[laneC] /rhubarb viseme endpoint (ffmpeg-style 503 gating)

GET /rhubarb?path= -> rhubarb -f json -> mouthCues for Lane A's viseme lane;
503 when the binary is absent (not installed on ultra yet). Path-guarded.
test_server.py: +503 gating assert (9 groups green).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scenegod/server.py

@@ -45,6 +45,7 @@ MEDIA_TYPES = {
 SCENES.mkdir(parents=True, exist_ok=True)
 RENDERS.mkdir(parents=True, exist_ok=True)
 HAVE_FFMPEG = shutil.which("ffmpeg") is not None
+HAVE_RHUBARB = shutil.which("rhubarb") is not None
 
 # MODELBEAST proxy (M4) — off unless SCENEGOD_MB=1. Token read from disk at
 # request time, never logged. Contract mirrors MESHGOD meshgod/ops.py.
@@ -347,6 +348,23 @@ def render_out(rid: str):
     return FileResponse(out, media_type="video/mp4")
 
 
+# ---- viseme lip-sync (M4) — feeds Lane A's viseme lane ----
+@app.get("/rhubarb")
+def rhubarb(path: str):
+    """Rhubarb Lip Sync on an asset audio file -> {metadata, mouthCues:[...]}.
+    503 if rhubarb absent (same pattern as ffmpeg). ponytail: synchronous —
+    VO clips are short; make it a render-style session if that ever bites."""
+    if not HAVE_RHUBARB:
+        raise HTTPException(503, "rhubarb not installed (see github.com/DanielSWolf/rhubarb-lip-sync)")
+    f = safe_under(ASSETS, path)
+    if not f.is_file():
+        raise HTTPException(404, "not found")
+    p = subprocess.run(["rhubarb", "-f", "json", str(f)], capture_output=True, text=True)
+    if p.returncode != 0:
+        raise HTTPException(500, f"rhubarb failed: {p.stderr[-500:]}")
+    return json.loads(p.stdout)
+
+
 # ---- MODELBEAST proxy (M4, gated) ----
 def _mb_post(path: str, data: bytes, content_type: str) -> dict:
     req = urllib.request.Request(MB_HOST + path, data=data, method="POST",

scripts/test_server.py

@@ -176,6 +176,11 @@ def main():
         else:
             print("(render test skipped — ffmpeg/ffprobe not found)")
 
+        # --- rhubarb: 503 when the binary is absent (happy path needs rhubarb) ---
+        if not shutil.which("rhubarb"):
+            assert req("GET", "/rhubarb?path=audio/x.wav")[0] == 503
+            n += 1
+
         # --- MODELBEAST proxy: gating + two-step contract (mock MB, no farm jobs) ---
         assert req("POST", "/mb/submit", json.dumps({"operator": "tts"}))[0] == 503  # gated off
         n += 1