Editing copy rules while the copier runs
While the copier runs, the Copy Rules editor is read-only. The page dims, and a note explains why: "Stop copying to edit these settings: changes while the copier is running are not allowed." The API refuses the same way, with a 409: "The copier is running: stop it before changing your copy rules." The line beside the page title reads "Stop copying to edit these rules."
Why the lock exists
The engine reads your configuration once, when it starts. An edit made mid-run would either do nothing until the next restart (silently) or, worse, re-target accounts that already hold positions under the old rules. Neither is acceptable, so the honest answer is to refuse. Stop, edit, save, start again.
Locked settings include the leader account and instrument, follower sizing, Max, Cross order, adding, renaming or deleting groups, and the "Blocked instruments" list.
What still works live
Two things are deliberately allowed while the copier runs, because they change which rules are on, never the rules themselves:
- The Follow switch, per account, on the Trade Desk. Flip a follower off and it stops copying; its settings are remembered.
- Pause all / Resume all, also on the Trade Desk, in the Positions heading while copying runs. The same switch, applied to everyone at once. When every follower is paused it reads Resume all, and then it shows even while the copier is stopped, so you never have to start copying with everyone off just to switch them back on.
Renaming a group is cosmetic, but it happens on Copy Rules, and that whole editor is locked while copying runs, so rename it once you have stopped.
Anything structural sent to the Follow-switch endpoint is refused outright: "Structural copy-rule edits go through the Copy Rules page: this endpoint only flips the Follow switches."
Reading your rules is never locked. On the Trade Desk, press Rules on a group's strip while copying runs, or View rules above your positions (that one works while the copier is stopped too). The panel shows the group's leader, every follower with its On or Paused state, its sizing, any cross-contract pairing such as ES to MES, its Max, and the "Blocked instruments" list. It is read-only. Its Open Copy Rules button takes you straight to that group on the Copy Rules page, and every open group on Copy Rules has a View on the Trade Desk link back (a folded group hides it).
Quick answers
Why does my save return 409?
The copier started after the page loaded. Stop it from the engine command strip, save again, then start. The page pulls the lock state as soon as the save is refused.
Can I pause one follower without stopping everything?
Yes. The Follow switch on the Trade Desk works mid-session. It flips the rule off in place; sizing and settings survive.
Does stopping the copier close my positions?
Stopping halts copying; it is not a close. If you want positions closed as well, that is what Flatten all is for. See engine controls explained.