diff --git a/nanobot/config/schema.py b/nanobot/config/schema.py
index 32b85cf..b030dac 100644
--- a/nanobot/config/schema.py
+++ b/nanobot/config/schema.py
@@ -186,6 +186,7 @@ class AgentDefaults(Base):
 
     workspace: str = "~/.nanobot/workspace"
     model: str = "anthropic/claude-opus-4-5"
+    provider: str = "auto"  # Provider name (e.g. "anthropic", "openrouter") or "auto" for auto-detection
     max_tokens: int = 8192
     temperature: float = 0.1
     max_tool_iterations: int = 40
@@ -301,6 +302,11 @@ class Config(BaseSettings):
         """Match provider config and its registry name. Returns (config, spec_name)."""
         from nanobot.providers.registry import PROVIDERS
 
+        forced = self.agents.defaults.provider
+        if forced != "auto":
+            p = getattr(self.providers, forced, None)
+            return (p, forced) if p else (None, None)
+
         model_lower = (model or self.agents.defaults.model).lower()
         model_normalized = model_lower.replace("-", "_")
         model_prefix = model_lower.split("/", 1)[0] if "/" in model_lower else ""