fix(mcp): pass the retain strategy to the worker

hindsight-api-slim/hindsight_api/mcp_tools.py

@@ -644,6 +644,7 @@ async def retain(
                 result = await memory.submit_async_retain(
                     bank_id=target_bank,
                     contents=[content_dict],
+                    strategy=content_dict.pop("strategy", None),
                     request_context=request_context,
                 )
                 return {
@@ -698,6 +699,7 @@ async def retain(
                 result = await memory.submit_async_retain(
                     bank_id=target_bank,
                     contents=[content_dict],
+                    strategy=content_dict.pop("strategy", None),
                     request_context=request_context,
                 )
                 return {

hindsight-api-slim/tests/test_mcp_tools.py

@@ -1062,6 +1062,25 @@ async def test_retain_with_document_id(self, mock_memory):
         contents = call_args.kwargs["contents"]
         assert contents[0]["document_id"] == "doc-1"
 
+    async def test_retain_passes_strategy_to_the_worker(self, mock_memory):
+        """The strategy must travel as the submit argument, not inside the content item.
+
+        ``submit_async_retain`` only puts a strategy into the task payload when it
+        is passed as the keyword; a strategy left inside the content dict never
+        reaches the worker, so every strategy override silently falls back to the
+        bank configuration.
+        """
+        mcp = _make_mcp_server(mock_memory, {"retain"}, include_bank_id=True)
+        await _tools(mcp)["retain"].fn(content="test", strategy="documents")
+        call_args = mock_memory.submit_async_retain.call_args
+        assert call_args.kwargs["strategy"] == "documents"
+
+    async def test_retain_passes_strategy_single_bank(self, mock_memory):
+        mcp = _make_mcp_server(mock_memory, {"retain"}, include_bank_id=False)
+        await _tools(mcp)["retain"].fn(content="test", strategy="documents")
+        call_args = mock_memory.submit_async_retain.call_args
+        assert call_args.kwargs["strategy"] == "documents"
+
     async def test_retain_without_new_params_backward_compat(self, mock_memory):
         """Existing behavior preserved when new params not provided."""
         mcp = _make_mcp_server(mock_memory, {"retain"})