feat(backend): CivitAI download support for other model types with subtype routing

tests/services/test_download_routing.py

@@ -38,3 +38,105 @@ def test_non_checkpoint_types_never_route_to_unet():
 def test_empty_inputs_stay_on_checkpoint_roots():
     assert not is_diffusion_model_download("checkpoint")
     assert not is_diffusion_model_download("checkpoint", file_types=[], base_model="")
+
+
+from py.services.download_routing import resolve_other_download_sub_type
+
+
+class TestResolveOtherDownloadSubType:
+    """Fixed priority: explicit file pick > model.type > file.type fallback."""
+
+    def test_explicit_file_pick_wins_over_model_type(self):
+        """User explicitly picked a VAE component file of a Checkpoint model —
+        the picked file type wins."""
+        assert (
+            resolve_other_download_sub_type(
+                "Checkpoint", file_types=["Model", "VAE"], selected_file_type="VAE"
+            )
+            == "vae"
+        )
+
+    @pytest.mark.parametrize(
+        "selected,expected",
+        [
+            ("VAE", "vae"),
+            ("Upscaler", "upscaler"),
+            ("Text Encoder", "text_encoder"),
+            ("Vision Encoder", "clip_vision"),
+            ("CLIPVision", "clip_vision"),
+            ("ControlNet", "controlnet"),
+        ],
+    )
+    def test_explicit_file_pick_maps_all_known_types(self, selected, expected):
+        assert (
+            resolve_other_download_sub_type("Other", selected_file_type=selected)
+            == expected
+        )
+
+    @pytest.mark.parametrize(
+        "model_type,expected",
+        [
+            ("VAE", "vae"),
+            ("Upscaler", "upscaler"),
+            ("TextEncoder", "text_encoder"),
+            ("CLIP", "text_encoder"),
+            ("CLIPVision", "clip_vision"),
+            ("Controlnet", "controlnet"),
+        ],
+    )
+    def test_model_type_mapping(self, model_type, expected):
+        assert resolve_other_download_sub_type(model_type) == expected
+
+    def test_model_type_beats_unmappable_file_pick(self):
+        """An explicit pick whose file type does not map (e.g. plain 'Model')
+        falls through to model.type."""
+        assert (
+            resolve_other_download_sub_type(
+                "TextEncoder", selected_file_type="Model"
+            )
+            == "text_encoder"
+        )
+
+    def test_bundled_component_files_never_override_model_type(self):
+        """Anti-misrouting: a TextEncoder model bundling a VAE component file
+        must stay text_encoder — file types are a fallback, not an override."""
+        assert (
+            resolve_other_download_sub_type(
+                "TextEncoder", file_types=["Model", "VAE"]
+            )
+            == "text_encoder"
+        )
+        assert (
+            resolve_other_download_sub_type(
+                "Controlnet", file_types=["Model", "Text Encoder"]
+            )
+            == "controlnet"
+        )
+
+    def test_file_type_fallback_when_model_type_unmapped(self):
+        """model.type 'Other' (or retired values) maps to nothing, so the
+        first mappable file type decides."""
+        assert (
+            resolve_other_download_sub_type("Other", file_types=["Model", "Upscaler"])
+            == "upscaler"
+        )
+
+    def test_file_type_fallback_for_civarchive_payload(self):
+        """CivArchive-shaped payload: same fields, same decision path."""
+        assert (
+            resolve_other_download_sub_type(
+                "Other",
+                file_types=["Config", "Text Encoder"],
+            )
+            == "text_encoder"
+        )
+
+    @pytest.mark.parametrize("model_type", ["Other", "", "SomethingNew"])
+    def test_undecidable_returns_none(self, model_type):
+        assert (
+            resolve_other_download_sub_type(model_type, file_types=["Model"]) is None
+        )
+        assert resolve_other_download_sub_type(model_type) is None
+
+    def test_model_type_matching_is_case_insensitive(self):
+        assert resolve_other_download_sub_type("vAe") == "vae"