Cursor functionality fix

[aaronvg]

Pull Request Template

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Issue Reference

Please link to any related issues

• This PR fixes/closes [bug] Go: CallFunction... BAML runtime methods leak goroutines #2883

Changes

Please describe the changes proposed in this pull request

This PR addresses a goroutine leak in the Go BAML client when context.Background() is used for function calls. Previously, a goroutine was spawned to monitor ctx.Done() for cancellation. If context.Background() was passed, this context would never complete, causing the monitoring goroutine to leak indefinitely even after the function call finished.

The fix introduces a done channel for CallFunction, CallFunctionStream, and CallFunctionParse. This channel is closed when the function or stream completes normally. The monitoring goroutine now uses a select statement to listen on both ctx.Done() and the new done channel, ensuring it exits cleanly upon either cancellation or normal function completion.

Testing

Please describe how you tested these changes

• Unit tests added/updated
• Manual testing performed (verified that the goroutines exit as expected)
• Tested in [local development environment]
• Verified Go code compiles (go build ./...)
• Ran existing Go tests (go test ./...)

Screenshots

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PR Checklist

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• I have read and followed the contributing guidelines
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Additional Notes

Add any other context about the PR here

The core problem was that context.Background() never signals Done(), leading to leaked goroutines. The done channel provides an alternative signal for normal completion, ensuring proper resource cleanup.

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Slack Thread

 

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Note

Fix goroutine leak in Go runtime

• Add done channels to CallFunction, CallFunctionStream, and CallFunctionParse so the context-monitor goroutines exit on normal completion or ctx.Done()
• In CallFunctionStream, close done on error/result and wrap the callback channel to ensure done is closed when the stream ends

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
promptfiddle	Skipped		Jan 3, 2026 7:08am

[cursor]

Wrapper goroutine can leak on context cancellation

The wrapper goroutine in CallFunctionStream is not context-aware. When context is cancelled, if the consumer stops reading from wrappedCallback (a common pattern), the goroutine blocks forever on wrappedCallback <- res. The PR fixes one goroutine leak but introduces a new one. The send to wrappedCallback needs to use a select that also checks ctx.Done() to allow the goroutine to exit when context is cancelled.