feat: crush-inspired TUI improvements, activity bar polish, startup fresh session

TUI improvements: - semantic icon constants (✓ ◆ ▣ ✕ ⌘ ◌ ◔ ◉) - pill-style metadata bar with model/provider/session/context - fuzzy command palette with deterministic subsequence scoring - input history navigation (ctrl+p / ctrl+n) - structured tool log cards (▣ tool_name + args preview) - no-background activity indicator and meta bar for cleaner rendering Startup behavior: - default startup creates a fresh session - explicit --resume <id> restores saved context - added main_test.go for initializeSession coverage
2026-06-24 18:16:53 -07:00
parent f235b8ce90
commit 7b8bad5e62
5 changed files with 549 additions and 79 deletions
@@ -6,7 +6,9 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"sort"
 	"strings"
+	"unicode"

 	"agentu/internal/agent"
 	"agentu/pkg/llm"
@@ -21,6 +23,8 @@ import (
 const (
 	minInputLines          = 1
 	maxInputLines          = 6
+	maxCommandPaletteItems = 8
+	maxInputHistory        = 100
 )

 type Options struct {
@@ -89,6 +93,10 @@ type model struct {
 	messages     []message
 	status       string
 	contextUsage string
+	inputHistory []string
+	historyIndex int
+	draftInput   string
+
 	running bool
 	cancel  context.CancelFunc
 	events  <-chan tea.Msg
@@ -120,6 +128,11 @@ type slashCommand struct {
 	Description string
 }

+type commandMatch struct {
+	command slashCommand
+	score   int
+}
+
 var slashCommands = []slashCommand{
 	{Name: "/clear", Description: "reset context"},
 	{Name: "/compact", Description: "compress context"},
@@ -174,6 +187,7 @@ func newModel(ctx context.Context, assistant *agent.Agent, opts Options) model {
 		input:        input,
 		spinner:      spin,
 		status:       "ready",
+		historyIndex: -1,
 	}
 	m.refreshContextUsage()
 	return m
@@ -249,6 +263,20 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 				return m, nil
 			}
 			return m.submit()
+		case "ctrl+p":
+			if m.running {
+				return m, nil
+			}
+			m.previousInputHistory()
+			m.afterInputChanged()
+			return m, nil
+		case "ctrl+n":
+			if m.running {
+				return m, nil
+			}
+			m.nextInputHistory()
+			m.afterInputChanged()
+			return m, nil
 		case "alt+enter", "ctrl+j":
 			return m.insertInputNewline()
 		}
@@ -297,6 +325,8 @@ func (m model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 		if !m.running {
 			nextInput, cmd := m.input.Update(msg)
 			m.input = nextInput
+			m.historyIndex = -1
+			m.draftInput = ""
 			m.afterInputChanged()
 			return m, cmd
 		}
@@ -343,6 +373,7 @@ func (m *model) submit() (tea.Model, tea.Cmd) {
 	if input == "" {
 		return *m, nil
 	}
+	m.rememberInput(input)

 	switch input {
 	case "/exit", "/quit":
@@ -402,6 +433,8 @@ func (m *model) insertInputNewline() (tea.Model, tea.Cmd) {
 	enter := tea.KeyMsg{Type: tea.KeyEnter}
 	nextInput, cmd := m.input.Update(enter)
 	m.input = nextInput
+	m.historyIndex = -1
+	m.draftInput = ""
 	m.afterInputChanged()
 	return *m, cmd
 }
@@ -472,6 +505,10 @@ func (m model) renderMessages() string {
 }

 func (m model) messageView(r role, content string, width int) string {
+	if r == roleTool {
+		return m.toolMessageView(content, width)
+	}
+
 	label := roleLabel(r)
 	style := m.styles.AssistantMsg
 	labelStyle := m.styles.SystemLabel
@@ -534,39 +571,112 @@ func roleLabel(r role) string {
 	}
 }

+type toolLogParts struct {
+	name string
+	args string
+}
+
+func parseToolLog(content string) toolLogParts {
+	content = strings.TrimSpace(content)
+	if content == "" {
+		return toolLogParts{}
+	}
+	idx := strings.IndexFunc(content, unicode.IsSpace)
+	if idx < 0 {
+		return toolLogParts{name: content}
+	}
+	return toolLogParts{
+		name: strings.TrimSpace(content[:idx]),
+		args: strings.TrimSpace(content[idx+1:]),
+	}
+}
+
+func (m model) toolMessageView(content string, width int) string {
+	parts := parseToolLog(content)
+	header := m.styles.ToolName.Render(strings.TrimSpace(iconTool + " " + parts.name))
+	lines := []string{header}
+	if parts.args != "" {
+		args := fitLine(parts.args, max(1, width-4))
+		lines = append(lines, m.styles.ToolValue.Render(args))
+	}
+	bodyContent := strings.Join(lines, "\n")
+	bodyWidth := messageBodyWidth(bodyContent, width, m.styles.ToolMessage)
+	return m.styles.ToolMessage.Width(bodyWidth).Render(bodyContent)
+}
+
+type metaPill struct {
+	text   string
+	accent bool
+}
+
+func (m model) renderMetaPills(parts []metaPill) string {
+	if len(parts) == 0 {
+		return ""
+	}
+
+	plain := make([]string, len(parts))
+	for i, part := range parts {
+		plain[i] = part.text
+	}
+
+	width := max(1, m.width-2)
+	visible := len(plain)
+	for visible > 1 && lipgloss.Width(strings.Join(plain[:visible], " ")) > width {
+		visible--
+	}
+	if lipgloss.Width(strings.Join(plain[:visible], " ")) > width {
+		return m.styles.PillAccent.Render(fitLine(plain[0], width))
+	}
+
+	rendered := make([]string, 0, visible)
+	for i := 0; i < visible; i++ {
+		style := m.styles.Pill
+		if parts[i].accent {
+			style = m.styles.PillAccent
+		}
+		rendered = append(rendered, style.Render(parts[i].text))
+	}
+	return strings.Join(rendered, " ")
+}
+
 func (m model) modelMetaView() string {
 	mode := "read-only tools"
 	if m.yolo {
 		mode = "yolo tools"
 	}
+
 	modelName := m.modelName
-	parts := []string{}
 	if m.models != nil {
-		if sessionName := m.models.CurrentSessionName(); sessionName != "" {
-			parts = append(parts, "session "+sessionName)
+		if currentModel := m.models.CurrentModel(); currentModel != "" {
+			modelName = currentModel
 		}
+	}
+
+	parts := []metaPill{{text: iconModel + " " + modelName, accent: true}}
+	if m.models != nil {
 		if provider := m.models.CurrentProvider(); provider != "" {
-			parts = append(parts, "provider "+provider)
+			parts = append(parts, metaPill{text: "provider " + provider})
 		}
-		modelName = m.models.CurrentModel()
 		if currentThinking := m.models.CurrentThinking(); currentThinking != "" && currentThinking != "unset" {
-			parts = append(parts, "thinking "+currentThinking)
+			parts = append(parts, metaPill{text: "thinking " + currentThinking})
+		}
+		if sessionName := m.models.CurrentSessionName(); sessionName != "" {
+			parts = append(parts, metaPill{text: iconSession + " " + sessionName})
 		}
 	}
 	if m.contextUsage != "" {
-		parts = append(parts, m.contextUsage)
+		parts = append(parts, metaPill{text: iconContext + " " + m.contextUsage})
 	}
-	parts = append([]string{modelName, mode}, parts...)
-	parts = append(parts, "theme "+string(m.theme.Mode))
-	line := fitLine(strings.Join(parts, " · "), max(1, m.width-2))
-	return m.styles.ModelMeta.Width(max(1, m.width)).Render(line)
+	parts = append(parts, metaPill{text: mode}, metaPill{text: "theme " + string(m.theme.Mode)})
+
+	return m.styles.ModelMeta.Width(max(1, m.width)).Render(m.renderMetaPills(parts))
 }

 func (m model) inputView() string {
-	suggestions := m.slashSuggestionsView()
+	palette := m.commandPaletteView()
 	box := m.styles.InputBox.Width(max(20, m.width-2)).Render(m.input.View())
-	if suggestions != "" {
-		return lipgloss.JoinVertical(lipgloss.Left, suggestions, box)
+	if palette != "" {
+		return lipgloss.JoinVertical(lipgloss.Left, palette, box)
 	}
 	return box
 }
@@ -579,12 +689,12 @@ func (m model) activityView() string {
 	if status == "" || status == "ready" {
 		status = "working..."
 	}
-	line := fitLine(fmt.Sprintf("%s Working · %s · esc cancels", m.spinner.View(), status), max(1, m.width-2))
-	return m.styles.Activity.Width(max(1, m.width)).Render(line)
+	line := m.styles.StatusInfo.Render(iconWorking) + " Working " + m.spinner.View() + " " + status + " · esc cancels"
+	return m.styles.Activity.Render(fitLine(line, max(1, m.width-2)))
 }

 func (m model) footerView() string {
-	hint := "enter send · ctrl+j newline · alt+enter newline · / commands"
+	hint := "enter send · ctrl+j newline · alt+enter newline · ctrl+p/ctrl+n history · / commands"
 	if m.running {
 		hint = "esc cancel · ctrl+c quit"
 	}
@@ -639,6 +749,51 @@ func (m *model) afterInputChanged() {
 	}
 }

+func (m *model) rememberInput(input string) {
+	input = strings.TrimSpace(input)
+	if input == "" {
+		return
+	}
+	if len(m.inputHistory) > 0 && m.inputHistory[len(m.inputHistory)-1] == input {
+		m.historyIndex = -1
+		m.draftInput = ""
+		return
+	}
+	m.inputHistory = append(m.inputHistory, input)
+	if len(m.inputHistory) > maxInputHistory {
+		m.inputHistory = m.inputHistory[len(m.inputHistory)-maxInputHistory:]
+	}
+	m.historyIndex = -1
+	m.draftInput = ""
+}
+
+func (m *model) previousInputHistory() {
+	if len(m.inputHistory) == 0 {
+		return
+	}
+	if m.historyIndex == -1 {
+		m.draftInput = m.input.Value()
+		m.historyIndex = len(m.inputHistory) - 1
+	} else if m.historyIndex > 0 {
+		m.historyIndex--
+	}
+	m.input.SetValue(m.inputHistory[m.historyIndex])
+}
+
+func (m *model) nextInputHistory() {
+	if len(m.inputHistory) == 0 || m.historyIndex == -1 {
+		return
+	}
+	if m.historyIndex < len(m.inputHistory)-1 {
+		m.historyIndex++
+		m.input.SetValue(m.inputHistory[m.historyIndex])
+		return
+	}
+	m.input.SetValue(m.draftInput)
+	m.historyIndex = -1
+	m.draftInput = ""
+}
+
 func (m *model) syncInputHeight() {
 	m.input.SetHeight(m.desiredInputHeight())
 }
@@ -661,47 +816,132 @@ func (m model) desiredInputHeight() int {

 func (m model) inputBlockHeight() int {
 	height := m.input.Height() + m.styles.InputBox.GetVerticalFrameSize()
-	if m.showSlashSuggestions() {
-		height += m.slashSuggestionCount()
+	if m.showCommandPalette() {
+		height += m.commandPaletteHeight()
 	}
 	return height
 }

-func (m model) slashSuggestionCount() int {
-	prefix := strings.TrimSpace(m.input.Value())
-	count := 0
-	for _, command := range slashCommands {
-		if strings.HasPrefix(command.Name, prefix) {
-			count++
-		}
+func (m model) commandPaletteHeight() int {
+	matches := commandMatches(commandPaletteQuery(m.input.Value()))
+	count := len(matches)
+	if count > maxCommandPaletteItems {
+		count = maxCommandPaletteItems
 	}
 	if count == 0 {
-		count = 1 // "No matching commands"
+		count = 1
 	}
-	return count
+	return 1 + count + m.styles.Palette.GetVerticalFrameSize()
 }

-func (m model) showSlashSuggestions() bool {
+func (m model) showCommandPalette() bool {
 	value := strings.TrimSpace(m.input.Value())
 	return strings.HasPrefix(value, "/") && !strings.Contains(value, " ")
 }

