make sure the models with lowest prices are forwarded

routstr/algorithm.py

@@ -126,11 +126,24 @@ def create_model_mappings(
         if isinstance(db_id, int):
             providers_by_db_id[db_id] = upstream
 
+    # Group upstreams by URL and keep only the one with the lowest fee for each URL
+    upstreams_by_url: dict[str, list["BaseUpstreamProvider"]] = {}
+    for upstream in upstreams:
+        url = getattr(upstream, "base_url", "")
+        if url not in upstreams_by_url:
+            upstreams_by_url[url] = []
+        upstreams_by_url[url].append(upstream)
+
+    filtered_upstreams: list["BaseUpstreamProvider"] = []
+    for providers in upstreams_by_url.values():
+        best_provider = min(providers, key=lambda p: p.provider_fee)
+        filtered_upstreams.append(best_provider)
+
     # Separate OpenRouter from other providers
     openrouter: "BaseUpstreamProvider" | None = None
     other_upstreams: list["BaseUpstreamProvider"] = []
 
-    for upstream in upstreams:
+    for upstream in filtered_upstreams:
         base_url = getattr(upstream, "base_url", "")
         if base_url == "https://openrouter.ai/api/v1":
             openrouter = upstream

tests/integration/test_provider_fee_enforcement.py

@@ -0,0 +1,132 @@
+from typing import Any, cast
+from unittest.mock import patch
+
+import pytest
+
+from routstr.core.db import ModelRow, UpstreamProviderRow
+from routstr.payment.models import Architecture, Model, Pricing
+from routstr.proxy import refresh_model_maps
+from routstr.upstream.base import BaseUpstreamProvider
+
+
+@pytest.mark.integration
+@pytest.mark.asyncio
+async def test_enforce_lowest_provider_fee_for_same_url(
+    integration_session: Any,
+) -> None:
+    """Test that the algorithm selects the provider with the lowest fee when URLs match."""
+
+    # 1. Create two providers with the same URL but different fees
+    url = "https://api.example.com"
+    p1 = UpstreamProviderRow(
+        provider_type="custom",
+        base_url=url,
+        api_key="key1",
+        enabled=True,
+        provider_fee=1.01,
+    )
+    p2 = UpstreamProviderRow(
+        provider_type="custom",
+        base_url=url,
+        api_key="key2",
+        enabled=True,
+        provider_fee=1.05,
+    )
+
+    integration_session.add(p1)
+    integration_session.add(p2)
+    await integration_session.commit()
+    await integration_session.refresh(p1)
+    await integration_session.refresh(p2)
+
+    assert p1.id is not None
+    assert p2.id is not None
+
+    # 2. Add a model for each provider
+    m1 = ModelRow(
+        id="model-a",
+        name="Model A",
+        created=1,
+        description="desc",
+        context_length=100,
+        architecture='{"modality": "text", "input_modalities": ["text"], "output_modalities": ["text"], "tokenizer": "tiktoken", "instruct_type": "chat"}',
+        pricing='{"prompt": 1.0, "completion": 1.0}',
+        upstream_provider_id=p1.id,
+        enabled=True,
+    )
+    m2 = ModelRow(
+        id="model-a",
+        name="Model A",
+        created=1,
+        description="desc",
+        context_length=100,
+        architecture='{"modality": "text", "input_modalities": ["text"], "output_modalities": ["text"], "tokenizer": "tiktoken", "instruct_type": "chat"}',
+        pricing='{"prompt": 1.0, "completion": 1.0}',
+        upstream_provider_id=p2.id,
+        enabled=True,
+    )
+
+    integration_session.add(m1)
+    integration_session.add(m2)
+    await integration_session.commit()
+
+    # 3. Create mock provider instances
+    class MockProvider(BaseUpstreamProvider):
+        db_id: int
+
+        def __init__(self, db_id: int, base_url: str, api_key: str, fee: float):
+            super().__init__(base_url, api_key, fee)
+            self.db_id = db_id
+            self.provider_type = "custom"
+
+        def get_cached_models(self) -> list[Model]:
+            return [
+                Model(
+                    id="model-a",
+                    name="Model A",
+                    created=1,
+                    description="desc",
+                    context_length=100,
+                    architecture=Architecture(
+                        modality="text",
+                        input_modalities=["text"],
+                        output_modalities=["text"],
+                        tokenizer="tiktoken",
+                        instruct_type="chat",
+                    ),
+                    pricing=Pricing(prompt=1.0, completion=1.0),
+                    enabled=True,
+                    upstream_provider_id=self.db_id,
+                )
+            ]
+
+        async def refresh_models_cache(self) -> None:
+            pass
+
+        def prepare_headers(self, request_headers: dict[str, str]) -> dict[str, str]:
+            return request_headers
+
+    # 4. Inject mock providers into the proxy
+    from routstr import proxy
+
+    assert p1.id is not None
+    assert p2.id is not None
+
+    # Need to patch proxy._upstreams
+    mp1: MockProvider = MockProvider(p1.id, url, "key1", 1.01)
+    mp2: MockProvider = MockProvider(p2.id, url, "key2", 1.05)
+
+    with patch("routstr.proxy._upstreams", [mp1, mp2]):
+        await refresh_model_maps()
+
+        # 5. Check which provider is selected for 'model-a'
+        provider_map = proxy.get_provider_for_model("model-a")
+
+        # Assertions
+        assert provider_map is not None
+        assert len(provider_map) >= 1
+
+        # Check the first one, cast to MockProvider to access db_id
+        best_provider = cast(MockProvider, provider_map[0])
+        assert best_provider.db_id == p1.id
+        assert best_provider.provider_fee == 1.01