Update AGENTS.md

AGENTS.md

@@ -236,3 +236,30 @@ Only commit when explicitly asked. When asked:
 - Stage only intended files.
 - Write a short, conventional commit message in present tense.
 - Never amend, force-push, or create PRs without a request.
+
+## Session Log — 2026-07-05
+
+### Completed
+- **DAG refactoring** (`scratchpad/dag.c`): Decoupled PrGraph from PrNodeManager.
+  Graph tracks its own active vertices (`vertex_count`, `max_vertex_ever`, `b8 active`).
+  `prGraphAddEdge`, `prGraphTopologicalSort` no longer take `PrNodeManager*`.
+  Kahn's algorithm integrated into `prGraphAddEdge` for cycle detection with rollback.
+  Output verified matching baseline.
+- **RHI research document** written to `documents/research/rendering-hardware-interface.md`.
+  Covers 8 reference RHIs, architecture patterns, core API surface, Vulkan-specific
+  considerations, Slang integration, and proposed directory layout / lifecycle design.
+- Added NVRHI to `documents/resources.md`.
+
+### Key Decisions
+- Graph API is self-contained — no graphics or node-manager dependencies.
+- RHI will use object-based + command-list-oriented architecture with vtbl dispatch.
+- Object lifecycle: `prRhiCreate*` / `prRhiDestroy*` with explicit `WpAllocator*`.
+- All GPU state explicit (no hidden pipeline state).
+- Per-frame command pools and descriptor pools, arena-allocated scratch.
+- `#version-macro` convention removed from Slang files; `__slang` define used instead.
+
+### Next Steps
+1. User reviews RHI research document, then iterate if needed.
+2. Begin implementing RHI layer: types header, device creation, Vulkan backend skeleton.
+3. Implement Slang shader compilation + reflection integration.
+4. Wire up per-frame lifecycle (command pool reset, descriptor pool reset, scratch reset).