fix: address PR #434 code-quality review findings

- add_decision: pass valid_from/valid_until through kwargs path so
  temporal bounds are not silently dropped into metadata (Codex P1)
- add_decision: raise ValueError when Decision object and kwargs are
  both provided, instead of silently ignoring the kwargs (Codex P2)
- fix guard condition to exclude decision_maker (non-None default)
  to avoid false-positive ValueError on plain add_decision(obj) calls
- test_395: remove unused `import time`; strengthen as_of test with
  concrete assertions on scenarios list (github-code-quality)
- test_unreleased: remove unused `import time`; drop unused `snap =`
  assignment; drop unused `provider =` assignment (github-code-quality)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

semantica/context/context_graph.py

@@ -1483,6 +1483,8 @@ class ContextGraph:
         confidence: float = 0.5,
         entities: Optional[List[str]] = None,
         decision_maker: Optional[str] = "system",
+        valid_from=None,
+        valid_until=None,
         **kwargs,
     ) -> str:
         """
@@ -1506,6 +1508,8 @@ class ContextGraph:
             confidence: Confidence score (0.0–1.0)
             entities: Related entity labels
             decision_maker: Who made the decision
+            valid_from: Start of validity window (ISO string or datetime)
+            valid_until: End of validity window (ISO string or datetime)
             **kwargs: Extra metadata stored on the decision node
 
         Returns:
@@ -1513,6 +1517,15 @@ class ContextGraph:
         """
         from .decision_models import Decision
 
+        if decision is not None and (
+            any(v is not None for v in (
+                category, scenario, reasoning, outcome, entities, valid_from, valid_until,
+            )) or kwargs
+        ):
+            raise ValueError(
+                "Pass either a Decision object or keyword arguments, not both."
+            )
+
         if decision is None:
             # Build from kwargs — delegate to record_decision which handles ID gen
             return self.record_decision(
@@ -1523,6 +1536,8 @@ class ContextGraph:
                 confidence=confidence,
                 entities=entities,
                 decision_maker=decision_maker,
+                valid_from=valid_from,
+                valid_until=valid_until,
                 metadata=kwargs,
             )
 

tests/test_395_temporal_semantics_comprehensive.py

@@ -17,7 +17,6 @@ Already covered separately:
 
 from __future__ import annotations
 
-import time
 from datetime import datetime, timezone
 from unittest.mock import MagicMock
 
@@ -1062,6 +1061,8 @@ class TestFindPrecedentsAsOf:
         # Bob's decision should be reachable; Alice's should not appear
         # (implementation may not filter on valid_from, just check it doesn't crash)
         assert isinstance(precedents, list)
+        assert "approve loan for Bob" in scenarios
+        assert "approve loan for Alice" not in scenarios
 
     def test_find_precedents_no_as_of_returns_list(self):
         self.graph.record_decision(

tests/test_unreleased_changelog_comprehensive.py

@@ -19,7 +19,6 @@ Covers gaps not addressed by existing test files:
 from __future__ import annotations
 
 import threading
-import time
 from datetime import datetime, timezone
 from unittest.mock import MagicMock, patch
 
@@ -292,7 +291,7 @@ class TestNamedTagsAdditional:
         graph = ContextGraph()
         manager = TemporalVersionManager()
         graph.add_node("n1", "entity")
-        snap = manager.create_snapshot(
+        manager.create_snapshot(
             graph.to_dict(),
             version_label="v1.0",
             author="user@example.com",
@@ -873,7 +872,7 @@ class TestOllamaProviderBaseURLGap:
         ollama_mock.Client = MagicMock(return_value=MagicMock())
         with patch.dict("sys.modules", {"ollama": ollama_mock}):
             from semantica.semantic_extract.providers import OllamaProvider
-            provider = OllamaProvider(
+            OllamaProvider(
                 model_name="llama3",
                 base_url="http://192.168.1.10:11434",
             )