8. Add playground prediction controls and output

[anish-sahoo]

• sync, streaming, and async prediction controls with bounded output tracing
• includes toolbar, webhook, output, hook, and trace unit tests
• cog-playground stack: 1. Add Go playground server and handlers #3109, 2. Add playground frontend scaffold and early CI #3108, 3. Add core playground types and utilities #3114, 4. Add shared playground UI and JSON editor #3110/5. Add Cog playground API client #3106, 6. Add playground connection feature #3105/7. Add playground input controls and validation #3111/8. Add playground prediction controls and output #3107, 9. Wire up Cog playground and documentation #3113, 10. Compose playground app and add browser e2e #3112

[ask-bonk]

I reviewed all 22 files in PR #3107 by reading the core implementation (hooks, utils, components) and tests. I identified one issue where the async prediction flow's eventSourceReady promise rejection is unhandled if the EventSource fails before the onerror handler is attached, which could cause an unhandled promise rejection.

github run

[anish-sahoo]

Reviewed the reported EventSource race. eventSourceReady installs onerror synchronously in its Promise executor; connection failures are awaited in run()'s try/catch, and the post-open handler is attached before a later browser task can deliver an error. No unhandled rejection path was found, so no code change is needed. Existing coverage includes post-connect failure and connection timeout.

This is a top-level comment, so GitHub provides no review thread to resolve.

[ask-bonk]

LGTM

github run