fix: extract position dict from CallToolResult.structuredContent

Fix negative cash bug where ContextInjector._current_position never updated.

Root cause: MCP tools return mcp.types.CallToolResult objects, not plain
dicts. The isinstance(result, dict) check always failed, preventing
_current_position from accumulating trades within a session.

This caused all trades to calculate from initial $10,000 position instead
of previous trade's ending position, resulting in negative cash balances
when total purchases exceeded $10,000.

Solution: Extract position dict from CallToolResult.structuredContent field
before validating. Maintains backward compatibility by handling both
CallToolResult objects (production) and plain dicts (unit tests).

Impact:
- Fixes negative cash positions (e.g., -$8,768.68 after 11 trades)
- Enables proper intra-day position tracking
- Validates sufficient cash before each trade based on cumulative position
- Trade tool responses now properly accumulate all holdings

Testing:
- All existing unit tests pass (handle plain dict results)
- Production logs confirm structuredContent extraction works
- Debug logging shows _current_position now updates after each trade

agent/context_injector.py

@@ -88,9 +88,28 @@ class ContextInjector:
 
         # Update position state after successful trade
         if request.name in ["buy", "sell"]:
-            # Check if result is a valid position dict (not an error)
-            if isinstance(result, dict) and "error" not in result and "CASH" in result:
+            # Debug: Log result type and structure
+            print(f"[DEBUG ContextInjector] Trade result type: {type(result)}")
+            print(f"[DEBUG ContextInjector] Trade result: {result}")
+
+            # Extract position dict from MCP result
+            # MCP tools return CallToolResult objects with structuredContent field
+            position_dict = None
+            if hasattr(result, 'structuredContent') and result.structuredContent:
+                position_dict = result.structuredContent
+                print(f"[DEBUG ContextInjector] Extracted from structuredContent: {position_dict}")
+            elif isinstance(result, dict):
+                position_dict = result
+                print(f"[DEBUG ContextInjector] Using result as dict: {position_dict}")
+
+            # Check if position dict is valid (not an error) and update state
+            if position_dict and "error" not in position_dict and "CASH" in position_dict:
                 # Update our tracked position with the new state
-                self._current_position = result.copy()
+                self._current_position = position_dict.copy()
+                print(f"[DEBUG ContextInjector] Updated _current_position: {self._current_position}")
+            else:
+                print(f"[DEBUG ContextInjector] Did NOT update _current_position - check failed")
+                print(f"[DEBUG ContextInjector] position_dict: {position_dict}")
+                print(f"[DEBUG ContextInjector] _current_position remains: {self._current_position}")
 
         return result

agent_tools/tool_trade.py

@@ -132,11 +132,14 @@ def _buy_impl(symbol: str, amount: int, signature: str = None, today_date: str =
         # Step 1: Get current position
         # Use injected position if available (for intra-day tracking),
         # otherwise query database for starting position
+        print(f"[DEBUG buy] _current_position received: {_current_position}")
         if _current_position is not None:
             current_position = _current_position
             next_action_id = 0  # Not used in new schema
+            print(f"[DEBUG buy] Using injected position: {current_position}")
         else:
             current_position, next_action_id = get_current_position_from_db(job_id, signature, today_date)
+            print(f"[DEBUG buy] Queried position from DB: {current_position}")
 
         # Step 2: Get stock price
         try:
@@ -189,6 +192,8 @@ def _buy_impl(symbol: str, amount: int, signature: str = None, today_date: str =
 
         conn.commit()
         print(f"[buy] {signature} bought {amount} shares of {symbol} at ${this_symbol_price}")
+        print(f"[DEBUG buy] Returning new_position: {new_position}")
+        print(f"[DEBUG buy] new_position keys: {list(new_position.keys())}")
         return new_position
 
     except Exception as e: