diff --git a/docs/tasks/streams.mdx b/docs/tasks/streams.mdx
index f0ac175de..375cacd2e 100644
--- a/docs/tasks/streams.mdx
+++ b/docs/tasks/streams.mdx
@@ -656,7 +656,8 @@ If `onError` is omitted, reconnect still returns `null` and continues without ca
 `baseURL` supports optional path prefixes and trailing slashes; both trigger and stream URLs
 are normalized consistently, surrounding whitespace is trimmed before normalization, and
 the resulting value must not be empty. The value must also be a valid absolute URL using
-the `http` or `https` protocol, without query parameters or hash fragments.
+the `http` or `https` protocol, without query parameters, hash fragments, or embedded
+username/password credentials.
 
 For richer TypeScript ergonomics in app code, `@trigger.dev/ai` also exports:
 
diff --git a/packages/ai/CHANGELOG.md b/packages/ai/CHANGELOG.md
index 7d61540b2..f298742f4 100644
--- a/packages/ai/CHANGELOG.md
+++ b/packages/ai/CHANGELOG.md
@@ -25,3 +25,4 @@
 - Added explicit validation that `baseURL` is a valid absolute URL.
 - Added explicit validation that `baseURL` uses `http` or `https`.
 - Added explicit validation that `baseURL` excludes query parameters and hash fragments.
+- Added explicit validation that `baseURL` excludes username/password credentials.
diff --git a/packages/ai/README.md b/packages/ai/README.md
index 44c8ef0dc..c83a66a0d 100644
--- a/packages/ai/README.md
+++ b/packages/ai/README.md
@@ -164,6 +164,7 @@ both cleanup steps (`set` inactive state and `delete`) even if one of them fails
 - `baseURL` must be a valid absolute URL.
 - `baseURL` must use the `http` or `https` protocol.
 - `baseURL` must not include query parameters or hash fragments.
+- `baseURL` must not include username/password URL credentials.
 
 ## `ai.tool(...)` example
 
diff --git a/packages/ai/src/chatTransport.test.ts b/packages/ai/src/chatTransport.test.ts
index 4b47251bd..947ba07f6 100644
--- a/packages/ai/src/chatTransport.test.ts
+++ b/packages/ai/src/chatTransport.test.ts
@@ -675,6 +675,17 @@ describe("TriggerChatTransport", function () {
     }).toThrowError("baseURL must not include query parameters or hash fragments");
   });
 
+  it("throws when baseURL includes username or password credentials", function () {
+    expect(function () {
+      new TriggerChatTransport({
+        task: "chat-task",
+        accessToken: "pk_trigger",
+        baseURL: "https://user:pass@example.com/base",
+        stream: "chat-stream",
+      });
+    }).toThrowError("baseURL must not include username or password credentials");
+  });
+
   it("accepts https baseURL values without throwing", function () {
     expect(function () {
       new TriggerChatTransport({
@@ -2925,6 +2936,17 @@ describe("TriggerChatTransport", function () {
     }).toThrowError("baseURL must not include query parameters or hash fragments");
   });
 
+  it("throws from factory when baseURL includes username or password credentials", function () {
+    expect(function () {
+      createTriggerChatTransport({
+        task: "chat-task",
+        accessToken: "pk_trigger",
+        baseURL: "https://user:pass@example.com/base",
+        stream: "chat-stream",
+      });
+    }).toThrowError("baseURL must not include username or password credentials");
+  });
+
   it("accepts https baseURL values from factory without throwing", function () {
     expect(function () {
       createTriggerChatTransport({
diff --git a/packages/ai/src/chatTransport.ts b/packages/ai/src/chatTransport.ts
index aba58f5d2..62fcbe367 100644
--- a/packages/ai/src/chatTransport.ts
+++ b/packages/ai/src/chatTransport.ts
@@ -484,6 +484,10 @@ function normalizeBaseUrl(baseURL: string) {
     throw new Error("baseURL must not include query parameters or hash fragments");
   }
 
+  if (parsedBaseUrl.username.length > 0 || parsedBaseUrl.password.length > 0) {
+    throw new Error("baseURL must not include username or password credentials");
+  }
+
   return normalizedBaseUrl;
 }