dx watch

dx watch [--apply] [--debug|--release] [flags] <build|test|run|lint|typecheck|format|check|fix> [scope ...] [-- bazel-options|--app-args ...]

Reruns one command when files change. Scope is re-resolved each iteration. Flags go to the wrapped command and are checked as dx <command> checks them: dx watch test --release, dx watch lint --report sarif=out.sarif. A flag the wrapped command rejects fails before watching starts. Short options work wherever the long option does. Bare lint, typecheck, format, and fix only check; pass --apply to write on every iteration. Args after -- reach the wrapped command unchanged.

• Wraps only build, test, run, lint, typecheck, format, check, and fix. Other commands fail with not watchable.
• Takes --output, --check, --apply, --fail-on, --report, --include-edits, --here, --affected, --debug, and --release, plus the global flags, when the wrapped command takes them.
• --here resolves once from the current directory. --affected re-resolves each iteration.
• Local only. Refuses CI=true. No daemon, cache, or remote execution.
• Ignores changes under .dx/, .git/, and bazel-* inside the workspace. Parent directories with those names do not matter. Also ignores the wrapped command's --report files and their temp files, matched by path relative to the workspace. Edits to dx.toml, dx.local.toml, BUILD and MODULE.bazel files rerun the command.

Except under run, changes made while the command runs queue one more iteration. Iterations never overlap. A failing command does not stop the watch. Each iteration takes a build slot and, on low disk, drops free slots' output bases first. Watch holds none while it waits for changes. See Build Slots and Disk Space.

watch run restarts the app on each change. The running app and every process it started get SIGTERM. Any still running after 10 seconds is killed. The replacement builds and launches only after the old app is gone. An app that exits on its own is relaunched on the next change. The app gets no stdin.

Output: --output text|diff|json, when the wrapped command takes that mode. Each iteration writes the wrapped command's own output. Watch adds one line per iteration and one line per trigger, naming the first changed absolute path. --quiet drops these lines. With --output json, --output diff, or --report <format>=-, they go to stderr so stdout holds only the wrapped command's output: under JSON, one event stream per iteration, each ending in command_finished. For a restarted app, command_finished reports 143.

scope= shows the given scopes, //... when none are given, or --affected.

watch:test:debounce=200ms scope=//... iteration=1
watching (Ctrl-C to stop)
changed /work/repo/src/main.rs (+1 more)
watch:test:debounce=200ms scope=//... iteration=2
stopped

Ctrl-C, SIGTERM or SIGHUP stops the watch. No new iteration starts after the signal. A running command gets the signal and is awaited first. Removing the workspace directory stops the watch with watch_failed.

Watch runs until stopped and has no success exit. Exit codes: 2 usage error, not watchable, or CI=true; 1 operational failures such as watch_failed; 141 when stdout closes; 129 after SIGHUP, 130 after Ctrl-C, 143 after SIGTERM.

bazel run @rules_dx//:dx -- watch build //...
bazel run @rules_dx//:dx -- watch test //cli/...
bazel run @rules_dx//:dx -- watch test --affected
bazel run @rules_dx//:dx -- watch lint --output json
bazel run @rules_dx//:dx -- watch run //app:bin