fix: handle invalid coaching payloads for nudges

Author: ccf

src/primer/mcp/tools.py

@@ -5,6 +5,7 @@
 import os
 
 import httpx
+from pydantic import ValidationError
 
 from primer.mcp.nudges import build_in_session_nudges
 from primer.mcp.sync import sync_sessions
@@ -251,7 +252,7 @@ def primer_in_session_nudges(
                 from primer.common.schemas import CoachingBrief
 
                 coaching_brief = CoachingBrief.model_validate(resp.json())
-        except httpx.RequestError:
+        except (ValidationError, ValueError, httpx.RequestError, json.JSONDecodeError):
             coaching_brief = None
 
     data = build_in_session_nudges(live_signals, coaching_brief)

tests/test_mcp_tools.py

@@ -366,6 +366,40 @@ def test_primer_in_session_nudges_success(mock_get_signals, mock_get):
     assert "Debugging playbook" in result
 
 
+@patch("primer.mcp.tools.httpx.get")
+@patch("primer.mcp.tools.get_live_session_signals")
+def test_primer_in_session_nudges_falls_back_when_coaching_payload_is_invalid(
+    mock_get_signals, mock_get
+):
+    mock_get_signals.return_value = LiveSessionSignalsResponse(
+        session_id="session-123",
+        agent_type="claude_code",
+        project_name="api-server",
+        total_messages=12,
+        risk_level="high",
+        satisfaction_signal="negative",
+        signals=[
+            LiveSessionSignal(
+                signal_type="verification_failure",
+                severity="warning",
+                title="Verification is failing",
+                detail="Recent test runs are failing repeatedly.",
+            )
+        ],
+    )
+    mock_resp = MagicMock()
+    mock_resp.status_code = 200
+    mock_resp.json.return_value = {"brief_type": "session_start", "sections": "invalid"}
+    mock_get.return_value = mock_resp
+
+    from primer.mcp.tools import primer_in_session_nudges
+
+    result = primer_in_session_nudges(project_name="api-server")
+
+    assert "In-Session Workflow Nudges" in result
+    assert "Tighten the verification loop" in result
+
+
 @patch("primer.mcp.tools.get_live_session_signals")
 def test_primer_in_session_nudges_error(mock_get_signals):
     mock_get_signals.side_effect = ValueError("No local sessions found")