feat(watcher): ungate file watcher + wire diff_version bump (#743)

packages/app/src/pages/session.tsx

@@ -1011,6 +1011,9 @@ export default function Page() {
     ),
   )
 
+  // Bump diff_version when the watcher reports external changes to files in the
+  // current session's worktree (#743). Debounced: 1s trailing-edge per session.
+  let watcherDebounce: ReturnType<typeof setTimeout> | undefined
   const stopVcs = sdk().event.listen((evt) => {
     const details = evt.details as { type: string; properties?: unknown }
     if (details.type !== "file.watcher.updated" && details.type !== "filesystem.changed") return
@@ -1020,8 +1023,18 @@ export default function Page() {
         : undefined
     const file = typeof props?.file === "string" ? props.file : undefined
     if (!file || file.startsWith(".git/")) return
+    const id = params.id
+    if (!id) return
+    if (watcherDebounce !== undefined) clearTimeout(watcherDebounce)
+    watcherDebounce = setTimeout(() => {
+      watcherDebounce = undefined
+      sync().set("diff_version", id, (v: number | undefined) => (v ?? 0) + 1)
+    }, 1000)
+  })
+  onCleanup(() => {
+    stopVcs()
+    if (watcherDebounce !== undefined) clearTimeout(watcherDebounce)
   })
-  onCleanup(stopVcs)
 
   createEffect(
     on(

packages/core/src/filesystem/watcher.ts

@@ -106,7 +106,7 @@ const layer = Layer.effect(
     const config = (yield* (yield* Config.Service).entries())
       .filter((entry): entry is Config.Document => entry.type === "document")
       .flatMap((item) => item.info.watcher?.ignore ?? [])
-    if (location.vcs && (yield* Flag.OPENCODE_EXPERIMENTAL_FILEWATCHER)) {
+    if (location.vcs) {
       yield* Effect.forkScoped(
         subscribe(location.directory, [...Ignore.PATTERNS, ...config, ...protecteds(location.directory)]),
       )

packages/core/src/flag/flag.ts

@@ -35,9 +35,6 @@ export const Flag = {
   OPENCODE_DISABLE_FFF: fff === undefined ? process.platform === "win32" : truthy("OPENCODE_DISABLE_FFF"),
 
   // Experimental
-  OPENCODE_EXPERIMENTAL_FILEWATCHER: Config.boolean("OPENCODE_EXPERIMENTAL_FILEWATCHER").pipe(
-    Config.withDefault(false),
-  ),
   OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: Config.boolean("OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER").pipe(
     Config.withDefault(false),
   ),

packages/core/test/filesystem/watcher.test.ts

@@ -30,11 +30,13 @@ const configLayer = Layer.succeed(
 
 const flagsLayer = ConfigProvider.layer(
   ConfigProvider.fromUnknown({
-    OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
     OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "false",
   }),
 )
 
+// Same flags — verifies the watcher runs without any explicit enable flag (#743).
+const defaultFlagsLayer = flagsLayer
+
 function provide(directory: string, vcs?: Location.Interface["vcs"]) {
   const locationLayer = Layer.succeed(
     Location.Service,
@@ -48,10 +50,24 @@ function provide(directory: string, vcs?: Location.Interface["vcs"]) {
   )
 }
 
+function provideDefault(directory: string, vcs?: Location.Interface["vcs"]) {
+  const locationLayer = Layer.succeed(
+    Location.Service,
+    Location.Service.of(location({ directory: AbsolutePath.make(directory) }, { vcs })),
+  )
+  return Effect.provide(
+    AppNodeBuilder.build(Watcher.node, [
+      [Config.node, configLayer],
+      [Location.node, locationLayer],
+    ]).pipe(Layer.provide(defaultFlagsLayer)),
+  )
+}
+
 function withTmp<A, E, R>(
   f: (directory: string, vcs?: Location.Interface["vcs"]) => Effect.Effect<A, E, R>,
-  options?: { git?: boolean; init?: (directory: string) => Promise<void> },
+  options?: { git?: boolean; init?: (directory: string) => Promise<void>; useDefaultFlags?: boolean },
 ) {
+  const providerFn = options?.useDefaultFlags ? provideDefault : provide
   return Effect.acquireRelease(
     Effect.promise(async () => {
       const tmp = await tmpdir()
@@ -66,7 +82,7 @@ function withTmp<A, E, R>(
       return { tmp, vcs: { type: "git" as const, store: AbsolutePath.make(path.join(tmp.path, ".git")) } }
     }),
     ({ tmp }) => Effect.promise(() => tmp[Symbol.asyncDispose]()),
-  ).pipe(Effect.flatMap(({ tmp, vcs }) => f(tmp.path, vcs).pipe(provide(tmp.path, vcs))))
+  ).pipe(Effect.flatMap(({ tmp, vcs }) => f(tmp.path, vcs).pipe(providerFn(tmp.path, vcs))))
 }
 
 function wait(check: (event: WatcherEvent) => boolean) {
@@ -263,4 +279,19 @@ describeWatcher("Watcher", () => {
       ),
     )
   })
+
+  it.live("runs by default for git repos without the enable flag (#743)", () =>
+    withTmp(
+      (directory) =>
+        Effect.gen(function* () {
+          const fs = yield* FSUtil.Service
+          const file = path.join(directory, "default-watch.txt")
+          yield* ready(directory)
+          expect(
+            yield* nextUpdate((event) => event.file === file && event.event === "add", fs.writeFileString(file, "a")),
+          ).toEqual({ file, event: "add" })
+        }),
+      { git: true, useDefaultFlags: true },
+    ),
+  )
 })

packages/desktop/src/main/server.ts

@@ -47,7 +47,6 @@ export function preferAppEnv(userDataPath: string) {
   Object.assign(process.env, {
     ...shellEnv,
     OPENCODE_EXPERIMENTAL_ICON_DISCOVERY: "true",
-    OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
     OPENCODE_CLIENT: "desktop",
     XDG_STATE_HOME: process.env.XDG_STATE_HOME ?? userDataPath,
   })