fix: render the TUI on the tty when stdout is piped

.github/workflows/ci.yml

@@ -35,7 +35,7 @@ jobs:
 
       - name: build and test
         run: |
-          go test -race -timeout=100s -covermode=atomic -coverprofile=$GITHUB_WORKSPACE/profile.cov_tmp ./...
+          go test -race -timeout=180s -covermode=atomic -coverprofile=$GITHUB_WORKSPACE/profile.cov_tmp ./...
           grep -v -E "_mock.go|/mocks/" $GITHUB_WORKSPACE/profile.cov_tmp > $GITHUB_WORKSPACE/profile.cov
 
       - name: golangci-lint

Makefile

@@ -26,7 +26,7 @@ fmt:
 	~/.claude/format.sh
 
 race:
-	go test -race -timeout=100s ./...
+	go test -race -timeout=180s ./...
 
 version:
 	@echo "branch: $(BRANCH), hash: $(HASH), timestamp: $(TIMESTAMP)"

app/config.go

@@ -209,8 +209,7 @@ func loadConfigFile(iniParser *flags.IniParser, configPath string) {
 	if err == nil || errors.Is(err, os.ErrNotExist) {
 		return
 	}
-	var pathErr *os.PathError
-	if errors.As(err, &pathErr) {
+	if _, ok := errors.AsType[*os.PathError](err); ok {
 		return // file access error (permission denied, etc.)
 	}
 	fmt.Fprintf(os.Stderr, "warning: config %s: %v\n", configPath, err)

app/diff/diff.go

@@ -734,8 +734,7 @@ func runVCSEnv(workDir string, env []string, binary string, args ...string) (str
 	cmd.Env = env
 	out, err := cmd.Output()
 	if err != nil {
-		var exitErr *exec.ExitError
-		if errors.As(err, &exitErr) {
+		if exitErr, ok := errors.AsType[*exec.ExitError](err); ok {
 			return "", fmt.Errorf("%s %s: %s", binary, strings.Join(args, " "), string(exitErr.Stderr))
 		}
 		return "", fmt.Errorf("%s %s: %w", binary, strings.Join(args, " "), err)

app/diff/directory.go

@@ -60,8 +60,7 @@ func NewJjDirectoryReader(workDir string) *DirectoryReader {
 func (dr *DirectoryReader) ChangedFiles(_ string, _ bool) ([]FileEntry, error) {
 	out, err := dr.listFiles()
 	if err != nil {
-		var exitErr *exec.ExitError
-		if errors.As(err, &exitErr) {
+		if exitErr, ok := errors.AsType[*exec.ExitError](err); ok {
 			stderr := strings.TrimSpace(string(exitErr.Stderr))
 			if stderr != "" {
 				return nil, fmt.Errorf("%s: %s", dr.listSource, stderr)

app/diff/fallback.go

@@ -254,8 +254,7 @@ func readFileAsContext(path string) ([]DiffLine, error) {
 
 	lines, err := readReaderAsContext(f)
 	if err != nil {
-		var ctxErr readerContextError
-		if errors.As(err, &ctxErr) {
+		if ctxErr, ok := errors.AsType[readerContextError](err); ok {
 			return nil, fmt.Errorf("%s file %s: %w", ctxErr.op, path, ctxErr.err)
 		}
 		return nil, fmt.Errorf("read file %s: %w", path, err)

app/main.go

@@ -9,6 +9,7 @@ import (
 
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/term"
 	"github.com/jessevdk/go-flags"
 	"github.com/muesli/termenv"
 
@@ -123,6 +124,22 @@ func run(opts options) (int, error) {
 	)
 
 	programOptions := []tea.ProgramOption{tea.WithAltScreen(), tea.WithoutSignalHandler()}
+	tuiOut, err := (tuiOutput{
+		stdout:     os.Stdout,
+		isTerminal: term.IsTerminal,
+		openTTY: func() (*os.File, error) {
+			// stdin mode and Bubble Tea's default input fallback open a separate
+			// read handle; each side owns and closes its handle independently.
+			return os.OpenFile("/dev/tty", os.O_WRONLY, 0)
+		},
+	}).open()
+	if err != nil {
+		return 0, err
+	}
+	if tuiOut != os.Stdout {
+		defer func() { _ = tuiOut.Close() }()
+	}
+	programOptions = append(programOptions, tea.WithOutput(tuiOut))
 	if !opts.NoMouse {
 		programOptions = append(programOptions, tea.WithMouseCellMotion())
 	}
@@ -292,6 +309,25 @@ func run(opts options) (int, error) {
 	return 0, nil
 }
 
+type tuiOutput struct {
+	stdout     *os.File
+	isTerminal func(uintptr) bool
+	openTTY    func() (*os.File, error)
+}
+
+// open keeps Bubble Tea's display traffic out of redirected stdout, which is
+// reserved for the final annotation stream. Terminal stdout is returned as-is.
+func (r tuiOutput) open() (*os.File, error) {
+	if r.isTerminal(r.stdout.Fd()) {
+		return r.stdout, nil
+	}
+	tty, err := r.openTTY()
+	if err != nil {
+		return nil, fmt.Errorf("revdiff requires an interactive terminal for the TUI: %w", err)
+	}
+	return tty, nil
+}
+
 type finalizeReq struct {
 	opts        options
 	annotations string