conductor(campaign): metadata_ssdl_defusing_20260624 - 3-child SSDL defusing campaign

Campaign: address the parent code_path_audit_20260607 Finding 1 (CRITICAL)
Metadata 4.01e22 effective codepaths via 3 SSDL techniques.

3 children, sequential, with budget gates:
1. metadata_nil_sentinel_20260624 (>= 10% drop): introduce
   NIL_METADATA sentinel + migrate 6 nil-check functions.
2. metadata_generational_handle_20260624 (>= 20% drop,
   BLOCKED_BY 1): wrap Metadata in (index, generation) handle;
   collapse lifetime branches to 1 lookup + 1 cmp.
3. metadata_field_cache_20260624 (>= 30% drop, BLOCKED_BY 2):
   MetadataFieldCache keyed by (handle.index, field_name);
   123 string-keyed entry.get('key', default) sites become
   cache lookups.

Each child has its own spec/plan/metadata/state. Budget gate
after each child: re-measure effective codepaths; if drop < threshold,
PAUSE the campaign and report to user.

End-of-campaign TRACK_COMPLETION captures the cumulative reduction
vs the 4.01e22 baseline. Deferred follow-up: apply the same
3 SSDL primitives to the 4 other dict[str, Any] aliases
(FileItem, CommsLogEntry, HistoryMessage, ToolDefinition, ToolCall).

16 files committed: 4 directories x 4 files each (spec, plan,
metadata, state).

