feat: link backup runs to snapshot records

Add a nullable SnapshotRecord foreign key to BackupRun and populate it
when run_pobsync_backup records a completed or failed snapshot. Keep the
existing snapshot_path for audit compatibility while making run-to-snapshot
navigation explicit in the database and admin.

src/pobsync_backend/admin.py

@@ -50,9 +50,10 @@ class HostConfigAdmin(admin.ModelAdmin):
 
 @admin.register(BackupRun)
 class BackupRunAdmin(admin.ModelAdmin):
-    list_display = ("host", "run_type", "status", "started_at", "ended_at", "snapshot_path")
+    list_display = ("host", "run_type", "status", "started_at", "ended_at", "snapshot")
     list_filter = ("run_type", "status", "started_at")
-    search_fields = ("host__host", "snapshot_path")
+    search_fields = ("host__host", "snapshot_path", "snapshot__dirname", "snapshot__path")
+    autocomplete_fields = ("snapshot",)
 
 
 @admin.register(SnapshotRecord)

src/pobsync_backend/management/commands/run_pobsync_backup.py

@@ -64,23 +64,26 @@ class Command(BaseCommand):
         rsync = result.get("rsync") if isinstance(result.get("rsync"), dict) else {}
         run.rsync_exit_code = rsync.get("exit_code")
         run.result = result
+        snapshot_record = None
+        if run.snapshot_path:
+            snapshot_path = Path(run.snapshot_path)
+            try:
+                kind = infer_snapshot_kind(snapshot_path)
+                snapshot_record, _created = upsert_snapshot_record(host=host, kind=kind, snapshot_dir=snapshot_path)
+            except ValueError:
+                snapshot_record = None
+        run.snapshot = snapshot_record
         run.save(
             update_fields=[
                 "status",
                 "ended_at",
                 "snapshot_path",
+                "snapshot",
                 "base_path",
                 "rsync_exit_code",
                 "result",
             ],
         )
-        if run.snapshot_path:
-            snapshot_path = Path(run.snapshot_path)
-            try:
-                kind = infer_snapshot_kind(snapshot_path)
-                upsert_snapshot_record(host=host, kind=kind, snapshot_dir=snapshot_path)
-            except ValueError:
-                pass
 
         if result.get("ok"):
             self.stdout.write(self.style.SUCCESS(f"Backup completed for {host.host}."))

src/pobsync_backend/migrations/0004_backuprun_snapshot.py

@@ -0,0 +1,24 @@
+from __future__ import annotations
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("pobsync_backend", "0003_structured_config_fields"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="backuprun",
+            name="snapshot",
+            field=models.ForeignKey(
+                blank=True,
+                null=True,
+                on_delete=django.db.models.deletion.SET_NULL,
+                related_name="backup_runs",
+                to="pobsync_backend.snapshotrecord",
+            ),
+        ),
+    ]

src/pobsync_backend/models.py

@@ -82,6 +82,13 @@ class BackupRun(models.Model):
     started_at = models.DateTimeField(null=True, blank=True)
     ended_at = models.DateTimeField(null=True, blank=True)
     snapshot_path = models.CharField(max_length=1024, blank=True)
+    snapshot = models.ForeignKey(
+        "SnapshotRecord",
+        on_delete=models.SET_NULL,
+        null=True,
+        blank=True,
+        related_name="backup_runs",
+    )
     base_path = models.CharField(max_length=1024, blank=True)
     rsync_exit_code = models.IntegerField(null=True, blank=True)
     result = models.JSONField(default=dict, blank=True)

src/pobsync_backend/tests/test_run_backup_records_snapshot.py

@@ -43,8 +43,10 @@ class RunBackupRecordsSnapshotTests(TestCase):
                 call_command("run_pobsync_backup", host.host, prefix=str(Path(tmp) / "home"), stdout=StringIO())
 
         self.assertEqual(BackupRun.objects.count(), 1)
+        run = BackupRun.objects.get()
         self.assertEqual(SnapshotRecord.objects.count(), 1)
         record = SnapshotRecord.objects.get()
+        self.assertEqual(run.snapshot, record)
         self.assertEqual(record.host, host)
         self.assertEqual(record.kind, "scheduled")
         self.assertEqual(record.status, "success")
@@ -74,6 +76,7 @@ class RunBackupRecordsSnapshotTests(TestCase):
         run = BackupRun.objects.get()
         self.assertEqual(run.status, BackupRun.Status.FAILED)
         record = SnapshotRecord.objects.get()
+        self.assertEqual(run.snapshot, record)
         self.assertEqual(record.kind, "incomplete")
         self.assertEqual(record.status, "failed")
 
@@ -99,4 +102,5 @@ class RunBackupRecordsSnapshotTests(TestCase):
                 )
 
         self.assertEqual(BackupRun.objects.count(), 1)
+        self.assertIsNone(BackupRun.objects.get().snapshot)
         self.assertEqual(SnapshotRecord.objects.count(), 0)