fix(sync): protect local issues from git-history-backfill during sync (#485)

Fix sync bug where newly created issues were incorrectly tombstoned during bd sync.

The root cause was git-history-backfill finding issues in local commits on the sync branch, then tombstoning them when they weren't in the merged JSONL. The fix protects issues from the left snapshot (local export) from git-history-backfill.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

internal/importer/importer.go

@@ -44,6 +44,7 @@ type Options struct {
 	ClearDuplicateExternalRefs bool           // Clear duplicate external_ref values instead of erroring
 	NoGitHistory               bool           // Skip git history backfill for deletions (prevents spurious deletion during JSONL migrations)
 	IgnoreDeletions            bool           // Import issues even if they're in the deletions manifest
+	ProtectLocalExportIDs      map[string]bool // IDs from left snapshot to protect from git-history-backfill (bd-sync-deletion fix)
 }
 
 // Result contains statistics about the import operation
@@ -65,6 +66,8 @@ type Result struct {
 	SkippedDeletedIDs     []string          // IDs that were skipped due to deletions manifest
 	ConvertedToTombstone  int               // Legacy deletions.jsonl entries converted to tombstones (bd-wucl)
 	ConvertedTombstoneIDs []string          // IDs that were converted to tombstones
+	PreservedLocalExport  int               // Issues preserved because they were in local export (bd-sync-deletion fix)
+	PreservedLocalIDs     []string          // IDs that were preserved from local export
 }
 
 // ImportIssues handles the core import logic used by both manual and auto-import.
@@ -894,6 +897,17 @@ func purgeDeletedIssues(ctx context.Context, sqliteStore *sqlite.SQLiteStorage,
 			// This could be:
 			// 1. Local work (new issue not yet exported)
 			// 2. Deletion was pruned from manifest (check git history)
+			// 3. Issue was in local export but lost during pull/merge (bd-sync-deletion fix)
+
+			// Check if this issue was in our local export (left snapshot)
+			// If so, it's local work that got lost during merge - preserve it!
+			if opts.ProtectLocalExportIDs != nil && opts.ProtectLocalExportIDs[dbIssue.ID] {
+				fmt.Fprintf(os.Stderr, "Preserving %s (was in local export, lost during merge)\n", dbIssue.ID)
+				result.PreservedLocalExport++
+				result.PreservedLocalIDs = append(result.PreservedLocalIDs, dbIssue.ID)
+				continue
+			}
+
 			needGitCheck = append(needGitCheck, dbIssue.ID)
 		}
 	}