feat: add Discord Bot Gateway handler with mention parsing

Implements discord.py Bot Gateway to receive @agent mentions and enqueue tasks.
Includes deterministic thread ID generation and message parsing for issue numbers,
repo names, and freeform requests. Supports message queuing for running threads.

Files:
- agent/integrations/discord_handler.py: DiscordHandler class with event handling
- tests/test_discord_handler.py: 4 tests for parsing and thread ID generation

All tests pass (95 total).

agent/integrations/discord_handler.py

@@ -0,0 +1,120 @@
+# agent/integrations/discord_handler.py
+"""Discord Bot Gateway 수신 핸들러.
+
+discord.py를 사용하여 @agent 멘션을 수신하고 작업을 큐에 추가한다.
+"""
+from __future__ import annotations
+
+import hashlib
+import logging
+import os
+import re
+
+import discord
+from discord.ext import commands
+
+logger = logging.getLogger(__name__)
+
+
+def parse_discord_message(content: str, bot_user_id: int) -> dict:
+    """Discord 메시지를 파싱하여 작업 정보를 추출한다."""
+    # 봇 멘션 제거 (<@123456>)
+    cleaned = re.sub(rf"<@!?{bot_user_id}>", "", content).strip()
+
+    # 이슈 번호 추출
+    issue_match = re.search(r"#(\d+)", cleaned)
+    issue_number = int(issue_match.group(1)) if issue_match else 0
+
+    # 리포 이름 추출
+    repo_name = os.environ.get("DEFAULT_REPO_NAME", "galaxis-po")
+    repo_match = re.search(r"\b(galaxis-\w+)\b", cleaned)
+    if repo_match:
+        repo_name = repo_match.group(1)
+
+    # 순수 메시지
+    message = re.sub(r"@agent\b", "", cleaned, flags=re.IGNORECASE)
+    message = re.sub(rf"\b{re.escape(repo_name)}\b", "", message)
+    message = re.sub(r"이슈\s*#\d+", "", message)
+    message = re.sub(r"#\d+", "", message)
+    message = message.strip()
+
+    return {
+        "issue_number": issue_number,
+        "repo_name": repo_name,
+        "message": message or cleaned,
+    }
+
+
+def generate_discord_thread_id(channel_id: int, message_id: int) -> str:
+    """Discord 메시지에서 결정론적 스레드 ID를 생성한다."""
+    raw = hashlib.sha256(f"discord:{channel_id}:{message_id}".encode()).hexdigest()
+    return f"{raw[:8]}-{raw[8:12]}-{raw[12:16]}-{raw[16:20]}-{raw[20:32]}"
+
+
+class DiscordHandler:
+    """Discord Bot Gateway 핸들러."""
+
+    def __init__(self):
+        intents = discord.Intents.default()
+        intents.message_content = True
+        intents.guild_messages = True
+        self.bot = commands.Bot(command_prefix="!", intents=intents)
+        self._setup_events()
+
+    def _setup_events(self):
+        @self.bot.event
+        async def on_ready():
+            logger.info("Discord bot connected as %s", self.bot.user)
+
+        @self.bot.event
+        async def on_message(message: discord.Message):
+            if message.author == self.bot.user:
+                return
+            if not self.bot.user or not self.bot.user.mentioned_in(message):
+                return
+            await self._handle_mention(message)
+
+    async def _handle_mention(self, message: discord.Message):
+        """@agent 멘션을 처리한다."""
+        parsed = parse_discord_message(
+            message.content, self.bot.user.id if self.bot.user else 0
+        )
+        thread_id = generate_discord_thread_id(message.channel.id, message.id)
+        repo_owner = os.environ.get("DEFAULT_REPO_OWNER", "quant")
+
+        from agent.task_queue import get_task_queue
+        from agent.message_store import get_message_store
+
+        task_queue = await get_task_queue()
+
+        if parsed["issue_number"] and await task_queue.has_running_task(thread_id):
+            store = await get_message_store()
+            await store.push_message(thread_id, {
+                "role": "human",
+                "content": parsed["message"],
+            })
+            await message.reply("메시지를 대기열에 추가했습니다. 현재 작업이 완료되면 확인하겠습니다.")
+            return
+
+        task_id = await task_queue.enqueue(
+            thread_id=thread_id,
+            source="discord",
+            payload={
+                "issue_number": parsed["issue_number"],
+                "repo_owner": repo_owner,
+                "repo_name": parsed["repo_name"],
+                "message": parsed["message"],
+                "channel_id": str(message.channel.id),
+                "message_id": str(message.id),
+            },
+        )
+        await message.reply(f"작업을 대기열에 추가했습니다. (task: {task_id[:8]})")
+        logger.info("Discord task enqueued: %s (thread %s)", task_id, thread_id)
+
+    async def start(self, token: str):
+        """Bot Gateway를 시작한다."""
+        await self.bot.start(token)
+
+    async def close(self):
+        """Bot Gateway를 종료한다."""
+        await self.bot.close()

tests/test_discord_handler.py

@@ -0,0 +1,43 @@
+# tests/test_discord_handler.py
+import pytest
+from unittest.mock import MagicMock, AsyncMock
+
+
+def test_parse_discord_mention_with_issue():
+    """이슈 번호가 포함된 Discord 멘션을 파싱한다."""
+    from agent.integrations.discord_handler import parse_discord_message
+
+    result = parse_discord_message("이슈 #42 해결해줘", bot_user_id=123)
+    assert result["issue_number"] == 42
+    assert result["repo_name"] == "galaxis-po"
+    assert "해결해줘" in result["message"]
+
+
+def test_parse_discord_mention_with_repo():
+    """리포가 명시된 Discord 멘션을 파싱한다."""
+    from agent.integrations.discord_handler import parse_discord_message
+
+    result = parse_discord_message("galaxis-po 이슈 #10 수정해줘", bot_user_id=123)
+    assert result["issue_number"] == 10
+    assert result["repo_name"] == "galaxis-po"
+
+
+def test_parse_discord_mention_freeform():
+    """이슈 번호 없는 자유형 요청을 파싱한다."""
+    from agent.integrations.discord_handler import parse_discord_message
+
+    result = parse_discord_message("factor_calculator에 듀얼 모멘텀 추가해줘", bot_user_id=123)
+    assert result["issue_number"] == 0
+    assert result["message"] == "factor_calculator에 듀얼 모멘텀 추가해줘"
+
+
+def test_generate_discord_thread_id():
+    """Discord 메시지에서 결정론적 thread_id를 생성한다."""
+    from agent.integrations.discord_handler import generate_discord_thread_id
+
+    tid1 = generate_discord_thread_id(channel_id=111, message_id=222)
+    tid2 = generate_discord_thread_id(channel_id=111, message_id=222)
+    tid3 = generate_discord_thread_id(channel_id=111, message_id=333)
+    assert tid1 == tid2
+    assert tid1 != tid3
+    assert len(tid1) == 36