## Summary
- Multiple components calling `useRunApp()` each registered their own
event listener for `onAppOutput`, causing duplicate log entries in the
console
- Extracted the event subscription into a new
`useAppOutputSubscription()` hook
- The new hook is called only once in `layout.tsx` at the root level,
eliminating duplicates

## Test plan
- Run an app and observe the System Messages console
- Verify that server log messages (stdout/stderr) appear only once
instead of multiple times
- Verify HMR updates still trigger iframe refreshes correctly

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Fix duplicate server log messages by subscribing to app output events
only once at the app root. Prevents repeated stdout/stderr entries while
keeping HMR iframe refreshes working.

- **Bug Fixes**
- Extracted event subscription from useRunApp into a new
useAppOutputSubscription hook.
- Call useAppOutputSubscription once in layout.tsx to avoid duplicate
listeners.
  - Preserved proxy URL processing and hot module reload behavior.

<sup>Written for commit 0f4df3f539c818e2100228e23602f31fe1d07742.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Eliminates duplicate server logs by centralizing app output
subscription.
> 
> - Extracts event listener logic from `useRunApp` into new
`useAppOutputSubscription()` and subscribes once in `src/app/layout.tsx`
> - Preserves HMR handling (refresh via preview panel key) and proxy URL
parsing in `processProxyServerOutput`
> - Refactors internals with `useCallback` dependencies to avoid
duplicate processing while keeping existing `useRunApp` API intact
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
0f4df3f539c818e2100228e23602f31fe1d07742. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>