conductor/tracks/metadata_ssdl_defusing_20260624/metadata.json

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+{
+  "track_id": "metadata_ssdl_defusing_20260624",
+  "name": "Metadata SSDL Defusing Campaign",
+  "track_type": "campaign",
+  "created_date": "2026-06-24",
+  "branch": "master",
+  "depends_on": ["code_path_audit_20260607"],
+  "blocks": [],
+  "child_tracks": [
+    {
+      "track_id": "metadata_nil_sentinel_20260624",
+      "name": "Child 1: Nil Sentinel",
+      "blocked_by_parent": false,
+      "blocks_within_campaign": ["metadata_generational_handle_20260624"]
+    },
+    {
+      "track_id": "metadata_generational_handle_20260624",
+      "name": "Child 2: Generational Handle",
+      "blocked_by_parent": true,
+      "blocks_within_campaign": ["metadata_field_cache_20260624"]
+    },
+    {
+      "track_id": "metadata_field_cache_20260624",
+      "name": "Child 3: Immediate-Mode Field Cache",
+      "blocked_by_parent": true,
+      "blocks_within_campaign": []
+    }
+  ],
+  "scope": {
+    "new_files": [
+      "conductor/tracks/metadata_ssdl_defusing_20260624/spec.md",
+      "conductor/tracks/metadata_ssdl_defusing_20260624/plan.md",
+      "conductor/tracks/metadata_ssdl_defusing_20260624/metadata.json",
+      "conductor/tracks/metadata_ssdl_defusing_20260624/state.toml",
+      "conductor/tracks/metadata_nil_sentinel_20260624/*",
+      "conductor/tracks/metadata_generational_handle_20260624/*",
+      "conductor/tracks/metadata_field_cache_20260624/*",
+      "tests/test_metadata_nil_sentinel.py",
+      "tests/test_metadata_generational_handle.py",
+      "tests/test_metadata_field_cache.py",
+      "docs/reports/campaign_measurements_20260624.md",
+      "docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md"
+    ],
+    "modified_files": [
+      "src/aggregate.py",
+      "src/ai_client.py",
+      "src/history.py",
+      "src/aggregate.py (additional functions as Tier 2 identifies)",
+      "conductor/tracks.md"
+    ],
+    "deleted_files": []
+  },
+  "estimated_effort": {
+    "method": "scope (per workflow.md §Tier 1 Track Initialization Rules). NO day estimates.",
+    "child_1": "1 atomic commit (sentinel + 6 migrations) + 1 test + 1 verification",
+    "child_2": "1 atomic commit (handle registry) + 1 test + 1 verification",
+    "child_3": "1 atomic commit (field cache) + 1 test + 1 verification",
+    "phase_4": "1 end-of-campaign report + state + tracks.md"
+  },
+  "verification_criteria": [
+    "VC1: All 3 child tracks SHIPPED (status=completed, current_phase=complete, all phases completed)",
+    "VC2: End-of-campaign report exists with 3 measurements + cumulative reduction",
+    "VC3: Full batched test suite is green (all 11 tiers PASS)",
+    "VC4: 4 audit gates remain clean",
+    "VC5: No new top-level src/<thing>.py files (per AGENTS.md file naming convention)",
+    "VC6: 3 behavioral tests for the 3 SSDL primitives exist and pass"
+  ],
+  "budget_gates": [
+    {
+      "child": "metadata_nil_sentinel_20260624",
+      "baseline": "4.01e22 effective codepaths for Metadata (pre-campaign)",
+      "expected_drop": ">= 10%",
+      "pause_threshold": "drop < 10%",
+      "pause_action": "STOP campaign; report to user; investigate why 6 nil-checks didn't reduce branch count"
+    },
+    {
+      "child": "metadata_generational_handle_20260624",
+      "baseline": "post-child-1 measurement",
+      "expected_drop": ">= 20%",
+      "pause_threshold": "drop < 20%",
+      "pause_action": "STOP campaign; report to user; investigate why lifetime branches didn't collapse"
+    },
+    {
+      "child": "metadata_field_cache_20260624",
+      "baseline": "post-child-2 measurement",
+      "expected_drop": ">= 30%",
+      "pause_threshold": "drop < 30%",
+      "pause_action": "STOP campaign; report to user; investigate why cache lookups didn't reduce branch count"
+    }
+  ],
+  "known_issues": [],
+  "deferred_to_followup_tracks": [
+    {
+      "id": "deferred-same-techniques-other-aggregates",
+      "title": "Apply the 3 SSDL primitives to the other 9 in-scope aggregates (FileItem, CommsLogEntry, HistoryMessage, ToolDefinition, ToolCall, Result, the 3 list-typed, the 3 candidates)",
+      "description": "The 3 SSDL primitives (NIL_METADATA, MetadataHandleRegistry, MetadataFieldCache) are general; the same pattern can be applied to other aggregates. The 4 other dict[str, Any] aggregates (FileItem, CommsLogEntry, HistoryMessage, ToolDefinition, ToolCall) show similar patterns per the parent audit Finding 2.",
+      "track_status": "separate campaign post-this one"
+    }
+  ],
+  "regressions_and_pre_existing_failures": [],
+  "pre_existing_failures_remaining": [],
+  "risk_register": [
+    {
+      "id": "risk-1",
+      "description": "Child 1 doesn't measurably drop the effective-codepaths number",
+      "likelihood": "low",
+      "impact": "Campaign pauses at child 1",
+      "mitigation": "Budget gate catches this; investigate the SSDL math or the audit if drop is 0"
+    },
+    {
+      "id": "risk-2",
+      "description": "Child 2 (generational handle) breaks code that expects raw Metadata",
+      "likelihood": "medium",
+      "impact": "Production code that does `entry['key']` directly fails; need wrapper migration",
+      "mitigation": "The handle is a wrapper; consumers can extract raw value via .value or similar; behavioral test verifies backwards-compat"
+    },
+    {
+      "id": "risk-3",
+      "description": "Child 3 (field cache) cache invalidation is wrong",
+      "likelihood": "medium",
+      "impact": "Stale values returned; subtle bug",
+      "mitigation": "Cache keyed by handle; when underlying value changes, handle generation bumps, invalidating cache entries"
+    },
+    {
+      "id": "risk-4",
+      "description": "Cumulative drop is less than expected",
+      "likelihood": "low",
+      "impact": "Campaign produces smaller improvement than expected",
+      "mitigation": "The campaign's value is in the TECHNIQUE, not the final number; techniques ship, numbers are heuristic"
+    }
+  ]
+}

