Runs at once
Runs at once is how many script runs your account can have going at the same moment. One pool serves everything that runs a script for you: the app, the Agent and the CLI, MCP server and API.
Free | Starter | Pro | Ultra | |
|---|---|---|---|---|
Runs at once | 1 | 2 | 3 | 5 |
What takes a slot
Every study run, whether you start it, the Agent starts it or the API does. Trade studies count too.
The test runs the Agent and the builders' agents make while writing an indicator, definition, study or app.
Every indicator, definition and study run started from the CLI or API.
Running a definition over history does not take a slot; it has its own limit in definition events. Neither do indicators on your charts, which run in your browser.
A slot is free again the moment its run finishes, fails or is stopped. Other accounts never use your slots.
When every slot is taken
The app has no display for this limit. What happens depends on the run:
A study run does not wait. It fails straight away with Study execution is currently at capacity. Please try again shortly. Start it again when another run has finished.
A test run waits for a slot, for up to two to three minutes depending on what it is testing. If none frees in time, it stops without a result and the agent is told there were too many runs in flight.
A CLI or API run waits in
queuedfor a slot within its time limit, except a study run, which does not wait. A run that gets no slot finishes asfailedwith kindbusy, marked retryable; the CLI printsfailed: busywith(retryable)and exits with code 5. Your account can hold its runs at once plus 4 more queued. Past that, starting another run is refused withbusystraight away, and the CLI retries, then exits with code 5.
The usual cause is the Agent working in another tab while you run something from the CLI, or several study runs started together.
Check how many are in use
chartnaut usage shows the runs going now against your plan's number, on the concurrent_runs line:
Limits covers how busy runs queue and retry from the CLI and API.
Get more
Wait for a run to finish, stop one you no longer need, or upgrade. A new plan's number applies within a minute.