fix(anthropic): preserve ordered replay cache markers

agent/anthropic_adapter.py

@@ -1891,6 +1891,18 @@ def _sanitize_replay_block(b: Dict[str, Any]) -> Optional[Dict[str, Any]]:
     return None
 
 
+def _apply_assistant_cache_control_to_last_cacheable_block(
+    blocks: List[Dict[str, Any]],
+    cache_control: Any,
+) -> None:
+    if not isinstance(cache_control, dict):
+        return
+    for block in reversed(blocks):
+        if isinstance(block, dict) and block.get("type") in {"text", "tool_use"}:
+            block.setdefault("cache_control", dict(cache_control))
+            break
+
+
 def _convert_assistant_message(m: Dict[str, Any]) -> Dict[str, Any]:
     """Convert an assistant message to Anthropic content blocks.
 
@@ -1945,6 +1957,9 @@ def _convert_assistant_message(m: Dict[str, Any]) -> Dict[str, Any]:
                     clean["input"] = redacted
             replayed.append(clean)
         if replayed:
+            _apply_assistant_cache_control_to_last_cacheable_block(
+                replayed, m.get("cache_control")
+            )
             return {"role": "assistant", "content": replayed}
 
     blocks = _extract_preserved_thinking_blocks(m)
@@ -1970,11 +1985,9 @@ def _convert_assistant_message(m: Dict[str, Any]) -> Dict[str, Any]:
             "name": fn.get("name", ""),
             "input": parsed_args,
         })
-    if isinstance(m.get("cache_control"), dict):
-        for block in reversed(blocks):
-            if isinstance(block, dict) and block.get("type") in {"text", "tool_use"}:
-                block.setdefault("cache_control", dict(m["cache_control"]))
-                break
+    _apply_assistant_cache_control_to_last_cacheable_block(
+        blocks, m.get("cache_control")
+    )
     # Kimi's /coding endpoint (Anthropic protocol) requires assistant
     # tool-call messages to carry reasoning_content when thinking is
     # enabled server-side.  Preserve it as a thinking block so Kimi

tests/agent/test_anthropic_adapter.py

@@ -1046,6 +1046,50 @@ class TestConvertMessages:
         assert tool_use["id"] == "tc_1"
         assert tool_use["cache_control"] == {"type": "ephemeral"}
 
+    def test_ordered_replay_tool_use_cache_control_is_preserved(self):
+        messages = apply_anthropic_cache_control([
+            {"role": "system", "content": "System prompt"},
+            {"role": "user", "content": "Run the tool"},
+            {
+                "role": "assistant",
+                "content": "",
+                "anthropic_content_blocks": [
+                    {
+                        "type": "thinking",
+                        "thinking": "Need a tool.",
+                        "signature": "sig_1",
+                    },
+                    {
+                        "type": "tool_use",
+                        "id": "tc_1",
+                        "name": "test_tool",
+                        "input": {"query": "raw"},
+                    },
+                ],
+                "tool_calls": [
+                    {
+                        "id": "tc_1",
+                        "function": {
+                            "name": "test_tool",
+                            "arguments": '{"query":"redacted"}',
+                        },
+                    },
+                ],
+            },
+            {"role": "tool", "tool_call_id": "tc_1", "content": "result"},
+        ], native_anthropic=True)
+
+        _, result = convert_messages_to_anthropic(messages)
+        assistant_msg = [m for m in result if m["role"] == "assistant"][0]
+        thinking, tool_use = assistant_msg["content"]
+
+        assert thinking["type"] == "thinking"
+        assert "cache_control" not in thinking
+        assert tool_use["type"] == "tool_use"
+        assert tool_use["id"] == "tc_1"
+        assert tool_use["input"] == {"query": "redacted"}
+        assert tool_use["cache_control"] == {"type": "ephemeral"}
+
     def test_tool_cache_control_is_preserved_on_tool_result_block(self):
         messages = apply_anthropic_cache_control([
             {"role": "system", "content": "System prompt"},