claim human-experience-filter-art session 0019 (placeholder) + sessions.json entry

The affect channel previously gated on BOTH knobs (strength = min(left, right)),
so the analytical Left brain co-controlled the emotion words. Per operator
direction, emotions are now driven by the Right (dreamlike) knob ALONE — Left no
longer gates them. This sharpens the split: Left = measurement (detections +
measurements), Right = the dream AND the feeling it evokes.

- player/alteration.py: `_affect_strength(right) = right` (was min(left,right));
  `_affect_intensity` keyed off Right. AffectOverlay + is_identity docs updated
  (is_identity still holds: right>0 ⇒ dream.strength>0).
- simulator/static/app.js: renderAffect comments (gating is Right via `strength`);
  the client logic already keyed min_level/tier off the passed strength + right.
- Affect design spec: revision note + every min(left,right) → right.
- Tests rewritten: affect is Right-driven (full Right + Left 0 surfaces affect;
  Right 0 + Left 4 surfaces none).

271 passed, 2 skipped. Live API verified: left=0/right=4 → strength 4; left=4/
right=0 → strength 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/superpowers/specs/2026-06-22-affect-channel-hud-design.md

@@ -1,27 +1,36 @@
 # Affect channel — emotions in the Left-brain HUD
 
-**Status:** approved (session 0013, 2026-06-22)
+**Status:** approved (session 0013, 2026-06-22); **revised session 0018, 2026-06-26**
 **Surface:** simulator preview (`simulator/`, `player/alteration.py`)
 **Builds on:** the machine-altered-perception design SPEC; the Left HUD look-and-feel
 pass (same session).
 
+> **Revision (session 0018) — affect is a RIGHT-brain output.** The original design
+> gated emotions on *both* knobs (`strength = min(left, right)`). Per operator
+> direction, **emotions are now controlled by the Right (dreamlike) knob alone** —
+> the analytical Left knob no longer gates them. This sharpens the left/right split:
+> Left = measurement (detections + measurements), Right = the dream **and** the
+> feeling it evokes. Every `min(left, right)` below now reads `right`. The data
+> shape, rendering, and per-word `min_level` mechanic are unchanged — only the knob
+> the strength is keyed off.
+
 ## Idea
 
 A third HUD channel beside the cyan *detections* and amber *measurements*: soft,
 glowing **emotion-words** that surface the feelings the experience may invoke.
-They appear only when *both* the analytical (Left) and dreamlike (Right) knobs are
-up — the dream leaking into the machine's reading. This is the uncanny edge of the
-thesis: the machine trying to quantify not just what is there, but how you are
-meant to feel.
+They are a **right-brain output: driven by the dreamlike Right knob alone** (the
+analytical Left knob does not gate them) — the dream surfacing as the machine's
+felt reading. This is the uncanny edge of the thesis: the machine trying to
+quantify not just what is there, but how you are meant to feel.
 
 ## Behaviour
 
-- **Trigger / intensity.** Affect strength = `min(left, right)` (0–4). Either knob
-  at 0 → no emotions at all. Opacity scales with that strength × `overlay_gain`.
-- **Escalation.** A **stable emotional palette per scene** — higher combined
-  strength reveals *more* words at higher opacity. Each word carries a `min_level`
-  (the same mechanic the detection channel uses), but compared against the
-  *combined* `min(left, right)` strength rather than Left alone.
+- **Trigger / intensity.** Affect strength = `right` (0–4). Right at 0 → no
+  emotions at all, regardless of Left. Opacity scales with that strength ×
+  `overlay_gain`.
+- **Escalation.** A **stable emotional palette per scene** — higher Right reveals
+  *more* words at higher opacity. Each word carries a `min_level` (the same
+  mechanic the detection channel uses), compared against the `right` strength.
 - **Rendering.** Floating words at authored scene positions — **no boxes or
   reticles**, lowercase, semi-transparent with a soft glow, in a distinct **violet**
   register so they read as affective and clearly *softer* than the hard clinical
@@ -33,15 +42,15 @@ Consistent with the existing split (alteration math in Python, label-selection i
 the client):
 
 - `player/alteration.py` gains an `AffectOverlay(strength, intensity)` on the
-  `RenderPlan`. `strength = min(left, right)`; `intensity = clamp(overlay_gain *
-  min(left,right) / KNOB_MAX, 0, 1)`. Returned in `render_plan_to_dict` under
-  `"affect"`. Pure, unit-tested.
+  `RenderPlan`. `strength = right`; `intensity = clamp(overlay_gain * right /
+  KNOB_MAX, 0, 1)`. Returned in `render_plan_to_dict` under `"affect"`. Pure,
+  unit-tested.
 - The simulator client picks *which* words to show by comparing each affect
   entry's `min_level` to `plan.affect.strength`, and renders them at
   `plan.affect.intensity` opacity.
 
