🤖 fix: optimize git status polling with subscriber filtering (#705)

_Generated with `mux`_

## Problem
Git status polling was polling all workspaces regardless of visibility,
causing performance issues.

## Solution
- Optimized polling loop to only query workspaces with active
subscribers (visible in sidebar)
- Added unit tests for subscriber filtering logic

Author: ammar-agent

src/browser/stores/GitStatusStore.test.ts

@@ -388,4 +388,39 @@ describe("GitStatusStore", () => {
       unsub();
     });
   });
+
+  test("skips polling when no subscribers", async () => {
+    const metadata = {
+      id: "ws1",
+      name: "main",
+      projectName: "test-project",
+      projectPath: "/path",
+      namedWorkspacePath: "/path",
+      runtimeConfig: DEFAULT_RUNTIME_CONFIG,
+    };
+
+    store.syncWorkspaces(new Map([["ws1", metadata]]));
+
+    // Ensure executeBash is cleared
+    mockExecuteBash.mockClear();
+
+    // Trigger update
+    // @ts-expect-error - Accessing private method
+    await store.updateGitStatus();
+
+    // Should not have called executeBash because no subscribers
+    expect(mockExecuteBash).not.toHaveBeenCalled();
+
+    // Add a subscriber
+    const unsub = store.subscribeKey("ws1", jest.fn());
+
+    // Trigger update again
+    // @ts-expect-error - Accessing private method
+    await store.updateGitStatus();
+
+    // Should have called executeBash
+    expect(mockExecuteBash).toHaveBeenCalled();
+
+    unsub();
+  });
 });

src/browser/stores/GitStatusStore.ts

@@ -146,12 +146,21 @@ export class GitStatusStore {
       return;
     }
 
+    // Only poll workspaces that have active subscribers
+    const workspaces = Array.from(this.workspaceMetadata.values()).filter((ws) =>
+      this.statuses.hasKeySubscribers(ws.id)
+    );
+
+    if (workspaces.length === 0) {
+      return;
+    }
+
     // Try to fetch workspaces that need it (background, non-blocking)
-    this.tryFetchWorkspaces(this.workspaceMetadata);
+    const workspacesMap = new Map(workspaces.map((ws) => [ws.id, ws]));
+    this.tryFetchWorkspaces(workspacesMap);
 
     // Query git status for each workspace
     // Rate limit: Process in batches to prevent bash process explosion
-    const workspaces = Array.from(this.workspaceMetadata.values());
     const results: Array<[string, GitStatus | null]> = [];
 
     for (let i = 0; i < workspaces.length; i += MAX_CONCURRENT_GIT_OPS) {

src/browser/stores/MapStore.ts

@@ -190,6 +190,13 @@ export class MapStore<K, V> {
     };
   }
 
+  /**
+   * Check if there are subscribers for a specific key.
+   */
+  hasKeySubscribers(key: K): boolean {
+    return this.perKey.has(key);
+  }
+
   private makeCacheKey(key: K, version: number): string {
     return `${String(key)}:${version}`;
   }