Add a simple "Run Now" button to the gateway even scripts dialog popup at the bottom by the ok, apply, and cancel buttons (perhaps with a confirmation as well) as an easy way to test the scripts without them being triggered "naturally".
Voted. Was going to suggest this myself a while back.
I'm confused on how you intend this to work. Various gateway event scripts already run immediately when you save the project, and saving the project is necessary to get them into the gateway so it is possible to run them. (Startup, Timer, Tag Change)
Message handlers cannot run without a payload--not sure what you expect to happen there. Gateway shutdown scripts and scheduled events are the only ones that might be helped here.
Yes, definitely some details to work out on that. I was specifically working with scheduled events. Startup, shutdown, tag change, and scheduled would be a good place to start.
Startup and tag change already run on project save.
If you have the other events delegate via one-liners to project library functions (and you should), you can decorate with my system.util.runInGateway toolkit function to make them triggerable from the designer script console. Can even be used with the events that need payloads.
(I wouldn't hold my breath on getting any functionality that doesn't include saving the project.)
My current, not-fully-crystallized thinking, is a variation of a "gateway script console" that allows the workspace you are in to "decorate" the console with extra values - e.g., if you open the gateway script console and are in Perspective, you have some ability to "mock" session props/component data/etc to test your scripts. Then if you swap over to gateway script(s), similar "helpers" for payload data shapes.
Or something along those lines. I'm not sure exactly how it will work and it won't happen in the immediate future (i.e. Ignition 2027) but that's where my thinking currently lands.