-`is_identity` is unaffected: `min(left,right) > 0` implies `left > 0`, which already
-makes `overlay.level > 0`.
+`is_identity` is unaffected: `affect.strength == right`, and `right > 0` already
+makes `dream.strength > 0`.
 
 ## Data
 

player/alteration.py

@@ -88,11 +88,12 @@ class AnalyticalOverlay:
 
 @dataclass(frozen=True)
 class AffectOverlay:
-    """Affect channel (Left x Right): emotion-words surfaced only when BOTH the
-    analytical (Left) and dreamlike (Right) knobs are up. `strength` is
-    `min(left, right)` (0..4) — a runtime affect track picks which feeling words
-    appear by it; `intensity` 0..1 is their opacity. The dream leaking into the
-    machine's reading (affect-channel design, session 0013)."""
+    """Affect channel (RIGHT brain): emotion-words surfaced by the Right (dreamlike)
+    knob alone — the analytical Left knob does NOT gate them. `strength` is the Right
+    knob (0..4) — a runtime affect track picks which feeling words appear by it;
+    `intensity` 0..1 is their opacity. Feeling is the right brain's output, surfaced
+    as the machine's felt reading (affect-channel design, session 0013; Right-only
+    since session 0018)."""
 
     strength: int
     intensity: float
@@ -122,8 +123,9 @@ class RenderPlan:
     @property
     def is_identity(self) -> bool:
         """True when the plan leaves the neutral base un-altered. Affect needs no
-        clause: `min(left,right) > 0` implies `left > 0`, so `overlay.level > 0`
-        already makes a plan with active affect non-identity."""
+        clause: `affect.strength == right`, and `right > 0` already makes
+        `dream.strength > 0`, so an active-affect plan is non-identity via the
+        dream check below."""
         return (
             self.grade.is_identity
             and self.overlay.level == 0
@@ -135,13 +137,14 @@ def _overlay_intensity(left: int, cal: Calibration) -> float:
     return _clamp(cal.overlay_gain * left / KNOB_MAX, 0.0, 1.0)
 
 
-def _affect_strength(left: int, right: int) -> int:
-    """Affect surfaces only when BOTH knobs are up — gated by the smaller one."""
-    return min(left, right)
+def _affect_strength(right: int) -> int:
+    """Affect is a RIGHT-brain output: the emotion channel is driven by the Right
+    (dreamlike) knob alone — the analytical Left knob no longer gates it."""
+    return right
 
 
-def _affect_intensity(left: int, right: int, cal: Calibration) -> float:
-    return _clamp(cal.overlay_gain * _affect_strength(left, right) / KNOB_MAX, 0.0, 1.0)
+def _affect_intensity(right: int, cal: Calibration) -> float:
+    return _clamp(cal.overlay_gain * _affect_strength(right) / KNOB_MAX, 0.0, 1.0)
 
 
 def _dream_intensity(right: int, cal: Calibration) -> float:
@@ -163,8 +166,8 @@ def plan_alteration(
             intensity=_overlay_intensity(coord.left, calibration),
         ),
         affect=AffectOverlay(
-            strength=_affect_strength(coord.left, coord.right),
-            intensity=_affect_intensity(coord.left, coord.right, calibration),
+            strength=_affect_strength(coord.right),
+            intensity=_affect_intensity(coord.right, calibration),
         ),
         dream=Dream(
             strength=coord.right,

sessions/0018/SESSION-0018.0-TRANSCRIPT-2026-06-25T09-42--INPROGRESS.md

@@ -0,0 +1,25 @@
+# Session 0018.0 — Transcript
+
+> App: human-experience-filter-art
+> Start: 2026-06-25T09-42 (PST)
+> Type: planning-and-executing
+> Posture: yolo
+> Claude-Session: b96041e5-c682-49f5-88ee-380ea7abb6af
+> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
+>
+> This file reserves session ID 0018 for human-experience-filter-art. The driver replaces this
+> body with the full transcript and renames the file to its final
+> SESSION-0018.0-TRANSCRIPT-2026-06-25T09-42--<end>.md form at session end.
+
+## Launch prompt
+
+```
+Find a better public-domain nebula flythrough video for the cosmos scale (the current text-free SVS Orion clip lost quality when cropped to remove its text overlay), or upscale the existing one if no better source exists.
+
+```
+
+## Deferred decisions
+
+_Autonomous-mode low-confidence calls the driver made and would have
+liked operator input on. Appended as the session runs; surfaced at
+finalize. Empty if none._

sessions/0019/SESSION-0019.0-TRANSCRIPT-2026-06-26T04-47--INPROGRESS.md

@@ -0,0 +1,25 @@
+# Session 0019.0 — Transcript
+
+> App: human-experience-filter-art
+> Start: 2026-06-26T04-47 (PST)
+> Type: brainstorming
+> Posture: careful
+> Claude-Session: d6ed1203-92b6-471f-80a4-4c773b645ca1
+> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
+>
+> This file reserves session ID 0019 for human-experience-filter-art. The driver replaces this
+> body with the full transcript and renames the file to its final
+> SESSION-0019.0-TRANSCRIPT-2026-06-26T04-47--<end>.md form at session end.
+
+## Launch prompt
+
+```
+Let's start talking about hardware. Let's assume for the first version I'm ok having my computer or laptop do the rendering. We'd still want a controller but it could be connected to the computer via wifi, USB, or bluetooth and would send commands to the software we've already written that would adjust left brain, right brain, etc. We'd prototype this by having a controller simulator run on another device, such as an ipad (just riffing here) but eventually move to a physical remote running on an Arduino or similar
+
+```
+
+## Deferred decisions
+
+_Autonomous-mode low-confidence calls the driver made and would have
+liked operator input on. Appended as the session runs; surfaced at
+finalize. Empty if none._

sessions/sessions.json

@@ -49,5 +49,11 @@
   },
   "0017": {
     "title": ""
+  },
+  "0018": {
+    "title": ""
+  },
+  "0019": {
+    "title": ""
   }
 }

simulator/app.py

@@ -59,6 +59,41 @@ def _asset_version() -> str:
     return hashlib.sha1("|".join(parts).encode()).hexdigest()[:16]
 
 
+# Content-hash tokens for served media, so the client can append `?v=<hash>` to a
+# /media URL. A clip re-baked under the SAME path (e.g. a re-sourced cosmos base)
+# changes its hash → its URL → a fresh fetch, busting any cached prior bytes
+# permanently (even an immutable-pinned entry a plain reload can't revalidate).
+# Cached by (mtime_ns, size) so the full-file hash is recomputed only when the
+# file actually changes — a re-bake is picked up without a server restart.
+_media_hash_cache: dict[str, tuple[int, int, str]] = {}
+
+
+def _media_version(rel: str) -> Optional[str]:
+    """Short content hash of the media file at `rel` under MEDIA_DIR, or None if
+    it's absent. Cheap on repeat calls: re-hashes only when (mtime, size) change."""
+    path = MEDIA_DIR / rel
+    try:
+        st = path.stat()
+    except OSError:
+        return None
+    cached = _media_hash_cache.get(rel)
+    if cached and cached[0] == st.st_mtime_ns and cached[1] == st.st_size:
+        return cached[2]
+    h = hashlib.sha1()
+    with path.open("rb") as f:
+        for chunk in iter(lambda: f.read(1 << 20), b""):
+            h.update(chunk)
+    token = h.hexdigest()[:12]
+    _media_hash_cache[rel] = (st.st_mtime_ns, st.st_size, token)
+    return token
+
+
+def _rev_file(file: str) -> str:
+    """The baked zoom-out companion path for a transition file (mirrors the
+    client's `reverseFile`): `<edge>.mp4` -> `<edge>.rev.mp4`."""
+    return file[:-4] + ".rev.mp4" if file.endswith(".mp4") else file
+
+
 class ControlsModel(BaseModel):
     content: str
     left: int = Field(ge=0, le=4)
@@ -160,6 +195,24 @@ def create_app(manifest_path: Optional[Path] = None) -> FastAPI:
     def api_clips():
         return {"clips": [c.to_dict() for c in app.state.clips]}
 
+    @app.get("/api/media-versions")
+    def api_media_versions():
+        """Per-file content-hash tokens the client appends to /media URLs as
+        `?v=<hash>`. Covers every served file: each clip's base footage plus each
+        ring transition and its baked reverse. A re-baked clip's hash changes, so
+        its URL changes and the browser refetches — a permanent cache-bust."""
+        files = {c.base_file for c in app.state.clips}
+        if app.state.ring is not None:
+            for t in app.state.ring.transitions:
+                files.add(t.file)
+                files.add(_rev_file(t.file))
+        versions = {}
+        for f in sorted(files):
+            v = _media_version(f)
+            if v:
+                versions[f] = v
+        return {"versions": versions}
+
     @app.get("/api/ring")
     def api_ring():
         if app.state.ring is None:

simulator/static/app.js

@@ -42,6 +42,11 @@ let lastOverlay = null;    // {level, intensity} from the most-recent renderOver
 async function loadData() {
   const clips = (await (await fetch("/api/clips")).json()).clips || [];
   clipsById = Object.fromEntries(clips.map((c) => [c.id, c]));
+  // Per-file content-hash tokens → appended to /media URLs as ?v=<hash> so a
+  // re-baked clip (new bytes, same path) gets a fresh URL the browser can't serve
+  // stale. Best-effort: an empty map just yields un-versioned URLs.
+  try { mediaVersions = (await (await fetch("/api/media-versions")).json()).versions || {}; }
+  catch (_) { mediaVersions = {}; }
   const r = await fetch("/api/ring");
   serverRing = r.ok;
   ring = r.ok ? await r.json() : null;
@@ -86,7 +91,12 @@ function activeClip() {
 // path, so swapping the altitude scale loads near-instantly (no fetch round-trip).
 // Falls back to the network path for anything not yet (or never) cached.
 const mediaBlobs = {};
-function mediaUrl(file) { return mediaBlobs[file] || ("/media/" + file); }
+let mediaVersions = {};   // file -> content-hash token (from /api/media-versions)
+// Network path for a media file, content-hash-versioned so a re-baked clip's URL
+// changes with its bytes (permanent cache-bust). The blob cache, when present,
+// wins — those bytes are already the current ones for this session.
+function mediaNetUrl(file) { const v = mediaVersions[file]; return "/media/" + file + (v ? "?v=" + v : ""); }
+function mediaUrl(file) { return mediaBlobs[file] || mediaNetUrl(file); }
 
 // Every media file the ring can show: each scale-pool clip's base footage plus the
 // per-edge transition clips. This is the full preload set (~two dozen files).
@@ -136,7 +146,12 @@ async function preloadAllMedia(concurrency = 4) {
       const file = files[i++];
       if (!mediaBlobs[file]) {
         try {
-          const blob = await (await fetch(mediaUrl(file))).blob();
+          // The content-hash `?v=` already makes a re-baked clip's URL unique, but
+          // `cache: "reload"` is belt-and-suspenders: it bypasses the HTTP cache for
+          // this fetch (so even an un-versioned or immutable-pinned prior entry can't
+          // serve stale) and refreshes the entry. The blob cache above still gives
+          // instant in-session swaps; this only affects the one fetch per (re)load.
+          const blob = await (await fetch(mediaNetUrl(file), { cache: "reload" })).blob();
           mediaBlobs[file] = URL.createObjectURL(blob);
         } catch (_) { /* leave it to the network path on demand */ }
       }
@@ -441,10 +456,11 @@ function renderOverlay(level, intensity) {
   lastOverlay = { level, intensity };
 }
 
-// Affect channel: soft, glowing emotion-words surfaced only when BOTH knobs are
-// up. `strength` = min(left, right); `intensity` is the layer opacity. Words are
-// placed at authored scene points (no boxes — feelings are scene-level) and read
-// softer than the clinical reticles — the dream leaking into the machine's read.
+// Affect channel: soft, glowing emotion-words — a RIGHT-brain output, surfaced by
+// the Right (dreamlike) knob alone (`strength` = right; the Left analytical knob no
+// longer gates them). `intensity` is the layer opacity. Words are placed at authored
+// scene points (no boxes — feelings are scene-level) and read softer than the
+// clinical reticles — feeling, not measurement.
 function renderAffect(strength, intensity, right) {
   const clip = activeClip();
   if (!affectLayer) return;      // tolerate a stale page missing the affect layer
@@ -457,7 +473,7 @@ function renderAffect(strength, intensity, right) {
     const [x, y] = f.at.map((n) => n * 100);
     const t = svg("text", { x, y, "text-anchor": "middle", class: "hud-affect" }, affectLayer);
     // RIGHT emotion tier: the vocabulary escalates basic -> compound as the Right
-    // knob rises (appearance still gated by min(left,right) above).
+    // knob rises (appearance is gated by the Right knob via `strength` above).
     const raw = strings[f.key];
     t.textContent = pickTier(raw !== undefined ? raw : f.key, clamp(right || 0, 1, tierCount(raw)));
   }
@@ -498,7 +514,7 @@ async function update() {
   if (!resp.ok) { readout.textContent = "invalid: " + resp.status; return; }
   const data = await resp.json();
   readout.textContent = JSON.stringify(data, null, 2);
-  if (!data.content.video) { black.classList.remove("hidden"); return; }
+  if (!data.content.video) { black.style.opacity = "1"; black.classList.remove("hidden"); return; }
   black.classList.add("hidden");
   try {
     ensureClipMedia();
@@ -553,6 +569,29 @@ function playTransition(file, blended, reversed) {
   });
 }
 
