diff --git a/__tests__/e2e.test.ts b/__tests__/e2e.test.ts
index 1071f857..b94b968f 100644
--- a/__tests__/e2e.test.ts
+++ b/__tests__/e2e.test.ts
@@ -422,6 +422,151 @@ describe.each(testMatrix())(
       });
     });
 
+    test('defaultCallOptions provides signal when caller omits it', async () => {
+      const clientTransport = getClientTransport('client');
+      const serverTransport = getServerTransport();
+      const services = { subscribable: SubscribableServiceSchema };
+      const server = createServer(serverTransport, services);
+      const abortController = new AbortController();
+      const client = createClient<typeof services>(
+        clientTransport,
+        serverTransport.clientId,
+        { defaultCallOptions: { signal: abortController.signal } },
+      );
+      addPostTestCleanup(async () => {
+        await cleanupTransports([clientTransport, serverTransport]);
+      });
+
+      // No signal passed at the call site — comes from defaultCallOptions.
+      const { resReadable } = client.subscribable.value.subscribe({});
+      let result = await readNextResult(resReadable);
+      expect(result).toStrictEqual({ ok: true, payload: { result: 0 } });
+
+      abortController.abort();
+      result = await readNextResult(resReadable);
+      expect(result).toStrictEqual({
+        ok: false,
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+        payload: expect.objectContaining({ code: CANCEL_CODE }),
+      });
+      expect(await isReadableDone(resReadable)).toEqual(true);
+
+      await testFinishesCleanly({
+        clientTransports: [clientTransport],
+        serverTransport,
+        server,
+      });
+    });
+
+    test('caller-supplied signal overrides defaultCallOptions', async () => {
+      const clientTransport = getClientTransport('client');
+      const serverTransport = getServerTransport();
+      const services = { subscribable: SubscribableServiceSchema };
+      const server = createServer(serverTransport, services);
+      const defaultAc = new AbortController();
+      const callerAc = new AbortController();
+      const client = createClient<typeof services>(
+        clientTransport,
+        serverTransport.clientId,
+        { defaultCallOptions: { signal: defaultAc.signal } },
+      );
+      addPostTestCleanup(async () => {
+        await cleanupTransports([clientTransport, serverTransport]);
+      });
+
+      // Caller signal is the one that should drive cancellation.
+      const { resReadable } = client.subscribable.value.subscribe(
+        {},
+        { signal: callerAc.signal },
+      );
+      let result = await readNextResult(resReadable);
+      expect(result).toStrictEqual({ ok: true, payload: { result: 0 } });
+
+      // Aborting the default-options signal must NOT cancel — caller wins.
+      defaultAc.abort();
+      const add1 = await client.subscribable.add.rpc({ n: 1 });
+      expect(add1).toMatchObject({ ok: true });
+      result = await readNextResult(resReadable);
+      expect(result).toStrictEqual({ ok: true, payload: { result: 1 } });
+
+      // Aborting the caller signal cancels.
+      callerAc.abort();
+      result = await readNextResult(resReadable);
+      expect(result).toStrictEqual({
+        ok: false,
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+        payload: expect.objectContaining({ code: CANCEL_CODE }),
+      });
+      expect(await isReadableDone(resReadable)).toEqual(true);
+
+      await testFinishesCleanly({
+        clientTransports: [clientTransport],
+        serverTransport,
+        server,
+      });
+    });
+
+    test('function-form defaultCallOptions is resolved per call', async () => {
+      const clientTransport = getClientTransport('client');
+      const serverTransport = getServerTransport();
+      const services = { subscribable: SubscribableServiceSchema };
+      const server = createServer(serverTransport, services);
+      let currentSignal: AbortSignal | undefined;
+      const client = createClient<typeof services>(
+        clientTransport,
+        serverTransport.clientId,
+        { defaultCallOptions: () => ({ signal: currentSignal }) },
+      );
+      addPostTestCleanup(async () => {
+        await cleanupTransports([clientTransport, serverTransport]);
+      });
+
+      // Each subscribe resolves the getter at call time, so each call
+      // captures whatever signal is current.
+      const ac1 = new AbortController();
+      currentSignal = ac1.signal;
+      const sub1 = client.subscribable.value.subscribe({});
+
+      const ac2 = new AbortController();
+      currentSignal = ac2.signal;
+      const sub2 = client.subscribable.value.subscribe({});
+
+      let r1 = await readNextResult(sub1.resReadable);
+      let r2 = await readNextResult(sub2.resReadable);
+      expect(r1).toStrictEqual({ ok: true, payload: { result: 0 } });
+      expect(r2).toStrictEqual({ ok: true, payload: { result: 0 } });
+
+      // ac1 cancels sub1 only — sub2 keeps streaming.
+      ac1.abort();
+      r1 = await readNextResult(sub1.resReadable);
+      expect(r1).toStrictEqual({
+        ok: false,
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+        payload: expect.objectContaining({ code: CANCEL_CODE }),
+      });
+      expect(await isReadableDone(sub1.resReadable)).toEqual(true);
+
+      const add1 = await client.subscribable.add.rpc({ n: 1 });
+      expect(add1).toMatchObject({ ok: true });
+      r2 = await readNextResult(sub2.resReadable);
+      expect(r2).toStrictEqual({ ok: true, payload: { result: 1 } });
+
+      ac2.abort();
+      r2 = await readNextResult(sub2.resReadable);
+      expect(r2).toStrictEqual({
+        ok: false,
+        // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+        payload: expect.objectContaining({ code: CANCEL_CODE }),
+      });
+      expect(await isReadableDone(sub2.resReadable)).toEqual(true);
+
+      await testFinishesCleanly({
+        clientTransports: [clientTransport],
+        serverTransport,
+        server,
+      });
+    });
+
     test('subscription idempotent close', async () => {
       // setup
       const clientTransport = getClientTransport('client');
diff --git a/package-lock.json b/package-lock.json
index bb735940..dedd385b 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@replit/river",
-  "version": "0.216.0",
+  "version": "0.216.1",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "@replit/river",
-      "version": "0.216.0",
+      "version": "0.216.1",
       "license": "MIT",
       "dependencies": {
         "@bufbuild/protobuf": "^2.11.0",
diff --git a/package.json b/package.json
index adccb671..d899c78b 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "@replit/river",
   "description": "It's like tRPC but... with JSON Schema Support, duplex streaming and support for service multiplexing. Transport agnostic!",
-  "version": "0.216.0",
+  "version": "0.216.1",
   "type": "module",
   "exports": {
     ".": {
diff --git a/router/client.ts b/router/client.ts
index 818a02bc..f3c6fb52 100644
--- a/router/client.ts
+++ b/router/client.ts
@@ -37,7 +37,7 @@ import {
   UNEXPECTED_DISCONNECT_CODE,
 } from './errors';
 
-interface CallOptions {
+export interface CallOptions {
   signal?: AbortSignal;
 }
 
@@ -205,6 +205,16 @@ function _createRecursiveProxy(
 export interface ClientOptions {
   connectOnInvoke: boolean;
   eagerlyConnect: boolean;
+  /**
+   * Default options merged into every leaf call (`rpc`, `stream`,
+   * `upload`, `subscribe`). Caller-supplied `options` win field-by-field,
+   * so a caller can override `signal` while keeping other defaults.
+   *
+   * Pass a function form when the default needs to be re-resolved per
+   * call (e.g. an ambient signal that changes between invocations of
+   * the same client).
+   */
+  defaultCallOptions?: CallOptions | (() => CallOptions);
 }
 
 const defaultClientOptions: ClientOptions = {
@@ -273,6 +283,11 @@ export function createClient<ServiceSchemaMap extends AnyServiceSchemaMap<any>>(
       );
     }
 
+    const merged = mergeCallOptions(
+      clientOptions.defaultCallOptions,
+      callOptions as CallOptions | undefined,
+    );
+
     return handleProc(
       procMethod === 'subscribe' ? 'subscription' : procMethod,
       transport,
@@ -280,11 +295,21 @@ export function createClient<ServiceSchemaMap extends AnyServiceSchemaMap<any>>(
       init,
       serviceName,
       procName,
-      callOptions ? (callOptions as CallOptions).signal : undefined,
+      merged.signal,
     );
   }, []) as Client<ServiceSchemaMap>;
 }
 
+function mergeCallOptions(
+  defaults: ClientOptions['defaultCallOptions'],
+  caller: CallOptions | undefined,
+): CallOptions {
+  const resolved = typeof defaults === 'function' ? defaults() : defaults ?? {};
+
+  // Caller fields win: spread defaults first, caller second.
+  return { ...resolved, ...caller };
+}
+
 type AnyProcReturn =
   | ReturnType<RpcFn<AnyService, string>>
   | ReturnType<UploadFn<AnyService, string>>
diff --git a/router/index.ts b/router/index.ts
index e6738093..f748101b 100644
--- a/router/index.ts
+++ b/router/index.ts
@@ -43,7 +43,7 @@ export {
   BaseErrorSchemaType,
 } from './errors';
 export { createClient } from './client';
-export type { Client } from './client';
+export type { CallOptions, Client, ClientOptions } from './client';
 export { createServer } from './server';
 export type {
   Server,