Codex becomes slow with frequent spinners and input lag when a thread history contains many large inline base64 PNG images #28916

What version of the Codex App are you using (From “About Codex” dialog)?

26.611.62324

What subscription do you have?

Pro

What platform is your computer?

Darwin 25.2.0 arm64 arm

What issue are you seeing?

Codex desktop becomes slow with frequent spinners and noticeable input lag when a thread history contains many large inline base64 PNG images (after asking the agnet to show diagrams inline). The thread had 121 inline pngs before it was fixed.

Root Cause
Large image payloads were stored directly inside session JSONL as data:image/png;base64,... strings. These payloads made the session file very large and expensive to load, parse, render, and search through during normal app usage.

Fix Applied
Older inline PNG payloads were extracted into local .png files under the thread’s assets folder. The JSONL now references those files by absolute local paths with clickable Markdown links.

Result
The affected thread JSONL was reduced substantially, while image access was preserved through local file links. Codex became normal again.

What steps can reproduce the bug?

Feedback ID: 019eb0c5-02e5-7200-99ca-d6f170ea78d3

What is the expected behavior?

No response

Additional information

No response