Stabilize core correctness and sync project plan state

tests/test_project_state.py

@@ -57,6 +57,12 @@ def test_set_state_invalid_category():
         set_state("myproject", "invalid_category", "key", "value")
 
 
+def test_set_state_validates_confidence():
+    """Project-state confidence should stay within the documented range."""
+    with pytest.raises(ValueError, match="Confidence must be between 0.0 and 1.0"):
+        set_state("myproject", "status", "phase", "Phase 1", confidence=1.2)
+
+
 def test_get_state_all():
     """Test getting all state entries for a project."""
     set_state("proj", "status", "phase", "Phase 1")