feat(ui): add flat tree mode via f or -flat

cmd/difi/main.go

@@ -16,6 +16,7 @@ var version = "dev"
 func main() {
 	showVersion := flag.Bool("version", false, "Show version")
 	plain := flag.Bool("plain", false, "Print a plain, non-interactive summary and exit")
+	flat := flag.Bool("flat", false, "Start in flat file list mode")
 
 	flag.Usage = func() {
 		w := os.Stderr
@@ -52,6 +53,7 @@ func main() {
 	}
 
 	cfg := config.Load()
+	cfg.Flat = *flat
 
 	p := tea.NewProgram(ui.NewModel(cfg, target), tea.WithAltScreen())
 	if _, err := p.Run(); err != nil {

internal/config/config.go

@@ -2,6 +2,7 @@ package config
 
 type Config struct {
 	UI   UIConfig
+	Flat bool
 }
 
 type UIConfig struct {

internal/tree/tree.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/charmbracelet/bubbles/list"
+	"github.com/charmbracelet/lipgloss"
 )
 
 // FileTree holds the state of the entire file graph.
@@ -32,6 +33,7 @@ type TreeItem struct {
 	Depth    int
 	Expanded bool
 	Icon     string
+	Flat     bool
 }
 
 // Implement list.Item interface
@@ -104,6 +106,40 @@ func (t *FileTree) Items() []list.Item {
 	return items
 }
 
+// FlatItems returns all leaf (file) nodes as a flat list with full paths.
+func (t *FileTree) FlatItems() []list.Item {
+	var items []list.Item
+	collectLeaves(t.Root, &items)
+	return items
+}
+
+// collectLeaves recursively collects all file (non-directory) nodes.
+func collectLeaves(node *Node, items *[]list.Item) {
+	children := make([]*Node, 0, len(node.Children))
+	for _, child := range node.Children {
+		children = append(children, child)
+	}
+
+	sort.Slice(children, func(i, j int) bool {
+		return strings.ToLower(children[i].FullPath) < strings.ToLower(children[j].FullPath)
+	})
+
+	for _, child := range children {
+		if child.IsDir {
+			collectLeaves(child, items)
+		} else {
+			*items = append(*items, TreeItem{
+				Name:     child.Name,
+				FullPath: child.FullPath,
+				IsDir:    false,
+				Depth:    0,
+				Icon:     getIcon(child.Name, false),
+				Flat:     true,
+			})
+		}
+	}
+}
+
 // flatten recursively builds the list, respecting expansion state.
 func flatten(node *Node, items *[]list.Item) {
 	// Collect children to sort
@@ -189,3 +225,22 @@ func getIcon(name string, isDir bool) string {
 		return ""
 	}
 }
+
+// ShortenPath truncates a path from the left to fit within maxWidth display columns.
+// "internal/tree/tree.go" → "…nal/tree/tree.go"
+func ShortenPath(path string, maxWidth int) string {
+	if lipgloss.Width(path) <= maxWidth {
+		return path
+	}
+	ellipsis := "…"
+	avail := maxWidth - lipgloss.Width(ellipsis)
+	if avail <= 0 {
+		return ellipsis
+	}
+	// Trim runes from the left until the remainder fits
+	runes := []rune(path)
+	for len(runes) > 0 && lipgloss.Width(string(runes)) > avail {
+		runes = runes[1:]
+	}
+	return ellipsis + string(runes)
+}

internal/ui/delegate.go

@@ -7,6 +7,7 @@ import (
 	"github.com/charmbracelet/bubbles/list"
 	tea "github.com/charmbracelet/bubbletea"
 	"github.com/charmbracelet/lipgloss"
+	"github.com/charmbracelet/x/ansi"
 	"github.com/oug-t/difi/internal/tree"
 )
 
@@ -24,7 +25,15 @@ func (d TreeDelegate) Render(w io.Writer, m list.Model, index int, item list.Ite
 		return
 	}
 
-	title := i.Title()
+	var title string
+	if i.Flat {
+		iconWidth := lipgloss.Width(i.Icon) + 1 // icon + space
+		path := tree.ShortenPath(i.FullPath, m.Width()-2-iconWidth)
+		title = fmt.Sprintf("%s %s", i.Icon, path)
+	} else {
+		title = i.Title()
+	}
+	title = ansi.Truncate(title, m.Width()-2, "…")
 
 	if index == m.Index() {
 		style := lipgloss.NewStyle().

