What causes "%s %w" in Jguer/yay?

Check the ref exists right before use: git rev-parse refs/has-been-reviewed in the package dir

%s %w

Error message

%s %w

What it means

getLastSeenHash wraps the failure of `git rev-parse <gitDiffRefName>` by concatenating git's stderr with the exec error via fmt.Errorf("%s %w", stderr, err). This ref stores the commit hash last shown to the user for PKGBUILD diffs; when it cannot be resolved the diff menu cannot compute what changed. The %w wrap keeps the underlying exec error inspectable.

Solutions

Check the ref exists right before use: git rev-parse refs/has-been-reviewed in the package dir
Recreate the ref from current HEAD: git update-ref refs/has-been-reviewed HEAD
Re-clone the AUR package if the repository is corrupt
Verify git is installed and on PATH (git --version)

Example fix

// before
return "", fmt.Errorf("%s %w", stderr, err)
// after
return "", fmt.Errorf("resolving last-seen ref %q in %s: %s: %w", gitDiffRefName, dir, stderr, err)

Defensive patterns

Strategy: try-catch

Validate before calling

out, err := exec.Command("git", "-C", dir, "rev-parse", "--verify", ref).Output()
if err != nil { /* ref missing: skip diff or recreate */ }

Type guard

func refExists(dir, ref string) bool {
	return exec.Command("git", "-C", dir, "rev-parse", "--verify", "--quiet", ref).Run() == nil
}

Try / catch

hash, err := getLastSeenHash(ctx, cb, dir)
if err != nil {
	log.Printf("no last-seen hash for %s: %v; showing full diff", dir, err)
	return "", nil // fall back to full diff
}

Prevention

Use `git rev-parse --verify --quiet <ref>` as an existence check instead of a separate boolean helper
Hold the package dir stable (no re-download) while diffing
Log stderr from Capture at debug level to catch transient git failures
Serialize diff sessions to avoid concurrent ref pruning

When it happens

Trigger: getLastSeenHash runs when gitHasLastSeenRef says the ref exists, but the subsequent `git rev-parse` of that ref fails (ref deleted between the check and the call, corrupted ref file, git repo removed mid-operation, git binary unavailable).

Common situations: Race where another yakuake/instance or `git gc` prunes refs/has-been-reviewed while the diff menu runs; package dir replaced by a fresh non-git download between check and read; PATH lacking git so cmdBuilder.Capture fails to exec.

Understand the failure class

Background: "git command failed": what it means when a tool shells out to git and git exits non-zero — this error's family across 21 libraries.

Related errors

AI-assisted analysis of Jguer/yay@328f4b4939 (2026-09-07). Data as JSON: /api/errors/25f504c8a3b72dcb. Report an issue: GitHub.

Appendix: source

Thrown at pkg/menus/diff_menu.go:152

// Return whether or not we have reviewed a diff yet. It checks for the existence of
// AUR_SEEN in the git ref-list.
func gitHasLastSeenRef(ctx context.Context, cmdBuilder exe.ICmdBuilder, dir string) bool {
	_, _, err := cmdBuilder.Capture(
		cmdBuilder.BuildGitCmd(ctx,
			dir, "rev-parse", "--quiet", "--verify", gitDiffRefName))

	return err == nil
}

// Returns the last reviewed hash. If AUR_SEEN exists it will return this hash.
// If it does not it will return empty tree as no diff have been reviewed yet.
func getLastSeenHash(ctx context.Context, cmdBuilder exe.ICmdBuilder, dir string) (string, error) {
	if gitHasLastSeenRef(ctx, cmdBuilder, dir) {
		stdout, stderr, err := cmdBuilder.Capture(
			cmdBuilder.BuildGitCmd(ctx,
				dir, "rev-parse", gitDiffRefName))
		if err != nil {
			return "", fmt.Errorf("%s %w", stderr, err)
		}

		lines := strings.Split(stdout, "\n")

		return lines[0], nil
	}

	return gitEmptyTree, nil
}

// Update the AUR_SEEN ref to HEAD. We use this ref to determine which diff were
// reviewed by the user.
func gitUpdateSeenRef(ctx context.Context, cmdBuilder exe.ICmdBuilder, dir string) error {
	_, stderr, err := cmdBuilder.Capture(
		cmdBuilder.BuildGitCmd(ctx,
			dir, "update-ref", gitDiffRefName, "HEAD"))
	if err != nil {
		return fmt.Errorf("%s %w", stderr, err)

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