feat(05-03): implement /next and /stop commands for round progression

Add /next to advance discussion with full context passed to models:
- Validates active discussion state
- Auto-completes when round limit reached
- Shows Round N/M progress indicator

Add /stop to end discussion early:
- Marks discussion as COMPLETED
- Clears session state
- Suggests /consensus for summarization

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/moai/bot/handlers/__init__.py

@@ -7,7 +7,13 @@ project management, discussion commands, and export functionality.
 from telegram.ext import Application, CommandHandler
 
 from moai.bot.handlers.commands import help_command, start_command
-from moai.bot.handlers.discussion import ask_command, discuss_command, open_command
+from moai.bot.handlers.discussion import (
+    ask_command,
+    discuss_command,
+    next_command,
+    open_command,
+    stop_command,
+)
 from moai.bot.handlers.projects import project_command, projects_command
 from moai.bot.handlers.status import status_command
 
@@ -33,3 +39,5 @@ def register_handlers(app: Application) -> None:
     app.add_handler(CommandHandler("ask", ask_command))
     app.add_handler(CommandHandler("open", open_command))
     app.add_handler(CommandHandler("discuss", discuss_command))
+    app.add_handler(CommandHandler("next", next_command))
+    app.add_handler(CommandHandler("stop", stop_command))

src/moai/bot/handlers/discussion.py

@@ -8,6 +8,7 @@ from moai.core.ai_client import MODEL_MAP, get_ai_client
 from moai.core.models import DiscussionType, RoundType
 from moai.core.orchestrator import query_models_parallel, run_discussion_round
 from moai.core.services.discussion import (
+    complete_discussion,
     create_discussion,
     create_message,
     create_round,
@@ -245,3 +246,100 @@ async def discuss_command(update: Update, context: ContextTypes.DEFAULT_TYPE) ->
 
     except Exception as e:
         await update.message.reply_text(f"Error: {e}")
+
+
+async def next_command(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
+    """Handle /next command - advance to the next discussion round.
+
+    Requires an active discussion started with /discuss. Runs the next
+    sequential round with full context from prior rounds.
+    """
+    # Check for active discussion state
+    state = context.user_data.get("discussion_state")
+    if state is None:
+        await update.message.reply_text("No active discussion. Start one with /open then /discuss.")
+        return
+
+    current_round = state["current_round"]
+    round_limit = state["round_limit"]
+
+    # Check if already at limit
+    if current_round > round_limit:
+        await update.message.reply_text(
+            f"Round limit ({round_limit}) reached. Start a new discussion with /open."
+        )
+        del context.user_data["discussion_state"]
+        return
+
+    # Show typing indicator
+    await update.message.chat.send_action("typing")
+
+    try:
+        # Load discussion with full context
+        discussion = await get_discussion(state["discussion_id"])
+        if discussion is None:
+            await update.message.reply_text("Discussion not found.")
+            del context.user_data["discussion_state"]
+            return
+
+        # Run the next round
+        responses = await run_discussion_round(
+            discussion=discussion,
+            models=state["models"],
+            project_name=state["project_name"],
+            round_number=current_round,
+        )
+
+        # Build response text
+        response_lines = [f"*Round {current_round}/{round_limit}:*\n"]
+        for model, response in responses.items():
+            response_lines.append(f"*{model.title()}:*\n{response}\n")
+
+        if current_round >= round_limit:
+            # Final round - complete discussion
+            await complete_discussion(state["discussion_id"])
+            response_lines.append(f"\n_Discussion complete ({round_limit} rounds)._")
+            del context.user_data["discussion_state"]
+        else:
+            response_lines.append(
+                f"\n_Round {current_round}/{round_limit} complete. Use /next or /stop._"
+            )
+            # Update state for next round
+            context.user_data["discussion_state"]["current_round"] = current_round + 1
+
+        await update.message.reply_text(
+            "\n".join(response_lines),
+            parse_mode="Markdown",
+        )
+
+    except Exception as e:
+        await update.message.reply_text(f"Error: {e}")
+
+
+async def stop_command(update: Update, context: ContextTypes.DEFAULT_TYPE) -> None:
+    """Handle /stop command - stop the current discussion early.
+
+    Completes the discussion at the current round and clears the session state.
+    """
+    # Check for active discussion state
+    state = context.user_data.get("discussion_state")
+    if state is None:
+        await update.message.reply_text("No active discussion to stop.")
+        return
+
+    current_round = state["current_round"]
+
+    try:
+        # Complete the discussion in database
+        await complete_discussion(state["discussion_id"])
+
+        # Clear session state
+        del context.user_data["discussion_state"]
+
+        await update.message.reply_text(
+            f"_Discussion stopped at round {current_round - 1}. Use /consensus to summarize._",
+            parse_mode="Markdown",
+        )
+
+    except Exception as e:
+        await update.message.reply_text(f"Error: {e}")