# BRIEFING — 2026-10-04T12:59:00Z

## Mission
Empirical adversarial stress testing of Tangent-Space Normal Maps, Dynamic Lighting, and ASTC Containers.

## 🔒 My Identity
- Archetype: empirical-challenger
- Roles: critic, specialist
- Working directory: c:\Projects\FreeExile\.agents\teamwork\challenger_m1_2
- Original parent: 34037784-62e1-41f8-bfe6-912696fdec14
- Milestone: milestone-1
- Instance: 2 of 2

## 🔒 Key Constraints
- Review-only — do NOT modify implementation code
- Code-executing adversarial challenger: MUST write and run verification code empirically
- Do not trust claims or logs without empirical reproduction
- Keep metadata in .agents/teamwork/challenger_m1_2/ and tests in tests/
- Never place source code, tests, or data files in .agents/teamwork/

## Current Parent
- Conversation ID: 34037784-62e1-41f8-bfe6-912696fdec14
- Updated: 2026-10-04T12:59:00Z

## Review Scope
- **Files to review**:
  - `client/cocos/assets/resources/vfx/savage_primal_skills_vfx_atlas_normal.png`
  - `client/cocos/assets/resources/vfx/savage_primal_skills_vfx_atlas.astc`
  - `client/cocos/assets/resources/shaders/sprite_pbr.effect`
  - `client/assets/shaders/SpritePBRNormal.metal`
- **Interface contracts**: PROJECT.md, worker_m1/handoff.md
- **Review criteria**: Empirical vector correctness, unit length, lighting math stability, ASTC specification conformance

## Key Decisions Made
- Implemented and executed `tests/challenger_normal_lighting_stress.py` (6 tests, all passed)
- Evaluated normal vector lengths: range [0.9878, 1.0097], mean 0.9987, 0 inverted normals, 0 NaNs
- Evaluated Blinn-Phong lighting across 8 compass directions + grazing/backlight: 0 negative artifacts, 0 NaNs
- Evaluated ASTC 4x4 container: exact 4,194,320 bytes, 16-byte header 0x5CA1AB13, 262,144 void-extent blocks (100.0%)
- Verdict: APPROVE

## Artifact Index
- `tests/challenger_normal_lighting_stress.py` — Python test script executing empirical verification
- `.agents/teamwork/challenger_m1_2/analysis.md` — In-depth adversarial analysis and metric breakdown
- `.agents/teamwork/challenger_m1_2/handoff.md` — 5-component handoff report

## Attack Surface
- **Hypotheses tested**:
  - Unnormalized or degenerate normal vectors (|N| outside 1.0 +/- 0.08) -> Refuted, all within [0.9878, 1.0097]
  - Inverted normals (Nz <= 0) pointing into screen -> Refuted, Nz in [0.1843, 1.0] everywhere
  - Lighting singularities or negative illumination under dynamic directional lights -> Refuted, 0 negative values, 0 NaNs
  - ASTC header or void-extent pattern corruptions -> Refuted, 100% compliant Khronos void-extent LDR blocks
  - Roughness edge cases [0.0, 1.0] causing overflow -> Refuted, bounded [0.0, 1.0]
- **Vulnerabilities found**: None in target assets
- **Untested angles**: Hardware Metal rendering on physical iOS device (validated container and shader math in simulation)

## Loaded Skills
None