feat: support per-bot workspace switching

plugin-src/client/workspace-snapshot-fence.js

@@ -0,0 +1,28 @@
+import * as React from 'react';
+
+/** Keep every full-snapshot response ordered behind the latest client mutation. */
+export function useWorkspaceSnapshotFence() {
+  const state = React.useRef({ version: 0, pendingMutations: 0 });
+  return React.useMemo(() => Object.freeze({
+    beginStatus() {
+      return state.current.pendingMutations === 0 ? state.current.version : null;
+    },
+    canCommitStatus(version) {
+      return version !== null
+        && state.current.pendingMutations === 0
+        && state.current.version === version;
+    },
+    beginMutation() {
+      state.current.pendingMutations += 1;
+      state.current.version += 1;
+      return state.current.version;
+    },
+    canCommitMutation(version) {
+      return state.current.version === version;
+    },
+    endMutation() {
+      state.current.pendingMutations = Math.max(0, state.current.pendingMutations - 1);
+      return state.current.pendingMutations === 0;
+    },
+  }), []);
+}