This issue is resolved in the new rule engine when using scripted automation. All scripts can have a function named scriptUnloaded that is called as the script is unloaded due to OH being shutdown or the file being saved. In this function, you can cancel all of the timers in your script. You would get similar functionality in the rules DSL with a rule triggered on ‘System shuts down’ that cancels all the timers.
You can mitigate to an extent by organizing rules into separate files, so that you do not touch the “parents” of long running timers very often. openHAB’s DSL rules engine doesn’t really cater for you to be editing rules every day.
It’s really all down to understanding your own system; if there were some mechanism that cleared away existing timers with an edit, this forum would fill with queries like “my sprinklers didn’t turn off this afternoon” that would take ages to resolve to “but I edited a lighting rule this morning”.
Asw the new rule engine offers per-rule tidying up, this is great step forward.
I’ve always doubted the syntax, variables and items, but I did not think that the timers would live on.
I’ve never worked with the rule engine, but I’ll take a look at that.