+// Briefly fade through the #black overlay while `swap` changes the displayed clip,
+// so a content swap reads as a deliberate cut, not a jarring jump. Restores #black
+// to its hidden/opaque resting state (the video-off use) afterward.
+function fadeThroughBlack(swap) {
+  return new Promise((resolve) => {
+    black.style.opacity = "0";
+    black.classList.remove("hidden");
+    void black.offsetWidth;                  // reflow so the 0 -> 1 transition runs
+    black.style.opacity = "1";
+    setTimeout(() => {
+      try { swap(); } catch (_) {}
+      setTimeout(() => {
+        black.style.opacity = "0";
+        setTimeout(() => {
+          black.classList.add("hidden");
+          black.style.opacity = "";          // back to CSS default for the video-off use
+          resolve();
+        }, 210);
+      }, 160);                               // let the chosen clip decode under black
+    }, 210);
+  });
+}
+
 async function advance(delta) {
   if (busy || !ring || ring.scales.length < 2) return;
   busy = true;
@@ -570,8 +609,16 @@ async function advance(delta) {
     }
     ringIndex = move.to_index;
     activeClipId = move.target_clip_id;   // the randomly-picked pool member to load
-    currentClipId = null;                 // force the target scale's base media to (re)load
     renderScaleReadout();
+    // The baked transition lands on the scale PRIMARY; if the rotating pool picked a
+    // DIFFERENT member, mask the swap behind a fade to black so it doesn't hard-cut
+    // from the primary to the chosen clip (e.g. coast birdrock -> surfgrass).
+    const landedPrimary = (ring.scales[move.to_index] || {}).clip_id;
+    if (move.target_clip_id && move.target_clip_id !== landedPrimary) {
+      await fadeThroughBlack(() => { currentClipId = null; ensureClipMedia(); });
+    } else {
+      currentClipId = null;               // same clip the transition ended on — plain (re)load
+    }
   } finally {
     busy = false;
     update();

simulator/static/style.css

@@ -39,7 +39,7 @@ main { display: flex; gap: 1rem; padding: 1rem; flex-wrap: wrap; }
 .hud-chip-text.measure { fill: #ffd79a; }
 .hud-conf { fill: #6cf; opacity: 0.8; }
 .hud-status { fill: #8fdcff; font: 2.4px monospace; opacity: 0.9; letter-spacing: 0.15px; }
-.black { position: absolute; inset: 0; background: #000; }
+.black { position: absolute; inset: 0; background: #000; opacity: 1; transition: opacity 200ms ease; }
 .hidden { display: none; }
 .panel { flex: 0 0 280px; display: flex; flex-direction: column; gap: 0.8rem; }
 fieldset { border: 1px solid #333; border-radius: 6px; }

tests/test_player_alteration.py

@@ -55,42 +55,44 @@ def test_left_and_right_stack_not_cancel():
     assert plan.dream.intensity == 1.0
 
 
-def test_affect_needs_both_knobs_up():
-    # affect-channel design (session 0013): emotion-words surface only when BOTH
-    # the Left and Right knobs are up — either at 0 means no affect at all.
+def test_affect_is_driven_by_the_right_knob_alone():
+    # Right-brain affect (session 0018): emotion-words are controlled by the Right
+    # knob alone — Right at 0 means no affect regardless of Left, and Left no longer
+    # gates the channel (full Right with Left at 0 still surfaces affect).
     assert plan_alteration(_coord(left=4, right=0)).affect.strength == 0
-    assert plan_alteration(_coord(left=0, right=4)).affect.strength == 0
     assert plan_alteration(_coord(left=4, right=0)).affect.intensity == 0.0
-    assert plan_alteration(_coord(left=0, right=4)).affect.intensity == 0.0
+    assert plan_alteration(_coord(left=0, right=4)).affect.strength == 4
+    assert plan_alteration(_coord(left=0, right=4)).affect.intensity == 1.0
 
