diff --git a/packages/core/src/ide/ide-client.ts b/packages/core/src/ide/ide-client.ts
index e9d25f1c013..25793f9956a 100644
--- a/packages/core/src/ide/ide-client.ts
+++ b/packages/core/src/ide/ide-client.ts
@@ -495,23 +495,13 @@ export class IdeClient {
     }
   }
 
-  private registerClientHandlers() {
+  // Must be invoked before client.connect so that errors surfaced during
+  // connection setup or by a long-lived SSE stream are routed through
+  // onerror instead of becoming unhandled promise rejections.
+  private registerTransportHandlers() {
     if (!this.client) {
       return;
     }
-
-    this.client.setNotificationHandler(
-      IdeContextNotificationSchema,
-      (notification) => {
-        ideContextStore.set(notification.params);
-        const isTrusted = notification.params.workspaceState?.isTrusted;
-        if (isTrusted !== undefined) {
-          for (const listener of this.trustChangeListeners) {
-            listener(isTrusted);
-          }
-        }
-      },
-    );
     this.client.onerror = (_error) => {
       const errorMessage = _error instanceof Error ? _error.message : `_error`;
       this.setState(
@@ -527,6 +517,25 @@ export class IdeClient {
         true,
       );
     };
+  }
+
+  private registerClientHandlers() {
+    if (!this.client) {
+      return;
+    }
+
+    this.client.setNotificationHandler(
+      IdeContextNotificationSchema,
+      (notification) => {
+        ideContextStore.set(notification.params);
+        const isTrusted = notification.params.workspaceState?.isTrusted;
+        if (isTrusted !== undefined) {
+          for (const listener of this.trustChangeListeners) {
+            listener(isTrusted);
+          }
+        }
+      },
+    );
     this.client.setNotificationHandler(
       IdeDiffAcceptedNotificationSchema,
       (notification) => {
@@ -597,6 +606,7 @@ export class IdeClient {
           headers: authToken ? { Authorization: `Bearer ${authToken}` } : {},
         },
       });
+      this.registerTransportHandlers();
       await this.client.connect(transport);
       this.registerClientHandlers();
       await this.discoverTools();
@@ -630,6 +640,7 @@ export class IdeClient {
         command,
         args,
       });
+      this.registerTransportHandlers();
       await this.client.connect(transport);
       this.registerClientHandlers();
       await this.discoverTools();