feat: TUI SFTP Browser Tab - Task 18

- SFTPBrowserTab with remote directory browsing
- Open via Ctrl+F from host list
- Navigate dirs, filter with /, refresh with r
- Dir/icon display with file sizes
- Sort dirs first, then by name

pkg/tui/host_list_tab.go

@@ -75,6 +75,14 @@ func (t *HostListTab) Update(msg tea.Msg) (Tab, tea.Cmd) {
 				}
 			}
 
+		case "ctrl+f":
+			if len(t.hosts) > 0 {
+				host := t.hosts[t.selectedIndex]
+				return t, func() tea.Msg {
+					return openSFTPMsg{host: host}
+				}
+			}
+
 		case "q", "ctrl+c":
 			return t, func() tea.Msg {
 				return quitMsg{}

pkg/tui/messages.go

@@ -45,6 +45,11 @@ type saveHostResultMsg struct {
 	err  error
 }
 
+// openSFTPMsg signals the TUI to open an SFTP browser tab
+type openSFTPMsg struct {
+	host *models.Host
+}
+
 // loadedHostsMsg is produced after reloading hosts from storage
 type loadedHostsMsg struct {
 	hosts []*models.Host

pkg/tui/sftp_browser_tab.go

@@ -0,0 +1,400 @@
+package tui
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path"
+	"sort"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/charmbracelet/bubbles/textinput"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/pkg/sftp"
+
+	"git.tukangketik.id/swanadiva/hostkeeper/internal/models"
+	sshclient "git.tukangketik.id/swanadiva/hostkeeper/pkg/ssh"
+)
+
+type connectionState int
+
+const (
+	stateConnecting connectionState = iota
+	stateConnected
+	stateError
+	stateDone
+)
+
+// SFTPBrowserTab provides a remote file browser via SFTP
+type SFTPBrowserTab struct {
+	host    *models.Host
+	dataDir string
+
+	sshClient *sshclient.Client
+	sftp      *sftp.Client
+	cwd       string
+
+	entries     []os.FileInfo
+	selectedIdx int
+	state       connectionState
+	err         error
+	width       int
+	height      int
+
+	mu      sync.Mutex
+	closeOnce sync.Once
+
+	// search/filter
+	searchMode bool
+	searchInput textinput.Model
+	filterText string
+}
+
+// NewSFTPBrowserTab creates a new SFTP browser tab
+func NewSFTPBrowserTab(host *models.Host, dataDir string) *SFTPBrowserTab {
+	si := textinput.New()
+	si.Placeholder = "Filter files..."
+
+	return &SFTPBrowserTab{
+		host:    host,
+		dataDir: dataDir,
+		cwd:     "/",
+		state:   stateConnecting,
+		searchInput: si,
+	}
+}
+
+func (t *SFTPBrowserTab) Name() string {
+	return "SFTP: " + t.host.Name
+}
+
+func (t *SFTPBrowserTab) Init() tea.Cmd {
+	go t.connect()
+	return t.poll
+}
+
+func (t *SFTPBrowserTab) poll() tea.Msg {
+	t.mu.Lock()
+	state := t.state
+	err := t.err
+	t.mu.Unlock()
+
+	if state == stateError {
+		return sftpDoneMsg{err: err}
+	}
+	if state == stateConnected {
+		return sftpReadyMsg{}
+	}
+	return nil
+}
+
+func (t *SFTPBrowserTab) connect() {
+	timeout := 30 * time.Second
+	cl := sshclient.NewClient(t.host, timeout)
+
+	ctx := context.Background()
+	if err := cl.Connect(ctx); err != nil {
+		t.mu.Lock()
+		t.state = stateError
+		t.err = fmt.Errorf("SSH connect failed: %w", err)
+		t.mu.Unlock()
+		return
+	}
+
+	sftpClient, err := sftp.NewClient(cl.GetClient())
+	if err != nil {
+		cl.Close()
+		t.mu.Lock()
+		t.state = stateError
+		t.err = fmt.Errorf("SFTP init failed: %w", err)
