Bun.serve Default idleTimeout Cuts LLM Streaming Responses at 10 Seconds

What this error means

Bun.serve missing idleTimeout — slow LLM streams cut at 10s default, retry loop burns 300s run timeout is a Node.js failure pattern reported for developers trying to fix bun.serve cutting off llm streaming responses due to missing idletimeout configuration. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

appstrate/appstrate issue #426: Bun.serve uses 10s default idleTimeout. LLM streams pause during reasoning phase (>10s) → connection cut → retry loop → burns 300s run timeout. Fix: set explicit idleTimeout on Bun.serve.

Common causes

• Developers building AI agent sidecars with Bun.serve find that LLM streams get cut off during reasoning phases or parallel tool-call generation when there’s a >10s pause. The default 10s idleTimeout triggers a retry loop that burns through the run timeout.
• appstrate/appstrate issue #426: Bun.serve uses 10s default idleTimeout. LLM streams pause during reasoning phase (>10s) → connection cut → retry loop → burns 300s run timeout. Fix: set explicit idleTimeout on Bun.serve.

Quick fixes

1. Confirm the exact error signature matches Bun.serve missing idleTimeout — slow LLM streams cut at 10s default, retry loop burns 300s run timeout.
2. Check the Node.js account, local tool state, and provider configuration involved in the failing workflow.
3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

• Verify the command, editor, extension, or API client that produced the error.
• Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
• Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

1. Capture the exact error message and the command, editor action, or request that triggered it.
2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
3. Review the source evidence below and compare it with your environment.
4. Apply one change at a time and rerun the smallest failing action.
5. Keep the working fix documented for the team or deployment environment.

How to prevent it

• Keep provider/tool configuration documented.
• Record non-secret diagnostics such as tool version, provider name, model name, and command path.
• Add a lightweight check before CI or production workflows depend on the tool.

Sources checked

• https://github.com/appstrate/appstrate/issues/426

Evidence note: appstrate/appstrate issue #426: Bun.serve uses 10s default idleTimeout. LLM streams pause during reasoning phase (>10s) → connection cut → retry loop → burns 300s run timeout. Fix: set explicit idleTimeout on Bun.serve.

Related errors

• Bun.serve connection timeout LLM
• SSE stream timeout Node.js

FAQ

What should I check first?

Start with the exact Bun.serve missing idleTimeout — slow LLM streams cut at 10s default, retry loop burns 300s run timeout text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Node.js workflow until the root cause is understood.

Is this guaranteed to have one fix?

No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.

How do I know the fix worked?

Rerun the same command, editor action, or request. The fix is working when that action completes without Bun.serve missing idleTimeout — slow LLM streams cut at 10s default, retry loop burns 300s run timeout.