gastownhall/beads · error

unsupported git object format %q

Error message

unsupported git object format %q

What it means

After querying `git rev-parse --show-object-format`, bd only accepts `sha1` (40-char OIDs) or `sha256` (64-char). Any other output triggers this error reporting the unexpected format string.

Source

Thrown at cmd/bd/worktree_cmd.go:1842

	return matches, nil
}

func repositoryObjectIDLength(
	ctx context.Context,
	git *worktreeRemovalGit,
	executionRoot string,
) (int, error) {
	output, err := git.output(ctx, executionRoot, "rev-parse", "--show-object-format")
	if err != nil {
		return 0, fmt.Errorf("failed to determine repository object format: %w", err)
	}
	switch strings.TrimSpace(string(output)) {
	case "sha1":
		return 40, nil
	case "sha256":
		return 64, nil
	default:
		return 0, fmt.Errorf("unsupported git object format %q", strings.TrimSpace(string(output)))
	}
}

func isHexObjectID(value string, length int) bool {
	if len(value) != length {
		return false
	}
	for _, character := range value {
		if character >= '0' && character <= '9' ||
			character >= 'a' && character <= 'f' ||
			character >= 'A' && character <= 'F' {
			continue
		}
		return false
	}
	return true
}

View on GitHub (pinned to 71377f2769)

Solutions

1. Check `git rev-parse --show-object-format` output directly; it must print `sha1` or `sha256`
2. Remove any git wrapper/shim that adds extra output
3. Reinstall a standard git build
4. Upgrade git if using a nonstandard hash algorithm build

Example fix

// diagnose
git rev-parse --show-object-format   # should print: sha1
// fix: remove wrapper emitting extra lines
which git && cat $(which git)

// shell pre-check
fmt=$(git rev-parse --show-object-format 2>/dev/null)
case "$fmt" in sha1|sha256) ;; *) echo "unexpected object format: '$fmt'" ;; esac

When it happens

Trigger: git returns an unexpected object-format value — empty output (command partially failed but exit 0), future/unknown hash algorithms, or whitespace/garbage output from a shimmed git binary.

Common situations: Wrapper scripts around `git` that emit extra output; experimental git builds; an empty repository where output is blank.

Related errors

• auto-export: git add failed: %w
• failed to read .gitignore: %w
• failed to write .gitignore: %w
• not in a git repository
• registered worktree not found: %s

AI-assisted analysis of gastownhall/beads@71377f2769 (2026-08-30). Data as JSON: /api/errors/b91eccfd64422dad. Report an issue: GitHub.