Testing across the full history turned up the worst case of getting stuck: a position that stayed open for 284 days.
The first reaction is that this is a risk finding. It is not, quite, and the distinction turned out to matter more than the number.
Nothing about that position threatened the account. The structure cannot be liquidated while the short is covered by the stack behind it, so the position could have sat there indefinitely without forcing anything. What it cost was the use of the capital: for 284 days that money was committed to a trade going nowhere instead of being available for trades that were working.
That is forgone return, not loss, and the two require different responses. Loss calls for a smaller position. Forgone return calls for a way out that is not a price.
Which is where the clock came from. A position that has been open too long inside a confirmed trend is closed on time rather than on price, at a loss if necessary, and that same trend is then refused until it stops confirming.
It cost us money the first time it fired in live trading, and it also stopped us re-entering a move that ran for another month. Both of those are the same rule. We report them together.