Claude Desktop Code mode crashes immediately (exit code 1) — works fine from CLI

Summary

Claude Desktop's Code mode (agent mode) crashes immediately with Claude Code process exited with code 1 when starting a session. Chat mode works fine. The same Claude Code binary works perfectly when invoked from the CLI in the same directory.

Environment

• macOS: Darwin 25.3.0 (Apple Silicon)
• Claude Desktop: v1.1.9310
• Embedded Claude Code: v2.1.85
• CLI Claude Code: v2.1.86

Reproduction

1. Open Claude Desktop in Code mode (sidebarMode: "code")
2. Navigate to a project folder (path contains Japanese characters and spaces)
3. Send any message
4. Session crashes instantly — no response

This occurs consistently across multiple restarts, sign-out/sign-in cycles, and full cache wipes.

Logs

From ~/Library/Logs/Claude/main.log (paths redacted):

[info] Starting local session local_XXXX in <project_dir>
[info] [CCD] Passing 9 plugin(s) to SDK (skills: 1, remote: 0, local: 8)
[info] Using Claude Code binary at: ~/Library/Application Support/Claude/claude-code/2.1.85/claude.app/Contents/MacOS/claude
[error] Session local_XXXX query error: Claude Code process exited with code 1
[info] [CCD CycleHealth] unhealthy cycle for local_XXXX (2s, hadFirstResponse=false, reason=no_response)

What I've tried (all failed)

• Sign out / sign in
• Full cache wipe (Session Storage/, Cache/, IndexedDB/, local-agent-mode-sessions/, bridge-state.json)
• Multiple app restarts
• New conversations
• Check for app updates (latest)
• Verified the binary runs fine from CLI: claude -p "test" → works
• Verified with Desktop-like flags (--output-format stream-json --input-format stream-json --verbose --permission-mode bypassPermissions) → works
• Verified with Desktop-like env vars (CLAUDE_CODE_ENTRYPOINT=claude-desktop, CLAUDE_CODE_PROVIDER_MANAGED_BY_HOST=1, etc.) → works

Key finding

• Chat mode: works normally
• Code mode: instant crash (exit code 1), no stderr visible
• CLI in same directory: works perfectly
• The Desktop does not expose stderr from the spawned Claude Code process, making it impossible to diagnose further from the user side
• The issue may be related to Japanese characters in the working directory path — the Desktop's shell wrapper (eval + zsh) may not handle certain CJK path names correctly

Additional issue found during investigation

bridge-state.json persisted a corrupted remote session causing infinite Epoch mismatch (409) loops. Manually resetting this file to {} resolved the chat mode issue, but Code mode remained broken.