Integrated terminal does not preserve Shift+Enter for child TUI applications

When running a TUI application such as OpenCode inside Fresh's integrated terminal, Shift+Enter is forwarded as a regular Enter.

Fresh itself receives and identifies the key correctly. :debug-keys shows Shift+Enter, but an application running inside Fresh's terminal cannot distinguish it from Enter.

The same application running directly in the parent terminal receives Shift+Enter correctly.

Environment

• OS: Windows 11
• Shell/environment: WSL Ubuntu
• Fresh: 0.5.1
• Parent terminal: Windows Terminal Canary
• Application used for testing: OpenCode
• TERM: xterm-256color
• Windows Terminal Canary supports the Kitty keyboard protocol

Reproduction

1. Directly in Windows Terminal Canary

Run OpenCode directly from WSL.

Press:

Shift+Enter

OpenCode correctly detects it as Shift+Enter and performs the corresponding action.

Ctrl+J also works correctly.

2. Check input received by Fresh

Start Fresh from the same WSL terminal and run:

:debug-keys

Press:

Shift+Enter

Fresh correctly reports:

Shift+Enter

So the key appears to be received correctly by Fresh from Windows Terminal.

3. Run OpenCode inside Fresh's integrated terminal

Open a terminal inside Fresh and start OpenCode.

Press:

Shift+Enter

OpenCode behaves as if a regular Enter was pressed.

Ctrl+J, however, is forwarded correctly and works as expected.

Observed input path

Direct:

Windows Terminal Canary
    -> OpenCode
    -> Shift+Enter works

Through Fresh:

Windows Terminal Canary
    -> Fresh
    -> :debug-keys sees Shift+Enter correctly
    -> Fresh integrated terminal
    -> OpenCode sees regular Enter

This seems to indicate that the distinction is lost when Fresh forwards/encodes the key event to the PTY used by its integrated terminal.

Expected behavior

Applications running inside Fresh's integrated terminal should be able to distinguish Shift+Enter from Enter, particularly when the parent terminal supports an enhanced keyboard protocol such as Kitty/CSI-u.

Additional observations

I initially encountered some other keyboard issues involving Alt/AltGr and an international keyboard layout. Those turned out to be related to an older Windows Terminal Kitty implementation and are fixed in Windows Terminal Canary.

With Windows Terminal Canary:

• Alt and AltGr are distinguished correctly
• international keyboard combinations work correctly
• Fresh :debug-keys reports Shift+Enter correctly
• OpenCode directly under Windows Terminal receives Shift+Enter correctly

The remaining issue appears specifically when a child TUI application is running inside Fresh's integrated terminal.

I also tested Fresh's keyboard_report_alternate_keys setting, but changing it does not affect this behavior.