add file watcher

packages/opencode/src/file/watch.ts

@@ -0,0 +1,50 @@
+import { z } from "zod"
+import { Bus } from "../bus"
+import fs from "fs"
+import { App } from "../app/app"
+import { Log } from "../util/log"
+
+export namespace FileWatcher {
+  const log = Log.create({ service: "file.watcher" })
+
+  export const Event = {
+    Updated: Bus.event(
+      "file.watcher.updated",
+      z.object({
+        file: z.string(),
+        event: z.union([z.literal("rename"), z.literal("change")]),
+      }),
+    ),
+  }
+
+  export function init() {
+    App.state(
+      "file.watcher",
+      () => {
+        const app = App.use()
+        const watcher = fs.watch(
+          app.info.path.cwd,
+          { recursive: true },
+          (event, file) => {
+            log.info("change", { file, event })
+            if (!file) return
+            // for some reason async local storage is lost here
+            // https://github.com/oven-sh/bun/issues/20754
+            App.provideExisting(app, async () => {
+              Bus.publish(Event.Updated, {
+                file,
+                event,
+              })
+            })
+          },
+        )
+        return {
+          watcher,
+        }
+      },
+      async (state) => {
+        state.watcher.close()
+      },
+    )()
+  }
+}