feat: config option to use the List Layout (prototype variant C) for the Picker

CONTEXT.md

@@ -40,6 +40,10 @@ _Avoid_: Import, index, crawl, rebuild
 The interactive screen that lists Projects and lets the user choose one to Jump to.
 _Avoid_: Menu, list, finder, selector
 
+**Layout**:
+One of the arrangements in which the Picker draws Projects: the Grouped Layout puts them under Kind headers, the List Layout in one flat run.
+_Avoid_: View, mode, style, theme, skin
+
 **Wrapper**:
 The shell function installed into the user's shell that turns a Project chosen in the Picker into a Jump.
 _Avoid_: Hook, integration, plugin, shim, alias

README.md

@@ -94,6 +94,22 @@ Vim key map (`keys.vim = true`): the list is focused on open.
 | `esc` / `q` | cancel |
 | `enter` | Jump to the selected Project |
 
+### Layout
+
+The Picker ships two Layouts, selected with `picker.layout`.
+
+The **Grouped Layout** (`grouped`, the default) groups Projects under Kind
+headers, marks the selected row with a caret, and puts the filter line
+above the list.
+
+The **List Layout** (`list`) is a flat fzf-style run: no Kind headers,
+Projects in History order with never-visited ones last, `kind/` muted
+before each Project name, the filter prompt below the list, and a `▌` bar
+plus a background highlight on the selected row.
+
+Both draw the same preview pane, use the same keys, status glyphs and
+colours, and degrade the same way on a narrow terminal.
+
 ## Config reference
 
