automation-triggers

Automation Triggers

Automation triggers create feedback loops that run formatting, linting, testing, or CI actions in response to file changes. They reduce manual intervention and catch issues immediately.

When to Use

• User wants files auto-formatted after every edit
• User asks about auto-linting or auto-testing on save
• User needs continuous feedback during development
• User wants to trigger CI checks or deploy previews automatically
• User mentions "run X every time I change Y"

Core Patterns

Auto-Format on Edit

Use a PostToolUse hook to format files immediately after modification:

{
  "hooks": {
    "PostToolUse": [
      {
        "matcher": "Edit|Write",
        "command": "if echo \"$CLAUDE_FILE_PATH\" | grep -qE '\\.(js|ts|jsx|tsx|css|json)$'; then npx prettier --write \"$CLAUDE_FILE_PATH\" 2>/dev/null; fi",
        "description": "Auto-format JS/TS/CSS/JSON files with Prettier"
      }
    ]
  }
}

For Python projects, use Black or Ruff:

{
  "matcher": "Edit|Write",
  "command": "if echo \"$CLAUDE_FILE_PATH\" | grep -qE '\\.py$'; then ruff format \"$CLAUDE_FILE_PATH\" 2>/dev/null && ruff check --fix \"$CLAUDE_FILE_PATH\" 2>/dev/null; fi",
  "description": "Auto-format and fix Python files with Ruff"
}

For Go projects:

{
  "matcher": "Edit|Write",
  "command": "if echo \"$CLAUDE_FILE_PATH\" | grep -qE '\\.go$'; then gofmt -w \"$CLAUDE_FILE_PATH\" && goimports -w \"$CLAUDE_FILE_PATH\" 2>/dev/null; fi",
  "description": "Auto-format Go files with gofmt and goimports"
}

Auto-Lint After Edit

Run linters as PostToolUse hooks to surface issues immediately:

{
  "matcher": "Edit|Write",
  "command": "if echo \"$CLAUDE_FILE_PATH\" | grep -qE '\\.(ts|tsx)$'; then npx eslint --no-warn-ignored \"$CLAUDE_FILE_PATH\" 2>&1 | head -30; fi",
  "description": "Auto-lint TypeScript files with ESLint"
}

Auto Type-Check

For TypeScript, run incremental type-checking after edits:

{
  "matcher": "Edit|Write",
  "command": "if echo \"$CLAUDE_FILE_PATH\" | grep -qE '\\.tsx?$'; then npx tsc --noEmit --pretty 2>&1 | tail -20; fi",
  "description": "Type-check TypeScript after edit"
}