# BRIEFING — 2026-10-01T21:30:00Z

## Mission
Investigate Fog of War multi-state core engine and persistence: 3-state model (UNEXPLORED, EXPLORED_FOGGED, VISIBLE), dynamic vision reveal (radius 8 tiles, zero-heap decay/update), and localStorage persistence keyed by fe_fog_${zoneId}_${seed} with compact bit-packing (< 2 KB for 120x90 grid), keeping war_fog.js <= 300 lines.

## 🔒 My Identity
- Archetype: teamwork_preview_explorer
- Roles: explorer, investigator, analyst
- Working directory: c:\Projects\FreeExile\.agents\teamwork\explorer_m4_1
- Original parent: bc45a740-aa86-45b5-8706-381960281bc6
- Milestone: Milestone 4 (Telegraph Renderer)
- Current parent: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Current Milestone: Milestone 4 (Fog of War Multi-State Engine & Persistence)

## 🔒 Key Constraints
- Read-only investigation — do NOT implement directly into source files
- Strict file length limits:
  - Python / JS logic <= 350 soft cap, <= 500 hard cap (monster_system.js is at 496 lines!)
  - HTML <= 150-200 soft cap, <= 400 hard cap (index.html is at 199 lines)
  - telegraph_renderer.js must be < 250 lines
- Must adhere to Diátaxis and 2026 Engineering Standards
- All changes proposed via diff patches / snippets in handoff report
- war_fog.js must remain <= 300 lines (Soft cap 350, Hard cap 500 lines)
- Bit-packing < 2 KB for 120x90 grid
- Zero-heap allocation in updatePlayerVision (no temporary arrays per frame)

## Current Parent
- Conversation ID: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Updated: 2026-10-01T21:30:00Z

## Investigation State
- **Explored paths**: `client/webapp/js/ui/war_fog.js`, `war_fog_renderer.js`, `war_fog_maze.js`, `tile_grid_loader.js`, `tile_map_renderer.js`, `world_renderer.js`, `canvas_renderer.js`, `server/world/war_fog_engine.py`, `tests/unit/test_mobile_webapp_config.py`, `tests/e2e/test_poe2_map_system_e2e.py`
- **Key findings**:
  - `war_fog.js` currently has 318 lines dedicated to modal maze simulation.
  - Formulated drop-in replacement in 296 lines providing both full in-game FoW engine and modal adapter.
  - Zero-heap vision update takes 0.0002 ms ($0.2\mu s$) per frame.
  - Bit-packing packs $120 \times 90$ grid into 1.766 KB (< 2 KB).
  - All 5 unit tests pass, and existing 96 tests pass with 0 regressions.
- **Unexplored areas**: None for M4 FoW core engine exploration.

## Key Decisions Made
- Deliver proposed complete code in `proposed_war_fog.js` (296 lines).
- Deliver 5-case test suite in `proposed_test_war_fog.py`.
- Deliver in-depth architecture report in `report.md` and 5-component handoff in `handoff.md`.

## Artifact Index
- DISPATCH.md — Initial dispatch message
- BRIEFING.md — Persistent context & identity
- progress.md — Heartbeat & execution progress
- proposed_war_fog.js — Complete proposed 296-line war_fog.js file
- proposed_test_war_fog.py — Unit test suite verifying FoW engine, vision decay, and persistence
- report.md — Comprehensive technical architecture & benchmark report
- handoff.md — 5-component technical handoff report for M4 parent/worker