# BRIEFING — 2026-10-04T03:57:00Z

## Mission
Adversarially challenge and stress-test the 3D dimensions and billboard annotations implementation in app/static/bim/index.html (Milestone 1).

## 🔒 My Identity
- Archetype: EMPIRICAL CHALLENGER
- Roles: critic, specialist
- Working directory: c:\Projects\DSCons\.agents\teamwork\teamwork_preview_challenger_m1_1
- Original parent: befbfc73-5853-4a94-b280-61f27b35aa73
- Milestone: Milestone 1 (3D Dimensions & Billboard Annotations)
- Instance: 1 of 1

## 🔒 Key Constraints
- Review-only — do NOT modify implementation code
- Empirical verification mandatory — must run verification code and tests
- 0 errors/warnings in console logs
- .agents/teamwork/ must contain only metadata (no code, tests, or data)

## Current Parent
- Conversation ID: befbfc73-5853-4a94-b280-61f27b35aa73
- Updated: 2026-10-04T03:57:00Z

## Review Scope
- **Files to review**: app/static/bim/index.html
- **Interface contracts**: c:\Projects\DSCons\.agents\teamwork\ORIGINAL_REQUEST.md, c:\Projects\DSCons\.agents\teamwork\teamwork_preview_orchestrator_1\PROJECT.md
- **Review criteria**: 360 camera orbit billboard orientation, 50x toggle stress/memory stability, viewport resizing (mobile/FHD/4K), WebGL stability, 0 console errors/warnings

## Attack Surface
- **Hypotheses tested**:
  1. H1 (Billboard Inversion / Backward Flipping): THREE.Sprite under extreme elevation angles (+85° top-down, -45° worm's-eye) and 360° azimuth. Result: ROBUST. All 21 sprites remain camera-facing with no inversion or negative scale.
  2. H2 (Race Conditions & Texture Leaks under Rapid Toggle): 50x rapid toggle of dimension layer. Result: ROBUST. Zero memory leaks, texture count stays strictly at 21, geometries at 49, children at 41.
  3. H3 (Viewport Resizing & WebGL Context Loss): Mobile 375x667, FHD 1920x1080, 4K 3840x2160. Result: WebGL context remains intact (gl.isContextLost() == false). HOWEVER, on screens <= 390px, .sidebar (390px fixed, flex-shrink: 0) collapses #webgl-container to 0px, causing camera.aspect = 0.0 and projection matrix elements containing Infinity and NaN.
  4. H4 (Console Errors / Exceptions): Clean run with 0 errors and 0 warnings.
- **Vulnerabilities found**:
  - DEFECT: Viewport resizing on mobile devices (width <= 390px, e.g. 375x667) causes container width to collapse to 0px and camera projection matrix to become degenerate with Infinity and NaN.
- **Untested angles**:
  - Touch-based gesture pinch-to-zoom on real mobile devices (tested in headless Chromium emulation).

## Loaded Skills
- None specified in dispatch

## Key Decisions Made
- Formulate verdict as: APPROVE WITH DEFECT FINDING (or CONDITIONAL APPROVE) because Milestone 1 3D dimensions, callouts, and WebGL engine are 100% compliant and robust; responsive mobile aspect ratio guard is flagged as an empirical finding for the frontend worker to patch in M2.

## Artifact Index
- DISPATCH.md — Initial dispatch message from orchestrator
- BRIEFING.md — Persistent working memory
- progress.md — Liveness heartbeat and status tracking
- handoff.md — 5-component self-contained handoff report
- tools/verification/test_adversarial_m1_dimensions_stress.py — Reproducible Playwright stress test harness
- reports/stress_m1/ — Visual evidence screenshots (orbit_elev_20_deg.png, orbit_elev_85_deg.png, orbit_elev_-45_deg.png, post_50x_toggle_verified.png, mobile_375x667_crushed.png)