merge: resolve vcs.ts conflict, keep effectified version

Convert Vcs from Instance.state namespace to an Effect ServiceMap.Service
on the Instances LayerMap. Uses Instance.bind for the Bus.subscribe
callback (same ALS pattern as FileWatcherService). Branch state is
managed in the layer closure with scope-based cleanup.

packages/opencode/AGENTS.md

@@ -34,6 +34,7 @@ Instructions to follow when writing Effect.
 - Use `Effect.gen(function* () { ... })` for composition.
 - Use `Effect.fn("ServiceName.method")` for named/traced effects and `Effect.fnUntraced` for internal helpers.
 - `Effect.fn` / `Effect.fnUntraced` accept pipeable operators as extra arguments, so avoid unnecessary `flow` or outer `.pipe()` wrappers.
+- **`Effect.callback`** (not `Effect.async`) for callback-based APIs. The classic `Effect.async` was renamed to `Effect.callback` in effect-smol/v4.
 
 ## Time
 
@@ -42,3 +43,37 @@ Instructions to follow when writing Effect.
 ## Errors
 
 - In `Effect.gen/fn`, prefer `yield* new MyError(...)` over `yield* Effect.fail(new MyError(...))` for direct early-failure branches.
+
+## Instance-scoped Effect services
+
+Services that need per-directory lifecycle (created/destroyed per instance) go through the `Instances` LayerMap:
+
+1. Define a `ServiceMap.Service` with a `static readonly layer` (see `FileWatcherService`, `QuestionService`, `PermissionService`, `ProviderAuthService`).
+2. Add it to `InstanceServices` union and `Layer.mergeAll(...)` in `src/effect/instances.ts`.
+3. Use `InstanceContext` inside the layer to read `directory` and `project` instead of `Instance.*` globals.
+4. Call from legacy code via `runPromiseInstance(MyService.use((s) => s.method()))`.
+
+### Instance.bind — ALS context for native callbacks
+
+`Instance.bind(fn)` captures the current Instance AsyncLocalStorage context and returns a wrapper that restores it synchronously when called.
+
+**Use it** when passing callbacks to native C/C++ addons (`@parcel/watcher`, `node-pty`, native `fs.watch`, etc.) that need to call `Bus.publish`, `Instance.state()`, or anything that reads `Instance.directory`.
+
+**Don't need it** for `setTimeout`, `Promise.then`, `EventEmitter.on`, or Effect fibers — Node.js ALS propagates through those automatically.
+
+```typescript
+// Native addon callback — needs Instance.bind
+const cb = Instance.bind((err, evts) => {
+  Bus.publish(MyEvent, { ... })
+})
+nativeAddon.subscribe(dir, cb)
+```
+
+## Flag → Effect.Config migration
+
+Flags in `src/flag/flag.ts` are being migrated from static `truthy(...)` reads to `Config.boolean(...).pipe(Config.withDefault(false))` as their consumers get effectified.
+
+- Effectful flags return `Config<boolean>` and are read with `yield*` inside `Effect.gen`.
+- The default `ConfigProvider` reads from `process.env`, so env vars keep working.
+- Tests can override via `ConfigProvider.layer(ConfigProvider.fromUnknown({ ... }))`.
+- Keep all flags in `flag.ts` as the single registry — just change the implementation from `truthy()` to `Config.boolean()` when the consumer moves to Effect.

packages/opencode/src/effect/instance-context.ts

@@ -0,0 +1,13 @@
+import { ServiceMap } from "effect"
+import type { Project } from "@/project/project"
+
+export declare namespace InstanceContext {
+  export interface Shape {
+    readonly directory: string
+    readonly project: Project.Info
+  }
+}
+
+export class InstanceContext extends ServiceMap.Service<InstanceContext, InstanceContext.Shape>()(
+  "opencode/InstanceContext",
+) {}

packages/opencode/src/effect/instances.ts

@@ -1,23 +1,21 @@
 import { Effect, Layer, LayerMap, ServiceMap } from "effect"
 import { registerDisposer } from "./instance-registry"
+import { InstanceContext } from "./instance-context"
 import { ProviderAuthService } from "@/provider/auth-service"
 import { QuestionService } from "@/question/service"
 import { PermissionService } from "@/permission/service"
+import { FileWatcherService } from "@/file/watcher"
+import { VcsService } from "@/project/vcs"
 import { Instance } from "@/project/instance"
-import type { Project } from "@/project/project"
 
-export declare namespace InstanceContext {
-  export interface Shape {
-    readonly directory: string
-    readonly project: Project.Info
-  }
-}
+export { InstanceContext } from "./instance-context"
 
