fix(agent): keep Codex reasoning replay on Codex path

agent/agent_runtime_helpers.py

@@ -881,6 +881,8 @@ def try_recover_primary_transport(
 
 def drop_thinking_only_and_merge_users(
     messages: List[Dict[str, Any]],
+    *,
+    drop_codex_reasoning_items: bool = True,
 ) -> List[Dict[str, Any]]:
     """Drop thinking-only assistant turns; merge any adjacent user messages left behind.
 
@@ -902,7 +904,13 @@ def drop_thinking_only_and_merge_users(
         return messages
 
     # Pass 1: drop thinking-only assistant turns.
-    kept = [m for m in messages if not _ra().AIAgent._is_thinking_only_assistant(m)]
+    kept = [
+        m for m in messages
+        if not _ra().AIAgent._is_thinking_only_assistant(
+            m,
+            drop_codex_reasoning_items=drop_codex_reasoning_items,
+        )
+    ]
     dropped = len(messages) - len(kept)
     if dropped == 0:
         return messages

agent/conversation_loop.py

@@ -707,7 +707,10 @@ def run_conversation(
         # a thinking-only turn. Runs on the per-call copy only — the
         # stored conversation history keeps the reasoning block for the
         # UI transcript and session persistence.
-        api_messages = agent._drop_thinking_only_and_merge_users(api_messages)
+        api_messages = agent._drop_thinking_only_and_merge_users(
+            api_messages,
+            drop_codex_reasoning_items=agent.api_mode != "codex_responses",
+        )
 
         # Normalize message whitespace and tool-call JSON for consistent
         # prefix matching.  Ensures bit-perfect prefixes across turns,