I hit the 5-hour Codex limit today and got offered Luna Reserve instead of being fully locked out.
That sounded great at first. The problem is that Reserve doesn’t just give you more time. It can change what the task is actually able to do.
I started the task on Sol Ultra 5.6. Once the normal allowance ran out, Luna Reserve kicked in. It first put me on Luna Medium, then I changed it to Luna Extra High and kept going.
The task was using Codex’s rendered browser to check live websites.
Once I was on Luna, that stopped working.
I tested it again in a completely fresh Codex chat. I manually opened a webpage in the built-in browser, left it visible beside the chat, and told Luna Extra High to inspect only that current tab.
It returned:
CURRENT TAB INSPECTION: FAIL
I sent the test to OpenAI Support. They told me the likely reason is that Luna currently doesn’t have the same browser/site inspection capability as Sol or Terra, and specifically mentioned WebMCP being disabled on GPT-5.6 Luna.
That’s the first problem.
Reserve isn’t always just “keep working on a cheaper model.”
Sometimes it’s “keep working on a different model that no longer has the tool your task was already using.”
Then I found another weird part.
I opened ChatGPT Work on the web. The UI showed Luna Reserve with about 90% remaining, but Work still refused to start a new task.
I tried Luna Max and Luna Extra High. Same result both times. Hard usage-limit message before the task even started.
Desktop Codex, meanwhile, could still start fresh Luna Reserve tasks after the normal 5-hour allowance was gone.
The reset times were also inconsistent. My actual usage dashboard said Codex and Work share the same 5-hour limit and that it resets at 2:06 PM. Desktop Codex also said 2:06 PM.
Web Work told me to try again at 4:06 AM.
So right now I’m seeing Reserve shown as available in Web Work while Web Work won’t actually let me use it, and desktop Codex can use it but loses browser capability.
Support has escalated the issue to a specialist.
I still think Luna Reserve is a good idea. I’d rather get a fallback than just hit a wall.
But Codex should tell you clearly before you accept it:
- what model you’re moving to
- what tools or capabilities you’re losing
And if Luna Reserve cannot actually be used in Web Work, the UI probably shouldn’t show a Reserve balance there like it can.
That’s the part I’d like clarified.