-export class InstanceContext extends ServiceMap.Service<InstanceContext, InstanceContext.Shape>()(
-  "opencode/InstanceContext",
-) {}
-
-export type InstanceServices = QuestionService | PermissionService | ProviderAuthService
+export type InstanceServices =
+  | QuestionService
+  | PermissionService
+  | ProviderAuthService
+  | FileWatcherService
+  | VcsService
 
 function lookup(directory: string) {
   const project = Instance.project
@@ -26,6 +24,8 @@ function lookup(directory: string) {
     Layer.fresh(QuestionService.layer),
     Layer.fresh(PermissionService.layer),
     Layer.fresh(ProviderAuthService.layer),
+    Layer.fresh(FileWatcherService.layer),
+    Layer.fresh(VcsService.layer),
   ).pipe(Layer.provide(ctx))
 }
 

packages/opencode/src/file/watcher.ts

@@ -1,7 +1,8 @@
 import { BusEvent } from "@/bus/bus-event"
 import { Bus } from "@/bus"
+import { InstanceContext } from "@/effect/instance-context"
+import { Instance } from "@/project/instance"
 import z from "zod"
-import { Instance } from "../project/instance"
 import { Log } from "../util/log"
 import { FileIgnore } from "./ignore"
 import { Config } from "../config/config"
@@ -9,118 +10,139 @@ import path from "path"
 // @ts-ignore
 import { createWrapper } from "@parcel/watcher/wrapper"
 import { lazy } from "@/util/lazy"
-import { withTimeout } from "@/util/timeout"
 import type ParcelWatcher from "@parcel/watcher"
-import { Flag } from "@/flag/flag"
 import { readdir } from "fs/promises"
 import { git } from "@/util/git"
 import { Protected } from "./protected"
+import { Flag } from "@/flag/flag"
+import { Cause, Effect, Layer, ServiceMap } from "effect"
 
 const SUBSCRIBE_TIMEOUT_MS = 10_000
 
 declare const OPENCODE_LIBC: string | undefined
 
-export namespace FileWatcher {
-  const log = Log.create({ service: "file.watcher" })
+const log = Log.create({ service: "file.watcher" })
 
-  export const Event = {
-    Updated: BusEvent.define(
-      "file.watcher.updated",
-      z.object({
-        file: z.string(),
-        event: z.union([z.literal("add"), z.literal("change"), z.literal("unlink")]),
-      }),
-    ),
+const event = {
+  Updated: BusEvent.define(
+    "file.watcher.updated",
+    z.object({
+      file: z.string(),
+      event: z.union([z.literal("add"), z.literal("change"), z.literal("unlink")]),
+    }),
+  ),
+}
+
+const watcher = lazy((): typeof import("@parcel/watcher") | undefined => {
+  try {
+    const binding = require(
+      `@parcel/watcher-${process.platform}-${process.arch}${process.platform === "linux" ? `-${OPENCODE_LIBC || "glibc"}` : ""}`,
+    )
+    return createWrapper(binding) as typeof import("@parcel/watcher")
+  } catch (error) {
+    log.error("failed to load watcher binding", { error })
+    return
   }
+})
 
-  const watcher = lazy((): typeof import("@parcel/watcher") | undefined => {
-    try {
-      const binding = require(
-        `@parcel/watcher-${process.platform}-${process.arch}${process.platform === "linux" ? `-${OPENCODE_LIBC || "glibc"}` : ""}`,
-      )
-      return createWrapper(binding) as typeof import("@parcel/watcher")
-    } catch (error) {
-      log.error("failed to load watcher binding", { error })
-      return
-    }
-  })
+function getBackend() {
+  if (process.platform === "win32") return "windows"
+  if (process.platform === "darwin") return "fs-events"
+  if (process.platform === "linux") return "inotify"
+}
 
-  const state = Instance.state(
-    async () => {
-      log.info("init")
-      const cfg = await Config.get()
-      const backend = (() => {
-        if (process.platform === "win32") return "windows"
-        if (process.platform === "darwin") return "fs-events"
-        if (process.platform === "linux") return "inotify"
-      })()
-      if (!backend) {
-        log.error("watcher backend not supported", { platform: process.platform })
-        return {}
-      }
-      log.info("watcher backend", { platform: process.platform, backend })
+export namespace FileWatcher {
+  export const Event = event
+  /** Whether the native @parcel/watcher binding is available on this platform. */
+  export const hasNativeBinding = () => !!watcher()
+}
 
-      const w = watcher()
-      if (!w) return {}
+const init = Effect.fn("FileWatcherService.init")(function* () {})
 