conductor/tracks/metadata_ssdl_defusing_20260624/plan.md

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+# Campaign Plan: metadata_ssdl_defusing_20260624
+
+3-child campaign executed sequentially with budget gates. The umbrella plan is intentionally minimal — each child has its own plan. The umbrella tracks the campaign-wide coordination only.
+
+## Phase 1: Child 1 — Nil Sentinel (metadata_nil_sentinel_20260624)
+
+Focus: Establish the sentinel fallback path. Independent of children 2 and 3.
+
+- [ ] Task 1.1: Tier 2 ships child 1 per its own plan.md.
+  - See `conductor/tracks/metadata_nil_sentinel_20260624/plan.md` for the 3-5 tasks.
+- [ ] Task 1.2: Run the budget gate.
+  - `uv run python -c "..."` to compute the new effective-codepaths number for Metadata.
+  - If drop ≥ 10% vs 4.01e22 baseline, proceed to Phase 2.
+  - If drop < 10%, PAUSE and report to user.
+- [ ] Task 1.3: Re-run the full batched test suite.
+  - `uv run python scripts/run_tests_batched.py` → all 11 tiers PASS.
+- [ ] Task 1.4: Capture the post-child-1 measurement in `docs/reports/campaign_measurements_20260624.md` (campaign-wide log).
+
+## Phase 2: Child 2 — Generational Handle (metadata_generational_handle_20260624)
+
+Focus: Wrap Metadata in (index, generation). BLOCKED_BY Phase 1 (the sentinel is the generation-mismatch fallback).
+
+- [ ] Task 2.1: Tier 2 ships child 2 per its own plan.md.
+- [ ] Task 2.2: Run the budget gate.
+  - Re-measure effective-codepaths.
+  - If drop ≥ 20% vs post-child-1 measurement, proceed to Phase 3.
+  - If drop < 20%, PAUSE and report.
+- [ ] Task 2.3: Re-run the full batched test suite.
+- [ ] Task 2.4: Append the post-child-2 measurement to the campaign log.
+
+## Phase 3: Child 3 — Field Cache (metadata_field_cache_20260624)
+
+Focus: Add the cache keyed by handle. BLOCKED_BY Phase 2 (the handle provides the stable cache key).
+
+- [ ] Task 3.1: Tier 2 ships child 3 per its own plan.md.
+- [ ] Task 3.2: Run the budget gate.
+  - Re-measure effective-codepaths.
+  - If drop ≥ 30% vs post-child-2 measurement, proceed to Phase 4.
+  - If drop < 30%, PAUSE and report.
+- [ ] Task 3.3: Re-run the full batched test suite.
+- [ ] Task 3.4: Append the post-child-3 measurement to the campaign log.
+
+## Phase 4: End-of-Campaign Report
+
+Focus: Quantify the cumulative effect.
+
+- [ ] Task 4.1: Write `docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md`.
+  - 3 measurements (post-child-1, -2, -3) + the 4.01e22 baseline.
+  - Total reduction.
+  - The 3 SSDL primitives' locations in `src/`.
+  - Links to each child's TRACK_COMPLETION.
+  - Verdict: did the campaign meet its goal? (Y/N + evidence)
+- [ ] Task 4.2: Update this track's `state.toml` to `status = "completed"`, `current_phase = "complete"`, all 4 phases `completed`.
+- [ ] Task 4.3: Update `conductor/tracks.md` to add the campaign row + the 3 child rows.
+
+## Budget Gate Quick Reference
+
+| Child | Expected drop | If drop < threshold, PAUSE and report |
+|---|---|---|
+| 1: Nil Sentinel | ≥ 10% | Pause; investigate why the 6 nil-checks didn't reduce branch count |
+| 2: Generational Handle | ≥ 20% | Pause; investigate why lifetime branches didn't collapse |
+| 3: Field Cache | ≥ 30% | Pause; investigate why cache lookup didn't reduce branch count |
+
+The thresholds are conservative estimates. Actual drops may be much larger (the heuristic's 4.01e22 is a worst-case upper bound; real numbers may be smaller by orders of magnitude once the techniques are applied).
+
+## Commit Log (Expected, Campaign-Wide)
+
+| Commit | Description |
+|---|---|
+| (from child 1) | `feat(metadata): NIL_METADATA sentinel + 6 nil-check migrations` |
+| (from child 1) | `test(metadata): behavioral test for nil sentinel` |
+| (from child 1) | `conductor(state): metadata_nil_sentinel_20260624 SHIPPED` |
+| (from child 2) | `feat(metadata): generational handle registry` |
+| (from child 2) | `test(metadata): behavioral test for handle lookup` |
+| (from child 2) | `conductor(state): metadata_generational_handle_20260624 SHIPPED` |
+| (from child 3) | `feat(metadata): MetadataFieldCache keyed by handle` |
+| (from child 3) | `test(metadata): behavioral test for cache hit/miss` |
+| (from child 3) | `conductor(state): metadata_field_cache_20260624 SHIPPED` |
+| (campaign) | `docs(reports): TRACK_COMPLETION for metadata_ssdl_defusing_20260624` |
+| (campaign) | `conductor(state): metadata_ssdl_defusing_20260624 SHIPPED` |
+| (campaign) | `conductor(tracks): add campaign + 3 child rows` |
+
+Plus per-task plan-update commits per the workflow.
+
+## Verification Commands (run at end of Phase 4)
+
+```bash
+# VC1: all 3 children SHIPPED
+cat conductor/tracks/metadata_nil_sentinel_20260624/state.toml | grep status
+cat conductor/tracks/metadata_generational_handle_20260624/state.toml | grep status
+cat conductor/tracks/metadata_field_cache_20260624/state.toml | grep status
+
+# VC2: end-of-campaign report
+cat docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md
+
+# VC3: full test suite
+uv run python scripts/run_tests_batched.py
+
+# VC4: 4 audit gates
+uv run python scripts/audit_weak_types.py --strict
+uv run python scripts/generate_type_registry.py --check
+uv run python scripts/audit_main_thread_imports.py
+uv run python scripts/audit_no_models_config_io.py
+
+# VC5: no new top-level src/ files
+git diff master..HEAD --stat -- 'src/*.py' | grep -E '\bsrc/[a-z_]+\.py\b' | sort -u
+
+# VC6: behavioral tests
+uv run pytest tests/test_metadata_nil_sentinel.py tests/test_metadata_generational_handle.py tests/test_metadata_field_cache.py -v
+```

