Add unit tests for service functionality and model caching

- Implement tests for ben2 and da3 model caching to ensure models are reused for matching runtime keys.
- Verify service state management, including client registration, job cancellation, and client expiration.
- Test discovery file creation and removal based on service ownership.
- Ensure frame extraction functionality works without models and produces expected results.

src/snapform/image_depth.py

@@ -49,7 +49,7 @@ VIDEO_NAME_SUFFIXES = (
 
 def image_depth_model_items(owner, context):
     from .models import model_enum_items
-    from .runtime import model_ready
+    from .client import model_ready
 
     return [
         item
@@ -223,7 +223,7 @@ def draw_process_resolution(layout, owner, image):
 
 
 def save_packed_image(image, scene):
-    from .runtime import temporary_input_path
+    from .client import temporary_input_path
 
     output_path = temporary_input_path()
     image_settings = scene.render.image_settings
@@ -281,7 +281,7 @@ def prepare_image_input(image, scene):
         return source_path, False
     sequence_frames = collect_sequence_frames(image)
     if sequence_frames:
-        from .runtime import temporary_input_directory
+        from .client import temporary_input_directory
 
         temporary_directory = Path(temporary_input_directory())
         try:
@@ -881,12 +881,14 @@ def material_node_group(depth_plane=False):
         return existing
     group = bpy.data.node_groups.new(group_name, "ShaderNodeTree")
     interface = group.interface
-    for name, socket_type in (
+    input_sockets = [
         ("Color", "NodeSocketColor"),
         ("Alpha", "NodeSocketFloat"),
-        ("Depth", "NodeSocketFloat"),
         ("Bump Scale", "NodeSocketFloat"),
-    ):
+    ]
+    if depth_plane:
+        input_sockets.insert(2, ("Depth", "NodeSocketFloat"))
+    for name, socket_type in input_sockets:
         socket = interface.new_socket(
             name=name,
             in_out="INPUT",
@@ -934,7 +936,6 @@ def material_node_group(depth_plane=False):
     displacement = None
 
     processed_alpha = group_input.outputs["Alpha"]
-    processed_depth = group_input.outputs["Depth"]
     bump_depth = group_input.outputs["Color"]
     if depth_plane:
         displacement = nodes.new("ShaderNodeDisplacement")
@@ -1174,8 +1175,6 @@ def create_material(
             output.inputs["Displacement"],
         )
         set_displacement_only(material)
-    else:
-        links.new(color_texture.outputs["Color"], material_inputs.inputs["Depth"])
     return material
 
 
@@ -1700,13 +1699,13 @@ class RemoveImageBackground(bpy.types.Operator):
     @classmethod
     def poll(cls, context):
         from .operators import active_job
-        from .runtime import host_busy, model_ready
+        from .client import service_busy, model_ready
         from .models import BEN2_MODEL
 
         return (
             is_image_empty(context.object)
             and active_job() is None
-            and not host_busy()
+            and not service_busy()
             and model_ready(BEN2_MODEL.key)
         )
 
@@ -1790,13 +1789,13 @@ class ConvertImageToDepthPlane(bpy.types.Operator):
     @classmethod
     def poll(cls, context):
         from .operators import active_job
-        from .runtime import host_busy, model_ready
+        from .client import service_busy, model_ready
         from .models import MODELS
 
         return (
             is_image_empty(context.object)
             and active_job() is None
-            and not host_busy()
+            and not service_busy()
             and any(model_ready(model_key) for model_key in MODELS)
         )
 
@@ -1823,7 +1822,7 @@ class ConvertImageToDepthPlane(bpy.types.Operator):
             available_models = image_depth_model_items(self, context)
             if not available_models:
                 estimate_box.label(text="No DA3 models installed", icon="ERROR")
-                estimate_box.label(text="Download one in AI Backend > Models")
+                estimate_box.label(text="Download one in Models")
             else:
                 estimate_box.prop(self, "snapform_model")
                 estimate_box.prop(self, "snapform_use_ray_pose")
@@ -1917,17 +1916,17 @@ class SnapFormImageMenu(bpy.types.Menu):
     bl_label = "SnapForm"
 
     def draw(self, _context):
-        from .runtime import runtime_ready
+        from .client import env_installed
 
         layout = self.layout
         layout.operator_context = "INVOKE_DEFAULT"
-        if not runtime_ready():
+        if not env_installed():
             operator = layout.operator(
                 "snapform.run_job",
-                text="Install Backend",
+                text="Install Environment",
                 icon="IMPORT",
             )
-            operator.job_type = "INSTALL_RUNTIME"
+            operator.job_type = "INSTALL_ENV"
             return
         layout.operator(
             "snapform.convert_image_to_depth_plane",