core/cli: /models and remote catalog for model selection

Cache GET /models, merge with config ids for Tab and choose; free-form model ids allowed.

tests/test_cli/test_models_source.py

@@ -0,0 +1,52 @@
+from __future__ import annotations
+
+import pytest
+
+from plyngent.cli.models_source import (
+    client_supports_models,
+    config_model_ids,
+    fetch_remote_model_ids,
+    merge_model_choices,
+    model_choices_for_provider,
+)
+from plyngent.config.models import ModelConfig, OpenAICompatibleProvider
+
+
+def test_merge_model_choices_union() -> None:
+    assert merge_model_choices(["b", "a"], ["a", "c"]) == ["a", "b", "c"]
+    assert merge_model_choices(["a"], None) == ["a"]
+    assert merge_model_choices([], ["z"]) == ["z"]
+
+
+def test_model_choices_for_provider() -> None:
+    provider = OpenAICompatibleProvider(
+        access_key_or_token="sk",
+        url="https://x/v1",
+        models={"cfg": ModelConfig()},
+    )
+    assert config_model_ids(provider) == ["cfg"]
+    assert model_choices_for_provider(provider, remote_ids=["remote", "cfg"]) == ["cfg", "remote"]
+
+
+def test_client_supports_models() -> None:
+    class Ok:
+        async def models(self) -> list[str]:
+            return ["m"]
+
+    class No:
+        pass
+
+    assert client_supports_models(Ok())
+    assert not client_supports_models(No())
+
+
+@pytest.mark.asyncio
+async def test_fetch_remote_model_ids() -> None:
+    class Ok:
+        async def models(self) -> list[str]:
+            return ["z", "a"]
+
+    assert await fetch_remote_model_ids(Ok()) == ["z", "a"]
+
+    with pytest.raises(TypeError, match="does not support"):
+        _ = await fetch_remote_model_ids(object())