fix(cache): stabilize tool ordering and cache markers for MCP

nanobot/providers/anthropic_provider.py

@@ -9,7 +9,6 @@ from collections.abc import Awaitable, Callable
 from typing import Any
 
 import json_repair
-from loguru import logger
 
 from nanobot.providers.base import LLMProvider, LLMResponse, ToolCallRequest
 
@@ -252,7 +251,38 @@ class AnthropicProvider(LLMProvider):
     # ------------------------------------------------------------------
 
     @staticmethod
+    def _tool_name(tool: dict[str, Any]) -> str:
+        name = tool.get("name")
+        if isinstance(name, str):
+            return name
+        fn = tool.get("function")
+        if isinstance(fn, dict):
+            fname = fn.get("name")
+            if isinstance(fname, str):
+                return fname
+        return ""
+
+    @classmethod
+    def _tool_cache_marker_indices(cls, tools: list[dict[str, Any]]) -> list[int]:
+        if not tools:
+            return []
+
+        tail_idx = len(tools) - 1
+        last_builtin_idx: int | None = None
+        for i in range(tail_idx, -1, -1):
+            if not cls._tool_name(tools[i]).startswith("mcp_"):
+                last_builtin_idx = i
+                break
+
+        ordered_unique: list[int] = []
+        for idx in (last_builtin_idx, tail_idx):
+            if idx is not None and idx not in ordered_unique:
+                ordered_unique.append(idx)
+        return ordered_unique
+
+    @classmethod
     def _apply_cache_control(
+        cls,
         system: str | list[dict[str, Any]],
         messages: list[dict[str, Any]],
         tools: list[dict[str, Any]] | None,
@@ -279,7 +309,8 @@ class AnthropicProvider(LLMProvider):
         new_tools = tools
         if tools:
             new_tools = list(tools)
-            new_tools[-1] = {**new_tools[-1], "cache_control": marker}
+            for idx in cls._tool_cache_marker_indices(new_tools):
+                new_tools[idx] = {**new_tools[idx], "cache_control": marker}
 
         return system, new_msgs, new_tools
 

nanobot/providers/openai_compat_provider.py

@@ -152,7 +152,36 @@ class OpenAICompatProvider(LLMProvider):
             os.environ.setdefault(env_name, resolved)
 
     @staticmethod
+    def _tool_name(tool: dict[str, Any]) -> str:
+        fn = tool.get("function")
+        if isinstance(fn, dict):
+            name = fn.get("name")
+            if isinstance(name, str):
+                return name
+        name = tool.get("name")
+        return name if isinstance(name, str) else ""
+
+    @classmethod
+    def _tool_cache_marker_indices(cls, tools: list[dict[str, Any]]) -> list[int]:
+        if not tools:
+            return []
+
+        tail_idx = len(tools) - 1
+        last_builtin_idx: int | None = None
+        for i in range(tail_idx, -1, -1):
+            if not cls._tool_name(tools[i]).startswith("mcp_"):
+                last_builtin_idx = i
+                break
+
+        ordered_unique: list[int] = []
+        for idx in (last_builtin_idx, tail_idx):
+            if idx is not None and idx not in ordered_unique:
+                ordered_unique.append(idx)
+        return ordered_unique
+
+    @classmethod
     def _apply_cache_control(
+        cls,
         messages: list[dict[str, Any]],
         tools: list[dict[str, Any]] | None,
     ) -> tuple[list[dict[str, Any]], list[dict[str, Any]] | None]:
@@ -180,7 +209,8 @@ class OpenAICompatProvider(LLMProvider):
         new_tools = tools
         if tools:
             new_tools = list(tools)
-            new_tools[-1] = {**new_tools[-1], "cache_control": cache_marker}
+            for idx in cls._tool_cache_marker_indices(new_tools):
+                new_tools[idx] = {**new_tools[idx], "cache_control": cache_marker}
         return new_messages, new_tools
 
     @staticmethod