diff --git a/simulator/e2e/tests/auto-advance.spec.ts b/simulator/e2e/tests/auto-advance.spec.ts
index fb5e4cf..0eddd30 100644
--- a/simulator/e2e/tests/auto-advance.spec.ts
+++ b/simulator/e2e/tests/auto-advance.spec.ts
@@ -1,55 +1,56 @@
 import { test, expect, Page } from "@playwright/test";
 
-// Auto-advance: after the dial sits idle for the interval, the altitude drifts one
-// step deeper (descend), wrapping past the deepest. A default-on toggle disables it.
-// The e2e injects a short interval via window.__hefAutoAdvanceMs before load.
+// Auto-advance moves to the next altitude when the altitude's loop VIDEO completes a
+// playthrough (not on a fixed timer). Descends one step + wraps; a default-on toggle
+// disables it; manual drag / a playing morph defer it. The e2e simulates a completed
+// loop by dispatching the loop element's "ended" (the wrap-point and ended share the
+// same advance path).
 
-async function boot(page: Page, intervalMs: number) {
-  await page.addInitScript((ms) => { (window as any).__hefAutoAdvanceMs = ms; }, intervalMs);
+async function boot(page: Page) {
   await page.goto("/");
   await page.waitForFunction(() => (window as any).__hefReady === true, null, { timeout: 45_000 });
   await page.locator("#welcome-launch").click();
   await page.waitForSelector("#welcome", { state: "detached", timeout: 10_000 });
+  await expect(page.locator("#scale-name")).toContainText("cosmos");
+}
+const state = (page: Page) => page.evaluate(() => (window as any).__hefState());
+const idx = async (page: Page) => (await state(page)).ringIndex as number;
+
+// Simulate the loop video finishing one playthrough.
+async function completeLoopVideo(page: Page) {
+  await page.evaluate(() => {
+    const v = document.querySelector("#vid-loop") as HTMLVideoElement;
+    v.dataset.loopTail = "1";              // armed, as after a real landing
+    v.dispatchEvent(new Event("ended"));
+  });
 }
 
-const idx = (page: Page) => page.evaluate(() => (window as any).__hefState().ringIndex as number);
-
-test("auto-advances one altitude (descending) after the idle interval", async ({ page }) => {
-  await boot(page, 1200);
-  const n = await page.evaluate(() => (window as any).__hefState && (document.querySelectorAll(".dial-label").length));
+test("a completed loop video advances one altitude (descending, wraps)", async ({ page }) => {
+  await boot(page);
+  const n = await page.evaluate(() => document.querySelectorAll(".dial-label").length);
   const start = await idx(page);
-  // Wait past the interval + the morph animation for the landing.
+  await completeLoopVideo(page);
   await page.waitForFunction((s) => (window as any).__hefState().ringIndex !== s, start, { timeout: 8000 });
-  const after = await idx(page);
-  expect(after).toBe((start + 1) % n);   // descended exactly one, wraps
+  expect(await idx(page)).toBe((start + 1) % n);
 });
 
-test("Auto-advance off keeps the altitude parked", async ({ page }) => {
-  // Disable BEFORE launch so the idle timer never arms (deterministic — no race with
-  // the first interval firing during boot).
-  await page.addInitScript(() => { (window as any).__hefAutoAdvanceMs = 800; });
-  await page.goto("/");
-  await page.waitForFunction(() => (window as any).__hefReady === true, null, { timeout: 45_000 });
+test("Auto-advance off: a completed video stays on the altitude", async ({ page }) => {
+  await boot(page);
   await page.evaluate(() => { (document.querySelector("#auto-advance") as HTMLInputElement).checked = false; });
-  await page.locator("#welcome-launch").click();
-  await page.waitForSelector("#welcome", { state: "detached", timeout: 10_000 });
-
   const start = await idx(page);
-  await page.waitForTimeout(2200);       // well past two 800ms intervals
-  expect(await idx(page)).toBe(start);   // never moved
+  await completeLoopVideo(page);
+  await page.waitForTimeout(1500);
+  expect(await idx(page)).toBe(start);
 });
 
