# BRIEFING — 2026-10-01T21:45:00Z

## Mission
Investigate world canvas visual fog overlay and entity suppression for Milestone 4 (Fog of War & Minimap HUD) in FreeExile's procedural tile map system.

## 🔒 My Identity
- Archetype: explorer
- Roles: read-only investigator, evidence chain analyst, synthesis
- Working directory: c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2
- Original parent: bc45a740-aa86-45b5-8706-381960281bc6
- Milestone: Milestone 4 (Visceral Telegraphing, Evasion i-Frame & Leashing)
- Generation 2 Parent: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Generation 2 Milestone: Milestone 4 (Procedural Tile Map Fog of War Overlay & Entity Suppression)

## 🔒 Key Constraints
- Read-only investigation — do NOT implement directly
- Line count constraints: `combat_skills.js` (489 lines) and `monster_system.js` (496 lines) must not exceed 500 lines Hard Cap!
- Verify server-side `server/world/combat_engine.py` and client-side webapp synchronization (250ms i-frame window)
- 5-Component Handoff Protocol (`handoff.md`) with precise line references and verified diff proposals
- `client/webapp/js/ui/war_fog_renderer.js` must remain <= 250 lines (Soft cap 350, Hard cap 500 lines)
- Zero heap allocation per render frame on world canvas fog overlay
- Entity suppression: monsters, NPCs, and dynamic loot items outside VISIBLE tiles MUST be hidden
- Viewport frustum culling for fog tiles with smooth 2:1 isometric radial transitions

## Current Parent
- Conversation ID: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Updated: 2026-10-01T21:45:00Z

## Investigation State
- **Explored paths**:
  - `client/webapp/js/ui/war_fog_renderer.js`
  - `client/webapp/js/ui/war_fog.js`
  - `client/webapp/js/engine/world_renderer.js`
  - `client/webapp/js/engine/entity_renderer.js`
  - `client/webapp/js/engine/monster_system.js`
  - `client/webapp/js/engine/canvas_renderer.js`
  - `client/webapp/js/engine/boss_gate_controller.js`
  - `client/webapp/js/engine/tile_map_renderer.js`
  - `client/webapp/js/engine/telegraph_renderer.js`
  - `tests/e2e/test_poe2_map_system_e2e.py`
  - `tests/unit/test_war_fog_and_procedural_map.py`
- **Key findings**:
  - `war_fog_renderer.js` was previously a 287-line modal renderer; redesigned into a 191-line zero-heap 2-pass batch world canvas overlay renderer.
  - Viewport frustum culling processes ~190 tiles in < 0.05 ms using 2 batched path fills + 1 radial vignette (<= 3 draw calls).
  - Ground drops, monsters, NPCs, and telegraphs are suppressed when `fogState !== 2`.
  - Props in `UNEXPLORED` (0) are suppressed; props in `EXPLORED_FOGGED` (1) render with 45% darkness attenuation.
  - Waypoints and Boss Gate runes remain hidden until discovered (`fogState >= 1`).
  - Heap delta across 5,000 continuous simulation frames is 0 bytes.
- **Unexplored areas**: None for M4.2 scope.

## Key Decisions Made
- Redesigned `war_fog_renderer.js` into an ultra-compact (191 lines) zero-heap class with backward-compatible `renderProceduralMap`.
- Selected 2-pass batch path rendering to minimize draw calls to <= 3.
- Designed 2:1 isometric radial vignette falloff around player vision horizon (radius 6.8 to 8.5).
- Created automated test harness `test_proposed_renderer.js` verifying draw calls and zero heap allocation.

## Artifact Index
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\DISPATCH.md` — Incoming dispatch records
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\BRIEFING.md` — Working memory
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\progress.md` — Liveness and progress tracking
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\proposed_war_fog_renderer.js` — Proposed 191-line renderer
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\war_fog_renderer.patch` — Unified diff patch
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\test_proposed_renderer.js` — Automated verification script
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\report.md` — In-depth technical report
- `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_2\handoff.md` — 5-component handoff report