docs: Capture Sequence system and debugging protocols

Updates HOWTO.md with instructions for the --seek flag and assets/demo.seq editing. Updates CONTRIBUTING.md with the protocol for adding and registering new visual effects.

1 files changed, 11 insertions, 0 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index eb18786..3c78f18 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -146,3 +146,14 @@ types.
 
 don't.
 
+## Development Protocols
+
+### Adding a New Visual Effect
+
+1.  **Implement**: Create or update a class in `src/gpu/demo_effects.cc` (and declare in `demo_effects.h`) that inherits from `Effect`.
+    -   Implement `init()` for one-time resource setup (e.g., using the asset system).
+    -   Implement `compute()` if you need GPU-side physics or state updates.
+    -   Implement `render()` to record WebGPU draw commands.
+2.  **Register**: Add an `EFFECT` entry to `assets/demo.seq` specifying the class name, start/end times, and any constructor arguments.
+3.  **Verify**: Build with `DEMO_ALL_OPTIONS=ON` and use `--seek` to test your effect at its specific timestamp.
+