Concept
Stress and Edge, in Keepers in the Dark, are not a measure of how the character is doing, as they are in Blades in the Dark and many other Forged in the Dark games.
They are a measure of suspension of disbelief. This is a TV show, after all.
Stress is not how things are impacting your character, but how your character's plot armor is impacting the audience. Yes, it's awesome to see the tough guy stand up after he takes a hit that should have taken him down, or the hacker manage to override security at literally the last second, but, crucially, you can only do that so much before it just becomes absurd and a little boring, and it just becomes clear the character literally are not allowed to lose.
The limited amount of Stress is how much you, not you in the character but you as in the writer of your character's story, can get away with. How much you are allowed to bend the rules for them.
Edge, likewise, is when a character manages to do something that looks so awesome that the audience is now momentarily more forgiving of things like plot holes and improbable escapes.
Stress
You have a fixed amount of Stress you can take. This is the major consumable resource of the game, used to deal with situations where the dice do not go your way.
As long as you have at least one one free Stress, you can do a Resistance Roll, or any other thing that uses Stress. 'Going over' doesn't matter, if you would go over, just fill it to the max instead.
Filling up your stress is a lot less harmful.than other Forged in the Dark games. Whenever your Stress fills up for more than a few seconds, you get the Moderate Harm 'Stressed', which applies to all rolls. This doesn't go away when you reduce your Stress, although you can reduce it to Lesser Harm via normal means.
Note that your Stress can fill up and and be immediately reduced without this triggering, if you or someone else uses an Edge to reduce it.
Ways to reduce Stress
You can only take six Stress during an episode, and thus you will likely want to reduce it during an episode, which at minimum you can do three times just by roleplaying each of your character Distinctions, or six if you allow those Distinctions to make things harder for you.
Someone else can reduce your Stress by one by talking to you for a few minutes when things are calm. They then have to do a Mind or Social Resistance Roll and take the stress from that.
There are likely other ways you can reduce Stress based on your abilities.
Edge
Edge is conceptually the opposite of Stress. You get it when you crit, and whenever certain things happens, and Abilities can give it to you, and the GM can just reward it for roleplay.
How you can spend Edge:
- Use it to Push Yourself, taking no Stress.
- Use it to reduce your own, or anyone else's, Stress by 1.
- Use it to add an additional 1d to your or anyone else's Action Roll, even Rolls that you would not normally be able to assist on, like Rolls made without you knowing in character that they are happening. Edge is not subject to narrative rules, and you don't have to explain how someone is being helped, although you certainly can. You can even assist on Resistence Rolls, although strategically that's a bad idea.
You can spend Edge at literally any time, including while other people are doing thing.
You can only have one Edge at a time. If you get Edge when you already have it, or get more than one Edge at once, you can immediately spend the extra by Pushing Yourself or clearing yours or someone else's Stress, instead of having to discard the extra.
Notes on strategy
Using an Edge to reduce Stress for yourself is usually the worst option, unless you absolutely need to. You're almost always better off keeping it for Pushing Yourself, because that otherwise costs anything between 1 and 3 Stress. Doing it instead with Edge saves you between 0-2 Stress. And you can use it at any time anyway, so no reason not to hold off.
The 'grace period' on Stress filling up is mostly useful after a Resistance Roll. It means if you have nearly full Stress and need to Push Yourself, and someone has an Edge they're going to use to help, instead of them reducing your Stress before that roll and hoping that -1 helped, you should roll first, take the Stress, which might fill you up, and then they can use the Edge to reduce it after. If you are in a really bad situation, and constantly having to Push Yourself and take Stress, this might end up happening multiple times, with multiple players burning Edge to keep you one Stress below the max. This is a very bad thing to have to do but it might be the only way to get you out of very bad situation.
If they got these Edges with Distinction, paradoxically, narratively, this is your character looking awesome and able to push themselves past any realistic level, but the other characters being a bunch of weird people who aren't that good at their job, so the audience is fine with your apparent hyper-competency.