diff --git a/packages/opencode/src/kilocode/background-process/runner.ts b/packages/opencode/src/kilocode/background-process/runner.ts
index 89b7f71891f..fe8488158d5 100644
--- a/packages/opencode/src/kilocode/background-process/runner.ts
+++ b/packages/opencode/src/kilocode/background-process/runner.ts
@@ -64,23 +64,23 @@ export namespace BackgroundProcessRunner {
     let size = (await file.stat()).size
     let queue = Promise.resolve()
     const append = (chunk: Buffer) => {
-      if (!process.stdout.destroyed) process.stdout.write(chunk)
       queue = queue.then(async () => {
         if (size + chunk.length <= MAX) {
           await file.write(chunk)
           size += chunk.length
-          return
+        } else {
+          await file.close()
+          const source = Bun.file(input.log)
+          const old = size
+            ? Buffer.from(await source.slice(Math.max(0, size - KEEP), size).arrayBuffer())
+            : Buffer.alloc(0)
+          const next = Buffer.concat([old, chunk])
+          const tail = next.subarray(Math.max(0, next.length - KEEP))
+          await Filesystem.write(input.log, tail, MODE)
+          file = await open(input.log, "a", MODE)
+          size = tail.length
         }
-        await file.close()
-        const source = Bun.file(input.log)
-        const old = size
-          ? Buffer.from(await source.slice(Math.max(0, size - KEEP), size).arrayBuffer())
-          : Buffer.alloc(0)
-        const next = Buffer.concat([old, chunk])
-        const tail = next.subarray(Math.max(0, next.length - KEEP))
-        await Filesystem.write(input.log, tail, MODE)
-        file = await open(input.log, "a", MODE)
-        size = tail.length
+        if (!process.stdout.destroyed) process.stdout.write(chunk)
       })
     }
     return {
diff --git a/packages/opencode/test/session/prompt.test.ts b/packages/opencode/test/session/prompt.test.ts
index 285546a1cf6..9634838f725 100644
--- a/packages/opencode/test/session/prompt.test.ts
+++ b/packages/opencode/test/session/prompt.test.ts
@@ -160,13 +160,36 @@ const status = SessionStatus.layer.pipe(Layer.provideMerge(Bus.layer))
 const run = SessionRunState.layer.pipe(Layer.provide(status))
 const infra = Layer.mergeAll(NodeFileSystem.layer, CrossSpawnSpawner.defaultLayer)
 
-const processorCreateStarted: Array<() => void> = []
+// kilocode_change start
+const agent: AgentSvc.Info = {
+  name: "build",
+  mode: "primary",
+  native: true,
+  permission: Permission.fromConfig({ "*": "allow" }),
+  model: ref,
+  options: {},
+}
+const fastAgents = Layer.mock(AgentSvc.Service)({
+  get: () => Effect.succeed(agent),
+  list: () => Effect.succeed([agent]),
+  defaultInfo: () => Effect.succeed(agent),
+  defaultAgent: () => Effect.succeed(agent.name),
+  guardRequirements: () => Effect.void,
+})
+
+const processorCreateStarted: Deferred.Deferred<void>[] = []
 const blockingProcessor = Layer.succeed(
   SessionProcessor.Service,
   SessionProcessor.Service.of({
-    create: () => Effect.sync(() => processorCreateStarted.shift()?.()).pipe(Effect.andThen(Effect.never)),
+    create: () =>
+      Effect.gen(function* () {
+        const started = processorCreateStarted.shift()
+        if (started) yield* Deferred.succeed(started, undefined).pipe(Effect.ignore)
+        return yield* Effect.never
+      }),
   }),
 )
+// kilocode_change end
 
 function makePrompt(input?: { processor?: "blocking" }) {
   const deps = Layer.mergeAll(
@@ -174,7 +197,7 @@ function makePrompt(input?: { processor?: "blocking" }) {
     Snapshot.defaultLayer,
     LLM.defaultLayer,
     Env.defaultLayer,
-    AgentSvc.defaultLayer,
+    input?.processor === "blocking" ? fastAgents : AgentSvc.defaultLayer, // kilocode_change
     Command.defaultLayer,
     Permission.defaultLayer,
     Plugin.defaultLayer,
@@ -357,14 +380,6 @@ const deferredAsPromise = <A>(deferred: Deferred.Deferred<A>): PromiseLike<A> =>
   },
 })
 
-function defer<T>() {
-  let resolve!: (value: T | PromiseLike<T>) => void
-  const promise = new Promise<T>((done) => {
-    resolve = done
-  })
-  return { promise, resolve }
-}
-
 const succeedVoid = (deferred: Deferred.Deferred<void>) => {
   Effect.runSync(Deferred.succeed(deferred, void 0).pipe(Effect.ignore))
 }
@@ -1149,10 +1164,12 @@ raceNoLLMServer.instance(
         parts: [{ type: "text", text: "first" }],
       })
 
-      const firstCreate = defer<void>()
-      processorCreateStarted.push(firstCreate.resolve)
+      // kilocode_change start
+      const firstCreate = yield* Deferred.make<void>()
+      processorCreateStarted.push(firstCreate)
       const first = yield* prompt.loop({ sessionID: chat.id }).pipe(Effect.forkChild)
-      yield* Effect.promise(() => firstCreate.promise)
+      yield* awaitWithTimeout(Deferred.await(firstCreate), "processor.create did not start for first turn")
+      // kilocode_change end
 
       yield* prompt.cancel(chat.id)
       const firstExit = yield* Fiber.await(first)
@@ -1175,10 +1192,12 @@ raceNoLLMServer.instance(
         parts: [{ type: "text", text: "second" }],
       })
 
-      const secondCreate = defer<void>()
-      processorCreateStarted.push(secondCreate.resolve)
+      // kilocode_change start
+      const secondCreate = yield* Deferred.make<void>()
+      processorCreateStarted.push(secondCreate)
       const second = yield* prompt.loop({ sessionID: chat.id }).pipe(Effect.forkChild)
-      yield* Effect.promise(() => secondCreate.promise)
+      yield* awaitWithTimeout(Deferred.await(secondCreate), "processor.create did not start for second turn")
+      // kilocode_change end
 
       yield* prompt.cancel(chat.id)
       const secondExit = yield* Fiber.await(second)