Summary

Fixes a critical file descriptor leak that occurs when skills contain Python virtual environments. The gateway was accumulating 36,000+ file descriptors and eventually failing with `spawn EBADF` errors.

Fixes #8721 (comment)
Fixes #2532
Fixes #9481

Root Cause

The chokidar file watcher in `src/agents/skills/refresh.ts` monitors all skills directories for changes, but was not ignoring Python virtual environment directories (`venv/`, `.venv/`, `pycache/`, `site-packages/`). Chokidar keeps file descriptors open for all monitored files, causing massive FD accumulation when skills contain Python packages.

Changes

1. Chokidar watcher fix (critical)

• Add Python venv directories to `DEFAULT_SKILLS_WATCH_IGNORED` in `src/agents/skills/refresh.ts`
• Prevents the file watcher from monitoring tens of thousands of Python package files
• This fix resolves the FD leak and spawn errors

Pattern Details

The fix adds these regex patterns to ignore:

• `/(^|[\/])venv([\/]|$)/` - Standard virtual environment directory
• `/(^|[\/]).venv([\/]|$)/` - Hidden virtual environment directory
• `/(^|[\/])pycache([\/]|$)/` - Python compiled bytecode cache
• `/(^|[\/])site-packages([\/]|$)/` - Installed Python packages

Testing

Before fix:

• Gateway FD count: 36,644
• Skills files held open: 141
• Result: `spawn EBADF` errors on command execution

After fix:

• Gateway FD count: 52
• Skills files held open: 0
• Result: No spawn errors, normal operation

Validation Results

• ✅ pnpm lint: Passed (0 warnings, 0 errors)
• ✅ pnpm tsgo: Passed (TypeScript type checking)
• ✅ Code follows existing patterns and style guidelines

Submission Checklist

• Clear problem statement (FD leak causing EBADF errors)
• Focused scope (single file change, 4 lines added)
• Documented behavior changes (before/after FD counts shown)
• Test results provided (FD count reduction verified)
• Manual testing steps included (can be verified by observing FD counts)
• Supporting evidence (related GitHub issues with detailed symptoms)
• Research completed (root cause identified in chokidar configuration)
• Validation commands passed (lint, TypeScript checks)

Implementation Notes

The fix is minimal and non-breaking:

• Only modifies the ignore patterns for the file watcher
• Doesn't change any logic or behavior except reducing monitored files
• Follows existing pattern convention in the codebase
• Compatible with all platforms (regex patterns use cross-platform separators)

🤖 Generated with Claude Code
Model usage: Haiku 4.5 (analysis and validation)
Effort level: Low (straightforward, focused fix)