-func (m model) slashSuggestionsView() string {
-	if !m.showSlashSuggestions() {
+func (m model) commandPaletteView() string {
+	if !m.showCommandPalette() {
 		return ""
 	}
-	prefix := strings.TrimSpace(m.input.Value())
-	var parts []string
+	matches := commandMatches(commandPaletteQuery(m.input.Value()))
+	lines := []string{m.styles.Header.Render(iconCommand + " Commands")}
+	if len(matches) == 0 {
+		lines = append(lines, m.styles.Muted.Render("No matching commands"))
+	} else {
+		for i, match := range matches {
+			if i >= maxCommandPaletteItems {
+				break
+			}
+			lines = append(lines, fmt.Sprintf("%s %s", m.styles.PaletteMatch.Render(match.command.Name), m.styles.Muted.Render(match.command.Description)))
+		}
+	}
+	return m.styles.Palette.Width(max(20, m.width-2)).Render(strings.Join(lines, "\n"))
+}
+
+func commandPaletteQuery(value string) string {
+	value = strings.TrimSpace(value)
+	if !strings.HasPrefix(value, "/") {
+		return ""
+	}
+	return strings.TrimPrefix(value, "/")
+}
+
+func commandMatches(query string) []commandMatch {
+	matches := make([]commandMatch, 0, len(slashCommands))
 	for _, command := range slashCommands {
-		if !strings.HasPrefix(command.Name, prefix) {
+		score, ok := scoreCommand(command, query)
+		if !ok {
 			continue
 		}
-		parts = append(parts, fmt.Sprintf("%s %s", command.Name, command.Description))
+		matches = append(matches, commandMatch{command: command, score: score})
 	}
-	if len(parts) == 0 {
-		parts = append(parts, "No matching commands")
+	sort.Slice(matches, func(i, j int) bool {
+		if matches[i].score != matches[j].score {
+			return matches[i].score < matches[j].score
 		}
-	return m.styles.CommandHint.Width(max(20, m.width-2)).Render(strings.Join(parts, "\n"))
+		return matches[i].command.Name < matches[j].command.Name
+	})
+	return matches
+}
+
+func scoreCommand(command slashCommand, query string) (int, bool) {
+	query = strings.ToLower(strings.TrimSpace(query))
+	name := strings.TrimPrefix(strings.ToLower(command.Name), "/")
+	if query == "" || query == name {
+		return 0, true
+	}
+	if strings.HasPrefix(name, query) {
+		return 100 + len(name) - len(query), true
+	}
+	if score, ok := subsequenceScore(name, query, 200); ok {
+		return score, true
+	}
+	candidate := name + " " + strings.ToLower(command.Description)
+	if score, ok := subsequenceScore(candidate, query, 300); ok {
+		return score, true
+	}
+	return 0, false
+}
+
+func subsequenceScore(candidate string, query string, base int) (int, bool) {
+	candidate = strings.ToLower(candidate)
+	query = strings.ToLower(query)
+	if query == "" {
+		return base, true
+	}
+	start := 0
+	last := -1
+	gaps := 0
+	for _, r := range query {
+		found := -1
+		for i, c := range candidate[start:] {
+			if c == r {
+				found = start + i
+				break
+			}
+		}
+		if found < 0 {
+			return 0, false
+		}
+		if last >= 0 {
+			gaps += found - last - 1
+		}
+		last = found
+		start = found + len(string(r))
+	}
+	return base + gaps, true
+}
+
+func (m model) slashSuggestionCount() int {
+	return m.commandPaletteHeight()
+}
+
+func (m model) showSlashSuggestions() bool {
+	return m.showCommandPalette()
+}
+
+func (m model) slashSuggestionsView() string {
+	return m.commandPaletteView()
 }

 func (m model) modelInfo() string {
@@ -21,7 +21,7 @@ func TestModelRendersChatShell(t *testing.T) {
 	m = next.(model)
 	rendered := m.View()

-	for _, want := range []string{"test-model", "yolo tools", "light", "ctrl+j", "alt+enter"} {
+	for _, want := range []string{"test-model", "yolo tools", "light", "ctrl+j", "alt+enter", "ctrl+p/ctrl+n history"} {
 		if !strings.Contains(rendered, want) {
 			t.Fatalf("rendered view missing %q:\n%s", want, rendered)
 		}
@@ -123,11 +123,14 @@ func TestRunningStateRendersActivityIndicator(t *testing.T) {
 	m.resize()

 	rendered := m.View()
-	for _, want := range []string{"Working", "thinking...", "esc cancels"} {
+	for _, want := range []string{iconWorking, "Working", "thinking...", "esc cancels"} {
 		if !strings.Contains(rendered, want) {
 			t.Fatalf("running view missing %q:\n%s", want, rendered)
 		}
 	}
+	if backgroundPattern.MatchString(m.activityView()) {
+		t.Fatalf("activity view should not paint a background:\n%q", m.activityView())
+	}
 }

 func TestUserMessageRendersFullWidthBubble(t *testing.T) {
@@ -276,17 +279,71 @@ func TestInputStartsAtOneLineAndGrows(t *testing.T) {
 	}
 }

-func TestSlashCommandSuggestions(t *testing.T) {
+func TestCommandPaletteFuzzyMatches(t *testing.T) {
 	m := newModel(context.Background(), nil, Options{ModelName: "test-model", Yolo: true})
 	next, _ := m.Update(tea.WindowSizeMsg{Width: 100, Height: 30})
 	m = next.(model)
-	m.input.SetValue("/")
+	m.input.SetValue("/mdl")
 	m.afterInputChanged()

-	rendered := m.View()
-	for _, want := range []string{"/clear reset context", "/compact compress context", "/exit quit", "/model model/provider/thinking"} {
-		if !strings.Contains(rendered, want) {
-			t.Fatalf("rendered suggestions missing %q:\n%s", want, rendered)
+	plain := stripANSI(m.View())
+	for _, want := range []string{iconCommand + " Commands", "/model model/provider/thinking"} {
+		if !strings.Contains(plain, want) {
+			t.Fatalf("rendered palette missing %q:\n%s", want, plain)
+		}
+	}
+
+	matches := commandMatches("m")
+	modelIndex := -1
+	renameIndex := -1
+	for i, match := range matches {
+		switch match.command.Name {
+		case "/model":
+			modelIndex = i
+		case "/rename":
+			renameIndex = i
+		}
+	}
+	if modelIndex < 0 || renameIndex < 0 || modelIndex > renameIndex {
+		t.Fatalf("/model should sort before /rename for /m query: %#v", matches)
+	}
+}
+
+func TestInputHistoryNavigation(t *testing.T) {
+	m := newModel(context.Background(), nil, Options{ModelName: "test-model"})
+	m.rememberInput("first")
+	m.rememberInput("second")
+
+	next, _ := m.Update(tea.KeyMsg{Type: tea.KeyCtrlP})
+	m = next.(model)
+	if got := m.input.Value(); got != "second" {
+		t.Fatalf("after ctrl+p input = %q", got)
+	}
+	next, _ = m.Update(tea.KeyMsg{Type: tea.KeyCtrlP})
+	m = next.(model)
+	if got := m.input.Value(); got != "first" {
+		t.Fatalf("after second ctrl+p input = %q", got)
+	}
+	next, _ = m.Update(tea.KeyMsg{Type: tea.KeyCtrlN})
+	m = next.(model)
+	if got := m.input.Value(); got != "second" {
+		t.Fatalf("after ctrl+n input = %q", got)
+	}
+	next, _ = m.Update(tea.KeyMsg{Type: tea.KeyCtrlN})
+	m = next.(model)
+	if got := m.input.Value(); got != "" {
+		t.Fatalf("after second ctrl+n input = %q", got)
+	}
+}
+
+func TestToolMessageRendersStructuredCard(t *testing.T) {
+	m := newModel(context.Background(), nil, Options{ModelName: "test-model"})
+	m.messages = append(m.messages, message{role: roleTool, content: `file_read {"path":"README.md"}`})
+
+	plain := stripANSI(m.renderMessages())
+	for _, want := range []string{iconTool + " file_read", "README.md"} {
+		if !strings.Contains(plain, want) {
+			t.Fatalf("tool card missing %q:\n%s", want, plain)
 		}
 	}
 }
@@ -15,6 +15,17 @@ const (
 	ThemeDark  ThemeMode = "dark"
 )

