diff --git a/packages/opencode/src/effect/runner.ts b/packages/opencode/src/effect/runner.ts
index cbd2359e91..1e7d4c2966 100644
--- a/packages/opencode/src/effect/runner.ts
+++ b/packages/opencode/src/effect/runner.ts
@@ -1,10 +1,10 @@
-import { Cause, Deferred, Effect, Exit, Fiber, Schema, Scope, SynchronizedRef } from "effect"
+import { Cause, Deferred, Effect, Exit, Fiber, Latch, Schema, Scope, SynchronizedRef } from "effect"
 
 export interface Runner<A, E = never> {
   readonly state: State<A, E>
   readonly busy: boolean
   readonly ensureRunning: (work: Effect.Effect<A, E>) => Effect.Effect<A, E>
-  readonly startShell: (work: Effect.Effect<A, E>, ready?: Deferred.Deferred<void>) => Effect.Effect<A, E>
+  readonly startShell: (work: Effect.Effect<A, E>, ready?: Latch.Latch) => Effect.Effect<A, E>
   readonly cancel: Effect.Effect<void>
 }
 
@@ -19,7 +19,7 @@ interface RunHandle<A, E> {
 interface ShellHandle<A, E> {
   id: number
   cancelled: Deferred.Deferred<void>
-  ready?: Deferred.Deferred<void>
+  ready?: Latch.Latch
   fiber: Fiber.Fiber<A, E>
 }
 
@@ -107,7 +107,7 @@ export const make = <A, E = never>(
 
   const stopShell = (shell: ShellHandle<A, E>) =>
     Effect.gen(function* () {
-      if (shell.ready) yield* Deferred.await(shell.ready).pipe(Effect.exit, Effect.asVoid)
+      if (shell.ready) yield* shell.ready.await.pipe(Effect.exit, Effect.asVoid)
       yield* Deferred.succeed(shell.cancelled, undefined).pipe(Effect.asVoid)
       yield* Fiber.interrupt(shell.fiber)
     })
@@ -137,7 +137,7 @@ export const make = <A, E = never>(
       }),
     ).pipe(Effect.flatten)
 
-  const startShell = (work: Effect.Effect<A, E>, ready?: Deferred.Deferred<void>) =>
+  const startShell = (work: Effect.Effect<A, E>, ready?: Latch.Latch) =>
     SynchronizedRef.modifyEffect(
       ref,
       Effect.fnUntraced(function* (st) {
diff --git a/packages/opencode/src/session/prompt.ts b/packages/opencode/src/session/prompt.ts
index 22d1da4e8f..4c259e4aef 100644
--- a/packages/opencode/src/session/prompt.ts
+++ b/packages/opencode/src/session/prompt.ts
@@ -45,7 +45,7 @@ import { AppFileSystem } from "@opencode-ai/core/filesystem"
 import { Truncate } from "@/tool/truncate"
 import { decodeDataUrl } from "@/util/data-url"
 import { Process } from "@/util/process"
-import { Cause, Deferred, Effect, Exit, Layer, Option, Scope, Context, Schema } from "effect"
+import { Cause, Effect, Exit, Latch, Layer, Option, Scope, Context, Schema } from "effect"
 import { zod } from "@/util/effect-zod"
 import { withStatics } from "@/util/schema"
 import * as EffectLogger from "@opencode-ai/core/effect/logger"
@@ -720,10 +720,10 @@ NOTE: At any point in time through this workflow you should feel free to ask the
       } satisfies MessageV2.TextPart)
     })
 
-    const shellImpl = Effect.fn("SessionPrompt.shellImpl")(function* (input: ShellInput, ready?: Deferred.Deferred<void>) {
+    const shellImpl = Effect.fn("SessionPrompt.shellImpl")(function* (input: ShellInput, ready?: Latch.Latch) {
       return yield* Effect.uninterruptibleMask((restore) =>
         Effect.gen(function* () {
-          const markReady = ready ? Deferred.succeed(ready, undefined).pipe(Effect.asVoid) : Effect.void
+          const markReady = ready ? ready.open.pipe(Effect.asVoid) : Effect.void
           const { msg, part, cwd } = yield* Effect.gen(function* () {
             const ctx = yield* InstanceState.context
             const session = yield* sessions.get(input.sessionID)
@@ -1509,7 +1509,7 @@ NOTE: At any point in time through this workflow you should feel free to ask the
 
     const shell: (input: ShellInput) => Effect.Effect<MessageV2.WithParts> = Effect.fn("SessionPrompt.shell")(
       function* (input: ShellInput) {
-        const ready = yield* Deferred.make<void>()
+        const ready = yield* Latch.make()
         return yield* state.startShell(input.sessionID, lastAssistant(input.sessionID), shellImpl(input, ready), ready)
       },
     )
diff --git a/packages/opencode/src/session/run-state.ts b/packages/opencode/src/session/run-state.ts
index 5ad95c9c7d..9d4986f174 100644
--- a/packages/opencode/src/session/run-state.ts
+++ b/packages/opencode/src/session/run-state.ts
@@ -1,6 +1,6 @@
 import { InstanceState } from "@/effect/instance-state"
 import { Runner } from "@/effect/runner"
-import { Deferred, Effect, Layer, Scope, Context } from "effect"
+import { Effect, Latch, Layer, Scope, Context } from "effect"
 import * as Session from "./session"
 import { MessageV2 } from "./message-v2"
 import { SessionID } from "./schema"
@@ -18,7 +18,7 @@ export interface Interface {
     sessionID: SessionID,
     onInterrupt: Effect.Effect<MessageV2.WithParts>,
     work: Effect.Effect<MessageV2.WithParts>,
-    ready?: Deferred.Deferred<void>,
+    ready?: Latch.Latch,
   ) => Effect.Effect<MessageV2.WithParts>
 }
 
@@ -96,7 +96,7 @@ export const layer = Layer.effect(
       sessionID: SessionID,
       onInterrupt: Effect.Effect<MessageV2.WithParts>,
       work: Effect.Effect<MessageV2.WithParts>,
-      ready?: Deferred.Deferred<void>,
+      ready?: Latch.Latch,
     ) {
       return yield* (yield* runner(sessionID, onInterrupt)).startShell(work, ready)
     })