[CLI] Windows: Intermittent infinite scroll animation loop when resuming long conversations after heavy usage

What version of Codex CLI is running?

<!-- Replace with your version, run codex --version -->
(Intermittent issue — version not recorded at time of report)

What subscription do you have?

(Not recorded)

Which model were you using?

(Not recorded)

What platform is your computer?

Windows 11 Home China 10.0.22631

What issue are you seeing?

On Windows, after a period of heavy/high-frequency usage (accumulating a very long conversation history, likely 9000+ messages), resuming a conversation via codex resume or codex continue can trigger an infinite scroll animation loop. The UI gets stuck continuously scrolling with no way to recover except killing the process.

This appears to be an intermittent issue — it does not happen on every resume. It seems to be triggered after prolonged, intensive usage over an extended period rather than by a single conversation alone. The exact trigger condition is unclear.

What steps can reproduce the bug?

1. Use Codex CLI intensively over a long period (many conversations, accumulating thousands of messages per session)
2. Close a session after a long conversation (9000+ messages)
3. Resume the session using codex resume or codex continue
4. In some cases, the UI enters an infinite scroll animation loop immediately or shortly after resuming

Note: The bug is intermittent — it does not reproduce on every resume. It only appears after a period of heavy, sustained usage. Exact reproduction steps are unclear.

What is the expected behavior?

After resuming a long conversation, the UI should properly render the conversation history and settle at the bottom, allowing normal interaction.

What is the actual behavior?

The UI enters an infinite scroll loop — the scroll position continuously changes, making the app unusable. The only recovery is to kill the process.

Additional notes

• This may be related to the viewport/recalculation issues described in #25430 (interactive picker hangs/freezes when session files are large), but manifests as a scroll animation loop rather than a complete freeze
• The intermittent nature suggests it could be a race condition triggered by the accumulated state of long-running sessions
• Shorter conversations resume without problems — the issue is specific to very long conversation histories
• The trigger is the combination of long history + extended heavy usage, not just history length alone