fix(schema): coerce null-ish strings in optional float fields

A weak model can write a placeholder ('None', 'N/A') into an optional price
field, tripping schema validation. Coerce null-ish strings to None on the
trader/PM float fields; real numeric strings still parse.

tests/test_structured_agents.py

@@ -15,6 +15,7 @@ from pydantic import ValidationError
 from tradingagents.agents.analysts.sentiment_analyst import create_sentiment_analyst
 from tradingagents.agents.managers.research_manager import create_research_manager
 from tradingagents.agents.schemas import (
+    PortfolioDecision,
     PortfolioRating,
     ResearchPlan,
     SentimentBand,
@@ -67,6 +68,36 @@ class TestRenderTraderProposal:
         assert "FINAL TRANSACTION PROPOSAL: **SELL**" in md
 
 
+@pytest.mark.unit
+class TestNullishFloatCoercion:
+    """A weak LLM may write "None"/"N/A" into an optional float field (#1058);
+    coerce those to None so the structured call validates instead of erroring."""
+
+    def test_trader_nullish_strings_coerce_to_none(self):
+        for sentinel in ("None", "N/A", "null", "-", "", "TBD"):
+            p = TraderProposal(
+                action=TraderAction.HOLD,
+                reasoning="x",
+                entry_price=sentinel,
+                stop_loss=sentinel,
+            )
+            assert p.entry_price is None
+            assert p.stop_loss is None
+
+    def test_trader_real_numeric_string_still_parses(self):
+        p = TraderProposal(action=TraderAction.BUY, reasoning="x", entry_price="189.5")
+        assert p.entry_price == 189.5
+
+    def test_pm_nullish_price_target_coerces_to_none(self):
+        d = PortfolioDecision(
+            rating=PortfolioRating.OVERWEIGHT,
+            executive_summary="s",
+            investment_thesis="t",
+            price_target="N/A",
+        )
+        assert d.price_target is None
+
+
 @pytest.mark.unit
 class TestRenderResearchPlan:
     def test_required_fields(self):

tradingagents/agents/schemas.py

@@ -21,7 +21,20 @@ from __future__ import annotations
 from enum import Enum
 from typing import Literal
 
-from pydantic import BaseModel, Field
+from pydantic import BaseModel, Field, field_validator
+
+# LLMs sometimes write a placeholder string ("None", "N/A", ...) into an optional
+# numeric field instead of omitting it. Coerce those to None so the structured
+# call validates instead of erroring (#1058). Pydantic still parses real numeric
+# strings ("189.5") to float.
+_NULLISH_FLOAT = {"", "none", "n/a", "na", "null", "nil", "-", "tbd", "unknown"}
+
+
+def _coerce_optional_float(value):
+    if isinstance(value, str) and value.strip().lower() in _NULLISH_FLOAT:
+        return None
+    return value
+
 
 # ---------------------------------------------------------------------------
 # Shared rating types
@@ -136,6 +149,11 @@ class TraderProposal(BaseModel):
         description="Optional sizing guidance, e.g. '5% of portfolio'.",
     )
 
+    @field_validator("entry_price", "stop_loss", mode="before")
+    @classmethod
+    def _nullish_float_to_none(cls, v):
+        return _coerce_optional_float(v)
+
 
 def render_trader_proposal(proposal: TraderProposal) -> str:
     """Render a TraderProposal to markdown.
@@ -204,6 +222,11 @@ class PortfolioDecision(BaseModel):
         description="Optional recommended holding period, e.g. '3-6 months'.",
     )
 
+    @field_validator("price_target", mode="before")
+    @classmethod
+    def _nullish_float_to_none(cls, v):
+        return _coerce_optional_float(v)
+
 
 def render_pm_decision(decision: PortfolioDecision) -> str:
     """Render a PortfolioDecision back to the markdown shape the rest of the system expects.