fix: add session lock in StockSelector, remove unused HEALTH_PORT_OFFSET, lint fixesHEADmaster

- Add asyncio.Lock to StockSelector._ensure_session() to prevent race condition
- Remove unused HEALTH_PORT_OFFSET constant from news-collector
- Auto-fix import sorting and formatting from ruff

2 files changed, 6 insertions, 6 deletions

diff --git a/services/news-collector/src/news_collector/main.py b/services/news-collector/src/news_collector/main.py
index 7265f00..c39fa67 100644
--- a/services/news-collector/src/news_collector/main.py
+++ b/services/news-collector/src/news_collector/main.py
@@ -25,9 +25,6 @@ from shared.sentiment import SentimentAggregator
 from shared.sentiment_models import MarketSentiment
 from shared.shutdown import GracefulShutdown
 
-# Health check port: base + 4
-HEALTH_PORT_OFFSET = 4
-
 
 async def run_collector_once(collector, db: Database, broker: RedisBroker) -> int:
     """Run a single collector, store results in DB, publish to Redis.
diff --git a/services/strategy-engine/src/strategy_engine/stock_selector.py b/services/strategy-engine/src/strategy_engine/stock_selector.py
index 5acef0f..8657b93 100644
--- a/services/strategy-engine/src/strategy_engine/stock_selector.py
+++ b/services/strategy-engine/src/strategy_engine/stock_selector.py
@@ -1,5 +1,6 @@
 """3-stage stock selector engine: sentiment → technical → LLM."""
 
+import asyncio
 import json
 import logging
 import re
@@ -218,11 +219,13 @@ class StockSelector:
         self._model = anthropic_model
         self._max_picks = max_picks
         self._http_session: aiohttp.ClientSession | None = None
+        self._session_lock = asyncio.Lock()
 
     async def _ensure_session(self) -> aiohttp.ClientSession:
-        if self._http_session is None or self._http_session.closed:
-            self._http_session = aiohttp.ClientSession()
-        return self._http_session
+        async with self._session_lock:
+            if self._http_session is None or self._http_session.closed:
+                self._http_session = aiohttp.ClientSession()
+            return self._http_session
 
     async def close(self) -> None:
         if self._http_session and not self._http_session.closed: