file-watcher

Original：🇺🇸 English

Translated

Configure file watching hooks to auto-react to config changes, env file updates, and dependency modifications. Use to set up reactive workflows.

14installs

Sourcerohitg00/pro-workflow

Added on2026-10-25

NPX Install

npx skill4agent add rohitg00/pro-workflow file-watcher

SKILL.md Content

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File Watcher

Use Claude Code's

FileChanged

and

CwdChanged

hooks to create reactive workflows that respond to file system changes.

Trigger

Use when:

Setting up auto-reload for config changes
Watching for dependency updates
Monitoring build output
Creating reactive development workflows

How File Watching Works

Claude Code's

SessionStart

and

CwdChanged

hooks support returning

watchPaths

to register file watchers. The current

cwd-changed.js

script focuses on env injection; to add watch registration, your hook script must output this JSON structure:

json

{
  "hookSpecificOutput": {
    "hookEventName": "SessionStart",
    "watchPaths": [
      "/absolute/path/to/.env",
      "/absolute/path/to/package.json"
    ]
  }
}

When watched files change, the

FileChanged

hook fires with:

json

{
  "hook_event_name": "FileChanged",
  "file_path": "/path/to/changed/file",
  "event": "change"
}

Environment Injection

CwdChanged

and

FileChanged

hooks can write to

CLAUDE_ENV_FILE

to inject environment variables into subsequent Bash commands:

bash

echo "export PROJECT_TYPE=node" >> "$CLAUDE_ENV_FILE"
echo "export TEST_CMD='npm test'" >> "$CLAUDE_ENV_FILE"

Common Watch Patterns

Watch .env for Changes

javascript

const envFile = path.join(projectRoot, '.env');
if (fs.existsSync(envFile)) {
  output.hookSpecificOutput = {
    hookEventName: 'SessionStart',
    watchPaths: [envFile]
  };
}

Watch package.json for Dependency Changes

Detect when dependencies change and remind to run

npm install

.

Watch tsconfig.json for Config Changes

Remind to restart TypeScript checks when config changes.

Setup

Add to hooks.json:

json

{
  "FileChanged": [{
    "matcher": ".env|package.json|tsconfig.json",
    "hooks": [{
      "type": "command",
      "command": "node scripts/file-changed.js"
    }]
  }]
}

Rules

Use absolute paths for watchPaths (required by Claude Code)
Matcher uses pipe-separated filenames
Watcher uses 500ms stability threshold and 200ms poll interval
Keep file-changed handlers fast (<5s) to avoid blocking
Use
```
CLAUDE_ENV_FILE
```
for injecting env vars, not direct export

file-watcher

NPX Install

Tags

SKILL.md Content

File Watcher

Trigger

How File Watching Works

Environment Injection

Common Watch Patterns

Watch .env for Changes

Watch package.json for Dependency Changes

Watch tsconfig.json for Config Changes

Setup

Rules