-      const subscribe: ParcelWatcher.SubscribeCallback = (err, evts) => {
-        if (err) return
-        for (const evt of evts) {
-          if (evt.type === "create") Bus.publish(Event.Updated, { file: evt.path, event: "add" })
-          if (evt.type === "update") Bus.publish(Event.Updated, { file: evt.path, event: "change" })
-          if (evt.type === "delete") Bus.publish(Event.Updated, { file: evt.path, event: "unlink" })
-        }
-      }
-
-      const subs: ParcelWatcher.AsyncSubscription[] = []
-      const cfgIgnores = cfg.watcher?.ignore ?? []
-
-      if (Flag.OPENCODE_EXPERIMENTAL_FILEWATCHER) {
-        const pending = w.subscribe(Instance.directory, subscribe, {
-          ignore: [...FileIgnore.PATTERNS, ...cfgIgnores, ...Protected.paths()],
-          backend,
-        })
-        const sub = await withTimeout(pending, SUBSCRIBE_TIMEOUT_MS).catch((err) => {
-          log.error("failed to subscribe to Instance.directory", { error: err })
-          pending.then((s) => s.unsubscribe()).catch(() => {})
-          return undefined
-        })
-        if (sub) subs.push(sub)
-      }
-
-      if (Instance.project.vcs === "git") {
-        const result = await git(["rev-parse", "--git-dir"], {
-          cwd: Instance.worktree,
-        })
-        const vcsDir = result.exitCode === 0 ? path.resolve(Instance.worktree, result.text().trim()) : undefined
-        if (vcsDir && !cfgIgnores.includes(".git") && !cfgIgnores.includes(vcsDir)) {
-          const gitDirContents = await readdir(vcsDir).catch(() => [])
-          const ignoreList = gitDirContents.filter((entry) => entry !== "HEAD")
-          const pending = w.subscribe(vcsDir, subscribe, {
-            ignore: ignoreList,
-            backend,
-          })
-          const sub = await withTimeout(pending, SUBSCRIBE_TIMEOUT_MS).catch((err) => {
-            log.error("failed to subscribe to vcsDir", { error: err })
-            pending.then((s) => s.unsubscribe()).catch(() => {})
-            return undefined
-          })
-          if (sub) subs.push(sub)
-        }
-      }
-
-      return { subs }
-    },
-    async (state) => {
-      if (!state.subs) return
-      await Promise.all(state.subs.map((sub) => sub?.unsubscribe()))
-    },
-  )
-
-  export function init() {
-    if (Flag.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER) {
-      return
-    }
-    state()
+export namespace FileWatcherService {
+  export interface Service {
+    readonly init: () => Effect.Effect<void>
   }
 }
+
+export class FileWatcherService extends ServiceMap.Service<FileWatcherService, FileWatcherService.Service>()(
+  "@opencode/FileWatcher",
+) {
+  static readonly layer = Layer.effect(
+    FileWatcherService,
+    Effect.gen(function* () {
+      const instance = yield* InstanceContext
+      if (yield* Flag.OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER) return FileWatcherService.of({ init })
+
+      log.info("init", { directory: instance.directory })
+
+      const backend = getBackend()
+      if (!backend) {
+        log.error("watcher backend not supported", { directory: instance.directory, platform: process.platform })
+        return FileWatcherService.of({ init })
+      }
+
+      const w = watcher()
+      if (!w) return FileWatcherService.of({ init })
+
+      log.info("watcher backend", { directory: instance.directory, platform: process.platform, backend })
+
+      const subs: ParcelWatcher.AsyncSubscription[] = []
+      yield* Effect.addFinalizer(() => Effect.promise(() => Promise.allSettled(subs.map((sub) => sub.unsubscribe()))))
+
+      const cb: ParcelWatcher.SubscribeCallback = Instance.bind((err, evts) => {
+        if (err) return
+        for (const evt of evts) {
+          if (evt.type === "create") Bus.publish(event.Updated, { file: evt.path, event: "add" })
+          if (evt.type === "update") Bus.publish(event.Updated, { file: evt.path, event: "change" })
+          if (evt.type === "delete") Bus.publish(event.Updated, { file: evt.path, event: "unlink" })
+        }
+      })
+
+      const subscribe = (dir: string, ignore: string[]) => {
+        const pending = w.subscribe(dir, cb, { ignore, backend })
+        return Effect.gen(function* () {
+          const sub = yield* Effect.promise(() => pending)
+          subs.push(sub)
+        }).pipe(
+          Effect.timeout(SUBSCRIBE_TIMEOUT_MS),
+          Effect.catchCause((cause) => {
+            log.error("failed to subscribe", { dir, cause: Cause.pretty(cause) })
+            // Clean up a subscription that resolves after timeout
+            pending.then((s) => s.unsubscribe()).catch(() => {})
+            return Effect.void
+          }),
+        )
+      }
+
+      const cfg = yield* Effect.promise(() => Config.get())
+      const cfgIgnores = cfg.watcher?.ignore ?? []
+
+      if (yield* Flag.OPENCODE_EXPERIMENTAL_FILEWATCHER) {
+        yield* subscribe(instance.directory, [...FileIgnore.PATTERNS, ...cfgIgnores, ...Protected.paths()])
+      }
+
+      if (instance.project.vcs === "git") {
+        const result = yield* Effect.promise(() =>
+          git(["rev-parse", "--git-dir"], {
+            cwd: instance.project.worktree,
+          }),
+        )
+        const vcsDir = result.exitCode === 0 ? path.resolve(instance.project.worktree, result.text().trim()) : undefined
+        if (vcsDir && !cfgIgnores.includes(".git") && !cfgIgnores.includes(vcsDir)) {
+          const ignore = (yield* Effect.promise(() => readdir(vcsDir).catch(() => []))).filter(
+            (entry) => entry !== "HEAD",
+          )
+          yield* subscribe(vcsDir, ignore)
+        }
+      }
+
+      return FileWatcherService.of({ init })
+    }).pipe(
+      Effect.catchCause((cause) => {
+        log.error("failed to init watcher service", { cause: Cause.pretty(cause) })
+        return Effect.succeed(FileWatcherService.of({ init }))
+      }),
+    ),
+  )
+}

packages/opencode/src/flag/flag.ts

@@ -1,3 +1,5 @@
+import { Config } from "effect"
+
 function truthy(key: string) {
   const value = process.env[key]?.toLowerCase()
   return value === "true" || value === "1"
@@ -40,8 +42,12 @@ export namespace Flag {
 
