Tier 2 — Interface Surfaces

• **stage-briefs/SB-*.md** - Thirteen stage briefs defining specifications for each module (SB-001 to SB-013)
• workspace/SPECTRE/ - SPECTRE hardware interface specifications and probe plans
• workspace/SHACHI-patterns/ - SHACHI asset pipeline pattern implementations
• workspace/shachi/ - SHACHI library implementation (assets, material, profiler, sh4math, vmu) shared with core
• src/include/d3tui/ - Public API headers exposed to consumers
• docs/API.md - Detailed API reference for developers
• docs/BUILD.md - Build instructions for setting up the development environment