conductor/tracks/metadata_ssdl_defusing_20260624/spec.md

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+# Campaign Specification: metadata_ssdl_defusing_20260624
+
+## Overview
+
+3-child campaign to defuse the `Metadata` aggregate's combinatoric explosion (4.01e22 effective codepaths) via Fleury's SSDL techniques. Each child produces one SSDL primitive, is independently shippable, and is gated by a budget check that re-measures effective codepaths after each child.
+
+The parent audit (`code_path_audit_20260607` / `AUDIT_REPORT.md` Finding 1, CRITICAL) identified 3 specific techniques:
+1. **Nil Sentinel `[N]`** for the 6 nil-check functions
+2. **Generational Handle** wrapping Metadata
+3. **Immediate-Mode Cache `[Q:key] -> [I:FetchCached] -> [T]`** for the 123 field-access sites
+
+The campaign executes them in dependency order: child 1 introduces the sentinel fallback that child 2's generation-mismatch path returns to; child 2's stable identity enables child 3's cache keying.
+
+## Current State Audit (as of master @ 7a9261c4, post-fix_test_failures_20260624 merge)
+
+The audit baseline is captured in `docs/reports/code_path_audit/2026-06-22/AUDIT_REPORT.md`:
+- **Metadata:** 483 producers / 752 consumers / 123 field-access sites (0 typed)
+- **Effective codepaths:** 4.01e22 (sum of 2^branches across 752 consumers)
+- **Branch points:** 3466 across consumer functions
+- **Nil-check functions:** 6 (the `is None` / `== None` / `!= None` detection sites)
+
+The behavioral SSDL test exists at `tests/test_code_path_audit_ssdl_behavioral.py` and uses a synthetic 5-function × 3-if-statements fixture to assert `compute_effective_codepaths` math (5 × 2^3 = 40). The real-Metadata measurement is captured by `src.code_path_audit_ssdl.compute_effective_codepaths(Metadata_profile)`.
+
+## Goals
+
+| ID | Goal | Acceptance |
+|---|---|---|
+| G1 | Child 1 (Nil Sentinel) ships: 6 nil-check functions use sentinel-return | 6 functions refactored; behavioral test for sentinel; 4.01e22 number drops measurably |
+| G2 | Child 2 (Generational Handle) ships: lifetime branches collapse to 1 lookup + 1 generation comparison | Registry in place; 1 lookup benchmark; further effective-codepath drop |
+| G3 | Child 3 (Field Cache) ships: 123 string-keyed `entry.get('key', default)` sites become cache hits | Cache in place; 123 sites benchmarked; further effective-codepath drop |
+| G4 | End-of-campaign report: cumulative effective-codepath measurement vs 4.01e22 baseline | `docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md` written |
+| G5 | All 4 audit gates remain clean | weak_types ≤ 112, type_registry in sync, main_thread_imports clean, no_models_config_io clean |
+
+## Non-Goals
+
+- Touching any aggregate OTHER than Metadata (the audit's other 9 in-scope aggregates + 3 candidates are out of scope; the SSDL primitives established by this campaign can be applied to them in follow-up campaigns)
+- Modifying the audit infrastructure (`src/code_path_audit*.py`); the campaign USES the audit to measure progress but does not change the audit
+- Refactoring the 7-file split (NG3 from `code_path_audit_polish_20260622`); that's a separate refactor track
+- Runtime profiling (the campaign uses the static `branch_count` heuristic; runtime profiling is Track F from the previous menu)
+
+## Per-Child Specs
+
+### Child 1: `metadata_nil_sentinel_20260624` (Nil Sentinel)
+
+**Scope:** Introduce `NIL_METADATA = Metadata(...)` constant with safe defaults. Migrate the 6 nil-check functions (detected by `src.code_path_audit_ssdl.detect_nil_check_pattern`) to sentinel-return: replace `if entry is None: ...` / `if entry == None: ...` / `if entry != None: ...` patterns with `entry = entry or NIL_METADATA` (or the function's equivalent).
+
+**Acceptance:**
+- 6 functions refactored
+- 1 behavioral test (`tests/test_metadata_nil_sentinel.py`): asserts the sentinel is used, asserts the 6 functions no longer have the 3-pattern nil-check branches
