Add READ_ONLY_API environment variable and enhance trading error handling

routers/charts.py

@@ -24,13 +24,66 @@ class ChartState:
     def __init__(self):
         self.latest_tick = None
         self.current_ticker = None
+        self.current_symbol = None
         self.current_minute = None
         self.current_ohlc = None
+        self.history_poll_task = None
+        self.last_realtime_update = 0.0
 
 
 chart_state = ChartState()
 
 
+async def _stop_history_poll_task() -> None:
+    task = chart_state.history_poll_task
+    chart_state.history_poll_task = None
+    if task is None or task.done():
+        return
+    task.cancel()
+    try:
+        await task
+    except asyncio.CancelledError:
+        pass
+
+
+async def _history_fallback_loop(symbol: str, contract) -> None:
+    ib = dependencies.get_ib()
+    try:
+        while chart_state.current_symbol == symbol:
+            # Only fall back when real-time bars have not updated recently.
+            if chart_state.last_realtime_update and (
+                time.monotonic() - chart_state.last_realtime_update
+            ) < 20:
+                await asyncio.sleep(15)
+                continue
+
+            try:
+                bars = await ib.reqHistoricalDataAsync(
+                    contract,
+                    endDateTime="",
+                    durationStr="1 D",
+                    barSizeSetting="1 min",
+                    whatToShow="TRADES",
+                    useRTH=True,
+                    formatDate=1,
+                )
+                if bars:
+                    last_bar = bars[-1]
+                    chart_state.latest_tick = {
+                        "time": int(last_bar.date.timestamp()),
+                        "open": last_bar.open,
+                        "high": last_bar.high,
+                        "low": last_bar.low,
+                        "close": last_bar.close,
+                    }
+            except Exception as exc:
+                logger.warning(f"Historical fallback update failed for {symbol}: {exc}")
+
+            await asyncio.sleep(15)
+    except asyncio.CancelledError:
+        pass
+
+
 @router.get("/", response_class=HTMLResponse)
 async def index(request: Request, symbol: str = ""):
     return templates.TemplateResponse(request, "index.html", {"symbol": symbol})
@@ -115,8 +168,13 @@ async def subscribe(request: Request):
             except Exception as e:
                 print(f"Error cancelling real-time bars: {e}")
 
+        await _stop_history_poll_task()
+
+        chart_state.current_symbol = symbol
+        chart_state.latest_tick = None
         chart_state.current_minute = None
         chart_state.current_ohlc = None
+        chart_state.last_realtime_update = 0.0
 
         ticker = ib.reqRealTimeBars(qualified[0], barSize=5, whatToShow="TRADES", useRTH=True)
         chart_state.current_ticker = ticker
@@ -152,9 +210,13 @@ async def subscribe(request: Request):
                     "close": bar.close,
                 }
 
+            chart_state.last_realtime_update = time.monotonic()
             chart_state.latest_tick = chart_state.current_ohlc.copy()
 
         ticker.updateEvent += on_bar
+        chart_state.history_poll_task = asyncio.create_task(
+            _history_fallback_loop(symbol, qualified[0])
+        )
 
         return {"status": "ok", "symbol": symbol}
     except Exception as e: