Claude Code Opus 4.7 stream stalls at ~660 bytes in every session

What this error means

stream_idle_partial lastChunkAgeMs=15001 bytesTotal=661 / sdk_stream_ended_no_result had_error=true is a Claude Code failure pattern reported for developers trying to fix claude code opus 4.7 streaming stall that crashes every session. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Multiple users report Opus 4.7 (1M context) stream stalls at 660-730 bytes in every session via VS Code extension. Stream emits one chunk then goes idle, fires stream_idle_partial every 15s, ends with had_error=true. Reproduces 100% across fresh sessions.

Common causes

• Premium Opus 4.7 model (1M context) is completely unusable — stream stalls after ~660 bytes then times out. Affects every session with no workaround, blocking developers paying for the highest tier.
• Multiple users report Opus 4.7 (1M context) stream stalls at 660-730 bytes in every session via VS Code extension. Stream emits one chunk then goes idle, fires stream_idle_partial every 15s, ends with had_error=true. Reproduces 100% across fresh sessions.

Quick fixes

1. Confirm the exact error signature matches stream_idle_partial lastChunkAgeMs=15001 bytesTotal=661 / sdk_stream_ended_no_result had_error=true.
2. Check the Claude Code 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/anthropics/claude-code/issues/59092

Evidence note: Multiple users report Opus 4.7 (1M context) stream stalls at 660-730 bytes in every session via VS Code extension. Stream emits one chunk then goes idle, fires stream_idle_partial every 15s, ends with had_error=true. Reproduces 100% across fresh sessions.

Related errors

• Claude Code stream timeout on long responses
• Claude Code VS Code extension connection reset

FAQ

What should I check first?

Start with the exact stream_idle_partial lastChunkAgeMs=15001 bytesTotal=661 / sdk_stream_ended_no_result had_error=true text and the smallest action that reproduces it.

Can I ignore this error?

No. Treat it as a failed Claude Code 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 stream_idle_partial lastChunkAgeMs=15001 bytesTotal=661 / sdk_stream_ended_no_result had_error=true.