Shift+Enter inconsistently creates newline in Cursor terminal (varies per session)

Description

Shift+Enter behavior is inconsistent in Cursor's integrated terminal. In some sessions it correctly inserts a newline, in others it submits the input (same as Enter). This happens within the same folder and same keybindings.json configuration — the behavior varies per terminal session.

Environment

• Claude Code v2.1.78
• Cursor (latest)
• macOS (Darwin 24.6.0)
• terminal.integrated.defaultLocation: "editor"

Steps to Reproduce

1. Open a folder in Cursor
2. Open multiple Claude Code sessions (terminal tabs)
3. Press Shift+Enter in each session's input
4. Some sessions create a newline, others submit the input

Configuration

/terminal-setup installs the following keybinding (as expected):

{
    "key": "shift+enter",
    "command": "workbench.action.terminal.sendSequence",
    "args": {
        "text": "\^[\r"
    },
    "when": "terminalFocus"
}

This binding is confirmed to fire correctly (verified by testing in a bash terminal where it sends ESC+CR). However, Claude Code's key parser inconsistently interprets the \^[\r sequence — sometimes as meta+return (→ newline) and sometimes as separate ESC + return (→ submit).

Additional Context

• editor.accessibilitySupport: "on" was found to cause a separate issue (Tab key leaking into TUI during Cmd+Shift+Tab). Changing to "auto" fixed that, but did not fix the Shift+Enter inconsistency.
• The \ (backslash) + Enter workaround works consistently.
• Since behavior varies per session (not per folder or config), this appears to be a race condition or timing issue in the terminal input parser's handling of the ESC (\^[) prefix for meta key detection.

Expected Behavior

Shift+Enter should consistently insert a newline in all terminal sessions.

Actual Behavior

Shift+Enter inserts a newline in some sessions but submits input in others, with no apparent pattern.