fix(models): thread incoming_provenance + protect multi-tool blocks

Rebase threading fix and a backward scan so a chronological insert
cannot split a multi-result tool block.

api/models.py

@@ -10382,16 +10382,22 @@ def _insert_state_message_chronologically(messages: list, msg: dict) -> bool:
             # preceding assistant's tool_calls, not just the first — a multi-tool
             # turn has several adjacent tool results, and inserting between any of
             # them splits the block (assistant, tool, <insert>, tool).
-            if (
-                idx < len(messages)
-                and messages[idx].get("role") == "tool"
-                and idx > 0
-                and messages[idx - 1].get("role") == "assistant"
-                and messages[idx - 1].get("tool_calls")
-            ):
-                while idx < len(messages) and messages[idx].get("role") == "tool":
-                    idx += 1
-                    advanced = True
+            if idx < len(messages) and messages[idx].get("role") == "tool":
+                # Walk back over any contiguous tool rows already emitted for
+                # this block, so the owning assistant is found even when idx
+                # lands on the SECOND result of a multi-tool turn (where
+                # messages[idx - 1] is another tool row, not the assistant).
+                owner = idx - 1
+                while owner >= 0 and messages[owner].get("role") == "tool":
+                    owner -= 1
+                if (
+                    owner >= 0
+                    and messages[owner].get("role") == "assistant"
+                    and messages[owner].get("tool_calls")
+                ):
+                    while idx < len(messages) and messages[idx].get("role") == "tool":
+                        idx += 1
+                        advanced = True
             # (b) Skip past an equal-timestamp run whose left neighbour shares
             # this message's role — inserting there would re-order an
             # already-matched same-role turn (user, <inserted user>, assistant).
@@ -10434,6 +10440,7 @@ def merge_session_messages_append_only(
             state_messages,
             truncation_watermark=truncation_watermark,
             truncation_boundary=truncation_boundary,
+            incoming_provenance=incoming_provenance,
         )
     finally:
         _STRUCTURED_IDENTITY_MEMO.reset(token)
@@ -10445,6 +10452,7 @@ def _merge_session_messages_append_only_impl(
     *,
     truncation_watermark=None,
     truncation_boundary=None,
+    incoming_provenance=None,
 ) -> list:
     """Merge sidecar/context and state.db messages without deleting local rows.