Loss limits and a kill switch that does not rewind the tape

A limit is a number that ends a permission. It is not a forecast of the largest loss you will see, and it is not a cushion that appears under the price. Captay's design uses four numbers around every strategy: how much of the account the rule may touch, how large one position may get, how far the slice may fall from its high-water mark, and how much it may lose between one session boundary and the next. This note is about the last two, and about the manual halt that sits beside them.

Two clocks

The daily loss limit looks at the change since the session opened. A quiet morning and a violent afternoon share one budget. If the budget is spent at noon, the afternoon does not get a fresh one because the strategy 'usually recovers.' The drawdown limit looks at a peak. A slow grind that never has a dramatic day can still cross it. Using only the daily figure would miss the grind. Using only the peak would miss a day that starts already wounded and then worsens inside the session. The design keeps both, and either one is sufficient to stop new orders.

Both are mark-to-market. A coin you have not sold is still a loss if the venue's price says so. Waiting for a round trip to 'complete' before you count is how a grid or a DCA schedule talks itself into a larger position. Realized loss is what the accountant may care about later. The halt cares about the position you are actually in.

What a hit does

When a limit is hit, the intended machine cancels resting orders for that strategy, refuses new ones, and writes a journal line that a person can read. It does not resize the limit and continue. It does not switch to a gentler order type. It does not send a closing order unless closing was a separate instruction you armed as its own act. The default is stop adding, not reverse.

Cancel is not instant in the sense that matters. A fill can land while the cancel is in flight. A gap can print a price the resting order never traded, and also a price your inventory now marks against. The journal should show the race. It cannot show it today, because there is no journal process and no order to race. The design still refuses to describe the limit as something that 'caps your loss at' the number. The number ends permission. The market may already have gone past it.

The halt you press

The kill switch is the same stop, started by a person rather than by a comparison. You do not need the daily figure to be exhausted. You need a reason of your own: a venue that looks wrong, a rule you no longer believe, a key you intend to delete. The switch cancels and blocks. It does not delete the key. Deleting the key is a separate gesture on the exchange, and it is the one that survives a bug in the switch.

After either kind of stop, the strategy stays disarmed. A timer that re-enables it at the next session boundary would convert the limit into a snooze. The person who re-arms has to look at the position that remains, including the coin the halt did not sell. If that look is unpleasant, the re-arm waits. Unpleasant is not an error state.

What remains in the account

An open coin is still an open coin. Its next move is not the strategy's problem only in the sense that the strategy has been told to be quiet. The move still changes the account. If you want it sold, you sell, or you arm an explicit flatten that you understand is a trade with a fee and a price you may dislike. Captay's design does not hide a flatten inside the word stop. Hiding it would let a halt become a market order you did not size.

Capital share and position size are the other two numbers, and they bind before the loss exists. They are how you avoid needing the halt to be clever. A share that is the whole account means the halt is negotiating with everything you have. A position cap that is decorative, set far above any schedule you will actually run, is not a cap. The pages that describe DCA and the grid say this in the language of those rules. The point here is the order of operations: size first, then the loss clocks, then a person.

Paper, later, is the rehearsal

A paper session would be the place to watch a limit fire without a venue accepting the order. It would still be a story about hypothetical fills, blind to queue position. It is not available. Describing it is not permission to treat the description as a drill you have completed. No limit is loaded. No switch is rendered in the closed cabinet beyond an empty panel that says the cabinet is closed.

If a future screen shows a loss figure, it will be a figure from a connected account, and it will be able to be a loss. This note does not preview one. A sample number would be a statistic the product has not earned. The brake is a shape: measure, cancel, refuse, wait for a person. The tape of fills stays where the exchange left it.