   // Experimental
   export const OPENCODE_EXPERIMENTAL = truthy("OPENCODE_EXPERIMENTAL")
-  export const OPENCODE_EXPERIMENTAL_FILEWATCHER = truthy("OPENCODE_EXPERIMENTAL_FILEWATCHER")
-  export const OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = truthy("OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER")
+  export const OPENCODE_EXPERIMENTAL_FILEWATCHER = Config.boolean("OPENCODE_EXPERIMENTAL_FILEWATCHER").pipe(
+    Config.withDefault(false),
+  )
+  export const OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER = Config.boolean(
+    "OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER",
+  ).pipe(Config.withDefault(false))
   export const OPENCODE_EXPERIMENTAL_ICON_DISCOVERY =
     OPENCODE_EXPERIMENTAL || truthy("OPENCODE_EXPERIMENTAL_ICON_DISCOVERY")
 

packages/opencode/src/permission/service.ts

@@ -1,6 +1,6 @@
 import { Bus } from "@/bus"
 import { BusEvent } from "@/bus/bus-event"
-import { InstanceContext } from "@/effect/instances"
+import { InstanceContext } from "@/effect/instance-context"
 import { ProjectID } from "@/project/schema"
 import { MessageID, SessionID } from "@/session/schema"
 import { PermissionTable } from "@/session/session.sql"

packages/opencode/src/project/bootstrap.ts

@@ -1,17 +1,18 @@
 import { Plugin } from "../plugin"
 import { Format } from "../format"
 import { LSP } from "../lsp"
-import { FileWatcher } from "../file/watcher"
+import { FileWatcherService } from "../file/watcher"
 import { File } from "../file"
 import { Project } from "./project"
 import { Bus } from "../bus"
 import { Command } from "../command"
 import { Instance } from "./instance"
-import { Vcs } from "./vcs"
+import { VcsService } from "./vcs"
 import { Log } from "@/util/log"
 import { ShareNext } from "@/share/share-next"
 import { Snapshot } from "../snapshot"
 import { Truncate } from "../tool/truncation"
+import { runPromiseInstance } from "@/effect/runtime"
 
 export async function InstanceBootstrap() {
   Log.Default.info("bootstrapping", { directory: Instance.directory })
@@ -19,9 +20,9 @@ export async function InstanceBootstrap() {
   ShareNext.init()
   Format.init()
   await LSP.init()
-  FileWatcher.init()
+  await runPromiseInstance(FileWatcherService.use((service) => service.init()))
   File.init()
-  Vcs.init()
+  await runPromiseInstance(VcsService.use((s) => s.init()))
   Snapshot.init()
   Truncate.init()
 

packages/opencode/src/project/instance.ts

@@ -101,6 +101,15 @@ export const Instance = {
     if (Instance.worktree === "/") return false
     return Filesystem.contains(Instance.worktree, filepath)
   },
+  /**
+   * Captures the current instance ALS context and returns a wrapper that
+   * restores it when called. Use this for callbacks that fire outside the
+   * instance async context (native addons, event emitters, timers, etc.).
+   */
+  bind<F extends (...args: any[]) => any>(fn: F): F {
+    const ctx = context.use()
+    return ((...args: any[]) => context.provide(ctx, () => fn(...args))) as F
+  },
   state<S>(init: () => S, dispose?: (state: Awaited<S>) => Promise<void>): () => S {
     return State.create(() => Instance.directory, init, dispose)
   },

packages/opencode/src/project/vcs.ts

@@ -1,11 +1,12 @@
 import { BusEvent } from "@/bus/bus-event"
 import { Bus } from "@/bus"
-import path from "path"
 import z from "zod"
 import { Log } from "@/util/log"
 import { Instance } from "./instance"
+import { InstanceContext } from "@/effect/instance-context"
 import { FileWatcher } from "@/file/watcher"
 import { git } from "@/util/git"
+import { Effect, Layer, ServiceMap } from "effect"
 
 const log = Log.create({ service: "vcs" })
 
@@ -27,50 +28,57 @@ export namespace Vcs {
       ref: "VcsInfo",
     })
   export type Info = z.infer<typeof Info>
+}
 
-  async function currentBranch() {
-    const result = await git(["rev-parse", "--abbrev-ref", "HEAD"], {
-      cwd: Instance.worktree,
-    })
-    if (result.exitCode !== 0) return
-    const text = result.text().trim()
-    if (!text) return
-    return text
-  }
-
-  const state = Instance.state(
-    async () => {
-      if (Instance.project.vcs !== "git") {
-        return { branch: async () => undefined, unsubscribe: undefined }
-      }
-      let current = await currentBranch()
-      log.info("initialized", { branch: current })
-
-      const unsubscribe = Bus.subscribe(FileWatcher.Event.Updated, async (evt) => {
-        if (!evt.properties.file.endsWith("HEAD")) return
-        const next = await currentBranch()
-        if (next !== current) {
-          log.info("branch changed", { from: current, to: next })
-          current = next
-          Bus.publish(Event.BranchUpdated, { branch: next })
-        }
-      })
-
-      return {
-        branch: async () => current,
-        unsubscribe,
-      }
-    },
-    async (state) => {
-      state.unsubscribe?.()
-    },
-  )
-
-  export async function init() {
-    return state()
-  }
-
-  export async function branch() {
-    return await state().then((s) => s.branch())
+export namespace VcsService {
+  export interface Service {
+    readonly init: () => Effect.Effect<void>
+    readonly branch: () => Effect.Effect<string | undefined>
   }
 }
+
+export class VcsService extends ServiceMap.Service<VcsService, VcsService.Service>()("@opencode/Vcs") {
+  static readonly layer = Layer.effect(
+    VcsService,
+    Effect.gen(function* () {
+      const instance = yield* InstanceContext
+      let current: string | undefined
+
+      if (instance.project.vcs === "git") {
+        const currentBranch = async () => {
+          const result = await git(["rev-parse", "--abbrev-ref", "HEAD"], {
+            cwd: instance.project.worktree,
+          })
+          if (result.exitCode !== 0) return undefined
+          const text = result.text().trim()
+          return text || undefined
+        }
+
+        current = yield* Effect.promise(() => currentBranch())
+        log.info("initialized", { branch: current })
+
+        const unsubscribe = Bus.subscribe(
+          FileWatcher.Event.Updated,
+          Instance.bind(async (evt) => {
+            if (!evt.properties.file.endsWith("HEAD")) return
+            const next = await currentBranch()
+            if (next !== current) {
+              log.info("branch changed", { from: current, to: next })
+              current = next
+              Bus.publish(Vcs.Event.BranchUpdated, { branch: next })
+            }
+          }),
+        )
+
+        yield* Effect.addFinalizer(() => Effect.sync(unsubscribe))
+      }
+
+      return VcsService.of({
+        init: Effect.fn("VcsService.init")(function* () {}),
+        branch: Effect.fn("VcsService.branch")(function* () {
+          return current
+        }),
+      })
+    }),
+  )
+}

