diff --git a/.changeset/smart-coins-hammer.md b/.changeset/smart-coins-hammer.md
new file mode 100644
index 0000000000..bea810c6ca
--- /dev/null
+++ b/.changeset/smart-coins-hammer.md
@@ -0,0 +1,5 @@
+---
+"@trigger.dev/core": patch
+---
+
+fix: Realtime streams: prevent enqueuing into closed ReadableStream
diff --git a/packages/core/src/v3/apiClient/stream.ts b/packages/core/src/v3/apiClient/stream.ts
index 77487954cf..d73d7d4a3f 100644
--- a/packages/core/src/v3/apiClient/stream.ts
+++ b/packages/core/src/v3/apiClient/stream.ts
@@ -89,8 +89,10 @@ class ReadableShapeStream<T extends Row<unknown> = Row> {
   readonly #changeStream: AsyncIterableStream<T>;
   #error: FetchError | false = false;
   #unsubscribe?: () => void;
+  #isStreamClosed: boolean = false;
 
   stop() {
+    this.#isStreamClosed = true;
     this.#unsubscribe?.();
   }
 
@@ -101,52 +103,69 @@ class ReadableShapeStream<T extends Row<unknown> = Row> {
     const source = new ReadableStream<Message<T>[]>({
       start: (controller) => {
         this.#unsubscribe = this.#stream.subscribe(
-          (messages) => controller.enqueue(messages),
+          (messages) => {
+            if (!this.#isStreamClosed) {
+              controller.enqueue(messages);
+            }
+          },
           this.#handleError.bind(this)
         );
       },
+      cancel: () => {
+        this.#isStreamClosed = true;
+        this.#unsubscribe?.();
+      }
     });
 
     // Create the transformed stream that processes messages and emits complete rows
     this.#changeStream = createAsyncIterableStream(source, {
       transform: (messages, controller) => {
-        const updatedKeys = new Set<string>();
-
-        for (const message of messages) {
-          if (isChangeMessage(message)) {
-            const key = message.key;
-            switch (message.headers.operation) {
-              case "insert": {
-                // New row entirely
-                this.#currentState.set(key, message.value);
-                updatedKeys.add(key);
-                break;
+        if (this.#isStreamClosed) {
+          return;
+        }
+
+        try {
+          const updatedKeys = new Set<string>();
+
+          for (const message of messages) {
+            if (isChangeMessage(message)) {
+              const key = message.key;
+              switch (message.headers.operation) {
+                case "insert": {
+                  this.#currentState.set(key, message.value);
+                  updatedKeys.add(key);
+                  break;
+                }
+                case "update": {
+                  const existingRow = this.#currentState.get(key);
+                  const updatedRow = existingRow
+                    ? { ...existingRow, ...message.value }
+                    : message.value;
+                  this.#currentState.set(key, updatedRow);
+                  updatedKeys.add(key);
+                  break;
+                }
               }
-              case "update": {
-                // Merge updates into existing row if any, otherwise treat as new
-                const existingRow = this.#currentState.get(key);
-                const updatedRow = existingRow
-                  ? { ...existingRow, ...message.value }
-                  : message.value;
-                this.#currentState.set(key, updatedRow);
-                updatedKeys.add(key);
-                break;
+            } else if (isControlMessage(message)) {
+              if (message.headers.control === "must-refetch") {
+                this.#currentState.clear();
+                this.#error = false;
               }
             }
-          } else if (isControlMessage(message)) {
-            if (message.headers.control === "must-refetch") {
-              this.#currentState.clear();
-              this.#error = false;
-            }
           }
-        }
 
-        // Now enqueue only one updated row per key, after all messages have been processed.
-        for (const key of updatedKeys) {
-          const finalRow = this.#currentState.get(key);
-          if (finalRow) {
-            controller.enqueue(finalRow);
+          // Now enqueue only one updated row per key, after all messages have been processed.
+          if (!this.#isStreamClosed) {
+            for (const key of updatedKeys) {
+              const finalRow = this.#currentState.get(key);
+              if (finalRow) {
+                controller.enqueue(finalRow);
+              }
+            }
           }
+        } catch (error) {
+          console.error("Error processing stream messages:", error);
+          this.#handleError(error as Error);
         }
       },
     });
@@ -192,6 +211,8 @@ class ReadableShapeStream<T extends Row<unknown> = Row> {
     if (e instanceof FetchError) {
       this.#error = e;
     }
+    this.#isStreamClosed = true;
+    this.#unsubscribe?.();
   }
 }