Opus 4.7 stream stall after Thinking step, UI surfaces misleading "missing file access" error

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

Stream stall during normal coding session, error surface shows misleading message.

What happened

Session started normally. Model successfully read ~9 project files (memory, voice guidelines, skill SKILL.md files, source files) via Read tool, ran 3 Glob queries correctly, entered Thinking phase, then stream stalled. No output produced after the Thinking step.

Error surfaced in UI: "Cannot proceed: missing local file access" + "Unhandled case: [object Object]".

Both messages are misleading: the model had just successfully read 9+ local files in the same session with no permission issues, and "[object Object]" is an unhandled JS exception, not an actual diagnostic.

Frequency

First occurrence in months of daily use of the same workflow. Reproduced multiple times in a 30-minute window on May 14, 2026 starting around 09:25 CEST (07:25 UTC).

Anthropic status page showed "All Systems Operational" with no incidents declared for May 14, but Opus 4.7 has had 4 declared incidents in the preceding 10 days (May 4, 7, 8, 12), so a sub-threshold degradation is plausible. Third-party monitors (IsDown, StatusGator, Pulsetic) report 144-196 user reports in the last 24h not reflected on the official status page.

What Should Happen?

Expected behavior:

1. Investigate backend stream stability for Claude Code sessions around the timestamps above (May 14, 2026, ~07:25 UTC onward), specifically for VS Code extension users on Windows.

1. Improve the error surface: "Cannot proceed: missing local file access" + "Unhandled case: [object Object]" sent me debugging file permissions for over an hour when the actual cause was a backend stream stall. A clearer message like "Stream timeout from model backend, retry or switch model" would have saved significant time.

1. Expose /bug, /feedback, /model in the VS Code extension UI or via command palette. Currently the VS Code extension lacks accessible channels for incident reporting from within the tool. They reply "isn't available in this environment". Documentation says "most CLI slash commands" are supported, but these three (which are fairly important) are missing.

Error Messages/Logs

Log signals (from VS Code output panel):

- Slow first byte: no stream chunk 30.0s after request sent (attempt 1)
- stream_idle_partial lastChunkAgeMs=15000 bytesTotal=707
- stream_idle_partial lastChunkAgeMs=30013 bytesTotal=779
- sdk_stream_ended_no_result had_error=true

Pattern: partial chunks received (707 bytes, then 779), then stream goes idle for 30+ seconds, then dies. Repeated across multiple retries in the same window.

UI surface error: "Cannot proceed: missing local file access" + "Unhandled case: [object Object]".

Steps to Reproduce

Not deterministically reproducible (backend-side issue), but the conditions when it occurred:

1. Start a Claude Code session in VS Code extension v2.1.141 on Windows with model claude-opus-4-7.
2. Use a real project with several files (memory, skills, source). Context usage ~50k tokens.
3. Let Claude read multiple files via Read tool and run a few Glob queries (worked fine).
4. Send a request that causes the model to enter Thinking phase.
5. Observe: stream produces partial output (~707-779 bytes), then goes idle for 30+ seconds, then dies with "sdk_stream_ended_no_result had_error=true".
6. UI surfaces "Cannot proceed: missing local file access" + "Unhandled case: [object Object]".

Workaround attempted:

• Switched to claude-sonnet-4-6 -> same stall behavior, so NOT specific to Opus 4.7.
• Restarted VS Code -> no effect.
• Verified internet connection (fiber, 940 Mbps down, ping 4ms) -> healthy.
• Checked for orphan node.exe processes -> none.
• Disabled 1M context window via CLAUDE_CODE_DISABLE_1M_CONTEXT=1 -> no effect on the stall.
• Tried /bug, /feedback, /model -> reported as "isn't available in this environment" in VS Code extension.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.141 (Claude Code VS Code extension)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

Environment

• Claude Code v2.1.141 (VS Code extension on Windows 10/11)
• Model: claude-opus-4-7 (1M context disabled via CLAUDE_CODE_DISABLE_1M_CONTEXT=1)
• Plan: Max
• Permission mode: auto, thinking level: default_on
• Project: local writing workflow, ~50k tokens context usage, 113k free space
• Connection: fiber 940 Mbps down, ping 4ms, verified before reporting

Note: Same stall behavior reproduced on claude-sonnet-4-6 too, so the backend issue is not specific to Opus 4.7.