in approved allowlist → B2 hook acceptance

Evidence Files:

hook-output-100346.txt — Hook stdout/stderr for directory 100346
hook-output-100348.txt — Hook stdout/stderr for directory 100348

B2 Hook Contract Reference

Specification: ~/system/specs/evidence-agent-field-contract.md
BookStack Page: Evidence Agent Field Contract (if published)

Required Fields (ZAKON #29)

Field	Type	Constraint	Example
agent	string	Must match approved allowlist	"proveo"
mc	string	Numeric MC task ID	"100385"
timestamp	string	ISO 8601 UTC format	"2026-05-11T18:45:22Z"
verdict	string	Optional; recommended: PASS/FAIL/PARTIAL/BLOCKED	"PASS"
evidence_files	array	Optional; list of artifact paths	["log.txt"]

Validation Logic (B2 Hook)

Path pattern match: /tmp/evidence-[0-9]*/verification.json
Forge artifact exclusion: Skip /tmp/evidence-*-rev*-check/, /tmp/forge-*/, /tmp/verify-*/, */system/prompts/forged/*
Grandfather check: If file mtime < 1747051700 (2026-05-11T17:15:00Z), exempt from validation
JSON parse: Extract agent, mc, timestamp fields
Blocklist check: Reject if agent matches blocklist (john, orchestrator, builder, minion, general-purpose, claude, user, fix-builder)
Allowlist check: Reject if agent NOT in approved allowlist (38 specialist agents)
Result: Return 0 (ACCEPT) or 1 (REJECT + stderr log)

Approved Agent Allowlist (38 specialists)

proveo, angie-jones, maria-santos, codecraft, petter-graff, martin-kleppmann,
hadi-hariri, lee-robinson, bruce-momjian, skillforge, securion, parisa-tabriz,
finverge, markos-zachariadis, flowforge, kelsey-hightower, vizu, brad-frost,
lea-verou, datavera, agentforge, chip-huyen, georgi-gerganov, lexicon, skybound,
paul-hudson, mehanik, resolver, sentinel-architect, sentinel-developer,
sentinel-tester, sentinel-validator, sentinel-ba, baseline-comparator,
evidence-verifier, verifier, validator, lexicon

Migration Breakdown

Files Migrated (2)

/tmp/evidence-100346/verification.json
- Before: "approver": "proveo"
- After: "agent": "proveo"
- Hook validation: EXIT 0 (ACCEPT)
/tmp/evidence-100348/verification.json
- Before: "approver": "proveo"
- After: "agent": "proveo"
- Hook validation: EXIT 0 (ACCEPT)

Files Already Compliant (5)

These directories already contained "agent" field in their verification.json:

MC #100385 (ZAKON Phase A B2 — introduced the contract)
MC #100390 (this migration task)
3 other recent evidence directories (exact IDs in migration-log.txt)

Files with Different Schema (7)

These verification.json files use alternate schemas (neither "approver" nor "agent" present):

Forge artifacts: /tmp/forge-*/verification.json
Verify workspaces: /tmp/verify-*/verification.json
Audit snapshots: /tmp/evidence-*-rev*-check/verification.json
Pre-ZAKON manual verifications (schema predates B2 hook)

These are excluded from B2 hook pattern matching and do not require migration.

Secondary Finding: Grandfather Exemption Bypass

Observation

Both migrated files (/tmp/evidence-100346/verification.json and /tmp/evidence-100348/verification.json) return filesystem mtime of epoch 0 when queried via date -r:

$ date -r /tmp/evidence-100346/verification.json +%s
0

Implications

Grandfather exemption triggers: The B2 hook checks file_epoch < 1747051700 (2026-05-11T17:15:00Z). Epoch 0 = 1970-01-01T00:00:00Z, which is far before the cutoff → these files are exempt from full ZAKON #29 schema validation.
Agent field validated, but not mc/timestamp/verdict/evidence_files: The B2 hook (bash) performs grandfather exemption check BEFORE Python schema parse. Result: files with epoch 0 mtime bypass the full schema enforcement in session-output-validator.sh (lines 271-398).
Current state is safe: Both files carry agent='proveo' which is in the allowlist, so they pass the agent field check. However, they lack mc, timestamp, verdict, and evidence_files fields required by ZAKON #29 canonical schema.
Latent risk: If a future evidence file is created with intentionally manipulated mtime (e.g., touch -t 197001010000), it could bypass full schema validation while still satisfying the agent allowlist check.

Recommendation

Follow-up MC (not blocking this migration): Enhance B2 hook to either:

Option A: Remove grandfather exemption after migration wave completes (set cutoff to current date + 7 days)
Option B: Add explicit schema version tagging ("schema_version": "1.0") and validate against declared version rather than mtime
Option C: Move grandfather check AFTER Python parse, so exempt files still get schema structure validation (just allow missing fields with a warning rather than rejection)

Current priority: LOW (no active exploit vector; all existing evidence directories authored by approved specialist agents).

Evidence SHA256 Digests

Evidence File	SHA256 (session ID)	Agent	Verdict
/tmp/evidence-100390/verification.json	a60fc0b4c7217fa65	codecraft	PASS
/tmp/evidence-100390/proveo-validation.json	a6476b789f9bf4409	angie-jones	PASS

Master Task Evidence: MC #100390 (ZAKON Phase A FU-1)
Parent Initiative: MC #100385 (ZAKON Phase A B2 — evidence agent field contract introduction)
Related: MC #100334 (gate-gaming incident — closure subagent fabrication)

Cross-References

ZAKON Enforcement System (2026-05-11)
Hard Constraints (HC#2: "No claim without evidence")
Reality Anchor Doctrine V1 Final
Evidence-SSoT Phase 0
File: ~/system/specs/evidence-agent-field-contract.md
Hook: ~/.claude/hooks/lib/evidence-agent-check.sh (154 lines)
Hook: ~/.claude/hooks/liveness-claim-validator.sh (lines 19-241)
Hook: ~/.claude/hooks/session-output-validator.sh (lines 271-398)

Change History

Date	MC	Change
2026-05-11	#100385	ZAKON Phase A B2: agent field contract introduced
2026-05-11	#100385	Grandfather epoch set to 1747051700 (2026-05-11T17:15:00Z)
2026-05-16	#100390	FU-1 migration: 2 files (100346, 100348) approver → agent
2026-05-16	#100391	Specification document authored (evidence-agent-field-contract.md)
2026-05-16	#100390	This migration documentation page created (Skillforge Subtask 3)

End of Document

Generated by Skillforge agent (ALAI Knowledge & Training)
Report to: John (AI Director, ALAI Holding AS)
Date: 2026-05-16T17:08:00Z