Struct WatchConfig 

pub struct WatchConfig {
    pub paths: Vec<PathBuf>,
    pub explicit_files: Vec<PathBuf>,
    pub ignore: Vec<PathBuf>,
    pub debounce: Duration,
    pub retry_unchanged_when: Option<Arc<dyn Fn() -> bool + Send + Sync>>,
}

Configuration for spawn_watcher.

Fields

paths: Vec<PathBuf>

Roots to watch recursively. Non-existent entries are silently skipped.

explicit_files: Vec<PathBuf>

Exact files to watch through their parent directories.

These files bypass ignore filtering, which lets a manifest under an ignored output directory act as an explicit synchronization point without forwarding unrelated bundle writes. Missing parents are watched non-recursively. Directory changes are forwarded as dependent file paths so hosts can refresh their watches.

ignore: Vec<PathBuf>

Subtrees to ignore. An event is suppressed when its path lives underneath any entry here. Typical values: the build’s out_dir, node_modules, .git, target.

Each entry is canonicalized at registration time so symlink and path-form differences (./dist vs dist) compare correctly.

debounce: Duration

Debounce window — events arriving within this window are coalesced into a single callback invocation.

retry_unchanged_when: Option<Arc<dyn Fn() -> bool + Send + Sync>>

Optional predicate that allows byte-identical file events through.

webui serve --watch uses this while a rebuild error is active so a no-op save can retry transient failures. When the predicate returns false (the common clean state), identical saves are still dropped.