-test("the idle countdown resets on interaction (no advance right after a manual turn)", async ({ page }) => {
-  await boot(page, 1500);
-  // Immediately before the first interval elapses, interact (keyboard step). That step
-  // itself advances by 1; the reset then means no AUTO advance fires for another
-  // full interval — so shortly after, we should still be at exactly that +1.
-  await page.waitForTimeout(900);
-  const before = await idx(page);
-  await page.locator("#dial").focus();
-  await page.locator("#dial").press("ArrowDown");            // manual descend + reset
-  await page.waitForFunction((b) => (window as any).__hefState().ringIndex !== b, before, { timeout: 4000 });
-  const manual = await idx(page);
-  await page.waitForTimeout(900);                            // < the 1500ms interval
-  expect(await idx(page)).toBe(manual);                      // countdown reset → no extra auto step yet
+test("keeps touring: a second completed video advances again", async ({ page }) => {
+  await boot(page);
+  const n = await page.evaluate(() => document.querySelectorAll(".dial-label").length);
+  const start = await idx(page);
+  await completeLoopVideo(page);
+  // wait until it has advanced AND settled (pos back on an integer detent)
+  await page.waitForFunction((s) => { const st = (window as any).__hefState(); return st.ringIndex !== s && Number.isInteger(st.pos); }, start, { timeout: 8000 });
+  await completeLoopVideo(page);
+  await page.waitForFunction((a) => (window as any).__hefState().ringIndex === (a.start + 2) % a.n, { start, n }, { timeout: 8000 });
+  expect(await idx(page)).toBe((start + 2) % n);
 });
diff --git a/simulator/e2e/tests/loop-recovery.spec.ts b/simulator/e2e/tests/loop-recovery.spec.ts
index 0352614..1d38f5a 100644
--- a/simulator/e2e/tests/loop-recovery.spec.ts
+++ b/simulator/e2e/tests/loop-recovery.spec.ts
@@ -4,12 +4,16 @@ import { test, expect } from "@playwright/test";
 // offset via a narrow timeupdate window. If that window is ever missed the clip
 // fires `ended` and — without a safety net — freezes on its last frame ("videos
 // aren't looping"). This asserts the `ended` safety net recovers playback.
+// (With Auto-advance ON — the default — a completed video instead moves to the next
+// altitude; that path is covered by auto-advance.spec.ts. Here we disable it to test
+// the loop-back recovery in isolation.)
 test("loop recovers when a clip reaches `ended` (no freeze on last frame)", async ({ page }) => {
   await page.goto("/");
   // Enter via the welcome screen (Video defaults on → the loop video loads).
   await page.waitForFunction(() => (window as any).__hefReady === true, null, { timeout: 45_000 });
   await page.locator("#welcome-launch").click();
   await page.waitForSelector("#welcome", { state: "detached", timeout: 10_000 });
+  await page.evaluate(() => { const c = document.querySelector("#auto-advance") as HTMLInputElement; if (c) c.checked = false; });
   // Wait for the loop video to actually have media before forcing the stuck state.
   await page.waitForFunction(
     () => { const v = document.getElementById("vid-loop") as HTMLVideoElement; return v && v.duration > 0; },
diff --git a/simulator/static/app.js b/simulator/static/app.js
index 55ca8ab..b802d54 100644
--- a/simulator/static/app.js
+++ b/simulator/static/app.js
@@ -328,6 +328,7 @@ function ensureClipMedia() {
 // tail. The morph element (#vid) is driven directly by the scrub.
 loopVid.addEventListener("timeupdate", () => {
   if (loopVid.dataset.loopTail === "1" && loopVid.duration && loopVid.currentTime >= loopVid.duration - 0.08) {
+    if (autoAdvanceOnLoopComplete()) return;   // completed a playthrough → next altitude
     try { loopVid.currentTime = loopStartFrame(); } catch (e) { /* not seekable */ }
   }
 });
@@ -339,6 +340,7 @@ loopVid.addEventListener("timeupdate", () => {
 // rarely hits this; loaded real machines do.
 loopVid.addEventListener("ended", () => {
   if (loopVid.dataset.loopTail !== "1") return;
+  if (autoAdvanceOnLoopComplete()) return;   // completed a playthrough → next altitude
   try { loopVid.currentTime = loopStartFrame(); } catch (e) { /* not seekable */ }
   loopVid.play().catch(() => {});
 });
@@ -848,7 +850,6 @@ function autoScrub(targetPos, perAltMs = PER_ALTITUDE_MS) {
 let wheelAccum = 0, wheelTimer = null;
 function onWheel(e) {
   e.preventDefault();
-  bumpAutoAdvance();
   wheelAccum += e.deltaY;
   clearTimeout(wheelTimer);
   wheelTimer = setTimeout(() => {
@@ -858,26 +859,19 @@ function onWheel(e) {
   }, 90);
 }
 