+const (
+	iconReady   = "✓"
+	iconWorking = "◆"
+	iconTool    = "▣"
+	iconError   = "✕"
+	iconCommand = "⌘"
+	iconSession = "◌"
+	iconContext = "◔"
+	iconModel   = "◉"
+)
+
 func ParseThemeMode(value string) (ThemeMode, error) {
 	switch ThemeMode(strings.ToLower(strings.TrimSpace(value))) {
 	case "", ThemeLight:
@@ -48,11 +59,23 @@ type styles struct {
 	App           lipgloss.Style
 	Muted         lipgloss.Style
 	Activity      lipgloss.Style
+	Header        lipgloss.Style
 	ModelMeta     lipgloss.Style
 	Footer        lipgloss.Style
 	Viewport      lipgloss.Style
 	InputBox      lipgloss.Style
 	CommandHint   lipgloss.Style
+	StatusReady   lipgloss.Style
+	StatusWarn    lipgloss.Style
+	StatusError   lipgloss.Style
+	StatusInfo    lipgloss.Style
+	Pill          lipgloss.Style
+	PillAccent    lipgloss.Style
+	Palette       lipgloss.Style
+	PaletteMatch  lipgloss.Style
+	ToolName      lipgloss.Style
+	ToolKey       lipgloss.Style
+	ToolValue     lipgloss.Style
 	UserLabel     lipgloss.Style
 	ToolLabel     lipgloss.Style
 	ErrorLabel    lipgloss.Style
@@ -116,14 +139,15 @@ func (t theme) styles() styles {
 			Foreground(lipgloss.Color(t.Muted)),

 		Activity: lipgloss.NewStyle().
-			Bold(true).
-			Foreground(lipgloss.Color(t.Background)).
-			Background(lipgloss.Color(t.Title)).
+			Foreground(lipgloss.Color(t.Muted)).
 			Padding(0, 1),

+		Header: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(lipgloss.Color(t.Title)),
+
 		ModelMeta: lipgloss.NewStyle().
-			Foreground(lipgloss.Color(t.Text)).
-			Background(lipgloss.Color(t.SurfaceAlt)).
+			Foreground(lipgloss.Color(t.Muted)).
 			Padding(0, 1),

 		Footer: lipgloss.NewStyle().
@@ -141,9 +165,51 @@ func (t theme) styles() styles {

 		CommandHint: lipgloss.NewStyle().
 			Foreground(lipgloss.Color(t.Muted)).
+			Padding(0, 1),
+
+		StatusReady: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Assistant)),
+
+		StatusWarn: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Tool)),
+
+		StatusError: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Error)),
+
+		StatusInfo: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.User)),
+
+		Pill: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Text)).
 			Background(lipgloss.Color(t.SurfaceAlt)).
 			Padding(0, 1),

+		PillAccent: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(lipgloss.Color(t.Title)).
+			Background(lipgloss.Color(t.SurfaceAlt)).
+			Padding(0, 1),
+
+		Palette: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Text)).
+			Border(lipgloss.ThickBorder()).
+			BorderForeground(lipgloss.Color(t.Border)).
+			Padding(0, 2),
+
+		PaletteMatch: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(lipgloss.Color(t.User)),
+
+		ToolName: lipgloss.NewStyle().
+			Bold(true).
+			Foreground(lipgloss.Color(t.Tool)),
+
+		ToolKey: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Muted)),
+
+		ToolValue: lipgloss.NewStyle().
+			Foreground(lipgloss.Color(t.Text)),
+
 		UserLabel:   labelStyle(t.User),
 		ToolLabel:   labelStyle(t.Tool),
 		ErrorLabel:  labelStyle(t.Error),
@@ -13,11 +13,11 @@ import (
 	"strings"

 	"agentu/internal/agent"
-	"agentu/pkg/config"
-	"agentu/pkg/llm"
 	"agentu/internal/session"
 	"agentu/internal/tools"
 	"agentu/internal/tui"
+	"agentu/pkg/config"
+	"agentu/pkg/llm"
 )

 const defaultConfigContent = `# agentu configuration
@@ -112,15 +112,8 @@ func run() error {
 		return err
 	}

