fix: surface git status stream errors to UI via onError callback

The subscribeToGitStatus function only updated the atom's data field on
stream events but never populated error or cause. This meant the error
display UI in GitActionsControl was dead code — gitStatusError was
always null.

Added an onError callback to SubscribeOptions (WsTransport) and
StreamSubscriptionOptions (wsRpcClient), invoked when the stream
disconnects with an error. subscribeToGitStatus now uses this callback
to set the error and cause fields on the git status atom, allowing the
existing UI error rendering path to work.

Author: cursoragent

apps/web/src/lib/gitStatusState.ts

@@ -193,6 +193,17 @@ function subscribeToGitStatus(cwd: string): () => void {
       onResubscribe: () => {
         markGitStatusPending(cwd);
       },
+      onError: (error) => {
+        const atom = gitStatusStateAtom(cwd);
+        const current = appAtomRegistry.get(atom);
+        const cause = Cause.fail(error as GitStatusStreamError);
+        appAtomRegistry.set(atom, {
+          data: current.data,
+          error: error as GitStatusStreamError,
+          cause,
+          isPending: false,
+        });
+      },
     },
   );
 }

apps/web/src/wsRpcClient.ts

@@ -22,6 +22,7 @@ type RpcInput<TTag extends RpcTag> = Parameters<RpcMethod<TTag>>[0];
 
 interface StreamSubscriptionOptions {
   readonly onResubscribe?: () => void;
+  readonly onError?: (error: unknown) => void;
 }
 
 type RpcUnaryMethod<TTag extends RpcTag> =

apps/web/src/wsTransport.ts

@@ -21,6 +21,7 @@ import {
 interface SubscribeOptions {
   readonly retryDelay?: Duration.Input;
   readonly onResubscribe?: () => void;
+  readonly onError?: (error: unknown) => void;
 }
 
 interface RequestOptions {
@@ -147,6 +148,11 @@ export class WsTransport {
           console.warn("WebSocket RPC subscription disconnected", {
             error: formatErrorMessage(error),
           });
+          try {
+            options?.onError?.(error);
+          } catch {
+            // Swallow onError callback errors so the retry loop continues.
+          }
           await sleep(retryDelayMs);
         }
       }