diff --git a/.gitignore b/.gitignore
index d515d75..74dbe87 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,6 +23,7 @@ simulator/sample_media/**/*.m4a
 # Local-only candidate review galleries (re-buildable; not shipped content).
 simulator/static/review.html
 simulator/static/review_audio.html
+simulator/static/review_binaural.html
 
 # Editor annotation/comment-thread metadata (not project content)
 .threads/
diff --git a/docs/binaural-candidate-pool.md b/docs/binaural-candidate-pool.md
new file mode 100644
index 0000000..5f69ea1
--- /dev/null
+++ b/docs/binaural-candidate-pool.md
@@ -0,0 +1,68 @@
+# Binaural / entrainment candidate pool — stress-relief "Music" tracks (2026-07-02)
+
+Candidates for evolving the **Music** audio option into a stress-relief set of
+**binaural-beat / brainwave-entrainment** tracks that **crossfade between each
+other** (not a single loop). Operator brief: "binaural beats for stress relief."
+
+**All 11 below are CC0** (public domain — no attribution legally required; we credit
+anyway as courtesy), **all stereo**, all sourced from freesound.org and license-
+verified by fetching each page. Review gallery (gitignored, local-only, like
+`review_audio.html`): `simulator/static/review_binaural.html` → open
+`/review_binaural.html` with the sim server running. It streams each track's public
+HQ preview so you can audition + tick keepers.
+
+## Caveats (operator, read before picking)
+
+- **True binaural (#1–7) needs headphones.** The beat *is* the L/R frequency
+  difference, so on speakers it collapses to a steady carrier tone (no entrainment).
+  **#8–11** are ambient sub-bass / pulsing drones that keep the calm feel on speakers.
+- **Band coverage:** heavy on **delta (0.5–1.5 Hz)** + one clean **theta (4 Hz, #2)**.
+  **No CC0 alpha (8–12 Hz)** track surfaced — widen to CC-BY (FMA/ccMixter) if wanted.
+- **No clean CC0/CC-BY isochronic or monaural** (the speaker-correct entrainment type)
+  was found — every hit was NC/SA or unlicensed (see rejects). For speaker playback,
+  lean on #8–11 for the "beat" feel.
+- **Previews vs originals:** the `cdn.freesound.org/…-hq.mp3` URLs are public streamable
+  previews (verified live, HTTP 206). The **originals** (WAV/AIF/full-MP3) need a free
+  freesound login; CC0 permits self-hosting, so for keepers download the originals and
+  host on R2 — do not hot-link the CDN in production.
+
+## Candidates
+
+| # | id | title | artist | source page | license | dur | type | beat / carrier |
+|---|---|---|---|---|---|---|---|---|
+| 1 | `fs75309`  | 60-64-delta | iantm | https://freesound.org/people/iantm/sounds/75309/ | CC0 | 0:30 | true-binaural | 4 Hz · 60/64 Hz |
+| 2 | `fs457654` | Binaural Beats (Theta Waves 4 Hz) | Fabrizio84 | https://freesound.org/people/Fabrizio84/sounds/457654/ | CC0 | 30:00 | true-binaural | 4 Hz theta |
+| 3 | `fs803742` | 1.23456789 Hz binaural beat (69L/70.23R) | itchytooth | https://freesound.org/people/itchytooth/sounds/803742/ | CC0 | 60:00 | true-binaural | 1.23 Hz delta · 69/70.23 Hz |
+| 4 | `fs414271` | Binaural Delta 440/440.5 Hz | pbabin | https://freesound.org/people/pbabin/sounds/414271/ | CC0 | 10:00 | true-binaural | 0.5 Hz · 440/440.5 Hz |
+| 5 | `fs414272` | Binaural Delta 500/501.5 Hz | pbabin | https://freesound.org/people/pbabin/sounds/414272/ | CC0 | 10:00 | true-binaural | 1.5 Hz · 500/501.5 Hz |