+- Budget gate: re-run `compute_effective_codepaths(Metadata_profile)`; if the number drops by < 10%, pause and report
+
+**Why first:** establishes the sentinel that child 2's generation-mismatch path returns to.
+
+### Child 2: `metadata_generational_handle_20260624` (Generational Handle)
+
+**Scope:** Wrap Metadata in `(index, generation)` resolved through a registry. Validation is one comparison: if `metadata.generation != registry.generations[metadata.index]`, return `NIL_METADATA`. Otherwise, the value is valid.
+
+**Acceptance:**
+- `MetadataHandleRegistry` (or equivalent) introduced in a sensible location (likely `src/aggregate.py` or a new sibling module per AGENTS.md §File Naming Convention)
+- Migration: the production `Metadata` value is now wrapped in a handle; lifetime-branch code (e.g., the 3466 branch points that include lifetime checks) collapses to 1 lookup + 1 comparison
+- 1 behavioral test: assert handle lookup is O(1), assert generation mismatch returns sentinel
+- Budget gate: re-run `compute_effective_codepaths(Metadata_profile)`; if the number drops by < 20%, pause and report (the generational handle is expected to produce a larger drop than the sentinel)
+
+**Why second:** builds on child 1's sentinel as the fallback path. Provides a stable identity for child 3's cache keying.
+
+### Child 3: `metadata_field_cache_20260624` (Immediate-Mode Cache)
+
+**Scope:** Introduce `MetadataFieldCache[(handle_id, field_name)] -> value`. Consumers request `(metadata_handle, 'field_name')`, get cached value. The 123 string-keyed `entry.get('key', default)` sites become 123 cache lookups.
+
+**Acceptance:**
+- `MetadataFieldCache` introduced
+- Migration: the 123 field-access sites in `src/` use the cache
+- 1 behavioral test: assert cache hit, assert cache miss with sentinel fallback
+- Budget gate: re-run `compute_effective_codepaths(Metadata_profile)`; if the number drops by < 30%, pause and report (the cache is expected to produce the largest drop)
+
+**Why third:** the cache needs the handle's stable identity (child 2) to use as a key.
+
+## Budget Gate Protocol
+
+After each child commits:
+
+1. **Measure:** run `uv run python -c "from src.code_path_audit import AggregateProfile, ...; from src.code_path_audit_ssdl import compute_effective_codepaths; profile = ...; print(compute_effective_codepaths(profile, 'src'))"`
+2. **Compare:** diff vs prior measurement (or 4.01e22 baseline for child 1)
+3. **Gate:** if drop < expected threshold (10% / 20% / 30% per child), PAUSE the campaign and report to user
+4. **Continue:** if drop ≥ threshold, proceed to next child
+
+The measurement is captured in the child track's TRACK_COMPLETION report and rolled up into the campaign's end-of-campaign report.
+
+## Functional Requirements
+
+### FR1: Each child preserves the existing test suite
+After each child, all 6 VCs from the parent `fix_test_failures_20260624` track remain green: 14 previously-failing tests still pass; no new failures.
+
+### FR2: Each child is independently shippable
+A child can be merged without the other 2 (the campaign gates are forward-looking; a child that meets its budget is shippable on its own).
+
+### FR3: The end-of-campaign report quantifies the cumulative effect
+`docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md` shows: pre-campaign baseline 4.01e22, post-child-1 number, post-child-2 number, post-child-3 number, total reduction.
+
+## Non-Functional Requirements
+
+- NFR1: 1-space indentation (project convention)
+- NFR2: CRLF line endings on Windows
+- NFR3: No comments in source code
+- NFR4: No new pip dependencies
+- NFR5: Per-task atomic commits with git notes
+- NFR6: Each child's `Result[T]` returns for fallible fns (per `conductor/code_styleguides/error_handling.md`)
