[BUG] Desktop app hangs on new messages in long sessions

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?

Summary

New messages sent to long-running sessions in the Claude Code desktop app hang indefinitely with no response, no error, and no timeout. The agent's loading indicator appears but nothing ever streams back. Fresh sessions on the same repos work normally, so the issue is correlated with session age/length rather than the codebase or environment.

Environment

| | |
|---|---|
| Surface | Claude Code desktop app |
| Model | Opus 4.7 (1M context, Max tier) |
| OS | macOS (MacBook Pro M5 Pro, 14-inch) |
| Plan | Max |
| Mode | Bypass permissions enabled |

Actual behavior

• Indicator appears, then nothing.
• No error message.
• No timeout — left it running, never resolved.
• No partial token stream.
• Reproduces on every new message in the affected sessions; not a one-off transient.
• Older turns in the same sessions all rendered successfully when they were originally sent.

What Should Happen?

The agent responds in the same session, same as a fresh session would.

Error Messages/Logs

Steps to Reproduce

1. Open a session with substantial existing history. Confirmed in three separate sessions: ReconBot, ReconBot (fork), IOS_bot. Each has multi-day history with code edits, file ops, and tool calls.
2. Send any new message — tested with single characters (?), greetings (hi, hello), and real prompts (what do you do now?, progress?).
3. The orange agent indicator (✳) appears at the bottom of the conversation. No output ever follows.

<img width="1112" height="950" alt="Image" src="https://github.com/user-attachments/assets/3500cf14-14d3-430e-b38f-bace4d0240d2" />

<img width="1110" height="941" alt="Image" src="https://github.com/user-attachments/assets/3344b435-9001-4386-b592-c7d44cf614be" />

<img width="1102" height="949" alt="Image" src="https://github.com/user-attachments/assets/315f7e23-e356-4342-943d-96cdd4da93ea" />

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.141

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_