Initial working version, positions show.

backend/app.py

@@ -0,0 +1,75 @@
+"""Flask backend for IB dashboard.
+
+Provides simple REST endpoints that the vanilla-JS frontend polls:
+- GET /api/quotes -> latest market quotes
+- GET /api/positions -> latest positions
+- POST /api/subscribe { symbols: ["AAPL","MSFT"] } -> start subscribing
+
+This app expects an IB Gateway or TWS running locally on port 7496.
+"""
+from flask import Flask, jsonify, request, send_from_directory
+import os
+import threading
+
+from ib_client import IBClient
+import time
+
+
+# Use an absolute path for the static folder so Flask can reliably serve files
+STATIC_FOLDER = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "frontend"))
+app = Flask(__name__, static_folder=STATIC_FOLDER, static_url_path="/static")
+
+# instantiate the IB client with a process-unique client id to avoid
+# collisions when Flask's reloader spawns multiple processes.
+ib = IBClient(client_id=os.getpid())
+# Start connection only in the main process (Werkzeug sets WERKZEUG_RUN_MAIN)
+if os.environ.get("WERKZEUG_RUN_MAIN") == "true" or not os.environ.get("WERKZEUG_RUN_MAIN"):
+    # attempt to start the connection; failures are logged by the client
+    try:
+        ib.connect_and_start()
+    except Exception:
+        pass
+
+
+@app.route("/")
+def index():
+    return send_from_directory(app.static_folder, "index.html")
+
+
+@app.route("/api/quotes")
+def api_quotes():
+    return jsonify(ib.get_quotes())
+
+
+@app.route("/api/positions")
+def api_positions():
+    # request a fresh positions snapshot from IB and wait briefly for callbacks
+    try:
+        ib.request_positions()
+    except Exception:
+        pass
+    # wait up to 2 seconds for positions to arrive
+    deadline = time.time() + 2.0
+    while time.time() < deadline:
+        positions = ib.get_positions()
+        if positions:
+            return jsonify(positions)
+        time.sleep(0.1)
+    # return whatever we have (possibly empty)
+    return jsonify(ib.get_positions())
+
+
+@app.route("/api/subscribe", methods=["POST"])
+def api_subscribe():
+    data = request.get_json(force=True)
+    symbols = data.get("symbols", []) if isinstance(data, dict) else []
+    if not isinstance(symbols, list):
+        return jsonify({"error": "symbols must be a list"}), 400
+    for s in symbols:
+        ib.subscribe_market_data(s)
+    return jsonify({"subscribed": symbols})
+
+
+if __name__ == "__main__":
+    # simple dev server; disable reloader to avoid duplicate IB client instances
+    app.run(debug=True, port=8000, use_reloader=False)