Validate normalized baseURL cannot be empty

Co-authored-by: Eric Allam <eric@trigger.dev>

Author: cursoragent

docs/tasks/streams.mdx

@@ -654,7 +654,8 @@ Subsequent reconnect calls will retry stale inactive-state cleanup until it succ
 If `onError` is omitted, reconnect still returns `null` and continues without callback reporting.
 
 `baseURL` supports optional path prefixes and trailing slashes; both trigger and stream URLs
-are normalized consistently, and surrounding whitespace is trimmed before normalization.
+are normalized consistently, surrounding whitespace is trimmed before normalization, and
+the resulting value must not be empty.
 
 For richer TypeScript ergonomics in app code, `@trigger.dev/ai` also exports:
 

packages/ai/CHANGELOG.md

@@ -21,3 +21,4 @@
 - Added retry semantics for stale inactive reconnect cleanup on subsequent reconnect attempts.
 - Added consistent baseURL normalization for trigger and stream endpoints (including path prefixes and trailing slashes).
 - Added surrounding-whitespace trimming for `baseURL` before endpoint normalization.
+- Added explicit validation that `baseURL` is non-empty after normalization.

packages/ai/README.md

@@ -160,6 +160,7 @@ both cleanup steps (`set` inactive state and `delete`) even if one of them fails
 - `baseURL` supports optional path prefixes (for example reverse-proxy mounts).
 - Trailing slashes are normalized automatically before trigger/stream requests.
 - Surrounding whitespace is trimmed before normalization.
+- `baseURL` must not be empty after trimming/normalization.
 
 ## `ai.tool(...)` example
 

packages/ai/src/chatTransport.test.ts

@@ -609,6 +609,17 @@ describe("TriggerChatTransport", function () {
     expect(observedStreamPath).toBe("/trimmed-prefix/realtime/v1/streams/run_trimmed_prefix/chat-stream");
   });
 
+  it("throws when baseURL is empty after trimming", function () {
+    expect(function () {
+      new TriggerChatTransport({
+        task: "chat-task",
+        accessToken: "pk_trigger",
+        baseURL: "   ///   ",
+        stream: "chat-stream",
+      });
+    }).toThrowError("baseURL must not be empty");
+  });
+
   it("combines path prefixes with run and stream URL encoding", async function () {
     let observedTriggerPath: string | undefined;
     let observedStreamPath: string | undefined;

packages/ai/src/chatTransport.ts

@@ -460,7 +460,13 @@ function resolvePayloadMapper<
 }
 
 function normalizeBaseUrl(baseURL: string) {
-  return baseURL.trim().replace(/\/+$/, "");
+  const normalizedBaseUrl = baseURL.trim().replace(/\/+$/, "");
+
+  if (normalizedBaseUrl.length === 0) {
+    throw new Error("baseURL must not be empty");
+  }
+
+  return normalizedBaseUrl;
 }
 
 function createTransportRequest<UI_MESSAGE extends UIMessage>(