-// --- Auto-advance: after the dial sits idle for AUTO_ADVANCE_MS, drift one altitude
-// deeper (descend; past the deepest it wraps back to the top), a slow kiosk tour. Any
-// manual interaction restarts the idle countdown; a default-on toggle disables it.
-// (E2E injects a short interval via window.__hefAutoAdvanceMs before load.)
-const AUTO_ADVANCE_MS = (typeof window !== "undefined" && window.__hefAutoAdvanceMs) || 60000;
-let autoAdvanceTimer = null;
+// --- Auto-advance: when the altitude's base loop VIDEO completes one playthrough, drift
+// one altitude deeper (descend; past the deepest it wraps back to the top) — a slow kiosk
+// tour paced by the footage itself. A default-on toggle disables it; a manual drag or a
+// playing morph defers the move (it happens on the NEXT completion instead). Hooked into
+// the loop element's completion points (the timeupdate wrap + the ended safety net).
 function autoAdvanceOn() { const el = $("auto-advance"); return el ? el.checked : true; }
-function scheduleAutoAdvance() {
-  clearTimeout(autoAdvanceTimer);
-  autoAdvanceTimer = null;
-  if (!autoAdvanceOn() || !videoEverOn) return;   // only while the experience is running
-  autoAdvanceTimer = setTimeout(onAutoAdvance, AUTO_ADVANCE_MS);
+function autoAdvanceOnLoopComplete() {
+  if (autoAdvanceOn() && videoEverOn && !dialDrag && !busy) {
+    autoScrub(Math.round(pos) + 1);   // completed a playthrough → next altitude
+    return true;                      // advanced — caller skips the normal loop-back
+  }
+  return false;
 }
-function onAutoAdvance() {
-  // Skip a beat (but keep the cadence) if the visitor is mid-drag or a morph is playing.
-  if (autoAdvanceOn() && videoEverOn && !dialDrag && !busy) autoScrub(Math.round(pos) + 1);
-  scheduleAutoAdvance();
-}
-// Restart the idle countdown on any manual interaction (drag/wheel/key/knob).
-function bumpAutoAdvance() { if (videoEverOn) scheduleAutoAdvance(); }
 
 // --- Altitude knob: the endless rotary encoder, drawn as a turnable dial ---
 // cosmos (highest) sits at the top; turning CLOCKWISE descends through the scales
@@ -1086,7 +1080,6 @@ function setPos(next) {
 function onDialDown(e) {
   if (!ring || ring.scales.length < 2) return;
   e.preventDefault();
-  bumpAutoAdvance();
   dialDrag = { lastAng: dialAngle(e), accum: 0, moved: 0, target: e.target, restPos: pos };
 }
 function onDialMove(e) {
@@ -1113,7 +1106,6 @@ function onDialUp(e) {
   // short way to the CLOSEST one and settle there (frac 0 locks). The result is the
   // same as a tap/label-click: a grab-and-release always lands on a discrete altitude.
   autoScrub(Math.round(pos));
-  bumpAutoAdvance();
 }
 
 // Click a label → auto-scrub the SHORTEST signed way around the ring to that scale.
@@ -1144,7 +1136,7 @@ function onDialKey(e) {
     case "End":  jumpToScale(ring.scales.length - 1); break;
     default: handled = false;
   }
-  if (handled) { e.preventDefault(); bumpAutoAdvance(); }
+  if (handled) e.preventDefault();
 }
 
 // --- Dev Mode: pool picker + live analysis, all under one toggle ---
@@ -1695,7 +1687,6 @@ function beginExperience() {
   updateAudioLevelLabel();
   applyAudio();
   applyPlaySpeed();
-  scheduleAutoAdvance();   // start the idle-drift countdown now that we're running
 }
 
 // Welcome screen ----------------------------------------------------------------
@@ -1770,9 +1761,7 @@ async function main() {
   initWelcome();              // wire the welcome-screen controls + Launch button
   renderScaleReadout();
   // Sliders stream on "input"; the toggles fire on "change".
-  for (const id of ["left", "right", "mood"]) $(id).addEventListener("input", () => { bumpAutoAdvance(); debounced(); });
-  // Auto-advance toggle: (re)start or cancel the idle-drift countdown on change.
-  $("auto-advance").addEventListener("change", scheduleAutoAdvance);
+  for (const id of ["left", "right", "mood"]) $(id).addEventListener("input", debounced);
   // Audio level dial: set the master soundtrack gain. Reconcile SYNCHRONOUSLY in this
   // input gesture so the first raise from 0 unlocks + plays on Safari (which blocks
   // play() outside a user gesture).