Use LM Studio-reported vision capability for image passthrough (#1130)

Read a model's capabilities.vision flag from LM Studio's native /api/v1/models so vision finetunes whose names lack a vision keyword still receive images, falling back to the name heuristic when the endpoint doesn't report it. The probe is short-TTL cached and restricted to local/LAN hosts, so remote/cloud endpoints are never contacted.

tests/test_lmstudio_vision.py

@@ -0,0 +1,104 @@
+"""Tests for LM Studio vision-capability passthrough: reading capabilities.vision
+from the native /api/v1/models endpoint, with no probing of cloud providers."""
+import pytest
+
+from src import chat_helpers
+
+
+class _FakeResponse:
+    def __init__(self, payload, ok=True):
+        self._payload = payload
+        self.is_success = ok
+
+    def json(self):
+        return self._payload
+
+
+# ════════════════════════════════════════════════════════════
+# lmstudio_supports_vision — reads capabilities.vision
+# ════════════════════════════════════════════════════════════
+
+class TestLmStudioSupportsVision:
+    # A vision finetune whose NAME has no vision keyword — the case the
+    # name-based heuristic gets wrong (the issue this fixes).
+    PAYLOAD = {"models": [
+        {"key": "qwen3.6-27b-custom-finetune", "architecture": "qwen35",
+         "capabilities": {"vision": True, "trained_for_tool_use": True}},
+        {"key": "text-only-llm", "architecture": "qwen35",
+         "capabilities": {"vision": False}},
+        {"key": "no-caps-model", "architecture": "qwen35"},
+    ]}
+    URL = "http://localhost:1234/v1/chat/completions"
+
+    @pytest.fixture(autouse=True)
+    def _clear_cache(self):
+        chat_helpers._lmstudio_models_cache.clear()
+        yield
+        chat_helpers._lmstudio_models_cache.clear()
+
+    def _serve(self, monkeypatch, payload):
+        monkeypatch.setattr(chat_helpers.httpx, "get",
+                            lambda url, timeout=None: _FakeResponse(payload))
+
+    def test_vision_true_from_capabilities(self, monkeypatch):
+        self._serve(monkeypatch, self.PAYLOAD)
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "qwen3.6-27b-custom-finetune") is True
+
+    def test_vision_false_from_capabilities(self, monkeypatch):
+        self._serve(monkeypatch, self.PAYLOAD)
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "text-only-llm") is False
+
+    def test_model_without_capabilities_returns_none(self, monkeypatch):
+        self._serve(monkeypatch, self.PAYLOAD)
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "no-caps-model") is None
+
+    def test_unknown_model_returns_none(self, monkeypatch):
+        self._serve(monkeypatch, self.PAYLOAD)
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "not-listed") is None
+
+    def test_non_lmstudio_endpoint_returns_none(self, monkeypatch):
+        self._serve(monkeypatch, {"data": [{"id": "gpt-4o"}]})
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "gpt-4o") is None
+
+    def test_empty_model_returns_none(self, monkeypatch):
+        self._serve(monkeypatch, self.PAYLOAD)
+        assert chat_helpers.lmstudio_supports_vision(self.URL, "") is None
+
+    def test_remote_endpoint_never_probed(self, monkeypatch):
+        calls = {"n": 0}
+
+        def tracking_get(url, timeout=None):
+            calls["n"] += 1
+            return _FakeResponse(self.PAYLOAD)
+
+        monkeypatch.setattr(chat_helpers.httpx, "get", tracking_get)
+        # A cloud provider host must short-circuit to None with no network probe.
+        assert chat_helpers.lmstudio_supports_vision(
+            "https://api.openai.com/v1/chat/completions", "gpt-4o") is None
+        assert calls["n"] == 0
+
+
+# ════════════════════════════════════════════════════════════
+# model_supports_vision — endpoint capability wins, name is fallback
+# ════════════════════════════════════════════════════════════
+
+class TestModelSupportsVision:
+    """Endpoint-aware vision check: API capability wins, name heuristic is the fallback."""
+
+    def test_api_capability_overrides_name_heuristic(self, monkeypatch):
+        # Name has no vision keyword, but the endpoint advertises vision=True.
+        monkeypatch.setattr(chat_helpers, "is_vision_model", lambda n: False)
+        monkeypatch.setattr(chat_helpers, "lmstudio_supports_vision", lambda url, m: True)
+        assert chat_helpers.model_supports_vision("qwen3.6-27b-finetune",
+                                                  "http://localhost:1234/v1/chat/completions") is True
+
+    def test_falls_back_to_name_when_no_endpoint(self):
+        # No endpoint URL → pure name heuristic.
+        assert chat_helpers.model_supports_vision("llava-1.6", "") is True
+        assert chat_helpers.model_supports_vision("mistral-7b", "") is False
+
+    def test_falls_back_to_name_when_endpoint_unknown(self, monkeypatch):
+        # Endpoint doesn't advertise (None) → name heuristic decides.
+        monkeypatch.setattr(chat_helpers, "lmstudio_supports_vision", lambda url, m: None)
+        assert chat_helpers.model_supports_vision("qwen2-vl-7b", "http://host/v1") is True
+        assert chat_helpers.model_supports_vision("plain-llm", "http://host/v1") is False