feat(app): wire the voyage together

Controller drives world and curtain; caption with Back to sea; play,
previous and next in the timeline bar; keyboard; no-WebGL frieze stage.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/voyage.test.ts

@@ -29,11 +29,13 @@ function fakes() {
     sailTo: (id) => later(`sail:${id}`),
     setLanding: (id) => later(`land:${id}`),
     setRibbons: () => {},
+    horizonFromFrieze: (y) => { log.push(`horizon:${y}`); },
   };
   const curtain: ControllerCurtain = {
     drop: (saga) => later(`drop:${saga}`),
     lift: () => later("lift"),
     fade: () => later("fade"),
+    groundY: () => 500,
   };
   const flush = async () => {
     for (let i = 0; i < 50; i++) {
@@ -57,7 +59,9 @@ test("rapid navigation ends at the last requested song with the curtain lifted",
   const drops = f.log.filter((l) => l.startsWith("drop:") || l === "fade").length;
   const lifts = f.log.filter((l) => l === "lift").length;
   expect(lifts).toBeGreaterThanOrEqual(drops === 0 ? 0 : 1);
-  expect(f.log.at(-1)).toBe("land:arena");
+  // covered → sail → landing → lift: the stage is uncovered last, already inside the arena
+  expect(f.log.lastIndexOf("land:arena")).toBeLessThan(f.log.lastIndexOf("lift"));
+  expect(f.log.at(-1)).toBe("lift");
   expect(ctl.busy()).toBe(false);
 });
 
@@ -71,6 +75,19 @@ test("without a world the controller still follows the songs (frieze-only browsi
   expect(f.log).toContain("drop:cyclops");
 });
 
+test("the horizon is matched to the frieze's ground line before the curtain lifts", async () => {
+  const f = fakes();
+  const store = createStore(DEFAULT_STATE, { history: false });
+  createController({ store, world: f.world, curtain: f.curtain, reducedMotion: false });
+  await f.flush();
+  store.set({ songId: "just-a-man" }); // same saga: no curtain
+  await f.flush();
+  expect(f.log.filter((l) => l.startsWith("horizon:"))).toHaveLength(0);
+  store.set({ songId: "polyphemus" }); // next saga: curtain
+  await f.flush();
+  expect(f.log.indexOf("horizon:500")).toBeLessThan(f.log.lastIndexOf("lift"));
+});
+
 test("reduced motion turns every scene change into a fade", async () => {
   const f = fakes();
   const store = createStore(DEFAULT_STATE, { history: false });
@@ -80,3 +97,17 @@ test("reduced motion turns every scene change into a fade", async () => {
   expect(f.log).toContain("fade");
   expect(f.log.some((l) => l.startsWith("drop:"))).toBe(false);
 });
+
+test("Back to sea leaves the landing without changing the song", async () => {
+  const f = fakes();
+  const store = createStore({ ...DEFAULT_STATE, songId: "survive" }, { history: false });
+  const ctl = createController({ store, world: f.world, curtain: f.curtain, reducedMotion: false });
+  await f.flush();
+  expect(ctl.landing()).toBe("cave");
+  const left = ctl.leaveLanding();
+  await f.flush();
+  await left;
+  expect(f.log.at(-1)).toBe("land:null");
+  expect(ctl.landing()).toBeNull();
+  expect(store.get().songId).toBe("survive");
+});