packages/opencode/src/pty/index.ts

@@ -167,40 +167,44 @@ export namespace Pty {
       subscribers: new Map(),
     }
     state().set(id, session)
-    ptyProcess.onData((chunk) => {
-      session.cursor += chunk.length
+    ptyProcess.onData(
+      Instance.bind((chunk) => {
+        session.cursor += chunk.length
 
-      for (const [key, ws] of session.subscribers.entries()) {
-        if (ws.readyState !== 1) {
-          session.subscribers.delete(key)
-          continue
+        for (const [key, ws] of session.subscribers.entries()) {
+          if (ws.readyState !== 1) {
+            session.subscribers.delete(key)
+            continue
+          }
+
+          if (ws.data !== key) {
+            session.subscribers.delete(key)
+            continue
+          }
+
+          try {
+            ws.send(chunk)
+          } catch {
+            session.subscribers.delete(key)
+          }
         }
 
-        if (ws.data !== key) {
-          session.subscribers.delete(key)
-          continue
-        }
-
-        try {
-          ws.send(chunk)
-        } catch {
-          session.subscribers.delete(key)
-        }
-      }
-
-      session.buffer += chunk
-      if (session.buffer.length <= BUFFER_LIMIT) return
-      const excess = session.buffer.length - BUFFER_LIMIT
-      session.buffer = session.buffer.slice(excess)
-      session.bufferCursor += excess
-    })
-    ptyProcess.onExit(({ exitCode }) => {
-      if (session.info.status === "exited") return
-      log.info("session exited", { id, exitCode })
-      session.info.status = "exited"
-      Bus.publish(Event.Exited, { id, exitCode })
-      remove(id)
-    })
+        session.buffer += chunk
+        if (session.buffer.length <= BUFFER_LIMIT) return
+        const excess = session.buffer.length - BUFFER_LIMIT
+        session.buffer = session.buffer.slice(excess)
+        session.bufferCursor += excess
+      }),
+    )
+    ptyProcess.onExit(
+      Instance.bind(({ exitCode }) => {
+        if (session.info.status === "exited") return
+        log.info("session exited", { id, exitCode })
+        session.info.status = "exited"
+        Bus.publish(Event.Exited, { id, exitCode })
+        remove(id)
+      }),
+    )
     Bus.publish(Event.Created, { info })
     return info
   }

packages/opencode/src/server/server.ts

@@ -14,7 +14,8 @@ import { LSP } from "../lsp"
 import { Format } from "../format"
 import { TuiRoutes } from "./routes/tui"
 import { Instance } from "../project/instance"
-import { Vcs } from "../project/vcs"
+import { Vcs, VcsService } from "../project/vcs"
+import { runPromiseInstance } from "@/effect/runtime"
 import { Agent } from "../agent/agent"
 import { Skill } from "../skill/skill"
 import { Auth } from "../auth"
@@ -330,7 +331,7 @@ export namespace Server {
           },
         }),
         async (c) => {
-          const branch = await Vcs.branch()
+          const branch = await runPromiseInstance(VcsService.use((s) => s.branch()))
           return c.json({
             branch,
           })

