feat: move termix identity into a plugin (C6)

plugins/termix-identity/src/frontend/linked-store.ts

@@ -0,0 +1,48 @@
+import type { TermixIdApi } from "./api";
+
+/**
+ * Which credentials have a published key, shared by every credential badge
+ * so the list fetches once instead of once per row. The panel calls
+ * refresh() after it publishes or removes a key.
+ */
+export function createLinkedStore(
+  api: TermixIdApi,
+  allowed: () => Promise<boolean>,
+) {
+  let ids = new Set<number>();
+  let loading: Promise<void> | null = null;
+  let loaded = false;
+  const listeners = new Set<() => void>();
+
+  const refresh = (): Promise<void> => {
+    loading = (async () => {
+      try {
+        ids = (await allowed())
+          ? new Set((await api.linkedCredentialIds()).credentialIds)
+          : new Set();
+      } catch {
+        // Badges are a hint; a failed lookup just shows none.
+      }
+      loaded = true;
+      listeners.forEach((listener) => listener());
+    })();
+    return loading;
+  };
+
+  return {
+    has: (id: number) => ids.has(id),
+    ids: () => ids,
+    ensure: () => {
+      if (!loaded && !loading) void refresh();
+    },
+    refresh,
+    subscribe: (listener: () => void) => {
+      listeners.add(listener);
+      return () => {
+        listeners.delete(listener);
+      };
+    },
+  };
+}
+
+export type LinkedStore = ReturnType<typeof createLinkedStore>;