feat: week numbers in schedule and week-wide assignment

Schedule table now shows ISO week number (W21) on the first
row of each week visible in the 14-day window (first row and
every Monday); other rows get a 4-space indent. Date column
widened from 16→18 to accommodate the prefix.

New W key in Schedule section opens the user picker in
week-assign mode, which assigns the selected user to all 7
days (Mon–Sun) of the ISO week containing the cursor. The +
key retains single-day assignment. The user picker header and
footer reflect which mode is active.

internal/tui/model.go

@@ -147,6 +147,7 @@ type Model struct {
 	users            []api.User
 	usersLoading     bool
 	userPickerTable  table.Model
+	pickerAssignWeek bool
 
 	// User management section
 	userManageTable   table.Model
@@ -328,7 +329,7 @@ func alertColumns(width int) []table.Column {
 }
 
 func scheduleColumns(width int) []table.Column {
-	dateW := 16
+	dateW := 18
 	onCallW := width - dateW - 6
 	if onCallW < 15 {
 		onCallW = 15
@@ -381,9 +382,15 @@ func scheduleRows(days []scheduleDay) []table.Row {
 	rows := make([]table.Row, len(days))
 	for i, d := range days {
 		dateStr := d.date.Format("2006-01-02")
-		label := d.date.Format("Jan 02  Mon")
+		showWeek := i == 0 || d.date.Weekday() == time.Monday
+		_, week := d.date.ISOWeek()
+		weekPrefix := "    "
+		if showWeek {
+			weekPrefix = fmt.Sprintf("W%02d ", week)
+		}
+		label := weekPrefix + d.date.Format("Jan 02 Mon")
 		if dateStr == today {
-			label = "Today   " + d.date.Format("Mon")
+			label = weekPrefix + "Today " + d.date.Format("Mon")
 		}
 		onCall := "—"
 		if d.entry != nil {
@@ -583,9 +590,9 @@ func fetchScheduleCmd(client *api.Client, from, to time.Time) tea.Cmd {
 	}
 }
 
-func assignScheduleCmd(client *api.Client, userID int64, date string, from, to time.Time) tea.Cmd {
+func assignScheduleCmd(client *api.Client, userID int64, dates []string, from, to time.Time) tea.Cmd {
 	return func() tea.Msg {
-		if _, err := client.AssignSchedule(userID, []string{date}); err != nil {
+		if _, err := client.AssignSchedule(userID, dates); err != nil {
 			return scheduleActionErrMsg{err}
 		}
 		entries, err := client.GetSchedule(from.Format("2006-01-02"), to.Format("2006-01-02"))

internal/tui/update.go

@@ -355,6 +355,20 @@ func (m Model) handleDashboardKey(msg tea.KeyMsg) (Model, tea.Cmd) {
 		if m.activeSection != sectionSchedule || !m.connected {
 			return m, nil
 		}
+		m.pickerAssignWeek = false
+		m.mode = modeScheduleUserPicker
+		if len(m.users) == 0 {
+			m.usersLoading = true
+			return m, fetchUsersCmd(m.client)
+		}
+		m.rebuildUserPickerTable()
+		return m, nil
+
+	case "W":
+		if m.activeSection != sectionSchedule || !m.connected {
+			return m, nil
+		}
+		m.pickerAssignWeek = true
 		m.mode = modeScheduleUserPicker
 		if len(m.users) == 0 {
 			m.usersLoading = true
@@ -596,12 +610,25 @@ func (m Model) handleUserPickerKey(msg tea.KeyMsg) (Model, tea.Cmd) {
 			m.mode = modeDashboard
 			return m, nil
 		}
-		date := m.scheduleDays[scheduleCursor].date.Format("2006-01-02")
+		d := m.scheduleDays[scheduleCursor].date
+		var dates []string
+		if m.pickerAssignWeek {
+			weekday := int(d.Weekday())
+			if weekday == 0 {
+				weekday = 7 // ISO: Sunday = 7
+			}
+			monday := d.AddDate(0, 0, -(weekday - 1))
+			for i := 0; i < 7; i++ {
+				dates = append(dates, monday.AddDate(0, 0, i).Format("2006-01-02"))
+			}
+		} else {
+			dates = []string{d.Format("2006-01-02")}
+		}
 		from := m.scheduleWindow
 		to := m.scheduleWindow.AddDate(0, 0, 13)
 		m.mode = modeDashboard
 		m.scheduleLoading = true
-		return m, assignScheduleCmd(m.client, user.ID, date, from, to)
+		return m, assignScheduleCmd(m.client, user.ID, dates, from, to)
 	}
 
 	return m, nil

internal/tui/view.go

@@ -128,7 +128,11 @@ func (m Model) renderFooter() string {
 		return "\n" + styleFooter.Render("  esc·back")
 
 	case modeScheduleUserPicker:
-		return "\n" + styleFooter.Render("  j/k·navigate  enter·select  esc·cancel")
+		mode := "day"
+		if m.pickerAssignWeek {
+			mode = "week"
+		}
+		return "\n" + styleFooter.Render(fmt.Sprintf("  j/k·navigate  enter·assign %s  esc·cancel", mode))
 
 	case modeUserCreate:
 		if m.statusMsg != "" {
@@ -160,7 +164,7 @@ func (m Model) renderFooter() string {
 
 	default:
 		if m.activeSection == sectionSchedule {
-			actions := styleFooter.Render("  +·assign  d·del  ←/→·shift week  tab·section  r·refresh  q·quit")
+			actions := styleFooter.Render("  +·assign day  W·assign week  d·del  ←/→·shift week  tab·section  r·refresh  q·quit")
 			if m.statusMsg != "" {
 				return styleStatus.Render("  "+m.statusMsg) + "\n" + actions
 			}
@@ -235,19 +239,31 @@ func (m Model) renderUserPicker() string {
 		return "\n" + styleMuted.Render("  Loading users…")
 	}
 
-	selectedDate := ""
+	var scope string
 	cursor := m.scheduleTable.Cursor()
 	if cursor < len(m.scheduleDays) {
-		d := m.scheduleDays[cursor]
+		d := m.scheduleDays[cursor].date
-		if d.date.Format("2006-01-02") == time.Now().UTC().Format("2006-01-02") {
+		if m.pickerAssignWeek {
-			selectedDate = "Today (" + d.date.Format("Mon") + ")"
+			weekday := int(d.Weekday())
+			if weekday == 0 {
+				weekday = 7
+			}
+			monday := d.AddDate(0, 0, -(weekday - 1))
+			sunday := monday.AddDate(0, 0, 6)
+			_, week := d.ISOWeek()
+			scope = fmt.Sprintf("week W%02d (%s–%s)",
+				week, monday.Format("Jan 02"), sunday.Format("Jan 02"))
 		} else {
-			selectedDate = d.date.Format("Jan 02 (Mon)")
+			if d.Format("2006-01-02") == time.Now().UTC().Format("2006-01-02") {
+				scope = "Today (" + d.Format("Mon") + ")"
+			} else {
+				scope = d.Format("Jan 02 (Mon)")
+			}
 		}
 	}
 
 	header := fmt.Sprintf("\n  Assign on-call for %s — select a user:\n\n",
-		styleBold.Render(selectedDate))
+		styleBold.Render(scope))
 	return header + m.userPickerTable.View()
 }