 `cdd` reads `config.toml` from `$XDG_CONFIG_HOME/cdd/config.toml`, falling
@@ -107,6 +123,8 @@ include_hidden = false
 max_visits = 1000         # must be >= 1
 [keys]
 vim = false
+[picker]
+layout = "grouped"        # or "list" for the flat fzf-style layout
 ```
 
 - `root` (required): the top-level directory whose Kinds are searched for
@@ -121,6 +139,9 @@ vim = false
 - `[keys].vim`: when `true`, the Picker opens with the list focused and
   uses the vim key map described above. Defaults to `false`, the default
   key map.
+- `[picker].layout`: which Layout the Picker draws, `"grouped"` (the
+  default) or `"list"`, as described above. Any other value is a config
+  error.
 
 History is stored at `$XDG_DATA_HOME/cdd/history`, falling back to
 `~/.local/share/cdd/history` when `XDG_DATA_HOME` is unset.

internal/config/config.go

@@ -1,13 +1,14 @@
 // Package config loads cdd's configuration: the Root to search for Kinds
 // and Projects, Exclude globs, hidden-directory handling, and the History
-// and Picker key settings.
+// and Picker settings.
 package config
 
 import (
 	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
+	"slices"
 	"strings"
 
 	toml "github.com/pelletier/go-toml/v2"
@@ -33,6 +34,9 @@ type Config struct {
 
 	// Keys configures the Picker's key map.
 	Keys Keys `toml:"keys"`
+
+	// Picker configures the Picker's appearance.
+	Picker Picker `toml:"picker"`
 }
 
 // History configures cdd's History of Visits.
@@ -50,6 +54,20 @@ type Keys struct {
 	Vim bool `toml:"vim"`
 }
 
+// Picker configures the Picker's appearance.
+type Picker struct {
+	// Layout selects which layout the Picker draws: "grouped" (the
+	// default) groups rows under Kind headers with a caret on the
+	// selected row; "list" is a flat fzf-style list with the filter
+	// prompt below it and a background-highlighted selected row. Both
+	// draw the same preview pane.
+	Layout string `toml:"layout"`
+}
+
+// pickerLayouts are the values Picker.Layout accepts, in the order the
+// error message lists them.
+var pickerLayouts = []string{"grouped", "list"}
+
 // defaultConfig returns a Config with every default applied, before a
 // config.toml's fields are decoded on top of it.
 func defaultConfig() Config {
@@ -58,6 +76,7 @@ func defaultConfig() Config {
 		IncludeHidden: false,
 		History:       History{MaxVisits: 1000},
 		Keys:          Keys{Vim: false},
+		Picker:        Picker{Layout: "grouped"},
 	}
 }
 
@@ -70,6 +89,8 @@ include_hidden = false
 max_visits = 1000         # must be >= 1
 [keys]
 vim = false
+[picker]
+layout = "grouped"        # or "list" for the flat fzf-style layout
 `
 
 // ExampleConfig returns an example config.toml, for the cli package to print
@@ -143,7 +164,8 @@ func describeDecodeError(err error) error {
 
 // validate checks the decoded Config against the rules Load and LoadFrom
 // enforce: Root is required, expanded, and must be an existing directory;
-// History.MaxVisits must be at least 1.
+// History.MaxVisits must be at least 1; Picker.Layout must name a known
+// layout.
 func (c *Config) validate(path string) error {
 	if c.Root == "" {
 		return fmt.Errorf("config: %s: root is required\n\nExample config.toml:\n\n%s", path, exampleConfigBody)
@@ -170,6 +192,10 @@ func (c *Config) validate(path string) error {
 		return fmt.Errorf("config: %s: history.max_visits must be >= 1, got %d", path, c.History.MaxVisits)
 	}
 
+	if !slices.Contains(pickerLayouts, c.Picker.Layout) {
+		return fmt.Errorf("config: %s: picker.layout must be %s, got %q", path, strings.Join(pickerLayouts, " or "), c.Picker.Layout)
+	}
+
 	return nil
 }
 

internal/config/config_test.go

@@ -60,6 +60,9 @@ func TestLoadFromMinimalAppliesDefaults(t *testing.T) {
 	if cfg.Keys.Vim {
 		t.Errorf("Keys.Vim = true, want false")
 	}
+	if cfg.Picker.Layout != "grouped" {
+		t.Errorf("Picker.Layout = %q, want %q", cfg.Picker.Layout, "grouped")
+	}
 }
 
 func TestLoadFromEachKey(t *testing.T) {
@@ -71,6 +74,8 @@ include_hidden = true
 max_visits = 42
 [keys]
 vim = true
+[picker]
+layout = "list"
 `
 	path := writeConfig(t, body)
 
@@ -100,6 +105,9 @@ vim = true
 	if !cfg.Keys.Vim {
 		t.Errorf("Keys.Vim = false, want true")
 	}
+	if cfg.Picker.Layout != "list" {
+		t.Errorf("Picker.Layout = %q, want %q", cfg.Picker.Layout, "list")
+	}
 }
 
 func TestLoadFromTildeExpansion(t *testing.T) {
@@ -154,6 +162,25 @@ max_visits = 0
 	}
 }
 
+func TestLoadFromUnknownPickerLayoutRejected(t *testing.T) {
+	root := t.TempDir()
+	body := `root = "` + root + `"
+[picker]
+layout = "fancy"
+`
+	path := writeConfig(t, body)
+
+	_, err := config.LoadFrom(path)
+	if err == nil {
+		t.Fatal(`LoadFrom layout = "fancy": got nil error, want error`)
+	}
+	for _, want := range []string{"picker.layout", "fancy", "grouped", "list"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Errorf("error = %q, want it to contain %q", err.Error(), want)
+		}
+	}
+}
+
 func TestLoadFromRootNotDirectoryRejected(t *testing.T) {
 	file, err := os.CreateTemp(t.TempDir(), "root-*")
 	if err != nil {
@@ -192,7 +219,7 @@ func TestLoadFromRootMissing(t *testing.T) {
 
 func TestExampleConfig(t *testing.T) {
 	got := config.ExampleConfig()
-	for _, want := range []string{"root =", "exclude =", "include_hidden =", "[history]", "max_visits =", "[keys]", "vim ="} {
+	for _, want := range []string{"root =", "exclude =", "include_hidden =", "[history]", "max_visits =", "[keys]", "vim =", "[picker]", "layout ="} {
 		if !strings.Contains(got, want) {
 			t.Errorf("ExampleConfig() = %q, want it to contain %q", got, want)
 		}

internal/jump/jump.go

@@ -76,7 +76,7 @@ func choose(cfg config.Config, projects []project.Project, latest []history.Visi
 		return s
 	}
 
-	row, ok, err := pick(rows, status, picker.Options{Vim: cfg.Keys.Vim, Query: query})
+	row, ok, err := pick(rows, status, picker.Options{Vim: cfg.Keys.Vim, Query: query, Layout: picker.LayoutStyle(cfg.Picker.Layout)})
 	if err != nil {
 		return "", "", fmt.Errorf("jump: %w", err)
 	}

internal/jump/resolve_test.go

@@ -118,6 +118,34 @@ func TestResolve_AmbiguousNameOpensPickerPrefilled(t *testing.T) {
 	assertRecorded(t, hist, "tools/cdd")
 }
 
+// TestResolve_ForwardsPickerOptions verifies that the config keys that
+// configure the Picker reach it: the vim key map and the layout.
+func TestResolve_ForwardsPickerOptions(t *testing.T) {
+	cfg, root := mkProjects(t, "tools/cdd")
+	cfg.Keys.Vim = true
+	cfg.Picker.Layout = "list"
+	hist := newHistory(t)
+
+	var got picker.Options
+	pick := func(rows []picker.Row, status picker.StatusFunc, opts picker.Options) (picker.Row, bool, error) {
+		got = opts
+		return picker.Row{Project: picker.Project{
+			Kind: "tools", Name: "cdd", Path: filepath.Join(root, "tools", "cdd"),
+		}}, true, nil
+	}
+
+	if _, err := jump.Resolve(context.Background(), cfg, hist, "", pick); err != nil {
+		t.Fatalf("Resolve: unexpected error: %v", err)
+	}
+
+	if !got.Vim {
+		t.Errorf("Options.Vim = false, want true")
+	}
+	if got.Layout != picker.LayoutList {
+		t.Errorf("Options.Layout = %q, want %q", got.Layout, picker.LayoutList)
+	}
+}
+
 func TestResolve_NoMatchOpensPickerPrefilled(t *testing.T) {
 	cfg, root := mkProjects(t, "tools/cdd")
 	hist := newHistory(t)

internal/picker/layout.go

@@ -1,6 +1,9 @@
 package picker
 
-import "time"
+import (
+	"strings"
+	"time"
+)
 
 // nameFloor is the smallest a truncated Project name is ever shrunk to.
 const nameFloor = 8
@@ -103,6 +106,62 @@ func ComputeLayout(longestName, widestStatus int, times []time.Time, now time.Ti
 	return l
 }
 
+// frameSize is the terminal size to draw at, standing in a default for
+// each dimension until the first tea.WindowSizeMsg lands.
+func (m Model) frameSize() (width, height int) {
+	width, height = m.width, m.height
+	if width <= 0 {
+		width = 80
+	}
+	if height <= 0 {
+		height = 24
+	}
+	return width, height
+}
+
+// computeLayout sizes one frame from the rows it has to show. The name
+// column holds the Project name in the grouped layout and "kind/name" in
