feat: Implement background depth distance feature for depth processing

- Added `background_depth_distance` property to `ActiveJob` and `RunJob` classes to manage background depth settings.
- Updated job execution to handle background depth distance, allowing for fixed negative displacement in depth calculations.
- Introduced new functions in the worker module to apply background depth distance to depth frames and manage original background depth.
- Enhanced tests to cover new functionality, ensuring correct behavior of background depth processing and reference depth extraction.
- Refactored job submission to run in a separate thread, improving responsiveness during execution.

src/snapform/runtime.py

@@ -6,6 +6,7 @@ import shutil
 import socket
 import subprocess
 import sys
+import threading
 import time
 import uuid
 from dataclasses import dataclass
@@ -65,6 +66,7 @@ _client_id = uuid.uuid4().hex
 _host_auto_start = False
 _host_snapshot = {"state": "STOPPED", "message": "Stopped"}
 _local_opener = build_opener(ProxyHandler({}))
+_client_label = f"Blender {getattr(bpy.app, 'version_string', '')}".strip()
 
 
 def preferences():
@@ -391,11 +393,10 @@ def ensure_host(timeout=60.0):
     last_launch = 0.0
     starting = False
     while time.monotonic() < deadline:
-        connection, _health = _discover_live_host(timeout=0.5)
+        connection, health = _discover_live_host(timeout=0.5)
         if connection is not None:
             _host_connection = connection
             _register_host_client(connection)
-            health = _check_host(connection, timeout=0.5)
             _host_snapshot = _format_host_snapshot(connection, health)
             _redraw_host_ui()
             return connection
@@ -415,7 +416,7 @@ def ensure_host(timeout=60.0):
 
 
 def submit_host_job(request):
-    connection = ensure_host()
+    connection = _host_connection or ensure_host()
     payload = dict(request.payload)
     payload["client_id"] = _client_id
     _host_http_request(
@@ -564,6 +565,24 @@ def host_busy():
     return _host_snapshot.get("state") == "BUSY"
 
 
+def mark_host_job_complete(job_id):
+    """Release a stale local busy snapshot after its terminal status is observed."""
+    global _host_snapshot
+
+    active = _host_snapshot.get("active_job")
+    if active and active.get("job_id") != job_id:
+        return
+    if _host_snapshot.get("state") != "BUSY":
+        return
+    _host_snapshot = {
+        **_host_snapshot,
+        "busy": False,
+        "active_job": None,
+        "state": "READY",
+        "message": "Ready",
+    }
+
+
 def _service_host_timer():
     global _host_connection, _host_snapshot, _registered_instance_id
 
@@ -619,12 +638,11 @@ def _register_host_client(connection):
 
     if _registered_instance_id == connection.instance_id:
         return
-    label = f"Blender {getattr(bpy.app, 'version_string', '')}".strip()
     _host_http_request(
         connection,
         "POST",
         "/clients",
-        payload={"client_id": _client_id, "label": label},
+        payload={"client_id": _client_id, "label": _client_label},
         timeout=2.0,
     )
     _registered_instance_id = connection.instance_id
@@ -641,6 +659,8 @@ def _format_host_snapshot(connection, health):
 
 
 def _redraw_host_ui():
+    if threading.current_thread() is not threading.main_thread():
+        return
     try:
         from .status_bar import redraw_ui
 
@@ -701,6 +721,7 @@ def remove_background_request(
     video_frames=None,
     start_frame=1,
     device=None,
+    background_depth_distance=0.0,
 ):
     return HostJobRequest(
         {
@@ -718,6 +739,9 @@ def remove_background_request(
                     else video_frames
                 ),
                 "start_frame": start_frame,
+                "background_depth_distance": float(
+                    background_depth_distance
+                ),
             },
         }
     )
@@ -761,6 +785,7 @@ def reconstruct_request(
     process_res_method=None,
     use_ray_pose=None,
     remove_background=False,
+    background_depth_distance=0.0,
     start_frame=1,
     device=None,
 ):
@@ -798,8 +823,9 @@ def reconstruct_request(
         "use_ray_pose": 1 if snapform_selected_ray_pose else 0,
         "ref_view_strategy": settings.ref_view_strategy,
         "remove_background_model_dir": "",
+        "background_depth_distance": float(background_depth_distance),
     }
-    if remove_background:
+    if remove_background or background_depth_distance > 0.0:
         parameters["remove_background_model_dir"] = str(
             model_directory(BEN2_MODEL.key)
         )