fix: resolve per-torrent qb save paths

tests/test_jobs.py

@@ -4,11 +4,13 @@ import stat
 import tempfile
 import threading
 import unittest
-from pathlib import Path
+from dataclasses import replace
+from pathlib import Path, PurePosixPath
 from unittest.mock import Mock, patch
 from uuid import uuid4
 
 from archive_clients.bencode import encode
+from archive_clients.config import RootMapping
 from archive_clients.jobs import (
     ClientJobExecutor,
     JobExecutionError,
@@ -246,6 +248,55 @@ class ClientJobHappyPathTests(unittest.TestCase):
                 content=b"x" * 4096,
             )
 
+    def test_nested_qb_save_path_stages_from_mapped_subdirectory(self):
+        with tempfile.TemporaryDirectory() as directory:
+            self._run_transfer(
+                Path(directory),
+                job_pb2.JOB_OPERATION_UNARCHIVE,
+                source_save_path="/downloads/Downloading",
+            )
+
+    def test_qb_save_path_preflight_rejects_unmapped_path(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            executor = ClientJobExecutor(
+                client_id="cache-1", qbittorrent=Mock(),
+                store=ClientStore(root / "state.db"), qb_root=root,
+                qb_api_root=PurePosixPath("/downloads"),
+                route_path=lambda _: root, syncthing_transport=Mock(),
+                sparse_supported=True,
+            )
+            resource = NormalizedResource(
+                resource_pb2.ResourceSummary(), (), Mock(),
+                save_path=PurePosixPath("/outside"),
+            )
+            with self.assertRaisesRegex(JobExecutionError, "outside"):
+                executor._resource_root(resource)
+
+    def test_qb_save_path_override_uses_its_dedicated_local_mount(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            primary = root / "primary"
+            override = root / "override"
+            primary.mkdir()
+            override.mkdir()
+            executor = ClientJobExecutor(
+                client_id="cache-1", qbittorrent=Mock(),
+                store=ClientStore(root / "state.db"), qb_root=primary,
+                qb_api_root=PurePosixPath("/downloads"),
+                qb_roots=RootMapping(
+                    PurePosixPath("/downloads"), primary,
+                    ((PurePosixPath("/downloads/slow"), override),),
+                ),
+                route_path=lambda _: root, syncthing_transport=Mock(),
+                sparse_supported=True,
+            )
+            resource = NormalizedResource(
+                resource_pb2.ResourceSummary(), (), Mock(),
+                save_path=PurePosixPath("/downloads/slow"),
+            )
+            self.assertEqual(executor._resource_root(resource), override)
+
     def test_mount_boundary_requires_copy_space_even_with_same_device(self):
         with tempfile.TemporaryDirectory() as directory:
             root = Path(directory)
@@ -390,6 +441,7 @@ class ClientJobHappyPathTests(unittest.TestCase):
         source_stage_free_bytes: int | None = None,
         content: bytes = b"archive-control-happy-path",
         syncthing: CompleteSyncthing | None = None,
+        source_save_path: str = "/downloads",
     ):
         source_root = root / "source"
         target_root = root / "target"
@@ -397,7 +449,12 @@ class ClientJobHappyPathTests(unittest.TestCase):
         source_root.mkdir()
         target_root.mkdir()
         route_root.mkdir()
-        (source_root / "fixture.bin").write_bytes(content)
+        save_relative = PurePosixPath(source_save_path).relative_to(
+            PurePosixPath("/downloads")
+        )
+        source_content_root = source_root.joinpath(*save_relative.parts)
+        source_content_root.mkdir(parents=True, exist_ok=True)
+        (source_content_root / "fixture.bin").write_bytes(content)
         info = {
             b"length": len(content),
             b"name": b"fixture.bin",
@@ -411,6 +468,7 @@ class ClientJobHappyPathTests(unittest.TestCase):
                 "hash": torrent_hash,
                 "name": "fixture.bin",
                 "state": "uploading",
+                "save_path": source_save_path,
             },
             [{
                 "index": 0,
@@ -454,8 +512,11 @@ class ClientJobHappyPathTests(unittest.TestCase):
         source_qb = Mock()
         source_qb.get_resource.return_value = resource
         target_qb = Mock()
+        target_resource = replace(
+            resource, save_path=PurePosixPath("/downloads")
+        )
         target_qb.get_resource.side_effect = [
-            None, None, resource, resource,
+            None, None, target_resource, target_resource,
         ]
         syncthing = syncthing or CompleteSyncthing()
         source = ClientJobExecutor(