diff --git a/packages/opencode/src/util/rpc.ts b/packages/opencode/src/util/rpc.ts
index 02586ebcfc6..19d845a96df 100644
--- a/packages/opencode/src/util/rpc.ts
+++ b/packages/opencode/src/util/rpc.ts
@@ -6,8 +6,12 @@ export function listen(rpc: Definition) {
   onmessage = async (evt) => {
     const parsed = JSON.parse(evt.data)
     if (parsed.type === "rpc.request") {
-      const result = await rpc[parsed.method](parsed.input)
-      postMessage(JSON.stringify({ type: "rpc.result", result, id: parsed.id }))
+      try {
+        const result = await rpc[parsed.method](parsed.input)
+        postMessage(JSON.stringify({ type: "rpc.result", result, id: parsed.id }))
+      } catch (error) {
+        postMessage(JSON.stringify({ type: "rpc.error", error: serializeError(error), id: parsed.id }))
+      }
     }
   }
 }
@@ -19,16 +23,35 @@ export function emit(event: string, data: unknown) {
 export function client<T extends Definition>(target: {
   postMessage: (data: string) => void | null
   onmessage: ((this: Worker, ev: MessageEvent<any>) => any) | null
+  addEventListener?: Worker["addEventListener"]
 }) {
-  const pending = new Map<number, (result: any) => void>()
+  const pending = new Map<number, { resolve: (result: any) => void; reject: (error: any) => void }>()
   const listeners = new Map<string, Set<(data: any) => void>>()
+  let failed: unknown
   let id = 0
+  const rejectPending = (error: unknown) => {
+    failed = error
+    for (const request of pending.values()) {
+      request.reject(error)
+    }
+    pending.clear()
+  }
+  target.addEventListener?.("error", (event) => {
+    rejectPending(errorFromEvent(event))
+  })
   target.onmessage = async (evt) => {
     const parsed = JSON.parse(evt.data)
     if (parsed.type === "rpc.result") {
-      const resolve = pending.get(parsed.id)
-      if (resolve) {
-        resolve(parsed.result)
+      const request = pending.get(parsed.id)
+      if (request) {
+        request.resolve(parsed.result)
+        pending.delete(parsed.id)
+      }
+    }
+    if (parsed.type === "rpc.error") {
+      const request = pending.get(parsed.id)
+      if (request) {
+        request.reject(deserializeError(parsed.error))
         pending.delete(parsed.id)
       }
     }
@@ -43,10 +66,16 @@ export function client<T extends Definition>(target: {
   }
   return {
     call<Method extends keyof T>(method: Method, input: Parameters<T[Method]>[0]): Promise<ReturnType<T[Method]>> {
+      if (failed) return Promise.reject(failed)
       const requestId = id++
-      return new Promise((resolve) => {
-        pending.set(requestId, resolve)
-        target.postMessage(JSON.stringify({ type: "rpc.request", method, input, id: requestId }))
+      return new Promise((resolve, reject) => {
+        pending.set(requestId, { resolve, reject })
+        try {
+          target.postMessage(JSON.stringify({ type: "rpc.request", method, input, id: requestId }))
+        } catch (error) {
+          pending.delete(requestId)
+          reject(error)
+        }
       })
     },
     on<Data>(event: string, handler: (data: Data) => void) {
@@ -63,4 +92,34 @@ export function client<T extends Definition>(target: {
   }
 }
 
+function errorFromEvent(event: Event): unknown {
+  const errorEvent = event as { error?: unknown; message?: unknown }
+  if (errorEvent.error) return errorEvent.error
+  if (typeof errorEvent.message === "string" && errorEvent.message) return new Error(errorEvent.message)
+  return new Error("Worker failed")
+}
+
+function serializeError(error: unknown): unknown {
+  if (!(error instanceof Error)) return error
+  return {
+    ...Object.fromEntries(Object.getOwnPropertyNames(error).map((key) => [key, error[key as keyof Error]])),
+    name: error.name,
+    message: error.message,
+    stack: error.stack,
+    cause: serializeError(error.cause),
+  }
+}
+
+function deserializeError(input: unknown): unknown {
+  if (!input || typeof input !== "object" || !("message" in input)) return input
+  const serialized = input as { name?: unknown; message?: unknown; stack?: unknown; cause?: unknown }
+  const error = new Error(typeof serialized.message === "string" ? serialized.message : String(serialized.message), {
+    cause: deserializeError(serialized.cause),
+  })
+  if (typeof serialized.name === "string") error.name = serialized.name
+  if (typeof serialized.stack === "string") error.stack = serialized.stack
+  Object.assign(error, input)
+  return error
+}
+
 export * as Rpc from "./rpc"
diff --git a/packages/opencode/test/util/rpc.test.ts b/packages/opencode/test/util/rpc.test.ts
new file mode 100644
index 00000000000..ba25531b09d
--- /dev/null
+++ b/packages/opencode/test/util/rpc.test.ts
@@ -0,0 +1,50 @@
+import { describe, expect, test } from "bun:test"
+import { Rpc } from "@/util/rpc"
+
+type TestRpc = {
+  fail(input: undefined): Promise<void>
+}
+
+type Target = Parameters<typeof Rpc.client<TestRpc>>[0]
+
+describe("Rpc", () => {
+  test("rejects pending calls when the worker reports an error", async () => {
+    const target: Target = {
+      postMessage(data) {
+        const request = JSON.parse(data)
+        target.onmessage?.call(
+          {} as Worker,
+          {
+            data: JSON.stringify({
+              type: "rpc.error",
+              id: request.id,
+              error: { name: "Error", message: "boom", stack: "Error: boom" },
+            }),
+          } as MessageEvent<any>,
+        )
+      },
+      onmessage: null,
+    }
+
+    await expect(Rpc.client<TestRpc>(target).call("fail", undefined)).rejects.toThrow("boom")
+  })
+
+  test("rejects pending and future calls when the worker crashes", async () => {
+    let onError: ((event: Event) => void) | undefined
+    const target: Target = {
+      postMessage() {},
+      onmessage: null,
+      addEventListener(type, listener) {
+        if (type !== "error" || typeof listener !== "function") return
+        onError = (event) => listener.call({} as Worker, event)
+      },
+    }
+    const client = Rpc.client<TestRpc>(target)
+    const pending = client.call("fail", undefined)
+
+    onError?.({ message: "worker crashed" } as Event)
+
+    await expect(pending).rejects.toThrow("worker crashed")
+    await expect(client.call("fail", undefined)).rejects.toThrow("worker crashed")
+  })
+})