fix(state): never emit created_at on the wire (#146)

#144 removed the ts -> created_at carry but left created_at in the
allowlist the serializer filters against, so a buffer record containing
that key literally would still pass straight through. Nothing writes it
today, so this was latent rather than live — but closing exactly this kind
of door is what the allowlist is for, and the test only supplied ts so it
could not catch it.

Splits the two concepts: _INTERACTION_DATA_FIELDS stays the model-contract
set (created_at IS a real InteractionData field, and the drift test pins
the set against the model), while _WIRE_FIELDS is what the serializer
filters on and excludes it.

Why created_at must not be emitted: the extractor's bookmark is keyed on
interaction created_at (last_processed_timestamp, compared with
created_at >= ?), so a backdated batch — one recovered after the bookmark
moved — is stored and then never extracted. That is permanent, silent loss
of learning data on precisely the offline-recovery path this buffer exists
for. Letting the server stamp its own time is the lesser evil until ingest
ordering stops depending on caller-supplied event time.

Caught by CodeRabbit on #144 after it merged.

Author: guangyu-reflexio

plugin/src/claude_smart/state.py

@@ -62,6 +62,16 @@
     }
 )
 
+# Fields actually put on the wire. `created_at` is a real InteractionData field
+# — so it must stay in the set above, which is pinned against the model — but it
+# must NOT be emitted. Sending a buffered event time backdates the interaction,
+# and the extractor's bookmark is keyed on `created_at` (`created_at >= ?`), so a
+# batch recovered after the bookmark moved is stored and then never extracted:
+# permanent, silent loss of learning data on exactly the offline-recovery path
+# this buffer exists for. Letting the server stamp its own time is the lesser
+# evil until ingest ordering stops depending on caller-supplied event time.
+_WIRE_FIELDS = _INTERACTION_DATA_FIELDS - {"created_at"}
+
 _VALID_CITATION_KINDS = frozenset(
     {"playbook", "profile", "user_playbook", "agent_playbook"}
 )
@@ -436,9 +446,7 @@ def unpublished_slice(
         # turn that rot into a publish failure this plugin's adapter swallows
         # without advancing its watermark.
         turn = {
-            key: value
-            for key, value in record.items()
-            if key in _INTERACTION_DATA_FIELDS
+            key: value for key, value in record.items() if key in _WIRE_FIELDS
         }
         turn["role"] = role
         # NOTE: deliberately does NOT send `created_at`. Carrying the buffer's

tests/test_state.py

@@ -544,6 +544,24 @@ def test_allowlist_covers_every_installed_model_field(self):
             " the slicer would silently drop them"
         )
 
+    def test_created_at_is_never_emitted_even_when_present(self):
+        """A literal `created_at` in the buffer must not reach the wire.
+
+        The field is in the model-contract set (it is a real InteractionData
+        field), so filtering on that set alone let it through. Only `ts` was
+        tested, which could not catch this. Backdating an interaction hides it
+        from the extractor permanently — see `_WIRE_FIELDS`.
+        """
+        _, turns = state.unpublished_slice(
+            [{"ts": 1, "role": "User", "content": "x", "created_at": 999}]
+        )
+        assert "created_at" not in turns[0], turns[0]
+
+    def test_wire_fields_excludes_created_at_but_contract_set_keeps_it(self):
+        assert "created_at" in state._INTERACTION_DATA_FIELDS
+        assert "created_at" not in state._WIRE_FIELDS
+        assert state._WIRE_FIELDS < state._INTERACTION_DATA_FIELDS
+
     def test_buffer_timestamp_is_not_sent(self):
         """`created_at` must stay off the wire.