[BUG] Subagent resume fails with tool_use_id mismatch error after Read tool calls

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?

The agent resume functionality fails when attempting to resume a subagent that has made Read tool calls (or any tool call with large output). The error occurs even with a single Read tool call.

What Should Happen?

Resume subagent successfully.

Error Messages/Logs

400 {"type":"error","error":{"type":"invalid_request_error","message":"messages.0.content.0: unexpected `tool_use_id` found in `tool_result` blocks: toolu_01KJNVQ6PTLkJyjxcr3cStTU. Each `tool_result` block must have a corresponding `tool_use` block in the previous message."},"request_id":"req_011CWrU78bnStxxh6gA4skXE"}

Steps to Reproduce

1. Create a file with large text content
2. Ask Claude code to:

``
Launch a general-purpose subagent and make 1 Read tool call on the file, then try to resume the subagent.
``

1. Result: Resume fails with the tool_use_id mismatch error

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_