+// the list layout; the two layouts spend the same total width on their
+// other columns, so one budget serves both.
+func (m Model) computeLayout(rows []match, now time.Time, width, height int) Layout {
+	longestName, widestStatus := 0, 1
+	times := make([]time.Time, 0, len(rows))
+	for _, mt := range rows {
+		n := len([]rune(mt.row.Project.Name))
+		if m.layout == LayoutList {
+			n += len([]rune(mt.row.Project.Kind)) + 1 // "kind/"
+		}
+		if n > longestName {
+			longestName = n
+		}
+		st, loaded := m.statuses[mt.row.Project.Path]
+		if w := statusClusterWidth(st, loaded); w > widestStatus {
+			widestStatus = w
+		}
+		times = append(times, mt.row.LastVisit)
+	}
+	return ComputeLayout(longestName, widestStatus, times, now, width, height)
+}
+
+// window clips lines to exactly height lines, scrolled just far enough to
+// keep cursorLine on screen and padded with blanks when lines run short.
+// Both layouts draw their body through it, so the frame always comes out
+// at the terminal height.
+func window(lines []string, cursorLine, height int) string {
+	height = max(height, 1)
+	start := 0
+	if cursorLine >= height {
+		start = cursorLine - height + 1
+	}
+	out := make([]string, height)
+	for i := range out {
+		if idx := start + i; idx < len(lines) {
+			out[i] = lines[idx]
+		}
+	}
+	return strings.Join(out, "\n")
+}
+
 // widestTime is the widest rendered relative time among times, using the
 // short form when short is true.
 func widestTime(times []time.Time, now time.Time, short bool) int {

internal/picker/model.go

@@ -32,6 +32,7 @@ type Model struct {
 	rows   []Row
 	status StatusFunc
 	vim    bool
+	layout LayoutStyle
 
 	query  string
 	focus  focus
@@ -55,10 +56,15 @@ func NewModel(rows []Row, status StatusFunc, opts Options) Model {
 	if opts.Vim {
 		f = focusList
 	}
+	layout := opts.Layout
+	if layout == "" {
+		layout = LayoutGrouped
+	}
 	return Model{
 		rows:     rows,
 		status:   status,
 		vim:      opts.Vim,
+		layout:   layout,
 		query:    opts.Query,
 		focus:    f,
 		statuses: make(map[string]git.Status, len(rows)),
@@ -167,6 +173,17 @@ func (m Model) visibleGroups() []kindGroup {
 	return groupByKind(m.visibleMatches())
 }
 
+// visibleRows returns the current query's matches in the order the active
+// layout draws them: grouped by Kind for LayoutGrouped, flat History order
+// for LayoutList. It is the order the cursor indexes into.
+func (m Model) visibleRows() []match {
+	matches := m.visibleMatches()
+	if m.layout == LayoutList {
+		return matches
+	}
+	return flatten(groupByKind(matches))
+}
+
 // flatten lays a Kind grouping out as a single ordered slice of matches,
 // matching the row order the list draws (header lines aside).
 func flatten(groups []kindGroup) []match {

internal/picker/picker.go

@@ -43,6 +43,22 @@ type Row struct {
 // without blocking the screen.
 type StatusFunc func(ctx context.Context, dir string) git.Status
 
+// LayoutStyle names one of the Picker's two layouts. It is a standing
+// preference, set once in config.toml, not a per-session toggle.
+type LayoutStyle string
+
+const (
+	// LayoutGrouped is the default layout: rows grouped under Kind
+	// headers, a caret on the selected row, and the filter line on top.
+	LayoutGrouped LayoutStyle = "grouped"
+
+	// LayoutList is the flat fzf-style layout: no Kind headers, rows in
+	// History order with "kind/" muted before each Project name, the
+	// filter prompt below the list, and a bar plus background highlight
+	// on the selected row.
+	LayoutList LayoutStyle = "list"
+)
+
 // Options configures a Run of the Picker.
 type Options struct {
 	// Vim selects the vim key map: the list is focused on open, j/k move,
@@ -55,6 +71,10 @@ type Options struct {
 
 	// Query seeds the filter line.
 	Query string
+
+	// Layout selects which layout is drawn. The zero value is
+	// LayoutGrouped.
+	Layout LayoutStyle
 }
 
 // concurrency bounds how many StatusFunc calls run at once, so a large