packages/opencode/test/file/watcher.test.ts

@@ -0,0 +1,236 @@
+import { $ } from "bun"
+import { afterEach, describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import path from "path"
+import { Deferred, Effect, Fiber, Option } from "effect"
+import { tmpdir } from "../fixture/fixture"
+import { watcherConfigLayer, withServices } from "../fixture/instance"
+import { FileWatcher, FileWatcherService } from "../../src/file/watcher"
+import { Instance } from "../../src/project/instance"
+import { GlobalBus } from "../../src/bus/global"
+
+// Native @parcel/watcher bindings aren't reliably available in CI (missing on Linux, flaky on Windows)
+const describeWatcher = FileWatcher.hasNativeBinding() && !process.env.CI ? describe : describe.skip
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+type BusUpdate = { directory?: string; payload: { type: string; properties: WatcherEvent } }
+type WatcherEvent = { file: string; event: "add" | "change" | "unlink" }
+
+/** Run `body` with a live FileWatcherService. */
+function withWatcher<E>(directory: string, body: Effect.Effect<void, E>) {
+  return withServices(
+    directory,
+    FileWatcherService.layer,
+    async (rt) => {
+      await rt.runPromise(FileWatcherService.use((s) => s.init()))
+      await Effect.runPromise(ready(directory))
+      await Effect.runPromise(body)
+    },
+    { provide: [watcherConfigLayer] },
+  )
+}
+
+function listen(directory: string, check: (evt: WatcherEvent) => boolean, hit: (evt: WatcherEvent) => void) {
+  let done = false
+
+  function on(evt: BusUpdate) {
+    if (done) return
+    if (evt.directory !== directory) return
+    if (evt.payload.type !== FileWatcher.Event.Updated.type) return
+    if (!check(evt.payload.properties)) return
+    hit(evt.payload.properties)
+  }
+
+  function cleanup() {
+    if (done) return
+    done = true
+    GlobalBus.off("event", on)
+  }
+
+  GlobalBus.on("event", on)
+  return cleanup
+}
+
+function wait(directory: string, check: (evt: WatcherEvent) => boolean) {
+  return Effect.callback<WatcherEvent>((resume) => {
+    const cleanup = listen(directory, check, (evt) => {
+      cleanup()
+      resume(Effect.succeed(evt))
+    })
+    return Effect.sync(cleanup)
+  }).pipe(Effect.timeout("5 seconds"))
+}
+
+function nextUpdate<E>(directory: string, check: (evt: WatcherEvent) => boolean, trigger: Effect.Effect<void, E>) {
+  return Effect.acquireUseRelease(
+    wait(directory, check).pipe(Effect.forkChild({ startImmediately: true })),
+    (fiber) =>
+      Effect.gen(function* () {
+        yield* trigger
+        return yield* Fiber.join(fiber)
+      }),
+    Fiber.interrupt,
+  )
+}
+
+/** Effect that asserts no matching event arrives within `ms`. */
+function noUpdate<E>(
+  directory: string,
+  check: (evt: WatcherEvent) => boolean,
+  trigger: Effect.Effect<void, E>,
+  ms = 500,
+) {
+  return Effect.gen(function* () {
+    const deferred = yield* Deferred.make<WatcherEvent>()
+
+    yield* Effect.acquireUseRelease(
+      Effect.sync(() =>
+        listen(directory, check, (evt) => {
+          Effect.runSync(Deferred.succeed(deferred, evt))
+        }),
+      ),
+      () =>
+        Effect.gen(function* () {
+          yield* trigger
+          expect(yield* Deferred.await(deferred).pipe(Effect.timeoutOption(`${ms} millis`))).toEqual(Option.none())
+        }),
+      (cleanup) => Effect.sync(cleanup),
+    )
+  })
+}
+
+function ready(directory: string) {
+  const file = path.join(directory, `.watcher-${Math.random().toString(36).slice(2)}`)
+  const head = path.join(directory, ".git", "HEAD")
+
+  return Effect.gen(function* () {
+    yield* nextUpdate(
+      directory,
+      (evt) => evt.file === file && evt.event === "add",
+      Effect.promise(() => fs.writeFile(file, "ready")),
+    ).pipe(Effect.ensuring(Effect.promise(() => fs.rm(file, { force: true }).catch(() => undefined))), Effect.asVoid)
+
+    const git = yield* Effect.promise(() =>
+      fs
+        .stat(head)
+        .then(() => true)
+        .catch(() => false),
+    )
+    if (!git) return
+
+    const branch = `watch-${Math.random().toString(36).slice(2)}`
+    const hash = yield* Effect.promise(() => $`git rev-parse HEAD`.cwd(directory).quiet().text())
+    yield* nextUpdate(
+      directory,
+      (evt) => evt.file === head && evt.event !== "unlink",
+      Effect.promise(async () => {
+        await fs.writeFile(path.join(directory, ".git", "refs", "heads", branch), hash.trim() + "\n")
+        await fs.writeFile(head, `ref: refs/heads/${branch}\n`)
+      }),
+    ).pipe(Effect.asVoid)
+  })
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+describeWatcher("FileWatcherService", () => {
+  afterEach(() => Instance.disposeAll())
+
+  test("publishes root create, update, and delete events", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const file = path.join(tmp.path, "watch.txt")
+    const dir = tmp.path
+    const cases = [
+      { event: "add" as const, trigger: Effect.promise(() => fs.writeFile(file, "a")) },
+      { event: "change" as const, trigger: Effect.promise(() => fs.writeFile(file, "b")) },
+      { event: "unlink" as const, trigger: Effect.promise(() => fs.unlink(file)) },
+    ]
+
+    await withWatcher(
+      dir,
+      Effect.forEach(cases, ({ event, trigger }) =>
+        nextUpdate(dir, (evt) => evt.file === file && evt.event === event, trigger).pipe(
+          Effect.tap((evt) => Effect.sync(() => expect(evt).toEqual({ file, event }))),
+        ),
+      ),
+    )
+  })
+
+  test("watches non-git roots", async () => {
+    await using tmp = await tmpdir()
+    const file = path.join(tmp.path, "plain.txt")
+    const dir = tmp.path
+
+    await withWatcher(
+      dir,
+      nextUpdate(
+        dir,
+        (e) => e.file === file && e.event === "add",
+        Effect.promise(() => fs.writeFile(file, "plain")),
+      ).pipe(Effect.tap((evt) => Effect.sync(() => expect(evt).toEqual({ file, event: "add" })))),
+    )
+  })
+
+  test("cleanup stops publishing events", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const file = path.join(tmp.path, "after-dispose.txt")
+
+    // Start and immediately stop the watcher (withWatcher disposes on exit)
+    await withWatcher(tmp.path, Effect.void)
+
+    // Now write a file — no watcher should be listening
+    await Effect.runPromise(
+      noUpdate(
+        tmp.path,
+        (e) => e.file === file,
+        Effect.promise(() => fs.writeFile(file, "gone")),
+      ),
+    )
+  })
+
+  test("ignores .git/index changes", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const gitIndex = path.join(tmp.path, ".git", "index")
+    const edit = path.join(tmp.path, "tracked.txt")
+
+    await withWatcher(
+      tmp.path,
+      noUpdate(
+        tmp.path,
+        (e) => e.file === gitIndex,
+        Effect.promise(async () => {
+          await fs.writeFile(edit, "a")
+          await $`git add .`.cwd(tmp.path).quiet().nothrow()
+        }),
+      ),
+    )
+  })
+
+  test("publishes .git/HEAD events", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const head = path.join(tmp.path, ".git", "HEAD")
+    const branch = `watch-${Math.random().toString(36).slice(2)}`
+    await $`git branch ${branch}`.cwd(tmp.path).quiet()
+
+    await withWatcher(
+      tmp.path,
+      nextUpdate(
+        tmp.path,
+        (evt) => evt.file === head && evt.event !== "unlink",
+        Effect.promise(() => fs.writeFile(head, `ref: refs/heads/${branch}\n`)),
+      ).pipe(
+        Effect.tap((evt) =>
+          Effect.sync(() => {
+            expect(evt.file).toBe(head)
+            expect(["add", "change"]).toContain(evt.event)
+          }),
+        ),
+      ),
+    )
+  })
+})

