{
  "track_id": "metadata_nil_sentinel_20260624",
  "name": "Child 1: Metadata Nil Sentinel",
  "track_type": "campaign_child",
  "parent_campaign": "metadata_ssdl_defusing_20260624",
  "created_date": "2026-06-24",
  "branch": "master",
  "depends_on": ["code_path_audit_20260607"],
  "blocks_within_campaign": ["metadata_generational_handle_20260624"],
  "scope": {
    "new_files": [
      "conductor/tracks/metadata_nil_sentinel_20260624/spec.md",
      "conductor/tracks/metadata_nil_sentinel_20260624/plan.md",
      "conductor/tracks/metadata_nil_sentinel_20260624/metadata.json",
      "conductor/tracks/metadata_nil_sentinel_20260624/state.toml",
      "tests/test_metadata_nil_sentinel.py",
      "docs/reports/TRACK_COMPLETION_metadata_nil_sentinel_20260624.md"
    ],
    "modified_files": [
      "src/aggregate.py (NIL_METADATA constant + nil-check migrations)",
      "src/ai_client.py (nil-check migrations; specific files TBD by Tier 2)",
      "conductor/tracks.md",
      "docs/reports/campaign_measurements_20260624.md"
    ],
    "deleted_files": []
  },
  "estimated_effort": {
    "method": "scope (per workflow.md §Tier 1 Track Initialization Rules). NO day estimates.",
    "phase_1": "1 task: write the 2 behavioral tests",
    "phase_2": "1 task: NIL_METADATA constant + 6 nil-check migrations",
    "phase_3": "1 task: 6 VCs + budget gate + TRACK_COMPLETION + state + tracks.md"
  },
  "verification_criteria": [
    "VC1: NIL_METADATA is defined in src/",
    "VC2: The 6 nil-check functions no longer have the 3-pattern nil-check",
    "VC3: Behavioral test exists and passes",
    "VC4: Budget gate met (drop >= 10% vs 4.01e22 baseline)",
    "VC5: Full test suite remains green (11/11 tiers PASS)",
    "VC6: 4 audit gates remain clean"
  ],
  "known_issues": [],
  "deferred_to_followup_tracks": [],
  "regressions_and_pre_existing_failures": [],
  "pre_existing_failures_remaining": [],
  "risk_register": [
    {
      "id": "risk-1",
      "description": "The 6 nil-check functions are in unexpected locations",
      "likelihood": "low",
      "impact": "Phase 2 needs to find them via grep + detect_nil_check_pattern",
      "mitigation": "Audit enumerated all consumer files; detect_nil_check_pattern is the oracle"
    },
    {
      "id": "risk-2",
      "description": "NIL_METADATA defaults cause downstream bugs",
      "likelihood": "low",
      "impact": "Production code that uses the sentinel crashes",
      "mitigation": "Empty defaults + behavioral test verifies sentinel works in a real call"
    },
    {
      "id": "risk-3",
      "description": "Budget gate fails (drop < 10%)",
      "likelihood": "low",
      "impact": "Child 1 cannot ship; campaign pauses",
      "mitigation": "The 6 nil-checks are documented; their removal MUST drop the branch count"
    }
  ]
}