stage-6: model selection and advanced commands

/model (show/change), /restart (owner), /logs, set_session_model API, model reset on /clear. 20 new tests (161 total).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/router.py

@@ -2,7 +2,14 @@
 
 import logging
 from src.config import Config
-from src.claude_session import send_message, clear_session, get_active_session, list_sessions
+from src.claude_session import (
+    send_message,
+    clear_session,
+    get_active_session,
+    list_sessions,
+    set_session_model,
+    VALID_MODELS,
+)
 
 log = logging.getLogger(__name__)
 
@@ -28,22 +35,30 @@ def route_message(channel_id: str, user_id: str, text: str, model: str | None =
 
     # Text-based commands (not slash commands — these work in any adapter)
     if text.lower() == "/clear":
+        default_model = _get_config().get("bot.default_model", "sonnet")
         cleared = clear_session(channel_id)
         if cleared:
-            return "Session cleared.", True
+            return f"Session cleared. Model reset to {default_model}.", True
         return "No active session.", True
 
     if text.lower() == "/status":
         return _status(channel_id), True
 
+    if text.lower().startswith("/model"):
+        return _model_command(channel_id, text), True
+
     if text.startswith("/"):
         return f"Unknown command: {text.split()[0]}", True
 
     # Regular message → Claude
     if not model:
-        # Get channel default model or global default
-        channel_cfg = _get_channel_config(channel_id)
-        model = (channel_cfg or {}).get("default_model") or _get_config().get("bot.default_model", "sonnet")
+        # Check session model first, then channel default, then global default
+        session = get_active_session(channel_id)
+        if session and session.get("model"):
+            model = session["model"]
+        else:
+            channel_cfg = _get_channel_config(channel_id)
+            model = (channel_cfg or {}).get("default_model") or _get_config().get("bot.default_model", "sonnet")
 
     try:
         response = send_message(channel_id, text, model=model)
@@ -66,6 +81,43 @@ def _status(channel_id: str) -> str:
     return f"Model: {model} | Session: {sid}... | Messages: {count}"
 
 
+def _model_command(channel_id: str, text: str) -> str:
+    """Handle /model [choice] text command."""
+    parts = text.strip().split()
+    if len(parts) == 1:
+        # /model — show current
+        session = get_active_session(channel_id)
+        if session:
+            current = session.get("model", "unknown")
+        else:
+            channel_cfg = _get_channel_config(channel_id)
+            current = (channel_cfg or {}).get("default_model") or _get_config().get("bot.default_model", "sonnet")
+        available = ", ".join(sorted(VALID_MODELS))
+        return f"Current model: {current}\nAvailable: {available}"
+
+    choice = parts[1].lower()
+    if choice not in VALID_MODELS:
+        return f"Invalid model '{choice}'. Choose from: {', '.join(sorted(VALID_MODELS))}"
+
+    session = get_active_session(channel_id)
+    if session:
+        set_session_model(channel_id, choice)
+    else:
+        # Pre-set for next message
+        from src.claude_session import _load_sessions, _save_sessions
+        from datetime import datetime, timezone
+        sessions = _load_sessions()
+        sessions[channel_id] = {
+            "session_id": "",
+            "model": choice,
+            "created_at": datetime.now(timezone.utc).isoformat(),
+            "last_message_at": datetime.now(timezone.utc).isoformat(),
+            "message_count": 0,
+        }
+        _save_sessions(sessions)
+    return f"Model changed to {choice}."
+
+
 def _get_channel_config(channel_id: str) -> dict | None:
     """Find channel config by ID."""
     channels = _get_config().get("channels", {})