-	// Resume session
-	if *resumeID != "" {
-		if err := modelManager.Resume(*resumeID); err != nil {
-			return fmt.Errorf("resume session: %w", err)
-		}
-	} else {
-		if err := modelManager.ResumeLatest(); err != nil {
-			return fmt.Errorf("resume latest session: %w", err)
-		}
+	if err := initializeSession(modelManager, *resumeID); err != nil {
+		return err
 	}

 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt)
@@ -141,6 +134,19 @@ func run() error {
 	return repl(ctx, assistant, modelManager)
 }

+func initializeSession(modelManager *session.Manager, resumeID string) error {
+	if resumeID != "" {
+		if err := modelManager.Resume(resumeID); err != nil {
+			return fmt.Errorf("resume session: %w", err)
+		}
+		return nil
+	}
+	if _, err := modelManager.NewSession(); err != nil {
+		return fmt.Errorf("start new session: %w", err)
+	}
+	return nil
+}
+
 func bootstrapConfig(configPath string) error {
 	resolved, err := config.ResolvePath(configPath)
 	if err != nil {
@@ -0,0 +1,101 @@
+package main
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	"agentu/internal/agent"
+	"agentu/internal/session"
+	"agentu/pkg/config"
+	"agentu/pkg/llm"
+)
+
+type startupProvider struct{}
+
+func (p *startupProvider) ChatStream(ctx context.Context, req llm.ChatRequest, emit func(llm.StreamEvent) error) error {
+	return emit(llm.StreamEvent{Content: "ok"})
+}
+
+func startupTestManager(t *testing.T) (*session.Manager, *agent.Agent) {
+	t.Helper()
+	cfg := &config.Config{
+		Providers: map[string]config.ProviderConfig{
+			"one": {
+				Name:          "one",
+				BaseURL:       "https://one.example.com",
+				APIKey:        "sk-test",
+				Model:         "model-a",
+				Models:        []string{"model-a"},
+				Thinking:      "none",
+				ThinkingParam: "thinking",
+			},
+		},
+	}
+	assistant := agent.New(agent.Options{
+		Provider:     &startupProvider{},
+		ProviderName: "one",
+		Model:        "model-a",
+	})
+	store, err := session.NewStore(filepath.Join(t.TempDir(), "sessions"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	manager, err := session.NewManager(cfg, assistant, nil, store)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return manager, assistant
+}
+
+func TestInitializeSessionStartsNewByDefault(t *testing.T) {
+	manager, assistant := startupTestManager(t)
+	if _, err := manager.NewSession(); err != nil {
+		t.Fatalf("new session: %v", err)
+	}
+	savedID := manager.CurrentSessionID()
+	assistant.SetMessages([]llm.Message{{Role: llm.RoleUser, Content: "old context"}})
+	if err := manager.Save(); err != nil {
+		t.Fatalf("save: %v", err)
+	}
+
+	if err := initializeSession(manager, ""); err != nil {
+		t.Fatalf("initialize: %v", err)
+	}
+	if manager.CurrentSessionID() == savedID {
+		t.Fatalf("default startup resumed latest session %s", savedID)
+	}
+	for _, msg := range assistant.Messages() {
+		if msg.Content == "old context" {
+			t.Fatal("default startup carried old context into new session")
+		}
+	}
+}
+
+func TestInitializeSessionResumesExplicitID(t *testing.T) {
+	manager, assistant := startupTestManager(t)
+	if _, err := manager.NewSession(); err != nil {
+		t.Fatalf("new session: %v", err)
+	}
+	savedID := manager.CurrentSessionID()
+	assistant.SetMessages([]llm.Message{{Role: llm.RoleUser, Content: "old context"}})
+	if err := manager.Save(); err != nil {
+		t.Fatalf("save: %v", err)
+	}
+
+	if err := initializeSession(manager, savedID); err != nil {
+		t.Fatalf("initialize: %v", err)
+	}
+	if manager.CurrentSessionID() != savedID {
+		t.Fatalf("expected resumed session %s, got %s", savedID, manager.CurrentSessionID())
+	}
+	found := false
+	for _, msg := range assistant.Messages() {
+		if msg.Content == "old context" {
+			found = true
+		}
+	}
+	if !found {
+		t.Fatal("explicit resume did not restore saved context")
+	}
+}