+		t.mu.Unlock()
+		return
+	}
+
+	t.mu.Lock()
+	t.sshClient = cl
+	t.sftp = sftpClient
+	t.mu.Unlock()
+
+	if err := t.refresh(); err != nil {
+		cl.Close()
+		sftpClient.Close()
+		t.mu.Lock()
+		t.state = stateError
+		t.err = err
+		t.mu.Unlock()
+		return
+	}
+
+	t.mu.Lock()
+	t.state = stateConnected
+	t.mu.Unlock()
+}
+
+func (t *SFTPBrowserTab) refresh() error {
+	t.mu.Lock()
+	sftpClient := t.sftp
+	cwd := t.cwd
+	t.mu.Unlock()
+
+	if sftpClient == nil {
+		return fmt.Errorf("not connected")
+	}
+
+	entries, err := sftpClient.ReadDir(cwd)
+	if err != nil {
+		return fmt.Errorf("read dir %s: %w", cwd, err)
+	}
+
+	sort.Slice(entries, func(i, j int) bool {
+		if entries[i].IsDir() != entries[j].IsDir() {
+			return entries[i].IsDir()
+		}
+		return strings.ToLower(entries[i].Name()) < strings.ToLower(entries[j].Name())
+	})
+
+	t.mu.Lock()
+	t.entries = entries
+	if t.selectedIdx >= len(entries) {
+		t.selectedIdx = 0
+	}
+	t.mu.Unlock()
+	return nil
+}
+
+func (t *SFTPBrowserTab) Update(msg tea.Msg) (Tab, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.WindowSizeMsg:
+		t.mu.Lock()
+		t.width = msg.Width
+		t.height = msg.Height
+		t.mu.Unlock()
+
+	case sftpReadyMsg:
+		return t, nil
+
+	case sftpDoneMsg:
+		t.mu.Lock()
+		t.state = stateDone
+		if msg.err != nil {
+			t.err = msg.err
+		}
+		t.mu.Unlock()
+		return t, nil
+
+	case sftpRefreshMsg:
+		if err := t.refresh(); err != nil {
+			t.mu.Lock()
+			t.err = err
+			t.mu.Unlock()
+		}
+
+	case tea.KeyMsg:
+		if t.searchMode {
+			switch msg.String() {
+			case "esc", "enter":
+				t.searchMode = false
+				t.filterText = ""
+				return t, nil
+			case "backspace":
+				t.searchInput.Update(msg)
+				t.filterText = t.searchInput.Value()
+				return t, nil
+			default:
+				t.searchInput.Update(msg)
+				t.filterText = t.searchInput.Value()
+				return t, nil
+			}
+		}
+
+		switch msg.String() {
+		case "/":
+			t.searchMode = true
+			t.searchInput.Reset()
+			t.filterText = ""
+			t.searchInput.Focus()
+			return t, nil
+
+		case "esc":
+			return t, func() tea.Msg { return closeFormMsg{} }
+
+		case "up", "k":
+			t.mu.Lock()
+			if t.selectedIdx > 0 {
+				t.selectedIdx--
+			}
+			t.mu.Unlock()
+
+		case "down", "j":
+			t.mu.Lock()
+			if t.selectedIdx < len(t.entries)-1 {
+				t.selectedIdx++
+			}
+			t.mu.Unlock()
+
+		case "enter":
+			t.mu.Lock()
+			entries := t.entries
+			idx := t.selectedIdx
+			t.mu.Unlock()
+
+			if idx < 0 || idx >= len(entries) {
+				return t, nil
+			}
+			entry := entries[idx]
+
+			if entry.IsDir() {
+				t.mu.Lock()
+				t.cwd = path.Join(t.cwd, entry.Name())
+				t.selectedIdx = 0
+				t.mu.Unlock()
+				if err := t.refresh(); err != nil {
+					t.mu.Lock()
+					t.err = err
+					t.mu.Unlock()
+				}
+			}
+
+		case "backspace":
+			t.mu.Lock()
+			parent := path.Dir(t.cwd)
+			if parent == "." {
+				parent = "/"
+			}
+			t.cwd = parent
+			t.selectedIdx = 0
+			t.mu.Unlock()
+			if err := t.refresh(); err != nil {
+				t.mu.Lock()
+				t.err = err
+				t.mu.Unlock()
+			}
+
+		case "r":
+			if err := t.refresh(); err != nil {
+				t.mu.Lock()
+				t.err = err
+				t.mu.Unlock()
+			}
+		}