packages/opencode/test/fixture/instance.ts

@@ -0,0 +1,47 @@
+import { ConfigProvider, Layer, ManagedRuntime } from "effect"
+import { InstanceContext } from "../../src/effect/instance-context"
+import { Instance } from "../../src/project/instance"
+
+/** ConfigProvider that enables the experimental file watcher. */
+export const watcherConfigLayer = ConfigProvider.layer(
+  ConfigProvider.fromUnknown({
+    OPENCODE_EXPERIMENTAL_FILEWATCHER: "true",
+    OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "false",
+  }),
+)
+
+/**
+ * Boot an Instance with the given service layers and run `body` with
+ * the ManagedRuntime. Cleanup is automatic — the runtime is disposed
+ * and Instance context is torn down when `body` completes.
+ *
+ * Layers may depend on InstanceContext (provided automatically).
+ * Pass extra layers via `options.provide` (e.g. ConfigProvider.layer).
+ */
+export function withServices<S>(
+  directory: string,
+  layer: Layer.Layer<S, any, InstanceContext>,
+  body: (rt: ManagedRuntime.ManagedRuntime<S, never>) => Promise<void>,
+  options?: { provide?: Layer.Layer<never>[] },
+) {
+  return Instance.provide({
+    directory,
+    fn: async () => {
+      const ctx = Layer.sync(InstanceContext, () =>
+        InstanceContext.of({ directory: Instance.directory, project: Instance.project }),
+      )
+      let resolved: Layer.Layer<S> = Layer.fresh(layer).pipe(Layer.provide(ctx)) as any
+      if (options?.provide) {
+        for (const l of options.provide) {
+          resolved = resolved.pipe(Layer.provide(l)) as any
+        }
+      }
+      const rt = ManagedRuntime.make(resolved)
+      try {
+        await body(rt)
+      } finally {
+        await rt.dispose()
+      }
+    },
+  })
+}

packages/opencode/test/permission/next.test.ts

@@ -977,7 +977,7 @@ test("ask - should deny even when an earlier pattern is ask", async () => {
   await Instance.provide({
     directory: tmp.path,
     fn: async () => {
-      const ask = PermissionNext.ask({
+      const err = await PermissionNext.ask({
         sessionID: SessionID.make("session_test"),
         permission: "bash",
         patterns: ["echo hello", "rm -rf /"],
@@ -987,24 +987,12 @@ test("ask - should deny even when an earlier pattern is ask", async () => {
           { permission: "bash", pattern: "echo *", action: "ask" },
           { permission: "bash", pattern: "rm *", action: "deny" },
         ],
-      })
+      }).then(
+        () => undefined,
+        (err) => err,
+      )
 
-      const out = await Promise.race([
-        ask.then(
-          () => ({ ok: true as const, err: undefined }),
-          (err) => ({ ok: false as const, err }),
-        ),
-        Bun.sleep(100).then(() => "timeout" as const),
-      ])
-
-      if (out === "timeout") {
-        await rejectAll()
-        await ask.catch(() => {})
-        throw new Error("ask timed out instead of denying immediately")
-      }
-
-      expect(out.ok).toBe(false)
-      expect(out.err).toBeInstanceOf(PermissionNext.DeniedError)
+      expect(err).toBeInstanceOf(PermissionNext.DeniedError)
       expect(await PermissionNext.list()).toHaveLength(0)
     },
   })

