refactor: extract tooling policy helpers

Move tool allowlist, tool_config, and tooling-context helpers into app/http/tooling_policy.py while keeping route behavior unchanged.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/http/tooling_policy.py

@@ -0,0 +1,120 @@
+from __future__ import annotations
+
+from typing import Any
+
+from fastapi import HTTPException
+
+from ..anthropic_schema import AnthropicMessagesRequest
+from ..config import Settings
+from ..openai_schema import ChatCompletionsRequest
+from .tool_bridge import (
+    _anthropic_forced_tool_name,
+    _anthropic_tool_name,
+    _openai_forced_tool_name,
+    _openai_tool_name,
+)
+
+
+def _tool_allowlist(settings: Settings) -> set[str]:
+    return {name.strip() for name in settings.tool_allowlist if isinstance(name, str) and name.strip()}
+
+
+def _filter_allowed_tools(
+    tools: list[dict[str, Any]], *, provider: str, settings: Settings
+) -> list[dict[str, Any]]:
+    allowlist = _tool_allowlist(settings)
+    if not allowlist:
+        return tools
+    name_fn = _openai_tool_name if provider == "openai" else _anthropic_tool_name
+    return [tool for tool in tools if (name := name_fn(tool)) and name in allowlist]
+
+
+def _ensure_tool_choice_allowed(tool_choice: Any, *, provider: str, settings: Settings) -> None:
+    allowlist = _tool_allowlist(settings)
+    if not allowlist:
+        return
+    forced_name = (
+        _openai_forced_tool_name(tool_choice)
+        if provider == "openai"
+        else _anthropic_forced_tool_name(tool_choice)
+    )
+    if forced_name and forced_name not in allowlist:
+        raise HTTPException(
+            status_code=400,
+            detail={
+                "error": {
+                    "type": "invalid_request_error",
+                    "message": f"tool '{forced_name}' is not allowed",
+                }
+            },
+        )
+
+
+def _openai_tool_config(req: ChatCompletionsRequest, *, settings: Settings) -> dict[str, Any] | None:
+    if not settings.tool_forward_enabled:
+        return None
+    has_tools = isinstance(req.tools, list) and len(req.tools) > 0
+    has_choice = req.tool_choice is not None
+    if not has_tools and not has_choice:
+        return None
+    _ensure_tool_choice_allowed(req.tool_choice, provider="openai", settings=settings)
+    tools = _filter_allowed_tools(req.tools or [], provider="openai", settings=settings)
+    return {
+        "provider": "openai",
+        "tools": tools,
+        "tool_choice": req.tool_choice,
+    }
+
+
+def _anthropic_tool_config(
+    req: AnthropicMessagesRequest, *, settings: Settings
+) -> dict[str, Any] | None:
+    if not settings.tool_forward_enabled:
+        return None
+    has_tools = isinstance(req.tools, list) and len(req.tools) > 0
+    has_choice = req.tool_choice is not None
+    if not has_tools and not has_choice:
+        return None
+    _ensure_tool_choice_allowed(req.tool_choice, provider="anthropic", settings=settings)
+    tools = _filter_allowed_tools(req.tools or [], provider="anthropic", settings=settings)
+    return {
+        "provider": "anthropic",
+        "tools": tools,
+        "tool_choice": req.tool_choice,
+    }
+
+
+def _openai_has_tooling_context(req: ChatCompletionsRequest, messages: list[dict[str, Any]]) -> bool:
+    if isinstance(req.tools, list) and len(req.tools) > 0:
+        return True
+    if req.tool_choice is not None:
+        return True
+    for m in messages:
+        role = m.get("role")
+        if role == "tool":
+            return True
+        if role == "assistant" and m.get("tool_calls"):
+            return True
+    return False
+
+
+def _anthropic_content_has_tool_blocks(content: Any) -> bool:
+    if not isinstance(content, list):
+        return False
+    for item in content:
+        if isinstance(item, dict) and item.get("type") in {"tool_use", "tool_result"}:
+            return True
+    return False
+
+
+def _anthropic_has_tooling_context(req: AnthropicMessagesRequest) -> bool:
+    if isinstance(req.tools, list) and len(req.tools) > 0:
+        return True
+    if req.tool_choice is not None:
+        return True
+    if _anthropic_content_has_tool_blocks(req.system):
+        return True
+    for m in req.messages:
+        if _anthropic_content_has_tool_blocks(m.content):
+            return True
+    return False