[BUG] Cowork: "No conversation found with session ID" on every new task (Windows 11)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet for the Cowork desktop tab
• [x] This is a single bug report
• [x] I am using the latest version of Claude Desktop

What's Wrong?

Cowork (beta) on Claude Desktop consistently fails with "No conversation found with session ID: <uuid>" on Windows 11. The error appears almost immediately after the task starts, making the feature unusable.

The Retry button does not recover the session — it produces the same error with the same session ID. New tasks fail the same way.

This looks like the same family of regressions tracked in #36865 / #36842 / #57102, but I'm filing separately because:

• This is the Cowork tab in Claude Desktop, not VS Code teleport.
• It reproduces on every new task, not only on resume.

Steps to Reproduce

1. Open Claude Desktop on Windows 11 (Max plan).
2. Switch to the Cowork tab.
3. Create a New task (project context: a custom project, but reproduces without a project too).
4. Send any short prompt.
5. Task runs briefly, then errors out with:

No conversation found with session ID: c9c7bce1-cb67-4539-af63-287ef6a1ea12

Expected Behavior

The task should accept the message and continue execution against the assigned session.

Actual Behavior

• The Cowork session errors out with No conversation found with session ID: <uuid>.
• "Retry" reproduces the same error with the same session ID.
• Creating a new task produces the same error with a fresh session ID.
• The progress sidebar shows the task partially advanced (2 of 3 steps checked) before the failure.

Screenshot: _(drag your screenshot into the issue editor here before submitting)_

Environment

• OS: Windows 11
• App: Claude Desktop (latest, Cowork beta enabled)
• Plan: Max
• Locale: ko-KR
• Project context: enabled (custom project)
• MCP servers configured: 20+ stdio servers (desktop-commander, ssh-synology, naver-search, law-info-v2, nh-coop, saju, jamidusu, etc.) — none are invoked before the failure.
• Model selected: Claude Opus 4.7

What I've Tried

• Pressing Retry → same error, same session ID.
• Creating a new task (same project) → new session ID, same error.
• Creating a new task without project context → same error.
• Restarting Claude Desktop fully → no change.
• Local Chat / Code tabs in the same Desktop app → working normally.

Additional Context

• Anthropic Status posted a related infrastructure incident on 2026-05-06 → resolved 2026-05-07 12:45 UTC (GitHub outbound IP change affecting Claude Code remote sessions). Cowork-side errors persist into 2026-05-08 KST, so the symptom likely outlasted that incident or is a separate Cowork regression.
• Similar pattern reported in:
• #36865 (VS Code, Windows — every new cloud session fails immediately)
• #36842 (VS Code, Windows — teleport returns 0 log entries)
• #57102 (area:cowork, Windows, regression — opened 2026-05-07)

Happy to provide additional logs from %APPDATA%\Claude\logs if useful — let me know which files are relevant.