Part of the screen is not rendering when the view is exactly the size of the screen

[Art-S-D]

Describe the bug When the View method returns a string that has as many lines as the terminal, only the first lines of the screen will be redrawn. It seems to only happen when using a strings.Builder and goes away when there are more lines than the height of the terminal

Setup Please complete the following information along with version numbers, if applicable.

• OS macOs
• Shell zsh
• Terminal Emulator default macos terminal
• Terminal Multiplexer none

To Reproduce

Here is a minimal version of the code I use

package main

import (
    "os"
    "strings"

    tea "github.com/charmbracelet/bubbletea"
)

type model struct {
    screenWidth  int
    screenHeight int
    screenStart  int

    content []string
}

func (m *model) Init() tea.Cmd {
    return nil
}

// this one works
func (m *model) View2() string {
    out := m.content[m.screenStart : m.screenStart+m.screenHeight]
    return strings.Join(out, "\n")
}

// this one does not work
func (m *model) View() string {
    var sb strings.Builder

    // uncommenting this line fixes the bug
    // sb.WriteRune('\n')

    for i, line := range m.content {
        if i >= m.screenStart && i < m.screenStart+m.screenHeight {
            sb.WriteString(line)
            sb.WriteRune('\n')
        }
    }
    return sb.String()
}

func (m *model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
    switch msg := msg.(type) {
    case tea.KeyMsg:
        switch msg.String() {
        case "ctrl+c", "q":
            return m, tea.Quit
        case "up":
            m.screenStart -= 1
            if m.screenStart < 0 {
                m.screenStart = 0
            }
        case "down":
            m.screenStart += 1
            if m.screenStart > len(m.content)-m.screenHeight {
                m.screenStart = len(m.content) - m.screenHeight
            }
        }
    case tea.WindowSizeMsg:
        m.screenHeight = msg.Height
        m.screenWidth = msg.Width
    }
    return m, nil
}

func main() {
    bytes, err := os.ReadFile("lorem_ipsum.txt")
    if err != nil {
        panic(err.Error())
    }
    lorem := string(bytes)
    model := model{
        content: strings.Split(lorem, "\n"),
    }
    p := tea.NewProgram(
        &model,
        tea.WithAltScreen(),
    )
    if _, err := p.Run(); err != nil {
        panic(err.Error())
    }
}

Scrolling the screen down works perfectly but when scrolling up it only redraws the first line.

Source Code https://github.com/Art-S-D/test-bubbletea

Expected behavior The entire screen should render.

Screenshots

[Art-S-D]

I tried logging the result from sb.String() to a file and it looks correct

[Art-S-D]

After looking at it more, it looks like it's the last \n that breaks things

[meowgorithm]

Hi! This is a dup of https://github.com/charmbracelet/bubbletea/issues/304 (which we should re-examine). If you feel it's not a dupe please reopen this issue.