diff --git a/docs/tasks/streams.mdx b/docs/tasks/streams.mdx
index 3a67db2ed..3b7e7c2e6 100644
--- a/docs/tasks/streams.mdx
+++ b/docs/tasks/streams.mdx
@@ -682,6 +682,7 @@ Examples:
 - ❌ `https://api.trigger.dev/\rinternal`
 - ❌ `https://api.trigger.dev/\u200Binternal`
 - ❌ `https://api.trigger.dev/\u200Cinternal`
+- ❌ `https://api.trigger.dev/\u200Dinternal`
 - ❌ `https://api.trigger.dev/\u202Finternal`
 - ❌ `https://api.trigger.dev/\u2028internal`
 - ❌ `https://api.trigger.dev/\u2029internal`
diff --git a/packages/ai/README.md b/packages/ai/README.md
index 6455935d5..0c56d0476 100644
--- a/packages/ai/README.md
+++ b/packages/ai/README.md
@@ -189,6 +189,7 @@ Examples:
 - ❌ `https://api.trigger.dev/\rinternal` (internal carriage-return characters)
 - ❌ `https://api.trigger.dev/\u200Binternal` (internal zero-width-space characters)
 - ❌ `https://api.trigger.dev/\u200Cinternal` (internal zero-width-non-joiner characters)
+- ❌ `https://api.trigger.dev/\u200Dinternal` (internal zero-width-joiner characters)
 - ❌ `https://api.trigger.dev/\u202Finternal` (internal narrow no-break space characters)
 - ❌ `https://api.trigger.dev/\u2028internal` (internal line-separator characters)
 - ❌ `https://api.trigger.dev/\u2029internal` (internal paragraph-separator characters)
diff --git a/packages/ai/src/chatTransport.test.ts b/packages/ai/src/chatTransport.test.ts
index ff5a08819..1c0144e52 100644
--- a/packages/ai/src/chatTransport.test.ts
+++ b/packages/ai/src/chatTransport.test.ts
@@ -852,6 +852,17 @@ describe("TriggerChatTransport", function () {
     }).toThrowError("baseURL must not contain internal whitespace characters");
   });
 
+  it("throws when baseURL contains internal zero-width-joiner characters", function () {
+    expect(function () {
+      new TriggerChatTransport({
+        task: "chat-task",
+        accessToken: "pk_trigger",
+        baseURL: "https://api.trigger.dev/\u200Dinternal",
+        stream: "chat-stream",
+      });
+    }).toThrowError("baseURL must not contain internal whitespace characters");
+  });
+
   it("throws when baseURL contains internal word-joiner characters", function () {
     expect(function () {
       new TriggerChatTransport({
@@ -3613,6 +3624,17 @@ describe("TriggerChatTransport", function () {
     }).toThrowError("baseURL must not contain internal whitespace characters");
   });
 
+  it("throws from factory when baseURL contains internal zero-width-joiner characters", function () {
+    expect(function () {
+      createTriggerChatTransport({
+        task: "chat-task",
+        accessToken: "pk_trigger",
+        baseURL: "https://api.trigger.dev/\u200Dinternal",
+        stream: "chat-stream",
+      });
+    }).toThrowError("baseURL must not contain internal whitespace characters");
+  });
+
   it("throws from factory when baseURL contains internal word-joiner characters", function () {
     expect(function () {
       createTriggerChatTransport({