[BUG] Large paste silently truncated from beginning in prompt input (v2.1.112)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Platform: Windows 11
Claude Code version: 2.1.112
Terminal: Windows Terminal

What's wrong:
When pasting a large multi-line block (~150+ lines) into the Claude Code prompt input, only the tail end of the pasted content is captured. The beginning of the paste is silently dropped with no warning or indication that content was cut off. The prompt input shows content starting partway through the pasted block rather than from the top.

What Should Happen?

Expected behavior:
Full paste content should be captured (either inline or collapsed to [Pasted text #N +M lines] chip as intended)
Actual behavior:
Paste is silently truncated from the beginning. No error, no indicator. Content from the top of the clipboard is missing.

Error Messages/Logs

Steps to Reproduce

Steps to reproduce:

Copy a multi-line text block of 150+ lines to clipboard
Open Claude Code and paste into the prompt input
Observe that only the last portion of the content appears — content from the beginning is missing

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.112

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Additional context:
Clipboard contents are confirmed intact (pasting into a text editor works correctly). Related to but distinct from #5017, #13328, #14771 which report end-truncation on older versions.