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file-watcher

Configure Claude Code hooks to watch files and react to config and dependency changes.

1|Updated May 6, 2026
Search Tags:#automation#claude code#hooks#configuration#file watching#reactive workflow#env injection
One-click install
npx skills add https://github.com/surfingalien/FinSurfing --skill file-watcher-surfingalien
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: file-watcher
Source: https://github.com/surfingalien/FinSurfing/tree/main/.claude/skills/file-watcher
Command: npx skills add https://github.com/surfingalien/FinSurfing --skill file-watcher-surfingalien

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Developers often miss config, env, or dependency changes during a session, leading to stale environments and confusing errors. This Skill sets up reactive workflows that automatically detect file changes and respond to them. ## Core Features & Use Cases - Watch Registration: Register watchPaths via SessionStart and CwdChanged hooks so Claude Code monitors files like .env, package.json, and tsconfig.json. - FileChanged Reactions: Trigger handler scripts when watched files change, such as reminding to run npm install after dependency updates. - Environment Injection: Write variables to CLAUDE_ENV_FILE from CwdChanged or FileChanged hooks to inject env vars into subsequent Bash commands. - Use Case: Watch package.json so that whenever a teammate's pull changes dependencies, the session immediately reminds you to run npm install before continuing. ## Quick Start Set up a file watcher that monitors my .env and package.json files and reminds me to reinstall dependencies when package.json changes.

Frequently Asked Questions about file-watcher

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I watch files for changes in Claude Code?▼

Register watchPaths in the hookSpecificOutput of a SessionStart or CwdChanged hook using absolute file paths. When a watched file changes, Claude Code fires the FileChanged hook with the file path and event type.

How to auto-run npm install when package.json changes?▼

Add package.json to your hook's watchPaths, then configure a FileChanged hook with a matcher like ".env|package.json|tsconfig.json" that runs a handler script. The handler can remind you to run npm install or inject environment variables.

Can Claude Code hooks inject environment variables into Bash commands?▼

Yes, CwdChanged and FileChanged hooks can append export statements to the CLAUDE_ENV_FILE, and those variables become available in subsequent Bash commands. Use this instead of direct exports, which do not persist across commands.

Why is my FileChanged hook not firing?▼

Watch paths must be absolute paths, and the file must be registered via watchPaths in a SessionStart or CwdChanged hook output. Also verify your matcher pattern uses pipe-separated filenames matching the changed file.

What are the performance limits of file watching hooks?▼

The watcher uses a 500ms stability threshold and 200ms poll interval. Keep FileChanged handler scripts under 5 seconds to avoid blocking the session workflow.

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