logging

apps/RenderCadenceCompositor/README.md

@@ -44,6 +44,7 @@ Included now:
 - render-thread-only GL commit once the artifact is ready
 - manifest-driven stateless single-pass shader packages
 - default float, vec2, color, boolean, enum, and trigger parameters
+- background logging with `log`, `warning`, and `error` levels
 - compact telemetry
 - non-GL frame-exchange tests
 
@@ -100,6 +101,10 @@ Use `--no-shader` to keep the simple motion fallback only.
 
 ## Expected Telemetry
 
+Startup, shutdown, shader-build, and render-thread event messages are written through the app logger. Telemetry is intentionally separate and remains a compact once-per-second cadence line.
+
+The logger writes to the console, `OutputDebugStringA`, and `logs/render-cadence-compositor.log` by default. Render-thread log calls use the non-blocking path so diagnostics do not become cadence blockers.
+
 The app prints one line per second:
 
 ```text