diff --git a/hindsight-api-slim/hindsight_api/engine/consolidation/consolidator.py b/hindsight-api-slim/hindsight_api/engine/consolidation/consolidator.py
index c525253fe..4f331149e 100644
--- a/hindsight-api-slim/hindsight_api/engine/consolidation/consolidator.py
+++ b/hindsight-api-slim/hindsight_api/engine/consolidation/consolidator.py
@@ -102,6 +102,15 @@ class _DedupDecision(BaseModel):
     text: str = ""  # the synthesized merged observation (when action == "merge")
     reason: str = ""
 
+    @field_validator("action", mode="before")
+    @classmethod
+    def _normalize_action(cls, value: object) -> str:
+        if isinstance(value, str) and value in {"merge", "keep"}:
+            return value
+
+        logger.warning("Invalid consolidation dedup action %r; defaulting to keep", value)
+        return "keep"
+
 
 _DEDUP_PROMPT = """You reconcile long-term memory observations. A NEW observation is about to be \
 stored, and it is highly similar to an EXISTING one:
diff --git a/hindsight-api-slim/tests/test_consolidation_dedup.py b/hindsight-api-slim/tests/test_consolidation_dedup.py
index aa8417e3a..25121c886 100644
--- a/hindsight-api-slim/tests/test_consolidation_dedup.py
+++ b/hindsight-api-slim/tests/test_consolidation_dedup.py
@@ -5,6 +5,7 @@
 the path stochastically.
 """
 
+import logging
 import types
 import uuid
 from dataclasses import dataclass
@@ -142,6 +143,38 @@ async def test_dedup_llm_missing_action_defaults_to_keep() -> None:
     conn.execute.assert_not_called()  # missing action is a conservative no-merge
 
 
+def test_dedup_decision_accepts_exact_valid_actions() -> None:
+    assert _DedupDecision(action="merge").action == "merge"
+    assert _DedupDecision(action="keep").action == "keep"
+
+
+def test_dedup_decision_invalid_action_defaults_to_keep(caplog) -> None:
+    with caplog.at_level(logging.WARNING):
+        decision = _DedupDecision(action="need_input", reason="model asked for more context")
+
+    assert decision.action == "keep"
+    assert "need_input" in caplog.text
+    assert "defaulting to keep" in caplog.text
+
+
+def test_dedup_decision_near_miss_merge_defaults_to_keep(caplog) -> None:
+    with caplog.at_level(logging.WARNING):
+        decision = _DedupDecision(action="Merge")
+
+    assert decision.action == "keep"
+    assert "Merge" in caplog.text
+
+
+def test_dedup_decision_non_scalar_action_defaults_to_keep(caplog) -> None:
+    with caplog.at_level(logging.WARNING):
+        list_decision = _DedupDecision(action=[])
+        dict_decision = _DedupDecision(action={"value": "merge"})
+
+    assert list_decision.action == "keep"
+    assert dict_decision.action == "keep"
+    assert "defaulting to keep" in caplog.text
+
+
 async def test_dedup_llm_merge_folds_into_twin() -> None:
     kwargs, conn, llm = _ctx()
     kwargs["create_source_ids"] = [uuid.uuid4(), uuid.uuid4()]