feat(chat): scenario-based training — choice of channel/Situation + realistic per-turn evaluation

Backend:
- Channel/initiation now driven by a SCENARIO chosen at chat start, not baked into the
  persona: social (customer opens), f2f_call (seller must open, proactive), recontact
  (customer re-contacts after 1-3 months).
- /chat/start accepts {scenario}; session stores scenario + internal{turns,score}.
- persona_reply takes scenario + adapts tone; system-role transcript entries are fed to
  the persona as hidden scene notes.
- JUDGE updated for realism: good response can WIN even in hard/tough-text scenarios;
  long/no-close chats (turns >~12) lose; pushy/ignoring-need loses. Efficiency rewarded.

Frontend:
- Scenario picker before chat (choose Social / Face-to-face-call / Re-contact).
- Chat thread renders role=system as a centered time-lapse/scene note.
- Choose-scenario i18n (EN+TH).
Rebuilt dist.

backend/app/api/chat_routes.py

@@ -27,6 +27,35 @@ def _sim(group, persona):
     return Simulator(llm)
 
 
+SCENARIOS = {
+    "social": {
+        "label": "Social Media",
+        "init": "customer",
+        "system_preamble": "💬 ช่องทาง ข้อความโซเชียล — ลูกค้าทักมาหาคุณก่อน (โทนสั้น ทักๆ ตามสไตล์แชท)",
+        "adapt": "You are chatting on a social-messaging app (LINE-style). Keep replies SHORT, casual, and quick — one line to a few lines. The customer opened the chat.",
+    },
+    "f2f_call": {
+        "label": "พบหน้า / โทรศัพท์",
+        "init": "seller",
+        "system_preamble": "📞 สถานการณ์ พบหน้าหรือโทรศัพท์ — คุณต้องเป็นฝ่ายเปิดการสนทนาเชิงรุกกับลีด (lead)",
+        "adapt": "This is a face-to-face or phone sales situation. You must sound natural and conversational like a live talk. The seller will open — you are the lead they are reaching out to.",
+    },
+    "recontact": {
+        "label": "ลูกค้ากลับมาติดต่อ (เคยได้ข้อมูล 1-3 เดือน)",
+        "init": "customer",
+        "system_preamble": "⏳ 1-3 เดือนผ่านไป... ลูกค้าคนนี้เคยได้รับข้อมูลสินค้าไปแล้ว ตอนนี้กลับมาติดต่อคุณอีกครั้ง (พร้อมตัดสินใจมากขึ้น)",
+        "adapt": "This customer researched you 1-3 months ago. They have already read about the product and are now more ready to decide. They re-contacted you on a messaging channel. Keep replies natural and fairly concise.",
+    },
+}
+
+
+def _scenario_config(scenario: str, persona: dict):
+    cfg = SCENARIOS.get(scenario, SCENARIOS["social"])
+    # OR with persona's own initiation preference: f2f/call forces seller-first unless persona
+    # is strongly customer-initiated (we let scenario win, but keep persona special handling).
+    return cfg, cfg["init"]
+
+
 def _get_ready_group(s, gid: str) -> dict:
     """Org-scoped group access for trainees + require ready status (IDOR defense)."""
     group = s["groups"].get_or_none(gid)
@@ -53,6 +82,12 @@ def start_session(gid: str, pid: str):
     if not persona:
         raise ApiError("persona not found", 404)
     actor = current_user()
+    # Scenario chosen by the trainee at chat start (not baked into the persona).
+    body = request.get_json(silent=True) or {}
+    scenario = (body.get("scenario") or "social").strip().lower()
+    if scenario not in ("social", "f2f_call", "recontact"):
+        scenario = "social"
+    scenario_meta, init_mode = _scenario_config(scenario, persona)
     # One-shot: reject if already finished this persona
     try:
         session = s["sessions"].create(
@@ -60,27 +95,35 @@ def start_session(gid: str, pid: str):
             persona_name=persona.get("name", "?"),
             persona_meta={
                 "tier": persona.get("tier"),
-                "initiation_mode": persona.get("initiation_mode"),
+                "initiation_mode": init_mode,
                 "channel": persona.get("channel"),
+                "scenario": scenario,
             },
         )
     except ValueError as exc:
         raise ApiError(str(exc), 400)
 
+    s["sessions"].update(
+        session["id"],
+        scenario=scenario,
+        internal={**(session.get("internal") or {}), "turns": 0, "score": 50, "signals": []},
+    )
     sim = _sim(group, persona)
-    # Seller-initiated: give the trainee an opening task (no persona message yet).
-    init_mode = persona.get("initiation_mode", "customer")
+    # Seed messages: system note(s) then customer opener for customer-first scenarios.
+    seeded = list(session.get("messages", []))
+    if scenario_meta.get("system_preamble"):
+        seeded.append({"role": "system", "text": scenario_meta["system_preamble"]})
     if init_mode == "customer":
-        # Customer opens: inject the persona's opener as the first message.
         opener = persona.get("opener") or "Hi, I saw your product and had a question."
-        s["sessions"].update(session["id"], messages=[{"role": "customer", "text": opener}])
-    else:
-        s["sessions"].update(
-            session["id"],
-            task="The customer did NOT message first. You must open the sale — start the "
-                 "conversation with this lead (e.g. introduce yourself and engage with interest).",
-        )
-    return jsonify({"session": s["sessions"].get(session["id"]), "initiation_mode": init_mode})
+        seeded.append({"role": "customer", "text": opener})
+    s["sessions"].update(session["id"], messages=seeded)
+    sess = s["sessions"].get(session["id"])
+    return jsonify({
+        "session": sess,
+        "initiation_mode": init_mode,
+        "scenario": scenario,
+        "scenario_meta": scenario_meta,
+    })
 
 
 @chat_bp.post("/<gid>/personas/<pid>/chat/send")
@@ -106,6 +149,8 @@ def send_message(gid: str, pid: str):
         raise ApiError("session context missing", 404)
     messages = list(session.get("messages", []))
     messages.append({"role": "seller", "text": text})
+    scenario = session.get("scenario", "social") or "social"
+    adapt = SCENARIOS.get(scenario, SCENARIOS["social"]).get("adapt", "")
 
     sim = _sim(group, persona)
     try:
@@ -114,12 +159,19 @@ def send_message(gid: str, pid: str):
             sales_kit=group.get("sales_kit") or {},
             messages=messages,
             internal=session.get("internal", {}),
+            scenario=scenario,
+            scenario_adapt=adapt,
         )
     except LLMError as exc:
         raise ApiError(f"LLM error: {exc}", 500)
     messages.append({"role": "customer", "text": reply})
 
-    s["sessions"].update(session["id"], messages=messages)
+    # Per-turn tracking: count exchanged turns + nudge score down as the chat drags.
+    internal = session.get("internal", {}) or {}
+    internal.setdefault("turns", 0)
+    internal["turns"] = internal.get("turns", 0) + 1
+
+    s["sessions"].update(session["id"], messages=messages, internal=internal)
     return jsonify({"reply": reply, "messages": messages})
 
 
@@ -139,7 +191,9 @@ def finish_session(gid: str, pid: str):
     sim = _sim(group, persona)
     messages = session.get("messages", [])
     try:
-        verdict = sim.judge(persona=persona, messages=messages)
+        verdict = sim.judge(
+            persona=persona, messages=messages, internal=session.get("internal", {})
+        )
     except LLMError as exc:
         raise ApiError(f"LLM error: {exc}", 500)