fix: honor hardlinks across client mount topology

tests/test_config.py

@@ -1,7 +1,7 @@
 import os
 import tempfile
 import unittest
-from pathlib import Path
+from pathlib import Path, PurePosixPath
 from unittest.mock import patch
 
 from archive_clients.config import ClientConfig, ConfigError, RootMapping
@@ -63,6 +63,21 @@ class ConfigTests(unittest.TestCase):
         with self.assertRaises(ConfigError):
             mapping.api_to_local("/elsewhere/file")
 
+    def test_mapping_can_override_one_syncthing_folder_locally(self):
+        mapping = RootMapping(
+            PurePosixPath("/sync"),
+            Path("/local/sync"),
+            ((PurePosixPath("/sync/DownloadsSync"), Path("/local/qb/Sync")),),
+        )
+        self.assertEqual(
+            mapping.api_to_local("/sync/DownloadsSync/job/ready.json"),
+            Path("/local/qb/Sync/job/ready.json"),
+        )
+        self.assertEqual(
+            mapping.local_root_for_api("/sync/DownloadsSync"),
+            Path("/local/qb/Sync"),
+        )
+
     def test_endpoint_scheme_and_job_keys_are_strict(self):
         with tempfile.TemporaryDirectory() as directory:
             root = Path(directory)

tests/test_jobs.py

@@ -78,6 +78,25 @@ class ClientJobHappyPathTests(unittest.TestCase):
                 content=b"x" * 4096,
             )
 
+    def test_mount_boundary_requires_copy_space_even_with_same_device(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            source_root = root / "source"
+            destination_root = root / "destination"
+            source_root.mkdir()
+            destination_root.mkdir()
+            (source_root / "fixture.bin").write_bytes(b"fixture")
+            with patch(
+                "archive_clients.jobs._mount_id",
+                side_effect=("source-mount", "destination-mount"),
+            ):
+                required = ClientJobExecutor._copy_required_bytes(
+                    source_root,
+                    destination_root,
+                    (("fixture.bin", 7),),
+                )
+            self.assertEqual(required, 7)
+
     def _run_transfer(
         self,
         root: Path,

tests/test_routes.py

@@ -62,6 +62,32 @@ class RouteDiscoveryTests(unittest.TestCase):
         self.assertEqual(routes[0].local_relative_path, "DownloadsSync")
         self.assertEqual(routes[0].state, route_pb2.ROUTE_STATE_DISCOVERED)
 
+    def test_discovery_accepts_a_safe_local_folder_override(self):
+        with tempfile.TemporaryDirectory() as directory:
+            root = Path(directory)
+            override = root / "qb/Sync"
+            override.mkdir(parents=True)
+            roots = RootMapping(
+                PurePosixPath("/var/syncthing"),
+                root / "sync",
+                ((PurePosixPath("/var/syncthing/DownloadsSync"), override),),
+            )
+            routes = discover_routes(
+                {"folders": [{
+                    "id": "DownloadsSync",
+                    "path": "~/DownloadsSync",
+                    "type": "sendreceive",
+                    "devices": [
+                        {"deviceID": "LOCAL"},
+                        {"deviceID": "ARCHIVE"},
+                    ],
+                }]},
+                "LOCAL",
+                roots,
+                True,
+            )
+        self.assertEqual([route.route_id for route in routes], ["DownloadsSync"])
+
 
 if __name__ == "__main__":
     unittest.main()