US06-02: Transfer, Verify, and Remove Active Sources (#78)

photo_pipeline/services/archives.py

@@ -24,6 +24,7 @@ Preflight proves, per concept §9 "Archive preflight":
   probed by writing them, not assumed.
 
 Blocker codes: ``no_library_root``, ``location_offline``, ``wrong_volume``,
+``archive_pending``,
 ``unsafe_destination``, ``destination_not_writable``, ``manifest_unwritable``,
 ``insufficient_capacity``, ``backup_unavailable``, ``lock_conflict``,
 ``rename_pending``, ``empty_scope``, ``destination_collision``,
@@ -57,6 +58,7 @@ from photo_pipeline.jobs.domain_handlers import ARCHIVE_LOCK, LIBRARY_WRITE_LOCK
 from photo_pipeline.models import ArchiveLocation, Asset, UploadBatch, UploadItem
 from photo_pipeline.path_policy import PathPolicyError, is_excluded, normalize_root, resolve_within
 from photo_pipeline.services.albums import album_label
+from photo_pipeline.services.archive_journal import ArchiveJournal
 from photo_pipeline.services.hashing import sha256_file
 from photo_pipeline.services.jobs import JobService
 from photo_pipeline.services.rename_journal import RenameJournal
@@ -291,6 +293,13 @@ class ArchiveService:
             blockers.append(
                 _issue("rename_pending", "an unresolved rename must be recovered before archiving")
             )
+        if ArchiveJournal(self._session_factory).blocks_mutation():
+            blockers.append(
+                _issue(
+                    "archive_pending",
+                    "an unresolved archive transfer must be recovered before archiving again",
+                )
+            )
         return blockers
 
     def _capacity(self, required: int, probe: dict) -> dict: