fix: bd sync fails in bare repo worktrees (#785)

The bug: In a bare repo + worktrees setup, jsonlRelPath was calculated
relative to the project root (which contains all worktrees), resulting in
paths like "main/.beads/issues.jsonl". But the sync branch worktree uses
sparse checkout for .beads/*, so files are at ".beads/issues.jsonl".

This caused copyJSONLToMainRepo to look in the wrong location, silently
returning when the file was not found.

Fix: Add normalizeBeadsRelPath() to strip leading path components before
".beads", ensuring correct path resolution in both directions:
- copyJSONLToMainRepo (worktree -> local)
- SyncJSONLToWorktreeWithOptions (local -> worktree)

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

internal/syncbranch/worktree.go

@@ -656,7 +656,12 @@ func extractJSONLFromCommit(ctx context.Context, worktreePath, commit, filePath
 
 // copyJSONLToMainRepo copies JSONL and related files from worktree to main repo.
 func copyJSONLToMainRepo(worktreePath, jsonlRelPath, jsonlPath string) error {
-	worktreeJSONLPath := filepath.Join(worktreePath, jsonlRelPath)
+	// GH#785: Handle bare repo worktrees where jsonlRelPath might include the
+	// worktree name (e.g., "main/.beads/issues.jsonl" instead of ".beads/issues.jsonl").
+	// The sync branch uses sparse checkout for .beads/* so we normalize the path
+	// to strip any leading components before .beads.
+	normalizedRelPath := normalizeBeadsRelPath(jsonlRelPath)
+	worktreeJSONLPath := filepath.Join(worktreePath, normalizedRelPath)
 
 	// Check if worktree JSONL exists
 	if _, err := os.Stat(worktreeJSONLPath); os.IsNotExist(err) {
@@ -1077,6 +1082,20 @@ func formatVanishedIssues(localIssues, mergedIssues map[string]issueSummary, loc
 	return lines
 }
 
+// normalizeBeadsRelPath strips any leading path components before .beads.
+// This handles bare repo worktrees where the relative path includes the worktree
+// name (e.g., "main/.beads/issues.jsonl" -> ".beads/issues.jsonl").
+// GH#785: Fix for sync failing across worktrees in bare repo setup.
+func normalizeBeadsRelPath(relPath string) string {
+	// Use filepath.ToSlash for consistent handling across platforms
+	normalized := filepath.ToSlash(relPath)
+	if idx := strings.Index(normalized, ".beads"); idx > 0 {
+		// Strip leading path components before .beads
+		return filepath.FromSlash(normalized[idx:])
+	}
+	return relPath
+}
+
 // HasGitRemote checks if any git remote exists
 func HasGitRemote(ctx context.Context) bool {
 	cmd := exec.CommandContext(ctx, "git", "remote")