+| 6 | `fs414273` | Binaural Delta 52/52.5 Hz | pbabin | https://freesound.org/people/pbabin/sounds/414273/ | CC0 | 10:00 | true-binaural | 0.5 Hz · 52/52.5 Hz |
+| 7 | `fs414274` | Binaural Delta 60/61.5 Hz | pbabin | https://freesound.org/people/pbabin/sounds/414274/ | CC0 | 10:00 | true-binaural | 1.5 Hz · 60/61.5 Hz |
+| 8 | `fs856225` | Delta Pulse Subharmonic Drone (MANTICE) | bassimat | https://freesound.org/people/bassimat/sounds/856225/ | CC0 | 5:00 | ambient+beats (speaker-ok) | delta sub-bass (procedural) |
+| 9 | `fs854874` | Void Monolith Subharmonic Drone (MANTICE) | bassimat | https://freesound.org/people/bassimat/sounds/854874/ | CC0 | 5:00 | ambient (speaker-ok) | dark sub-drone |
+| 10 | `fs860122` | Expanding & Vibrating Stereo Pulsating Drone (MANTICE) | bassimat | https://freesound.org/people/bassimat/sounds/860122/ | CC0 | 2:00 | ambient+beats (speaker-ok) | slow stereo pulsation |
+| 11 | `fs493524` | Pulse Breath *(lower pref)* | phylobates | https://freesound.org/people/phylobates/sounds/493524/ | CC0 | 1:40 | ambient binaural | octaves of G / G♭ |
+
+Preview MP3s (for the review page) follow `https://cdn.freesound.org/previews/<dir>/<id>_<uploader>-hq.mp3`
+— exact URLs are embedded in `review_binaural.html`.
+
+## Rejected / could not verify
+
+- **archive.org "Binaural Beats – Alpha/Beta/Theta/Delta"** & **"Isochronic Tones &
+  Binaural Beats Combined"** (loopool / Jean-Paul Garnier) — **CC BY-NC-SA 3.0** (NC).
+  The most promising isochronic set — rejected for the NC clause.
+- **archive.org "Om Alpha Brainwave Entrainment Loop"** (Entraino / KS Chauhan;
+  freesound chauhans/100370) — **CC BY-NC 3.0**. Rejected (NC).
+- **archive.org "1hr 30 Min Theta Binaural Beat (7 Hz)"** (Chari G) — no license shown.
+  Rejected (unverifiable).
+- **freesound "deadthetawaves.wav"** (NoiseCollector/43295) — license fine (**CC BY 3.0**)
+  but "evil sounding loop of the living dead" — rejected for *fit*, not license. Back
+  pocket only if an unsettling deep-scale track is ever wanted.
+- **TunePocket / dialedggsound / miraclefrequencies / audio.com "Theta 7Hz"** —
+  "royalty-free"/commercial pages, murky redistribution, no per-track CC license.
+
+## Next
+
+Operator auditions `review_binaural.html`, ticks keepers (Copy picks). Then we wire the
+playback: the **Music** source becomes a multi-track set that crossfades between the kept
+tracks (architecture decision — replace vs. join the ethereal loop — deferred to that
+step; see [[audio-music-option]]).
diff --git a/simulator/e2e/tests/auto-advance.spec.ts b/simulator/e2e/tests/auto-advance.spec.ts
index 88d5205..fb5e4cf 100644
--- a/simulator/e2e/tests/auto-advance.spec.ts
+++ b/simulator/e2e/tests/auto-advance.spec.ts
@@ -24,15 +24,18 @@ test("auto-advances one altitude (descending) after the idle interval", async ({
   expect(after).toBe((start + 1) % n);   // descended exactly one, wraps
 });
 
-test("toggling Auto-advance off keeps the altitude parked", async ({ page }) => {
-  await boot(page, 1000);
-  await page.evaluate(() => {
-    const c = document.querySelector("#auto-advance") as HTMLInputElement;
-    c.checked = false;
-    c.dispatchEvent(new Event("change", { bubbles: true }));
-  });
+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 });
+  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(2600);       // well past two intervals
+  await page.waitForTimeout(2200);       // well past two 800ms intervals
   expect(await idx(page)).toBe(start);   // never moved
 });