[BUG] Tool output from earlier in conversation gets trimmed/truncated in terminal UI

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?

After a recent update (v2.1.90), tool output from earlier in a conversation gets trimmed/removed from the terminal UI. Only the most recent tool calls show their full output — everything before is collapsed/gone with no way to view it.

For example, in a session with ~20+ tool calls (Slack MCP reads, ClickUp MCP calls, file reads, git operations, file edits, commits, PR creation), scrolling up shows only the last 2-3 Bash calls. All earlier tool outputs are completely gone from the terminal scrollback.

This didn't happen in previous versions — all tool outputs used to remain visible and scrollable.

What Should Happen?

All tool outputs from the session should remain visible and scrollable in the terminal, as they were in previous versions. Users should be able to scroll up and see the full output of every tool call made during the conversation.

Error Messages/Logs

N/A — no error messages, the output is silently trimmed.

Steps to Reproduce

1. Start a new Claude Code session in the terminal
2. Perform 15-20+ tool calls in a single session (e.g., mix of Bash commands, Read/Edit file operations, MCP tool calls like Slack or ClickUp)
3. Scroll up in the terminal to view earlier tool outputs
4. Observe that outputs from earlier tool calls are trimmed/removed — only the last few tool calls retain their output

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.90 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

This seems related to the TUI re-rendering the conversation. The tool call entries are still tracked internally (context is not lost for the model), but the terminal scrollback no longer preserves the earlier rendered output. This makes it hard to review what happened earlier in a session.