test: reproduce forwarded model ID alias regression

tests/integration/test_admin_forwarded_model_id.py

@@ -0,0 +1,143 @@
+"""Regression tests for admin model alias persistence (GitHub issue #639)."""
+
+import json
+from datetime import datetime, timedelta, timezone
+from unittest.mock import patch
+
+import pytest
+from httpx import AsyncClient
+from sqlmodel.ext.asyncio.session import AsyncSession
+
+from routstr.core.admin import admin_sessions
+from routstr.core.db import ModelRow, UpstreamProviderRow
+from routstr.proxy import reinitialize_upstreams
+
+MODEL_ID = "deepseek/deepseek-chat"
+ARCHITECTURE = {
+    "modality": "text",
+    "input_modalities": ["text"],
+    "output_modalities": ["text"],
+    "tokenizer": "unknown",
+    "instruct_type": None,
+}
+PRICING = {
+    "prompt": 1e-7,
+    "completion": 2e-7,
+    "request": 0.0,
+    "image": 0.0,
+    "web_search": 0.0,
+    "internal_reasoning": 0.0,
+}
+
+
+def _admin_headers() -> dict[str, str]:
+    token = "test-admin-forwarded-model-id-token"
+    admin_sessions[token] = int(
+        (datetime.now(timezone.utc) + timedelta(minutes=5)).timestamp()
+    )
+    return {"Authorization": f"Bearer {token}"}
+
+
+def _model_payload(
+    *, forwarded_model_id: str | None, include_alias: bool
+) -> dict[str, object]:
+    payload: dict[str, object] = {
+        "id": MODEL_ID,
+        "name": "DeepSeek Chat",
+        "description": "DeepSeek Chat test model",
+        "created": 0,
+        "context_length": 128000,
+        "architecture": ARCHITECTURE,
+        "pricing": PRICING,
+        "per_request_limits": None,
+        "top_provider": None,
+        "canonical_slug": None,
+        "alias_ids": [],
+        "enabled": True,
+    }
+    if include_alias:
+        payload["forwarded_model_id"] = forwarded_model_id
+    return payload
+
+
+def _model_row(provider_id: int, *, forwarded_model_id: str | None) -> ModelRow:
+    return ModelRow(
+        id=MODEL_ID,
+        upstream_provider_id=provider_id,
+        name="DeepSeek Chat",
+        description="DeepSeek Chat test model",
+        created=0,
+        context_length=128000,
+        architecture=json.dumps(ARCHITECTURE),
+        pricing=json.dumps(PRICING),
+        enabled=True,
+        forwarded_model_id=forwarded_model_id,
+    )
+
+
+async def _create_provider(
+    session: AsyncSession, *, base_url: str
+) -> UpstreamProviderRow:
+    provider = UpstreamProviderRow(
+        provider_type="generic",
+        base_url=base_url,
+        api_key="test-key",
+        provider_fee=1.0,
+    )
+    session.add(provider)
+    await session.commit()
+    await session.refresh(provider)
+    assert provider.id is not None
+    return provider
+
+
+@pytest.mark.integration
+@pytest.mark.asyncio
+async def test_admin_create_without_forwarded_model_id_preserves_null(
+    integration_client: AsyncClient,
+    integration_session: AsyncSession,
+) -> None:
+    """Saving an unaliased model must not invent a self-alias."""
+    provider = await _create_provider(
+        integration_session, base_url="https://issue-639-create.example/v1"
+    )
+    await reinitialize_upstreams()
+
+    with patch("routstr.payment.models.sats_usd_price", return_value=1e-6):
+        response = await integration_client.post(
+            f"/admin/api/upstream-providers/{provider.id}/models",
+            headers=_admin_headers(),
+            json=_model_payload(forwarded_model_id=None, include_alias=False),
+        )
+
+    assert response.status_code == 200
+    row = await integration_session.get(ModelRow, (MODEL_ID, provider.id))
+    assert row is not None
+    assert row.forwarded_model_id is None
+
+
+@pytest.mark.integration
+@pytest.mark.asyncio
+async def test_admin_update_can_clear_forwarded_model_id(
+    integration_client: AsyncClient,
+    integration_session: AsyncSession,
+) -> None:
+    """An explicit JSON null must remove an existing upstream alias."""
+    provider = await _create_provider(
+        integration_session, base_url="https://issue-639-clear.example/v1"
+    )
+    row = _model_row(provider.id, forwarded_model_id="upstream-deepseek-chat")
+    integration_session.add(row)
+    await integration_session.commit()
+    await reinitialize_upstreams()
+
+    with patch("routstr.payment.models.sats_usd_price", return_value=1e-6):
+        response = await integration_client.post(
+            f"/admin/api/upstream-providers/{provider.id}/models",
+            headers=_admin_headers(),
+            json=_model_payload(forwarded_model_id=None, include_alias=True),
+        )
+
+    assert response.status_code == 200
+    await integration_session.refresh(row)
+    assert row.forwarded_model_id is None

tests/unit/test_algorithm.py

@@ -230,6 +230,45 @@ def test_create_model_mappings_applies_override_only_to_matching_provider(
     assert {p for _, p in provider_map["same-id"]} == {provider_a, provider_b}
 
 
+def test_create_model_mappings_does_not_split_self_alias_from_base_identity(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """A write-time self-alias must not advertise one shared model twice (#639)."""
+    model_id = "deepseek/deepseek-chat"
+    provider_a = create_test_provider(
+        "provider-a",
+        "https://provider-a.example/v1",
+        db_id=1,
+        models=[create_test_model(model_id)],
+    )
+    provider_b = create_test_provider(
+        "provider-b",
+        "https://provider-b.example/v1",
+        db_id=2,
+        models=[create_test_model(model_id)],
+    )
+
+    admin_saved_model = create_test_model(model_id)
+    admin_saved_model.forwarded_model_id = model_id
+    override_row = SimpleNamespace(id=model_id, upstream_provider_id=1, enabled=True)
+
+    def fake_row_to_model(*args, **kwargs) -> Model:  # type: ignore[no-untyped-def]
+        return admin_saved_model
+
+    monkeypatch.setattr("routstr.payment.models._row_to_model", fake_row_to_model)
+
+    _, _, unique_models = create_model_mappings(
+        upstreams=[provider_a, provider_b],
+        overrides_by_key={(model_id, 1): (override_row, 1.0)},
+        disabled_model_keys=set(),
+    )
+
+    advertised_ids = sorted(
+        model.forwarded_model_id or model.id for model in unique_models.values()
+    )
+    assert advertised_ids == ["deepseek-chat"]
+
+
 def test_create_model_mappings_disables_only_matching_provider() -> None:
     """Disabled overrides are scoped to the provider row, not the shared model id."""
     provider_a = create_test_provider(