+- NFR7: The new SSDL primitives are exported from a sensible location; no new top-level `src/<thing>.py` files (per AGENTS.md §File Naming Convention) unless the user explicitly approves
+
+## Architecture Reference
+
+- `docs/reports/code_path_audit/2026-06-22/AUDIT_REPORT.md` — Finding 1 (CRITICAL) and the 3 proposed fixes
+- `src/code_path_audit_ssdl.py:84-100` — `detect_nil_check_pattern` (the function that identifies the 6 nil-check sites)
+- `src/code_path_audit_ssdl.py:39-55` — `compute_effective_codepaths` (the measurement function)
+- `src/code_path_audit.py:271-296` — `CANONICAL_MEMORY_DIM` and `MEMORY_DIM_FILE_HEURISTIC` (where to file new primitives)
+- `conductor/code_styleguides/data_oriented_design.md` — the canonical DOD reference
+- `conductor/code_styleguides/error_handling.md` — the `Result[T]` convention
+- `conductor/code_styleguides/agent_memory_dimensions.md` — the 4 memory dimensions (Metadata is `discussion`)
+
+## Out of Scope
+
+- Aggregates other than Metadata (FileItem, CommsLogEntry, HistoryMessage, ToolDefinition, ToolCall, Result, the 3 list-typed, the 3 candidates) — the SSDL primitives are general but the campaign is Metadata-specific
+- Modifying `src/code_path_audit*.py` (the audit infrastructure)
+- Refactoring the 7-file split
+- Runtime profiling (Track F from the previous menu)
+- Modifying the campaign structure (3 children are fixed; adding a 4th is out of scope)
+
+## Verification Criteria (Definition of Done)
+
+| # | Criterion | Verification command |
+|---|---|---|
+| VC1 | All 3 children SHIPPED | Each child track has `status = "completed"`, `current_phase = "complete"`, all phases `completed` |
+| VC2 | End-of-campaign report exists | `cat docs/reports/TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md` shows the 3 measurements + cumulative reduction |
+| VC3 | Full test suite remains green | `uv run python scripts/run_tests_batched.py` → all 11 tiers PASS |
+| VC4 | 4 audit gates remain clean | weak_types ≤ 112, type_registry in sync, main_thread_imports clean, no_models_config_io clean |
+| VC5 | No new `src/<thing>.py` files created (per AGENTS.md) | `git diff master..HEAD --stat -- 'src/*.py' \| grep -E 'src/[a-z_]+\.py'` returns only the existing `src/` modules; the new SSDL primitives live in existing files |
+| VC6 | Behavioral tests for each child exist and pass | `uv run pytest tests/test_metadata_nil_sentinel.py tests/test_metadata_generational_handle.py tests/test_metadata_field_cache.py -v` → all pass |
+
+## Risks
+
+| # | Risk | Likelihood | Mitigation |
+|---|---|---|---|
+| R1 | Child 1 doesn't measurably drop the effective-codepaths number | low | The 6 nil-checks are documented in AUDIT_REPORT.md; their removal MUST drop the number. If not, the audit or the SSDL math is wrong (separate investigation). |
+| R2 | Child 2 (generational handle) breaks code that expects raw `Metadata` | medium | The handle is a wrapper; consumers can still extract the raw value via `.value` or similar. Behavioral test verifies backwards-compat for the common cases. |
+| R3 | Child 3 (field cache) cache invalidation is wrong | medium | The cache is keyed by `(handle_id, field_name)`. When the underlying value changes, the handle's generation bumps, invalidating all cache entries for that handle. The cache is a write-through thin wrapper. |
+| R4 | The cumulative drop is less than expected (e.g., 4.01e22 → 1e15 instead of 4.01e22 → 1e5) | low | The campaign's value is in the TECHNIQUE, not the final number. The numbers are heuristic; the actual goal is the structural improvement (sentinel, handle, cache). If the techniques ship, the campaign succeeds regardless of the final heuristic number. |
+| R5 | New `src/<thing>.py` files needed for the SSDL primitives | low | Per AGENTS.md, helpers go in the parent module. The new primitives live in `src/aggregate.py` (the parent module for `Metadata`). If the user explicitly approves new top-level files, the campaign can be extended. |

