You're forty minutes into a refactor.
The agent knows which files you've touched, why that one test is skipped, and the approach you already tried and dropped. It's going well. Then the message shows up: usage limit reached.
Now you can wait for the reset, or open a different agent and spend a while re-explaining everything. Either way you lose the thread, and it tends to happen at the worst possible moment.
Limit Rescue is meant to take the sting out of that. It tells you you're running low while you can still finish a thought, and it gives you a short handoff note so the next agent isn't starting from zero.