packages/opencode/test/project/vcs.test.ts

@@ -0,0 +1,117 @@
+import { $ } from "bun"
+import { afterEach, describe, expect, test } from "bun:test"
+import fs from "fs/promises"
+import path from "path"
+import { Layer, ManagedRuntime } from "effect"
+import { tmpdir } from "../fixture/fixture"
+import { watcherConfigLayer, withServices } from "../fixture/instance"
+import { FileWatcher, FileWatcherService } from "../../src/file/watcher"
+import { Instance } from "../../src/project/instance"
+import { GlobalBus } from "../../src/bus/global"
+import { Vcs, VcsService } from "../../src/project/vcs"
+
+// Skip in CI — native @parcel/watcher binding needed
+const describeVcs = FileWatcher.hasNativeBinding() && !process.env.CI ? describe : describe.skip
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function withVcs(
+  directory: string,
+  body: (rt: ManagedRuntime.ManagedRuntime<FileWatcherService | VcsService, never>) => Promise<void>,
+) {
+  return withServices(
+    directory,
+    Layer.merge(FileWatcherService.layer, VcsService.layer),
+    async (rt) => {
+      await rt.runPromise(FileWatcherService.use((s) => s.init()))
+      await rt.runPromise(VcsService.use((s) => s.init()))
+      await Bun.sleep(200)
+      await body(rt)
+    },
+    { provide: [watcherConfigLayer] },
+  )
+}
+
+type BranchEvent = { directory?: string; payload: { type: string; properties: { branch?: string } } }
+
+/** Wait for a Vcs.Event.BranchUpdated event on GlobalBus */
+function nextBranchUpdate(directory: string, timeout = 5000) {
+  return new Promise<string | undefined>((resolve, reject) => {
+    const timer = setTimeout(() => {
+      GlobalBus.off("event", on)
+      reject(new Error("timed out waiting for BranchUpdated event"))
+    }, timeout)
+
+    function on(evt: BranchEvent) {
+      if (evt.directory !== directory) return
+      if (evt.payload.type !== Vcs.Event.BranchUpdated.type) return
+      clearTimeout(timer)
+      GlobalBus.off("event", on)
+      resolve(evt.payload.properties.branch)
+    }
+
+    GlobalBus.on("event", on)
+  })
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+describeVcs("Vcs", () => {
+  afterEach(() => Instance.disposeAll())
+
+  test("branch() returns current branch name", async () => {
+    await using tmp = await tmpdir({ git: true })
+
+    await withVcs(tmp.path, async (rt) => {
+      const branch = await rt.runPromise(VcsService.use((s) => s.branch()))
+      expect(branch).toBeDefined()
+      expect(typeof branch).toBe("string")
+    })
+  })
+
+  test("branch() returns undefined for non-git directories", async () => {
+    await using tmp = await tmpdir()
+
+    await withVcs(tmp.path, async (rt) => {
+      const branch = await rt.runPromise(VcsService.use((s) => s.branch()))
+      expect(branch).toBeUndefined()
+    })
+  })
+
+  test("publishes BranchUpdated when .git/HEAD changes", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const branch = `test-${Math.random().toString(36).slice(2)}`
+    await $`git branch ${branch}`.cwd(tmp.path).quiet()
+
+    await withVcs(tmp.path, async () => {
+      const pending = nextBranchUpdate(tmp.path)
+
+      const head = path.join(tmp.path, ".git", "HEAD")
+      await fs.writeFile(head, `ref: refs/heads/${branch}\n`)
+
+      const updated = await pending
+      expect(updated).toBe(branch)
+    })
+  })
+
+  test("branch() reflects the new branch after HEAD change", async () => {
+    await using tmp = await tmpdir({ git: true })
+    const branch = `test-${Math.random().toString(36).slice(2)}`
+    await $`git branch ${branch}`.cwd(tmp.path).quiet()
+
+    await withVcs(tmp.path, async (rt) => {
+      const pending = nextBranchUpdate(tmp.path)
+
+      const head = path.join(tmp.path, ".git", "HEAD")
+      await fs.writeFile(head, `ref: refs/heads/${branch}\n`)
+
+      await pending
+      const current = await rt.runPromise(VcsService.use((s) => s.branch()))
+      expect(current).toBe(branch)
+    })
+  })
+})

packages/opencode/test/pty/pty-session.test.ts

@@ -6,7 +6,7 @@ import type { PtyID } from "../../src/pty/schema"
 import { tmpdir } from "../fixture/fixture"
 import { setTimeout as sleep } from "node:timers/promises"
 
-const wait = async (fn: () => boolean, ms = 2000) => {
+const wait = async (fn: () => boolean, ms = 5000) => {
   const end = Date.now() + ms
   while (Date.now() < end) {
     if (fn()) return
@@ -20,7 +20,7 @@ const pick = (log: Array<{ type: "created" | "exited" | "deleted"; id: PtyID }>,
 }
 
 describe("pty", () => {
-  test("publishes created, exited, deleted in order for /bin/ls + remove", async () => {
+  test("publishes created, exited, deleted in order for a short-lived process", async () => {
     if (process.platform === "win32") return
 
     await using dir = await tmpdir({ git: true })
@@ -37,7 +37,11 @@ describe("pty", () => {
 
         let id: PtyID | undefined
         try {
-          const info = await Pty.create({ command: "/bin/ls", title: "ls" })
+          const info = await Pty.create({
+            command: "/usr/bin/env",
+            args: ["sh", "-c", "sleep 0.1"],
+            title: "sleep",
+          })
           id = info.id
 
           await wait(() => pick(log, id!).includes("exited"))