test(pricing): one invariant for the direct-route models.dev fallback

Replaces the per-case Xiaomi fixtures with a single parametrized invariant:
direct OpenAI/xAI routes price a snapshot-missing model at the models.dev
list price, and the same model on a relay host, a downgraded origin, the
xai-oauth subscription route or a custom endpoint stays unknown. Red on
origin/main for the direct rows; red for the relay/http rows when the host
check is removed.

tests/agent/test_usage_pricing.py

@@ -38,158 +38,38 @@ def test_astra_whole_request_price_tier_includes_cache_writes():
     assert below.amount_usd < above.amount_usd
 
 
-def test_unknown_named_provider_uses_models_dev_pricing_after_snapshot_miss(monkeypatch):
-    """A known provider absent from the local snapshot can still price from models.dev."""
-    from agent.models_dev import ModelInfo
-
-    expected = ModelInfo(
-        id="mimo-v2-flash",
-        name="MiMo V2 Flash",
-        family="mimo",
-        provider_id="xiaomi",
-        cost_input=0.6,
-        cost_output=2.4,
-        cost_cache_read=0.06,
-        cost_cache_write=0.75,
-    )
-    calls = []
-
-    def fake_get_model_info(provider, model):
-        calls.append((provider, model))
-        return expected
-
-    monkeypatch.setattr(
-        "agent.usage_pricing.fetch_endpoint_model_metadata",
-        lambda *_args, **_kwargs: {},
-    )
-    monkeypatch.setattr("agent.models_dev.get_model_info", fake_get_model_info)
-
-    entry = get_pricing_entry(
-        "mimo-v2-flash",
-        provider="xiaomi",
-        base_url="https://api.xiaomimimo.com/v1",
-    )
-
-    assert calls == [("xiaomi", "mimo-v2-flash")]
-    assert entry is not None
-    assert entry.input_cost_per_million == Decimal("0.6")
-    assert entry.output_cost_per_million == Decimal("2.4")
-    assert entry.cache_read_cost_per_million == Decimal("0.06")
-    assert entry.cache_write_cost_per_million == Decimal("0.75")
-    assert entry.source == "provider_models_api"
-    assert entry.source_url == "https://models.dev"
-
-    estimate = estimate_usage_cost(
-        "mimo-v2-flash",
-        CanonicalUsage(
-            input_tokens=1_000_000,
-            output_tokens=1_000_000,
-            cache_read_tokens=1_000_000,
-            cache_write_tokens=1_000_000,
-        ),
-        provider="xiaomi",
-        base_url="https://api.xiaomimimo.com/v1",
-    )
-    assert estimate.amount_usd == Decimal("3.81")
-    assert estimate.status == "estimated"
-    assert estimate.source == "provider_models_api"
+_MODELS_DEV_REGISTRY = {
+    "openai": {"models": {"gpt-5-nano": {"cost": {"input": 0.05, "output": 0.4, "cache_read": 0.005}}}},
+    "xai": {"models": {"grok-4.3": {"cost": {"input": 1.25, "output": 2.5, "cache_read": 0.2}}}},
+}
+_USAGE = CanonicalUsage(input_tokens=1_000_000, output_tokens=1_000_000, cache_read_tokens=1_000_000)
 
 
-@pytest.mark.parametrize(
-    ("base_url", "uses_models_dev"),
-    [
-        ("", True),
-        ("http://api.xiaomimimo.com/v1", False),
-        ("https://api.xiaomimimo.com:8443/v1", False),
-        ("https://api.xiaomimimo.com:443/v1", True),
-        ("https://token-plan-sgp.xiaomimimo.com/v1", True),
-    ],
-)
-def test_models_dev_pricing_requires_canonical_xiaomi_origin(monkeypatch, base_url, uses_models_dev):
-    from agent.models_dev import ModelInfo
+@pytest.fixture
+def models_dev_registry(monkeypatch):
+    """A models.dev cache holding the vendors' rate cards; the providers' own /models carry no prices."""
+    import agent.models_dev as models_dev
 
-    calls = []
-    expected = ModelInfo(id="mimo-v2-flash", name="MiMo V2 Flash", family="mimo", provider_id="xiaomi", cost_input=0.6)
-    monkeypatch.setattr("agent.usage_pricing.fetch_endpoint_model_metadata", lambda *_args, **_kwargs: {})
-    monkeypatch.setattr(
-        "agent.models_dev.get_model_info", lambda *args: calls.append(args) or expected,
-    )
-
-    entry = get_pricing_entry("mimo-v2-flash", provider="xiaomi", base_url=base_url)
-
-    assert bool(entry) is uses_models_dev
-    assert calls == ([("xiaomi", "mimo-v2-flash")] if uses_models_dev else [])
+    monkeypatch.setattr(models_dev, "_models_dev_cache", _MODELS_DEV_REGISTRY)
+    monkeypatch.setattr("agent.usage_pricing.fetch_endpoint_model_metadata", lambda *_a, **_k: {})
 
