Add debug logging to Anthropic OAuth provider

Logs thinking block presence, character count, and token usage
in API responses. Also logs request parameters including thinking
budget configuration.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

nanobot/providers/anthropic_oauth.py

@@ -5,10 +5,13 @@ which require Authorization: Bearer header instead of x-api-key.
 """
 
 import json
+import logging
 from typing import Any
 
 import httpx
 
+logger = logging.getLogger(__name__)
+
 from nanobot.providers.base import LLMProvider, LLMResponse, ToolCallRequest
 from nanobot.providers.oauth_utils import get_auth_headers, get_claude_code_system_prefix
 
@@ -223,6 +226,12 @@ class AnthropicOAuthProvider(LLMProvider):
         if tools:
             payload["tools"] = tools
 
+        logger.info(
+            "Anthropic request: model=%s max_tokens=%d thinking=%s",
+            payload.get("model"), payload.get("max_tokens"),
+            payload.get("thinking", "disabled"),
+        )
+
         response = await client.post(
             self._get_api_url(),
             headers=self._get_headers(),
@@ -304,6 +313,21 @@ class AnthropicOAuthProvider(LLMProvider):
                 ),
             }
 
+        # Log usage and thinking info
+        if thinking_blocks:
+            thinking_chars = sum(len(b.get("thinking", "")) for b in thinking_blocks)
+            logger.info(
+                "Anthropic response: %d thinking block(s) (%d chars), "
+                "input=%d output=%d tokens",
+                len(thinking_blocks), thinking_chars,
+                usage.get("prompt_tokens", 0), usage.get("completion_tokens", 0),
+            )
+        else:
+            logger.info(
+                "Anthropic response: no thinking blocks, input=%d output=%d tokens",
+                usage.get("prompt_tokens", 0), usage.get("completion_tokens", 0),
+            )
+
         return LLMResponse(
             content=text_content or None,
             tool_calls=tool_calls,