+	}
+
+	return t, t.poll
+}
+
+func (t *SFTPBrowserTab) View() string {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	switch t.state {
+	case stateConnecting:
+		return HighlightStyle.Render(fmt.Sprintf("Connecting SFTP to %s...", t.host.Name))
+	case stateError:
+		return fmt.Sprintf("%s\n\n%s",
+			ErrorStyle.Render(fmt.Sprintf("SFTP Error: %v", t.err)),
+			SubtitleStyle.Render("Press Esc to close this tab"))
+	case stateDone:
+		return fmt.Sprintf("%s\n\n%s",
+			SubtitleStyle.Render("SFTP session ended"),
+			SubtitleStyle.Render("Press Esc to close this tab"))
+	}
+
+	var b strings.Builder
+
+	b.WriteString(AppTitleStyle.Render(fmt.Sprintf("SFTP: %s@%s", t.host.Username, t.host.Hostname)))
+	b.WriteString("\n")
+	b.WriteString(SubtitleStyle.Render(fmt.Sprintf("  %s", t.cwd)))
+	b.WriteString("\n\n")
+
+	if t.err != nil {
+		b.WriteString(ErrorStyle.Render(fmt.Sprintf("Error: %v", t.err)))
+		b.WriteString("\n\n")
+	}
+
+	if t.sftp == nil {
+		b.WriteString(SubtitleStyle.Render("Not connected."))
+		return b.String()
+	}
+
+	var visible []os.FileInfo
+	if t.searchMode || t.filterText != "" {
+		lower := strings.ToLower(t.filterText)
+		for _, e := range t.entries {
+			if strings.Contains(strings.ToLower(e.Name()), lower) {
+				visible = append(visible, e)
+			}
+		}
+	} else {
+		visible = t.entries
+	}
+
+	if len(visible) == 0 {
+		b.WriteString(SubtitleStyle.Render("  (empty)"))
+	} else {
+		for i, entry := range visible {
+			name := entry.Name()
+			var line string
+
+			if entry.IsDir() {
+				line = fmt.Sprintf("  %s/", name)
+			} else {
+				size := formatSize(entry.Size())
+				line = fmt.Sprintf("  %s  (%s)", name, size)
+			}
+
+			if i == t.selectedIdx {
+				b.WriteString(SelectedStyle.Render(line))
+			} else {
+				style := HostDetailStyle
+				if entry.IsDir() {
+					style = InfoStyle
+				}
+				b.WriteString(style.Render(line))
+			}
+			b.WriteString("\n")
+		}
+	}
+
+	if t.searchMode {
+		b.WriteString("\n" + SubtitleStyle.Render("Filter: ") + t.searchInput.View())
+	} else {
+		b.WriteString("\n" + SubtitleStyle.Render("/:filter  r:refresh  Esc:close"))
+	}
+
+	return b.String()
+}
+
+func (t *SFTPBrowserTab) Close() {
+	t.closeOnce.Do(func() {
+		if t.sftp != nil {
+			t.sftp.Close()
+		}
+		if t.sshClient != nil {
+			t.sshClient.Close()
+		}
+	})
+}
+
+func formatSize(size int64) string {
+	switch {
+	case size >= 1<<30:
+		return fmt.Sprintf("%.1f GiB", float64(size)/float64(1<<30))
+	case size >= 1<<20:
+		return fmt.Sprintf("%.1f MiB", float64(size)/float64(1<<20))
+	case size >= 1<<10:
+		return fmt.Sprintf("%.1f KiB", float64(size)/float64(1<<10))
+	default:
+		return fmt.Sprintf("%d B", size)
+	}
+}
+
+// Message types for SFTP tab
+type sftpReadyMsg struct{}
+
+type sftpDoneMsg struct {
+	err error
+}
+
+type sftpRefreshMsg struct{}

pkg/tui/tui.go

@@ -76,6 +76,11 @@ func (m *Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		cmd := m.tabs.Add(tab)
 		return m, cmd
 
+	case openSFTPMsg:
+		tab := NewSFTPBrowserTab(msg.host, m.dataDir)
+		cmd := m.tabs.Add(tab)
+		return m, cmd
+
 	case closeFormMsg:
 		if m.tabs.Len() > 1 {
 			m.tabs.CloseActive()