Add watch flake smoke test scaffolding

Author: pasunboneleve

AGENTS.md

@@ -18,6 +18,9 @@ without hard-coding knowledge of any one repository.
   avoid baking it into the core.
 - Do not push unless explicitly asked. This repository may not even have a
   remote during early development.
+- Do not use `sleep` to resolve races. Races must be resolved with
+  deterministic logic, explicit readiness signals, or ordered state
+  transitions.
 - Run quality gates for code changes: `cargo fmt`, `cargo test`,
   `cargo clippy --all-targets --all-features -- -D warnings`.
 

CHANGELOG.md

@@ -4,6 +4,19 @@ All notable changes to `devloop` will be recorded in this file.
 
 ## [Unreleased]
 
+### Added
+- Added a configurable watcher backend with non-breaking `native`
+  default behavior plus a `poll` fallback mode for environments where
+  native filesystem notifications are unreliable.
+- Added a Rust repeated-edit watch flake smoke test that runs under
+  `cargo test` and therefore in GitHub Actions alongside the existing
+  runtime smoke test.
+
+### Changed
+- `devloop` now derives concrete watch targets from configured watch
+  patterns and asks the backend to watch only those files or
+  directories instead of always watching the whole repository root.
+
 ## [0.7.0] - 2026-03-27
 
 ### Added

Cargo.lock

@@ -21,3 +21,6 @@ toml = "0.8.22"
 tracing = "0.1.41"
 tracing-subscriber = { version = "0.3.19", features = ["env-filter", "fmt"] }
 unicode-width = "0.2"
+
+[dev-dependencies]
+tempfile = "3.20.0"

Cargo.toml

@@ -49,13 +49,17 @@ merged back into the live session.
 
 ## Watching and debounce
 
-`devloop` watches the configured `root` recursively.
+`devloop` derives concrete filesystem watch targets from the configured
+watch-group patterns and watches only those files or directories.
 
 - Only relevant file-system events are considered.
 - Events are batched for `debounce_ms`.
 - Matching changes are grouped by workflow name before execution.
 - Each workflow receives the set of changed relative paths that matched
   it during the debounce window.
+- The default backend uses native filesystem notifications. A polling
+  backend can be selected in config as a fallback for environments
+  where native events are unreliable.
 
 If multiple watch groups map to the same workflow, their matched paths
 are merged for that workflow run.

docs/behavior.md

@@ -26,6 +26,21 @@ startup_workflows = ["startup"]
 - `startup_workflows`: workflows to run after autostart processes have
   been started.
 
+Optional watcher backend config:
+
+```toml
+[watcher]
+kind = "native"
+poll_interval_ms = 250
+```
+
+- `watcher.kind`: watcher backend to use. `native` is the default and
+  uses the platform-recommended `notify` backend. `poll` uses
+  `notify`'s polling watcher as a fallback for environments where
+  native filesystem events are unreliable.
+- `watcher.poll_interval_ms`: polling interval used when
+  `watcher.kind = "poll"`. Default: `250`.
+
 Optional browser reload server config:
 
 ```toml
@@ -51,6 +66,10 @@ workflow = "rust"
 - `workflow`: workflow to run when a matching file changes. If omitted,
   the watch-group name is used as the workflow name.
 
+`devloop` derives concrete watch targets from these patterns and asks
+the backend to watch only those literal files or directories instead of
+always watching the whole repository root recursively.
+
 ## Processes
 
 Processes are long-running commands supervised by `devloop`.

docs/configuration.md

@@ -6,6 +6,9 @@ debounce_ms = 300
 state_file = "./.devloop/state.json"
 startup_workflows = ["startup"]
 
+[watcher]
+kind = "native"
+
 [watch.rust]
 paths = ["src/**/*.rs", "Cargo.toml", "content/layout.html", "content/banner.html", "content/site.toml"]
 workflow = "rust"

examples/blog/devloop.toml

@@ -135,6 +135,7 @@ mod tests {
         Config {
             root: ".".into(),
             debounce_ms: 100,
+            watcher: crate::config::WatcherConfig::default(),
             state_file: Some("./state.json".into()),
             startup_workflows: vec![],
             watch: BTreeMap::new(),