 
-def test_affect_strength_is_the_smaller_knob():
-    # strength = min(left, right) — the smaller knob gates the channel.
-    assert plan_alteration(_coord(left=2, right=4)).affect.strength == 2
+def test_affect_strength_is_the_right_knob():
+    # strength = right — Left is irrelevant to the affect channel.
+    assert plan_alteration(_coord(left=2, right=4)).affect.strength == 4
     assert plan_alteration(_coord(left=4, right=2)).affect.strength == 2
-    assert plan_alteration(_coord(left=4, right=4)).affect.strength == 4
-    assert plan_alteration(_coord(left=3, right=1)).affect.strength == 1
+    assert plan_alteration(_coord(left=0, right=3)).affect.strength == 3
+    assert plan_alteration(_coord(left=4, right=1)).affect.strength == 1
 
 
-def test_affect_intensity_scales_with_strength_over_full_scale():
-    for lo in range(5):
-        plan = plan_alteration(_coord(left=lo, right=4))
-        assert plan.affect.intensity == pytest.approx(lo / 4)
-    assert plan_alteration(_coord(left=4, right=4)).affect.intensity == 1.0
+def test_affect_intensity_scales_with_right_over_full_scale():
+    for r in range(5):
+        plan = plan_alteration(_coord(left=0, right=r))
+        assert plan.affect.intensity == pytest.approx(r / 4)
+    assert plan_alteration(_coord(left=0, right=4)).affect.intensity == 1.0
 
 
 def test_affect_intensity_honors_overlay_gain():
-    # affect rides the same overlay_gain as the analytical HUD it belongs to.
+    # affect text rides the overlay-opacity gain, but is keyed off the Right knob.
     cal = Calibration(overlay_gain=0.5)
-    assert plan_alteration(_coord(left=4, right=4), cal).affect.intensity == pytest.approx(0.5)
+    assert plan_alteration(_coord(left=0, right=4), cal).affect.intensity == pytest.approx(0.5)
     clamp = Calibration(overlay_gain=10.0)
-    assert plan_alteration(_coord(left=4, right=4), clamp).affect.intensity == 1.0
+    assert plan_alteration(_coord(left=0, right=4), clamp).affect.intensity == 1.0
 
 
 def test_affect_active_implies_non_identity():
-    # min(left,right) > 0 implies left > 0, so an active affect plan is never identity.
-    plan = plan_alteration(_coord(left=2, right=3))
-    assert plan.affect.strength == 2
+    # affect.strength == right, and right > 0 makes dream.strength > 0, so an active
+    # affect plan (even with Left at 0) is never identity.
+    plan = plan_alteration(_coord(left=0, right=3))
+    assert plan.affect.strength == 3
     assert not plan.is_identity
 
 

tests/test_simulator_api.py

@@ -76,6 +76,30 @@ def test_clips_returns_the_manifest(client):
     assert data["clips"][0]["annotations"][0]["key"] == "detected.water"
 
 
+def test_media_versions_endpoint_shape(client):
+    resp = client.get("/api/media-versions")
+    assert resp.status_code == 200
+    assert isinstance(resp.json()["versions"], dict)
+
+
+def test_media_version_is_a_content_hash(tmp_path, monkeypatch):
+    import hashlib
+
+    import simulator.app as appmod
+
+    # Point the media root at a temp dir (the served dir is otherwise fixed).
+    monkeypatch.setattr(appmod, "MEDIA_DIR", tmp_path)
+    (tmp_path / "clip").mkdir()
+    f = tmp_path / "clip" / "base.mp4"
+    f.write_bytes(b"hello-bytes")
+    assert appmod._media_version("clip/base.mp4") == hashlib.sha1(b"hello-bytes").hexdigest()[:12]
+    # Absent file -> None (it's simply omitted from the versions map).
+    assert appmod._media_version("clip/missing.mp4") is None
+    # Re-baked under the same path (new bytes) -> a new token, not the cached one.
+    f.write_bytes(b"different-bytes-entirely")
+    assert appmod._media_version("clip/base.mp4") == hashlib.sha1(b"different-bytes-entirely").hexdigest()[:12]
+
+
 def test_retired_selection_endpoints_are_gone(client):
     # The route no longer exists; the static catch-all yields 404 on GET and
     # 405 on the (now-unrouted) POST. Either proves the endpoint is gone.