Codex Desktop appears to consume Exec quota while idle with no visible background activity

Summary

While investigating unexpectedly high Exec usage on ChatGPT Pro, I observed that leaving Codex Desktop open caused my Exec quota to continue decreasing (~1% at regular intervals) even when I was not interacting with the app. Quitting Codex Desktop immediately stopped the quota drain.

Environment

• Codex Desktop (VS Code Externsion is not affected by this)
• macOS
• GPT-5.5

Investigation

• Audited local sessions with ccusage.
• Inspected raw ~/.codex/sessions JSONL logs.
• Largest sessions were cache-read heavy (~90% cache reads).
• No evidence of runaway shell loops, retry storms, or repeated tool invocations.
• Event types were primarily response_item/event_msg, with no recorded tool.name entries.
• Sessions appeared to be normal Codex Desktop rollouts, including forked sessions.

Observed behavior

1. Exec quota reset.
2. Without submitting prompts, Exec continued decreasing by ~1% at regular intervals.
3. Closing Codex Desktop immediately stopped the decrease.

Expected behavior

If Codex Desktop is performing background execution after the user stops interacting, there should be a clear UI indication explaining that work is still in progress and consuming quota. Otherwise, idle/open state should not appear to consume Exec.

Can you clarify whether this is expected behavior, background session continuation, or a bug? I can provide sanitized session logs, ccusage reports, and dashboard screenshots if useful.