Remove hardcoded identity strings from system prompt

- Remove "# nanobot" branding and "You are nanobot" from context.py
- Remove "You are a helpful AI assistant" personality line
- Remove fake "required" Claude Code system prefix from OAuth provider
- Identity is now fully customizable via IDENTITY.md in workspace

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

nanobot/agent/context.py

@@ -71,7 +71,7 @@ Skills with available="false" need dependencies installed first - you can try in
         return "\n\n---\n\n".join(parts)
     
     def _get_identity(self) -> str:
-        """Get the core identity section."""
+        """Get the core identity section with runtime context."""
         from datetime import datetime
         import time as _time
         now = datetime.now().strftime("%Y-%m-%d %H:%M (%A)")
@@ -79,10 +79,8 @@ Skills with available="false" need dependencies installed first - you can try in
         workspace_path = str(self.workspace.expanduser().resolve())
         system = platform.system()
         runtime = f"{'macOS' if system == 'Darwin' else system} {platform.machine()}, Python {platform.python_version()}"
-        
-        return f"""# nanobot 🐈
 
-You are nanobot, a helpful AI assistant. You have access to tools that allow you to:
+        return f"""You have access to tools that allow you to:
 - Read, write, and edit files
 - Execute shell commands
 - Search the web and fetch web pages

nanobot/providers/anthropic_oauth.py

@@ -11,7 +11,7 @@ import httpx
 from loguru import logger
 
 from nanobot.providers.base import LLMProvider, LLMResponse, ToolCallRequest
-from nanobot.providers.oauth_utils import get_auth_headers, get_claude_code_system_prefix
+from nanobot.providers.oauth_utils import get_auth_headers
 
 
 class AnthropicOAuthProvider(LLMProvider):
@@ -78,7 +78,7 @@ class AnthropicOAuthProvider(LLMProvider):
 
         Returns (system_prompt, anthropic_messages)
         """
-        system_parts = [get_claude_code_system_prefix()]
+        system_parts = []
         converted: list[dict[str, Any]] = []
 
         for msg in messages:

nanobot/providers/oauth_utils.py

@@ -36,11 +36,3 @@ def get_auth_headers(token: str, is_oauth: bool = False) -> dict[str, str]:
         headers["x-api-key"] = token
 
     return headers
-
-
-def get_claude_code_system_prefix() -> str:
-    """Get the required system prompt prefix for OAuth tokens.
-
-    Anthropic requires this identity declaration for OAuth auth.
-    """
-    return "You are Claude Code, Anthropic's official CLI for Claude."