 
-@pytest.mark.parametrize("provider", ["deepseek", "openai"])
-def test_models_dev_pricing_denies_untrusted_no_base_providers(monkeypatch, provider):
-    calls = []
-    monkeypatch.setattr("agent.models_dev.get_model_info", lambda *args: calls.append(args))
+@pytest.mark.parametrize(("provider", "base_url", "model", "expected"), [
+    ("openai-api", "https://api.openai.com/v1", "gpt-5-nano", ("estimated", Decimal("0.455"))),
+    ("openai", "", "gpt-5-nano", ("estimated", Decimal("0.455"))),
+    ("xai", "https://api.x.ai/v1", "grok-4.3", ("estimated", Decimal("3.95"))),
+    # The vendor's list price needs the vendor's own API: same provider name on
+    # someone else's host, a downgraded origin, a subscription route or a custom
+    # endpoint keep ``unknown`` rather than inheriting it.
+    ("xai", "https://grok-relay.example.com/v1", "grok-4.3", ("unknown", None)),
+    ("xai", "http://api.x.ai/v1", "grok-4.3", ("unknown", None)),
+    ("xai-oauth", "https://api.x.ai/v1", "grok-4.3", ("unknown", None)),
+    ("custom", "https://api.x.ai/v1", "grok-4.3", ("unknown", None)),
+])
+def test_direct_first_party_route_prices_models_missing_from_snapshot(models_dev_registry, provider, base_url, model, expected):
+    cost = estimate_usage_cost(model, _USAGE, provider=provider, base_url=base_url)
 
-    entry = get_pricing_entry("unlisted-model", provider=provider)
-
-    assert entry is None
-    assert calls == []
-
-
-def test_models_dev_pricing_denies_registry_injected_no_base_provider(monkeypatch):
-    from agent.models_dev import PROVIDER_TO_MODELS_DEV
-
-    calls = []
-    monkeypatch.setitem(PROVIDER_TO_MODELS_DEV, "attacker", "unregistered")
-    monkeypatch.setattr("agent.models_dev.get_model_info", lambda *args: calls.append(args))
-
-    entry = get_pricing_entry("unlisted-model", provider="attacker")
-
-    assert entry is None
-    assert calls == []
-
-
-def test_generic_custom_route_does_not_guess_models_dev_provider(monkeypatch):
-    """A custom endpoint lacks trusted vendor identity, so it must stay unpriced."""
-    calls = []
-
-    def fake_get_model_info(provider, model):
-        calls.append((provider, model))
-        raise AssertionError("custom routes must not query models.dev")
-
-    monkeypatch.setattr("agent.models_dev.get_model_info", fake_get_model_info)
-
-    entry = get_pricing_entry("mimo-v2-flash", provider="custom")
-
-    assert entry is None
-    assert calls == []
-
-
-def test_registered_proxy_host_does_not_use_models_dev_pricing(monkeypatch):
-    """Provider profiles must not extend the trusted direct-host set."""
-    import agent.model_metadata as model_metadata
-
-    calls = []
-    monkeypatch.setitem(model_metadata._URL_TO_PROVIDER, "proxy.invalid", "xiaomi")
-    monkeypatch.setattr(
-        "agent.usage_pricing.fetch_endpoint_model_metadata",
-        lambda *_args, **_kwargs: {},
-    )
-    monkeypatch.setattr(
-        "agent.models_dev.get_model_info",
-        lambda *args: calls.append(args),
-    )
-
-    entry = get_pricing_entry(
-        "mimo-v2-flash", provider="xiaomi", base_url="https://proxy.invalid/v1"
-    )
-    estimate = estimate_usage_cost(
-        "mimo-v2-flash",
-        CanonicalUsage(input_tokens=1_000_000),
-        provider="xiaomi",
-        base_url="https://proxy.invalid/v1",
-    )
-
-    assert entry is None
-    assert estimate.amount_usd is None
-    assert estimate.status == "unknown"
-    assert calls == []
+    assert (cost.status, cost.amount_usd) == expected
 
 
 def test_normalize_usage_reads_deepseek_native_cache_hit_tokens():