Add seed param to /reset: demo pins to seed=0 per stage for consistent known episodes

demo/index.html

@@ -239,7 +239,7 @@ async function loadCase(stage) {
   const labels = {1:'Stage 1 — Landmark', 2:'Stage 2 — Contested', 3:'Stage 3 — Reversal', 4:'Stage 4 — Schema Drift (BNSS)'};
   document.getElementById('stageLabel').textContent = 'Live Demo Case — ' + (labels[stage] || 'Stage '+stage);
   try {
-    const res = await fetch(BASE + '/reset?stage=' + stage, { method: 'POST' });
+    const res = await fetch(BASE + '/reset?stage=' + stage + '&seed=0', { method: 'POST' });
     const data = await res.json();
     sessionId = data.session_id;
     const obs = data.observation;
@@ -279,8 +279,8 @@ async function runDemo() {
   document.getElementById('toolLog').innerHTML = '';
   document.getElementById('rewardCard').classList.remove('visible');
 
-  log('POST /reset?stage=' + stage, 'tool');
-  const res = await fetch(BASE + '/reset?stage=' + stage, { method: 'POST' });
+  log('POST /reset?stage=' + stage + '&seed=0', 'tool');
+  const res = await fetch(BASE + '/reset?stage=' + stage + '&seed=0', { method: 'POST' });
   const data = await res.json();
   sessionId = data.session_id;
   log('Session ready: ' + sessionId.slice(0,8) + '...', 'ok');

server/app.py

@@ -69,12 +69,12 @@ def health():
 
 
 @app.post("/reset")
-def reset(stage: int = 1, session_id: str = None):
+def reset(stage: int = 1, session_id: str = None, seed: int = None):
     if session_id is None:
         session_id = str(uuid.uuid4())
     env = get_or_create_env(session_id)
     env.set_stage(stage)
-    obs = env.reset(stage=stage)
+    obs = env.reset(stage=stage, seed=seed)
     return {
         "session_id": session_id,
         "observation": obs.model_dump(),

server/dataset.py

@@ -282,16 +282,27 @@ class BailDataset:
         self,
         stage: Optional[int] = None,
         apply_drift: bool = True,
+        seed: Optional[int] = None,
     ) -> Dict[str, Any]:
-        """Sample an episode from the requested curriculum stage."""
+        """Sample an episode from the requested curriculum stage.
+
+        Args:
+            stage: Curriculum stage 1-4. Defaults to current stage.
+            apply_drift: Apply BNSS schema drift for stage 4 episodes.
+            seed: If set, deterministically picks episode at index (seed % len).
+                  Used by the demo to always show the same illustrative case.
+        """
         s = stage if stage is not None else self._current_stage
 
         # Fallback: if stage is empty, try adjacent stages
         for candidate in [s, s-1, s+1, 1, 2, 3, 4]:
             if 1 <= candidate <= 4 and self._episodes[candidate]:
                 eps = self._episodes[candidate]
-                idx = self._episode_index[candidate] % len(eps)
-                self._episode_index[candidate] += 1
+                if seed is not None:
+                    idx = seed % len(eps)
+                else:
+                    idx = self._episode_index[candidate] % len(eps)
+                    self._episode_index[candidate] += 1
                 ep = eps[idx]
                 if apply_drift and s == 4:
                     ep = maybe_apply_drift(ep, probability=0.4)

server/undertrial_environment.py

@@ -80,7 +80,7 @@ class UndertriAIEnvironment(Environment):
         """Start a new episode. Returns initial case observation."""
         self._reset_rubric() if hasattr(self, '_reset_rubric') else None
         s = stage or self._current_stage
-        self._episode    = self.dataset.sample_episode(stage=s)
+        self._episode    = self.dataset.sample_episode(stage=s, seed=seed)
         self._episode_id = episode_id or str(uuid.uuid4())
         self._step_count = 0
         self._flags      = []