feat(llm): detect whether a model accepts image input

Add model_supports_images(): OpenRouter models are checked against architecture.input_modalities from OpenRouter's public model list (fetched once per process), others against LiteLLM's supports_vision. Unknown models and lookup failures count as image-capable. Not wired in yet.

strix/config/models.py

@@ -10,6 +10,7 @@ import os
 import time
 import uuid
 from collections.abc import AsyncGenerator
+from functools import cache
 from typing import TYPE_CHECKING, Any, cast
 
 from agents import (
@@ -905,6 +906,36 @@ def model_supports_reasoning(model_name: str) -> bool:
     return bool(entry and entry.get("supports_reasoning"))
 
 
+_OPENROUTER_MODELS_URL = "https://openrouter.ai/api/v1/models"
+
+
+@cache
+def _openrouter_input_modalities() -> dict[str, list[str]] | None:
+    import requests
+
+    try:
+        response = requests.get(_OPENROUTER_MODELS_URL, timeout=5)
+        response.raise_for_status()
+        return {
+            model["id"].lower(): model["architecture"]["input_modalities"]
+            for model in response.json()["data"]
+        }
+    except Exception:  # noqa: BLE001
+        logger.warning("Could not fetch OpenRouter model modalities", exc_info=True)
+        return None
+
+
+def model_supports_images(model_name: str) -> bool:
+    """Return whether the model accepts image input; unknown models are assumed to."""
+    if is_openrouter_model(model_name):
+        slug = model_name.strip().lower().split("openrouter/", 1)[1]
+        modalities = (_openrouter_input_modalities() or {}).get(slug)
+        if modalities is not None:
+            return "image" in modalities
+    entry = _catalog_entry(model_name)
+    return bool(entry.get("supports_vision", True)) if entry else True
+
+
 def _bare_openai_name(model_name: str) -> str:
     name = model_name.strip().lower()
     for prefix in ("litellm/", "any-llm/", "openai/"):

tests/test_models.py

@@ -2,8 +2,11 @@
 
 from __future__ import annotations
 
+from typing import TYPE_CHECKING, Any
+
 import litellm
 import pytest
+import requests
 from agents.extensions.models.litellm_model import LitellmModel
 from agents.model_settings import ModelSettings
 from agents.models import _openai_shared
@@ -16,6 +19,7 @@ from strix.config.models import (
     _NonStreamingModel,
     _TurnGuardModel,
     configure_sdk_model_defaults,
+    model_supports_images,
     request_timeout_extra_args,
     resolve_api_type,
     routes_through_litellm,
@@ -26,6 +30,10 @@ from strix.config.settings import Settings
 from strix.llm.request_log import RequestLoggingModel
 
 
+if TYPE_CHECKING:
+    from collections.abc import Iterator
+
+
 def test_request_timeout_extra_args_positive() -> None:
     assert request_timeout_extra_args(300) == {"timeout": 300}
     assert request_timeout_extra_args(10) == {"timeout": 10}
@@ -202,3 +210,73 @@ def test_configure_sdk_api_route_follows_the_given_model(
     models.configure_sdk_api_route("my-private-model", settings)
 
     assert routes == ["responses", "chat_completions"]
+
+
+class _FakeOpenRouterResponse:
+    def raise_for_status(self) -> None:
+        pass
+
+    def json(self) -> dict[str, Any]:
+        return {
+            "data": [
+                {"id": "z-ai/glm-5.3", "architecture": {"input_modalities": ["text"]}},
+                {"id": "openai/gpt-5", "architecture": {"input_modalities": ["text", "image"]}},
+            ]
+        }
+
+
+@pytest.fixture
+def openrouter_models(monkeypatch: pytest.MonkeyPatch) -> Iterator[list[str]]:
+    calls: list[str] = []
+
+    def fake_get(url: str, **_kwargs: Any) -> _FakeOpenRouterResponse:
+        calls.append(url)
+        return _FakeOpenRouterResponse()
+
+    monkeypatch.setattr(requests, "get", fake_get)
+    models._openrouter_input_modalities.cache_clear()
+    yield calls
+    models._openrouter_input_modalities.cache_clear()
+
+
+def test_openrouter_image_support_follows_input_modalities(openrouter_models: list[str]) -> None:
+    assert model_supports_images("openrouter/z-ai/glm-5.3") is False
+    assert model_supports_images("litellm/openrouter/openai/gpt-5") is True
+    assert len(openrouter_models) == 1
+
+
+@pytest.mark.usefixtures("openrouter_models")
+def test_openrouter_model_missing_from_listing_falls_back_to_catalog(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.setitem(litellm.model_cost, "openrouter/acme/text-only", {"supports_vision": False})
+    assert model_supports_images("openrouter/acme/text-only") is False
+    assert model_supports_images("openrouter/acme/unknown") is True
+
+
+def test_openrouter_fetch_failure_fails_open(
+    monkeypatch: pytest.MonkeyPatch, caplog: pytest.LogCaptureFixture
+) -> None:
+    def failing_get(*_args: Any, **_kwargs: Any) -> None:
+        raise requests.ConnectionError("offline")
+
+    monkeypatch.setattr(requests, "get", failing_get)
+    models._openrouter_input_modalities.cache_clear()
+    try:
+        assert model_supports_images("openrouter/acme/unknown") is True
+        assert model_supports_images("openrouter/acme/other") is True
+    finally:
+        models._openrouter_input_modalities.cache_clear()
+    assert caplog.text.count("Could not fetch OpenRouter model modalities") == 1
+
+
+def test_non_openrouter_image_support_uses_catalog(monkeypatch: pytest.MonkeyPatch) -> None:
+    def unexpected_get(*_args: Any, **_kwargs: Any) -> None:
+        raise AssertionError("non-OpenRouter models must not fetch the OpenRouter listing")
+
+    monkeypatch.setattr(requests, "get", unexpected_get)
+    monkeypatch.setitem(litellm.model_cost, "acme-text", {"supports_vision": False})
+    monkeypatch.setitem(litellm.model_cost, "acme-vision", {"supports_vision": True})
+    assert model_supports_images("acme-text") is False
+    assert model_supports_images("openai/acme-vision") is True
+    assert model_supports_images("acme-unknown-model") is True