internal/ui/model.go

@@ -58,6 +58,7 @@ type Model struct {
 
 	focus    Focus
 	showHelp bool
+	flatMode bool
 
 	width, height int
 }
@@ -68,7 +69,12 @@ func NewModel(cfg config.Config, targetBranch string) Model {
 	files, _ := git.ListChangedFiles(targetBranch)
 
 	t := tree.New(files)
-	items := t.Items()
+	var items []list.Item
+	if cfg.Flat {
+		items = t.FlatItems()
+	} else {
+		items = t.Items()
+	}
 
 	delegate := TreeDelegate{Focused: true}
 	l := list.New(items, delegate, 0, 0)
@@ -90,6 +96,7 @@ func NewModel(cfg config.Config, targetBranch string) Model {
 		targetBranch:  targetBranch,
 		repoName:      git.GetRepoName(),
 		showHelp:      false,
+		flatMode:      cfg.Flat,
 		inputBuffer:   "",
 		pendingZ:      false,
 	}
@@ -222,7 +229,7 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			m.inputBuffer = ""
 
 		case "enter":
-			if m.focus == FocusTree {
+			if m.focus == FocusTree && !m.flatMode {
 				if i, ok := m.fileList.SelectedItem().(tree.TreeItem); ok && i.IsDir {
 					m.treeState.ToggleExpand(i.FullPath)
 					m.fileList.SetItems(m.treeState.Items())
@@ -255,6 +262,37 @@ func (m Model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 				return m, openFugitive(m.selectedPath, line)
 			}
 
+		case "f":
+			m.flatMode = !m.flatMode
+			prevPath := m.selectedPath
+			if m.flatMode {
+				m.fileList.SetItems(m.treeState.FlatItems())
+			} else {
+				m.fileList.SetItems(m.treeState.Items())
+			}
+			// Restore selection to the same file if possible
+			restored := false
+			for idx, item := range m.fileList.Items() {
+				if ti, ok := item.(tree.TreeItem); ok && ti.FullPath == prevPath {
+					m.fileList.Select(idx)
+					restored = true
+					break
+				}
+			}
+			// In flat mode, auto-select the first file if nothing was restored
+			if m.flatMode && !restored {
+				if first, ok := m.fileList.Items()[0].(tree.TreeItem); ok {
+					m.fileList.Select(0)
+					m.selectedPath = first.FullPath
+					m.diffCursor = 0
+					m.diffViewport.GotoTop()
+					m.inputBuffer = ""
+					return m, git.DiffCmd(m.targetBranch, m.selectedPath)
+				}
+			}
+			m.inputBuffer = ""
+			return m, nil
+
 		case "z":
 			if m.focus == FocusDiff {
 				m.pendingZ = true
@@ -432,7 +470,7 @@ func (m *Model) updateSizes() {
 	// 1 line Top Bar + 1 line Bottom Bar = 2 reserved
 	reservedHeight := 2
 	if m.showHelp {
-		reservedHeight += 6
+		reservedHeight += 7
 	}
 
 	contentHeight := m.height - reservedHeight
@@ -471,7 +509,7 @@ func (m Model) View() string {
 	var mainContent string
 	contentHeight := m.height - 2
 	if m.showHelp {
-		contentHeight -= 6
+		contentHeight -= 7
 	}
 	if contentHeight < 0 {
 		contentHeight = 0
@@ -658,7 +696,7 @@ func (m Model) renderTopBar() string {
 }
 
 func (m Model) viewStatusBar() string {
-	shortcuts := StatusKeyStyle.Render("? Help  q Quit  Tab Switch")
+	shortcuts := StatusKeyStyle.Render("? Help  q Quit  Tab Switch  f Flat")
 	return StatusBarStyle.Width(m.width).Render(shortcuts)
 }
 
@@ -678,6 +716,7 @@ func (m Model) renderHelpDrawer() string {
 	col4 := lipgloss.JoinVertical(lipgloss.Left,
 		HelpTextStyle.Render("H/M/L Move Cursor"),
 		HelpTextStyle.Render("e     Edit File"),
+		HelpTextStyle.Render("f     Flat Tree"),
 	)
 
 	return HelpDrawerStyle.Copy().