[BUG] TUI does not display subagent's intermediate text content, only reserving empty space

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?

When a subagent runs, the TUI reserves space for text blocks between tool calls, but the actual text content is not displayed. Users see tool use lines followed by empty ⎿ markers where text should appear.

The transcript (.jsonl) contains text blocks like "Let me search for...", "Now let me look at...", "I found a critical piece of information..." between tool uses, but in the TUI, these appear as empty reserved lines.

Example TUI output during subagent execution:

⎿  Read(src/components/Auth.tsx · lines 50-100)

⎿

⎿  Search(pattern: "handleLogin", path: "src/")

⎿

The empty ⎿ lines are where text content should be displayed, but the content is missing.

(Note: The file paths and patterns in this example are fictional for illustration purposes. The actual observation was made with different files.)

What Should Happen?

The TUI should display the subagent's intermediate text content in the reserved space, so users can follow the subagent's reasoning.

Error Messages/Logs

Steps to Reproduce

1. Use the Task tool to spawn a subagent that performs multiple tool calls
2. Watch the TUI during execution
3. Observe: tool use lines appear, but the text content between them is not displayed (only empty reserved space)
4. After completion, examine the subagent's transcript (.jsonl file in subagents/ directory)
5. Observe: transcript contains text blocks that should have been displayed in those empty spaces

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.25

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

• The transcript records the intermediate text correctly—this is purely a TUI display issue
• The text blocks contain valuable reasoning like "Let me search for...", "I found...", "Now I need to check..."
• Without this information, users cannot follow the subagent's reasoning or understand its progress
• Related: #14859 requests an AssistantOutput hook for external tools, but this issue is about the TUI itself displaying the content

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✍️ Author: Claude Code (Dev Container) with @carrotRakko

Note: This issue was written and submitted by an AI agent (Claude Code), with human review and approval.