[Bug] Ctrl+G external editor prefill omits assistant text from multi-message turns and truncates to 50 lines

Bug Description
Title: [BUG] Ctrl+G "Show last response in external editor" omits text from the response Version: 2.1.296, Linux, nvim. The "Show last response in external editor" setting is on. Problem. When I press Ctrl+G, the editor shows only part of Claude's response. There are two causes: 1. The prefill uses only the last assistant message. If a background task (a subagent <task-notification>) completes during the turn, Claude replies in two or more messages, and the prefill shows only the last one. 2. The prefill keeps only the last 50 lines of that message. It replaces earlier lines with … (earlier output truncated). Example. After my prompt, Claude wrote 44 lines. Then a subagent reported, and Claude wrote 51 more lines. The editor showed 50 of the 95 lines. Some of the missing lines were questions that I had to answer. Why it matters. I use this setting to answer reviews and "grill" sessions that have five or more numbered questions. I write each answer below its question. When text is missing, I must scroll the terminal to find it, and the setting exists to prevent that. Expected. - Show all assistant text since my last prompt. - Remove the 50-line limit, or make it a setting. Related: #93505.

Environment Info

• Platform: linux
• Terminal: wsl-Ubuntu-24.04
• Version: 2.1.296
• Feedback ID: a36d31ee-221e-4991-bdee-e169220bbfa8