# BRIEFING — 2026-10-01T21:24:35Z

## Mission
Design Minimap HUD component (client/webapp/js/ui/minimap_hud.js) and DOM mounting in index.html (<= 200 lines) with fog of war integration, dynamic indicators (player, waypoints, boss gate, POIs), battery-optimized throttled updates, and verification test specs.

## 🔒 My Identity
- Archetype: teamwork_preview_explorer
- Roles: Read-only investigation, problem analysis, synthesis, structured reports
- Working directory: c:\Projects\FreeExile\.agents\teamwork\explorer_m4_3
- Original parent: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Milestone: Milestone 4 / R4: Fog of War & Minimap HUD Exploration

## 🔒 Key Constraints
- Read-only investigation — do NOT implement or modify source code directly
- Output structured analysis and handoff report in `c:\Projects\FreeExile\.agents\teamwork\explorer_m4_3\handoff.md` and `report.md`
- Index.html must remain <= 200 lines (Soft cap 200, Hard cap 400 lines)
- minimap_hud.js must remain <= 280 lines (Soft cap 350, Hard cap 500 lines)
- Battery optimization: throttled refresh rate (15-30 Hz) on mobile
- Dedicated 120x80 px canvas in top-right HUD
- Aspect-ratio preserving scaling for zone grid (W x H)
- Fog integration with WarFog (UNEXPLORED, EXPLORED_FOGGED, VISIBLE)
- Dynamic indicators: player blip with orientation, waypoints, locked/unlocked Boss Gate, POIs

## Current Parent
- Conversation ID: 1cc48fc5-ce57-4f48-8964-24cab4bfcacc
- Updated: 2026-10-01T21:24:35Z

## Investigation State
- **Explored paths**:
  - `c:\Projects\FreeExile\.agents\teamwork\ORIGINAL_REQUEST.md` (§ R4)
  - `c:\Projects\FreeExile\.agents\teamwork\orchestrator_11\PROJECT.md`
  - `client/webapp/index.html` (198 lines)
  - `client/webapp/js/engine/tile_grid_loader.js` (currentMapGrid, currentMapMetadata)
  - `client/webapp/js/engine/tile_map_renderer.js` (BIOME_TINTS, TILE_PALETTES)
  - `client/webapp/js/engine/canvas_renderer.js` (renderLoop, isGamePaused, HUD update hooks)
  - `client/webapp/js/ui/war_fog.js` and `war_fog_renderer.js`
- **Key findings**:
  1. Projection math: Uniform scale factor `min((120-4)/W, (80-4)/H)` with symmetric `padX, padY` provides perfect aspect ratio preservation for any zone dimension without distortion.
  2. Dual-layer caching: Baking base terrain and fog onto an offscreen $120 \times 80\text{px}$ canvas and only re-baking when `mapDirty || fogDirty` reduces typical per-frame drawing to 1 image blit + ~5 vector marker calls.
  3. Throttling: 30 Hz ($33.3\text{ms}$) throttle in `update()` saves $75\%$ CPU draw calls compared to 120 FPS; full freeze during pause (`isGamePaused`).
  4. Line budget: `proposed_minimap_hud.js` is 252 lines ($\le 280$ target). `index.html` integration brings total lines to 199 lines ($\le 200$ Soft Cap).
  5. Verification: 14 unit test items created and validated with 100% pass rate in 0.25s.
- **Unexplored areas**: None for M4.3 scope.

## Key Decisions Made
- Use offscreen canvas caching for base terrain and fog overlay.
- Mask POI markers on minimap when tile is UNEXPLORED.
- Include directional notch on player blip matching `facingAngle`.
- Keep index.html at 199 lines by removing redundant blank line 89.

## Artifact Index
- `DISPATCH.md` — Assignment record
- `BRIEFING.md` — Agent working memory
- `progress.md` — Liveness heartbeat and completion status
- `report.md` — Comprehensive technical architecture report
- `handoff.md` — 5-component handoff report
- `proposed_minimap_hud.js` — Complete proposed Minimap HUD implementation (252 lines)
- `proposed_test_fog_and_minimap.py` — Automated unit test suite (14 passed)
- `proposed_index_patch.diff` — Patch diff for index.html DOM mounting