first publish

src/components/motion/transition-store.ts

@@ -0,0 +1,55 @@
+/**
+ * Tiny framework-free store for the page transition („Umblättern“).
+ * TransitionLink calls `startTransition`; Curtain subscribes, animates,
+ * pushes the route and finally calls `endTransition`.
+ */
+export type TransitionPhase = "idle" | "cover" | "pushed" | "reveal";
+
+export interface TransitionState {
+  phase: TransitionPhase;
+  href: string | null;
+  label?: string;
+}
+
+type Listener = (state: TransitionState) => void;
+
+let state: TransitionState = { phase: "idle", href: null };
+const listeners = new Set<Listener>();
+
+function emit() {
+  listeners.forEach((cb) => cb(state));
+}
+
+/** Begins a transition. Returns false when one is already running (double clicks). */
+export function startTransition(href: string, label?: string): boolean {
+  if (state.phase !== "idle") return false;
+  state = { phase: "cover", href, label };
+  emit();
+  return true;
+}
+
+/** Internal: Curtain advances the phase. */
+export function setTransitionPhase(phase: TransitionPhase) {
+  state = { ...state, phase };
+  emit();
+}
+
+export function endTransition() {
+  state = { phase: "idle", href: null };
+  emit();
+}
+
+export function isTransitioning(): boolean {
+  return state.phase !== "idle";
+}
+
+export function getTransitionState(): TransitionState {
+  return state;
+}
+
+export function subscribe(cb: Listener): () => void {
+  listeners.add(cb);
+  return () => {
+    listeners.delete(cb);
+  };
+}