# BRIEFING — 2026-10-01T22:04:00Z

## Mission
Empirically stress-test the remediated Fog of War engine, anti-maphack combat targeting, memory stability, and bit-packing corruption handling.

## 🔒 My Identity
- Archetype: teamwork_preview_challenger
- Roles: critic, specialist
- Working directory: c:\Projects\FreeExile\.agents\teamwork\challenger_m4_fix_1
- Original parent: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Milestone: M4 Iteration 2
- Instance: 1 of 1

## 🔒 Key Constraints
- Review-only — do NOT modify implementation code
- Empirical verification mandatory — must write and run tests/stress harnesses directly
- Write all findings to handoff.md with verdict APPROVE or REQUEST_CHANGES
- Send result to parent via send_message

## Current Parent
- Conversation ID: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Updated: not yet

## Review Scope
- **Files to review**:
  - `client/webapp/js/engine/monster_system.js`
  - `client/webapp/js/ui/war_fog.js`
  - `client/webapp/js/ui/minimap_hud.js`
  - `tests/unit/test_fog_and_minimap.py`
  - `tests/e2e/test_poe2_map_system_e2e.py`
- **Interface contracts**: `PROJECT.md` / `GEMINI.md` / `ORIGINAL_REQUEST.md` (R4)
- **Review criteria**:
  - Correctness of target acquisition under Fog of War (10,000 queries)
  - Memory stability during rapid vision updates (5,000 iterations)
  - Robustness of Base64 bit-packing on corrupted inputs (120x90 maps)
  - Test suite pass rates (`test_fog_and_minimap.py`, `test_poe2_map_system_e2e.py`)

## Attack Surface
- **Hypotheses tested**:
  - Combat target acquisition anti-maphack: Tested 10,000 randomized queries across randomized monsters, positions, and fog states -> 0 leaks confirmed.
  - Heap growth: Tested 5,000 rapid vision updates across varied trajectories on 120x90 map -> zero heap growth (35.57 KB net delta, 7.28 bytes/update).
  - Corrupted Base64: Tested 14 direct corrupted inputs, 4 header mismatches, 8 truncated payloads, oversized payload (50KB), 500 fuzz mutations, and dimension sanitization on 120x90 maps -> 100% resilient.
- **Vulnerabilities found**:
  - None blocking. Minor edge case: `initFog(NaN, Infinity)` triggers RangeError because `typeof Infinity === "number"` and `Infinity > 0` evaluates to true; `Number.isFinite` is recommended for future hardening.
- **Untested angles**:
  - Concurrent multi-tab localStorage write race conditions (out of scope for single-client webapp).

## Loaded Skills
- None

## Key Decisions Made
- Authored dedicated empirical stress test harness `tests/unit/test_challenger_m4_fix_1_stress.js` (482 lines, strictly compliant with hard cap 500 lines).
- Verdict: APPROVE remediation.

## Artifact Index
- `.agents/teamwork/challenger_m4_fix_1/BRIEFING.md` — persistent memory index
- `.agents/teamwork/challenger_m4_fix_1/progress.md` — liveness heartbeat
- `.agents/teamwork/challenger_m4_fix_1/handoff.md` — final handoff report
- `tests/unit/test_challenger_m4_fix_1_stress.js` — empirical stress verification harness