fix(router): use large request size for model selection

smart_router.py

@@ -228,9 +228,14 @@ class SmartRouter:
         return min(available, key=lambda p: p.score(self.strategy))
 
     def get_model_for_provider(
-        self, provider: Provider, claude_model: str
+        self,
+        provider: Provider,
+        claude_model: str,
+        is_large_request: bool = False,
     ) -> str:
         """Map a Claude model name to the provider's actual model."""
+        if is_large_request:
+            return provider.big_model
         is_large = any(
             keyword in claude_model.lower()
             for keyword in ["opus", "sonnet", "large", "big"]
@@ -289,7 +294,11 @@ class SmartRouter:
             )
 
         provider = min(available, key=lambda p: p.score(self.strategy))
-        model = self.get_model_for_provider(provider, claude_model)
+        model = self.get_model_for_provider(
+            provider,
+            claude_model,
+            is_large_request=large,
+        )
 
         logger.debug(
             f"SmartRouter: routing to {provider.name}/{model} "

test_smart_router.py

@@ -7,6 +7,7 @@ Run: pytest test_smart_router.py -v
 
 import pytest
 import asyncio
+import os
 from unittest.mock import AsyncMock, MagicMock, patch
 from smart_router import SmartRouter, Provider
 
@@ -27,7 +28,9 @@ def make_provider(name, healthy=True, configured=True,
     p.avg_latency_ms = latency
     p.error_count = errors
     p.request_count = requests
-    if not configured:
+    if configured:
+        os.environ.setdefault("FAKE_KEY", "test-key")
+    else:
         p.api_key_env = ""  # makes is_configured False for non-ollama
     return p
 
@@ -122,6 +125,13 @@ def test_get_model_large_request():
     assert model == "openai-big"
 
 
+def test_get_model_large_message_overrides_claude_label():
+    p = make_provider("openai")
+    r = make_router()
+    model = r.get_model_for_provider(p, "claude-haiku", is_large_request=True)
+    assert model == "openai-big"
+
+
 def test_get_model_small_request():
     p = make_provider("openai")
     r = make_router()
@@ -140,6 +150,16 @@ async def test_route_returns_best_provider():
     assert result["provider"] == "cheap"
 
 
+@pytest.mark.asyncio
+async def test_route_uses_big_model_for_large_message_bodies():
+    p = make_provider("openai")
+    r = make_router(providers=[p])
+    result = await r.route([
+        {"role": "user", "content": "x" * 3001},
+    ], "claude-haiku")
+    assert result["model"] == "openai-big"
+
+
 @pytest.mark.asyncio
 async def test_route_raises_when_no_providers():
     p = make_provider("a", healthy=False)