[BUG] Cowork Settings > Instructions field silently reverts to stale content (server-side, ~15 min latency)

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?

The Cowork desktop app's Settings → Cowork → "Instructions" field silently reverts to a stale cached version approximately 15 minutes after every manual save. This has been happening consistently for over five weeks (mid-March to 19 April 2026).

This is the field described as "Instructions here apply to all Cowork sessions." It feeds into .claude/CLAUDE.md in each session VM.

Steps to Reproduce:

1. Open Claude desktop app → Settings → Cowork
2. Delete everything in the Instructions field
3. Paste a simple test string: TEST RULE 001
4. Save — dialog closes cleanly
5. Reopen Settings → Cowork — confirm TEST RULE 001 is there
6. Wait 20+ minutes, do nothing
7. Reopen Settings → Cowork

Actual: An older, stale version of instructions has replaced it.

Key Evidence:

• Settings → General → "Personal preferences" persists correctly. Only the Cowork "Instructions" field reverts.
• The two fields are confirmed independent — they show different content simultaneously and appear in different locations in the session system prompt (<user_preferences> vs .claude/CLAUDE.md).
• The stale content does not exist anywhere on the local machine. Byte-level searches of %APPDATA%\Claude, %LOCALAPPDATA%\Claude, and ~/.claude/ returned empty. The revert source is server-side.
• No other devices are writing to this field — ruled out web UI, phone app, local files, and Windows scheduled tasks.
• The stale version it reverts TO is always the same ~16K char snapshot. My current version is ~10K chars.
• I have a scheduled 3-hourly drift monitor with timestamped SHA256 evidence of every reversion.

Environment:

• Claude desktop app v1.3109.0 (Electron/41.2.0)
• Claude Code CLI v2.1.104
• Windows 10 build 26200, MSIX install
• Account: felixjbpope@gmail.com
• Previously reported via email to support@anthropic.com on 16 April 2026

What Should Happen?

When I save content in Settings → Cowork → Instructions, it should persist permanently until I manually change it again. No background process should silently overwrite manual edits.

Error Messages/Logs

No error messages — the save appears to succeed silently. The revert happens server-side with no client-side indication. The only way to detect it is by reopening Settings or starting a new session and observing the stale content.

Steps to Reproduce

1. Open Claude desktop app → Settings → Cowork
2. Delete everything in the Instructions text field
3. Paste a simple test string: TEST RULE 001
4. Save — dialog closes cleanly
5. Reopen Settings → Cowork — confirm TEST RULE 001 is there
6. Wait 20+ minutes, do nothing
7. Reopen Settings → Cowork
8. Observe: the old stale content (~16K chars) has replaced your test string

Note: Settings → General → "Personal preferences" is NOT affected — only the Cowork-specific Instructions field reverts. This has reproduced every time for over 5 weeks.

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.104 (Claude Code CLI) / 1.3109.0 (Claude Desktop App, Electron/41.2.0)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

This bug affects the Cowork desktop app (Electron-based), not the Claude Code CLI directly. Filed here because Cowork desktop issues are tracked in this repo.

Previously reported to support@anthropic.com on 16 April 2026 with full evidence including SHA256-timestamped drift logs from a 3-hourly automated monitor. Support directed me to /bug which correctly identified this as a server-side issue outside CLI scope.

The bug has persisted for over 5 weeks (mid-March to 19 April 2026). This is the primary configuration surface for Claude's behaviour across all Cowork sessions — when it silently reverts, sessions receive outdated instructions with no warning.