conductor/tracks/metadata_ssdl_defusing_20260624/state.toml

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+# Campaign state for metadata_ssdl_defusing_20260624
+# 3-child campaign; sequential with budget gates.
+# Tier 2 to execute per conductor/workflow.md.
+
+[meta]
+track_id = "metadata_ssdl_defusing_20260624"
+name = "Metadata SSDL Defusing Campaign"
+status = "active"
+current_phase = 0
+last_updated = "2026-06-24"
+
+[parent]
+# Independent campaign (not part of an umbrella)
+
+[blocked_by]
+code_path_audit_20260607 = "shipped"
+
+[blocks]
+# This campaign blocks no other tracks. It is an exploratory campaign.
+
+[child_tracks]
+metadata_nil_sentinel_20260624 = { status = "pending", short_name = "child_1_nil_sentinel" }
+metadata_generational_handle_20260624 = { status = "pending", short_name = "child_2_handle" }
+metadata_field_cache_20260624 = { status = "pending", short_name = "child_3_cache" }
+
+[phases]
+phase_1 = { status = "pending", checkpointsha = "", name = "Child 1: Nil Sentinel (with budget gate >= 10% drop)" }
+phase_2 = { status = "pending", checkpointsha = "", name = "Child 2: Generational Handle (with budget gate >= 20% drop)" }
+phase_3 = { status = "pending", checkpointsha = "", name = "Child 3: Field Cache (with budget gate >= 30% drop)" }
+phase_4 = { status = "pending", checkpointsha = "", name = "End-of-Campaign Report" }
+
+[tasks]
+# Phase 1
+t1_1 = { status = "pending", commit_sha = "", description = "Tier 2 ships child 1 per its own plan.md" }
+t1_2 = { status = "pending", commit_sha = "", description = "Run child 1 budget gate (>= 10% drop); pause if not met" }
+t1_3 = { status = "pending", commit_sha = "", description = "Re-run full batched test suite; verify all 11 tiers PASS" }
+t1_4 = { status = "pending", commit_sha = "", description = "Capture post-child-1 measurement in campaign_measurements_20260624.md" }
+# Phase 2
+t2_1 = { status = "pending", commit_sha = "", description = "Tier 2 ships child 2 per its own plan.md" }
+t2_2 = { status = "pending", commit_sha = "", description = "Run child 2 budget gate (>= 20% drop); pause if not met" }
+t2_3 = { status = "pending", commit_sha = "", description = "Re-run full batched test suite" }
+t2_4 = { status = "pending", commit_sha = "", description = "Append post-child-2 measurement to campaign log" }
+# Phase 3
+t3_1 = { status = "pending", commit_sha = "", description = "Tier 2 ships child 3 per its own plan.md" }
+t3_2 = { status = "pending", commit_sha = "", description = "Run child 3 budget gate (>= 30% drop); pause if not met" }
+t3_3 = { status = "pending", commit_sha = "", description = "Re-run full batched test suite" }
+t3_4 = { status = "pending", commit_sha = "", description = "Append post-child-3 measurement to campaign log" }
+# Phase 4
+t4_1 = { status = "pending", commit_sha = "", description = "Write TRACK_COMPLETION_metadata_ssdl_defusing_20260624.md" }
+t4_2 = { status = "pending", commit_sha = "", description = "Update this state.toml to status=completed" }
+t4_3 = { status = "pending", commit_sha = "", description = "Update conductor/tracks.md with campaign + 3 child rows" }
+
+[verification]
+vc1_all_3_children_shipped = false
+vc2_end_of_campaign_report_exists = false
+vc3_full_batched_suite_green = false
+vc4_audit_gates_clean = false
+vc5_no_new_top_level_src_files = false
+vc6_3_behavioral_tests_pass = false
+
+[measurements]
+# Format: baseline_4.01e22 = sum of 2^branches across all 752 Metadata consumers
+# Populated by Tier 2 as children ship
+pre_campaign = 4.01e+22
+post_child_1 = null
+post_child_2 = null
+post_child_3 = null