[Bug] Selection deletion only removes single character in flicker-free mode

Bug Description
In flicker-free mode, selecting text with mouse and pressing Delete should delete the selection, but it only deletes one character at a time — expected editor-like behavior.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.96
• Feedback ID: 7a27349f-0c19-4cb5-94c4-957905489fcb

Errors

[{"error":"RangeError [ERR_CHILD_PROCESS_STDIO_MAXBUFFER]: stdout maxBuffer length exceeded\n    at Socket.onChildStdout (node:child_process:484:14)\n    at Socket.emit (node:events:508:28)\n    at addChunk (node:internal/streams/readable:559:12)\n    at readableAddChunkPushByteMode (node:internal/streams/readable:510:3)\n    at Readable.push (node:internal/streams/readable:390:5)\n    at Pipe.onStreamRead (node:internal/stream_base_commons:189:23)","timestamp":"2026-04-11T16:39:23.120Z"}]