Create standalone browser port of LTX Athena with authenticated native API transport

frontend/lib/generation-active.ts

@@ -0,0 +1,43 @@
+import { useSyncExternalStore } from 'react'
+
+// Local, live "is a generation running?" signal for the renderer UI.
+// Ref-counted because generations can overlap.
+let activeCount = 0
+const listeners = new Set<() => void>()
+function emit() { for (const l of listeners) l() }
+
+function subscribe(cb: () => void): () => void {
+  listeners.add(cb)
+  return () => { listeners.delete(cb) }
+}
+function getSnapshot(): boolean {
+  return activeCount > 0
+}
+
+export function useIsGenerationActive(): boolean {
+  return useSyncExternalStore(subscribe, getSnapshot, getSnapshot)
+}
+
+// Local generation can starve the backend's event loop; withGenerationActive tells main so the
+// liveness monitor doesn't kill a busy backend. We also keep a local count for the UI signal above.
+export async function withGenerationActive<T>(fn: () => Promise<T>): Promise<T> {
+  activeCount += 1; emit()
+  void window.electronAPI.notifyGenerationActive({ active: true })
+  try {
+    return await fn()
+  } finally {
+    activeCount = Math.max(0, activeCount - 1); emit()
+    void window.electronAPI.notifyGenerationActive({ active: false })
+  }
+}
+
+/** Evaluate at job start and freeze — live Settings must not flip Stop mid-request. */
+export function canCancelLocalJob(
+  kind: 'video' | 'image',
+  videoUsesLtxApi: boolean,
+  imageUsesFalApi: boolean,
+): boolean {
+  if (kind === 'image') return !imageUsesFalApi
+  if (kind === 'video') return !videoUsesLtxApi
+  return false
+}