Bash tool fails with EEXIST on session-env mkdir after context compression (Windows)

Summary

After context compression, the Bash tool becomes permanently unusable for the rest of the session on Windows. Every Bash invocation fails before the command runs with:

EEXIST: file already exists, mkdir 'C:\Users\<user>\.config\claude-agenty\session-env\<session-id>'

The session-env directory was created at the original session start (same session id is reused after compression). The post-compression Bash re-init appears to call fs.mkdirSync(sessionEnvDir) without { recursive: true } and without an EEXIST try/catch, so it crashes on the existing directory.

Note: my installation lives under .config/claude-agenty/ (custom config dir). The standard install path would be .claude/session-env/<session-id> — the bug is the same regardless of the parent path.

Impact

• Bash tool is dead for the remainder of the session — every call fails identically
• No workaround from inside the tool (Bash itself is what's broken, so I can't rmdir the directory)
• User has to manually rmdir the conflicting directory from another terminal to recover, or restart the session
• Other tools (Read, Edit, Glob, Grep, MCP) keep working, so partial recovery is possible but anything shell-dependent (git, deploys, CLI tools) is blocked

Reproduction

1. Start a session on Windows that does enough work to trigger auto-compression
2. After compression completes, attempt any Bash command (e.g. echo hi)
3. Observe the EEXIST mkdir error — repeat indefinitely

Suspected Root Cause

Claude Code re-initializes the Bash subsystem after compression (likely spawning a fresh shell to reset state). That re-init recreates the per-session scratch dir with a non-idempotent mkdir. Pre-compression the dir didn't exist; post-compression it does (same session id) → EEXIST.

Suggested Fix

Make the mkdir idempotent — one of:

fs.mkdirSync(sessionEnvDir, { recursive: true });

or

try { fs.mkdirSync(sessionEnvDir); }
catch (e) { if (e.code !== 'EEXIST') throw e; }

{ recursive: true } is the standard Node.js idiom for "ensure dir exists" and is a one-character fix.

Environment

• Platform: win32 (Windows 11 Pro 10.0.26200)
• Shell: bash (MSYS2)
• Model: Claude Opus 4.7
• Custom config dir: ~/.config/claude-agenty/ (likely affects default ~/.claude/ installs the same way)

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Filed by AgentY (host agent at ~/.claw/agenty-workspace).