feat: expose delete_memory_unit as HTTP DELETE endpoint

hindsight-api-slim/hindsight_api/api/http.py

@@ -2412,6 +2412,50 @@ async def api_get_memory(
             logger.error(f"Error in /v1/default/banks/{bank_id}/memories/{memory_id}: {error_detail}")
             raise HTTPException(status_code=500, detail=str(e))
 
+
+    @app.delete(
+        "/v1/default/banks/{bank_id}/memories/{memory_id}",
+        response_model=DeleteResponse,
+        summary="Delete a memory unit",
+        description="Delete a single memory unit and all its associated links, entity associations, "
+        "and derived observations.\n\n"
+        "Due to CASCADE DELETE constraints, this will automatically delete:\n"
+        "- All links from/to this memory unit\n"
+        "- All entity associations\n"
+        "- All derived observations (remaining source memories are reset for re-consolidation)\n\n"
+        "This operation cannot be undone.",
+        operation_id="delete_memory",
+        tags=["Memory"],
+    )
+    @audited("delete_memory", request_param=None)
+    async def api_delete_memory(
+        bank_id: str,
+        memory_id: str,
+        request_context: RequestContext = Depends(get_request_context),
+    ):
+        """Delete a single memory unit and all its associated data."""
+        try:
+            result = await app.state.memory.delete_memory_unit(
+                memory_id,
+                request_context=request_context,
+            )
+            if not result.get("success"):
+                raise HTTPException(status_code=404, detail=f"Memory unit '{memory_id}' not found")
+            return DeleteResponse(
+                success=True,
+                message=result.get("message", "Memory unit deleted successfully"),
+            )
+        except OperationValidationError as e:
+            raise HTTPException(status_code=e.status_code, detail=e.reason)
+        except (AuthenticationError, HTTPException):
+            raise
+        except Exception as e:
+            import traceback
+
+            error_detail = f"{str(e)}\n\nTraceback:\n{traceback.format_exc()}"
+            logger.error(f"Error in DELETE /v1/default/banks/{bank_id}/memories/{memory_id}: {error_detail}")
+            raise HTTPException(status_code=500, detail=str(e))
+
     @app.get(
         "/v1/default/banks/{bank_id}/memories/{memory_id}/history",
         summary="Get observation history",

hindsight-api-slim/tests/test_http_api_integration.py

@@ -503,6 +503,81 @@ async def test_document_deletion_with_slashes_in_id(api_client):
         await api_client.delete(f"/v1/default/banks/{test_bank_id}")
 
 
+
+@pytest.mark.asyncio
+async def test_delete_memory_unit(api_client):
+    """Test deleting a single memory unit via DELETE endpoint.
+
+    Workflow:
+    1. Create a bank by storing memories
+    2. List memories and pick one
+    3. Delete that single memory unit
+    4. Verify it returns 404 on GET
+    5. Verify other memories still exist
+    6. Delete again returns 404
+    """
+    test_bank_id = f"delete_memory_test_{datetime.now().timestamp()}"
+
+    # 1. Store two memories
+    response = await api_client.post(
+        f"/v1/default/banks/{test_bank_id}/memories",
+        json={
+            "items": [
+                {
+                    "content": "Alice is a software engineer who loves hiking.",
+                    "context": "team info",
+                },
+                {
+                    "content": "Bob is a data scientist who enjoys painting.",
+                    "context": "team info",
+                },
+            ]
+        },
+    )
+    assert response.status_code == 200
+    assert response.json()["success"] is True
+
+    # 2. List memories and pick one to delete
+    response = await api_client.post(
+        f"/v1/default/banks/{test_bank_id}/memories/list",
+        json={},
+    )
+    assert response.status_code == 200
+    memories = response.json()["items"]
+    assert len(memories) >= 2
+    memory_to_delete = memories[0]["id"]
+    other_memory = memories[1]["id"]
+
+    # 3. Delete the memory unit
+    response = await api_client.delete(
+        f"/v1/default/banks/{test_bank_id}/memories/{memory_to_delete}"
+    )
+    assert response.status_code == 200
+    delete_result = response.json()
+    assert delete_result["success"] is True
+
+    # 4. Verify deleted memory returns 404
+    response = await api_client.get(
+        f"/v1/default/banks/{test_bank_id}/memories/{memory_to_delete}"
+    )
+    assert response.status_code == 404
+
+    # 5. Verify other memory still exists
+    response = await api_client.get(
+        f"/v1/default/banks/{test_bank_id}/memories/{other_memory}"
+    )
+    assert response.status_code == 200
+
+    # 6. Try to delete again (should return 404)
+    response = await api_client.delete(
+        f"/v1/default/banks/{test_bank_id}/memories/{memory_to_delete}"
+    )
+    assert response.status_code == 404
+
+    # Cleanup
+    await api_client.delete(f"/v1/default/banks/{test_bank_id}")
+
+
 @pytest.mark.asyncio
 async def test_delete_bank(api_client):
     """Test delete bank endpoint.