rewatch

Cross-platform file watcher that restarts commands on changes. Designed for development workflows with AI coding agents (Claude Code, Cursor, Copilot, etc.) and manual editing alike.

Event-driven (no polling), kills entire process tree, waits for your confirmation before restarting. Supports a trigger file for fully automated restart loops with AI agents.

Install

cargo install rewatch

Usage

With CLI arguments

rewatch -w src,Cargo.toml -e rs,toml -- cargo run

With config file

Create rewatch.toml in your project root:

command = "cargo run"
watch = ["src", "Cargo.toml"]
ext = ["rs", "toml"]

[env]
RUST_LOG = "debug"

Then just run:

rewatch

CLI arguments override config file values.

How it works

1. Starts your command
2. Watches specified files/directories for changes
3. On change — kills the process (entire tree) and shows what changed with diff-style indicators (+ created, ~ modified, - removed)
4. Waits for Enter before restarting (so you can finish your edits)
5. On process crash — shows exit code, waits for Enter

Using with AI coding agents

rewatch is designed to work seamlessly with AI coding agents like Claude Code, Cursor, GitHub Copilot, and others. The trigger file feature enables a fully automated edit-build-test loop:

1. Run rewatch with a trigger file configured
2. The AI agent edits your code — rewatch detects changes and kills the running process
3. When the agent is done, it creates/touches the trigger file — rewatch restarts immediately without waiting for Enter
4. The agent sees build output (errors or success) and iterates

Setup with Claude Code

Add to your rewatch.toml:

command = "cargo run"
watch = ["src"]
ext = ["rs", "toml"]
trigger = ".rewatch-trigger"

Add to your CLAUDE.md:

After making code changes that require a rebuild, run: touch .rewatch-trigger

Add to .gitignore:

.rewatch-trigger

Now run rewatch in one terminal and Claude Code in another — they work together automatically.

CLI options

Config file

rewatch.toml fields:

command = "cargo run --release"     # command to execute (shell-style quoting supported)
watch = ["src", "Cargo.toml"]       # files/directories to watch
ext = ["rs", "toml"]                # filter by extension (optional)
trigger = ".rewatch-trigger"        # trigger file (optional)

[env]                               # environment variables for the child process
RUST_LOG = "debug"
SQLX_MIGRATE_IGNORE_MISSING = "true"

Trigger file

The trigger file enables automated restarts without pressing Enter. When rewatch detects that the trigger file was created or modified, it restarts the command immediately.

This is the key feature for AI agent workflows — the agent edits code (rewatch kills the process), then touches the trigger file when ready (rewatch restarts without human intervention).

trigger = ".rewatch-trigger"

Platform support

• Windows: kills process tree via Win32 Job Objects
• Linux: kills process group via kill(-pgid, SIGTERM)
• macOS: same as Linux

Powered by notify (OS-native file system events) and process-wrap (from the watchexec project).

License

MIT