Can you rename this to GOTIFY_OIDC_PROMPT with type text and default login. This should be used for both login and elevate. And be independent of the auto redirect feature.

Makes sense, but if we do that, since we then pass whatever is the value of that env var to the IdP as a url param, I would suggest we also check the value provided against the allowed values according to the oidc spec
I really dont want to pass any unvalidated data to a login system

I think it's okay to do this unvalidated as this setting set by administrators. If the spec changes we'd have to adjust the validation, so I don't think there is much benefit in validating it.

Well, yes, if a protocol you use changes, you have might have to adjust the code.

If i remember correctly, the OIDC spec follows semnatic versioning, that means future minor version bumps shouldnt remove existing params or values, only add to it.

I already added validation as func parseOIDCPrompt to config/parse.go

func parseOIDCPrompt(target *string, env string) error {
	raw, ok, err := lookupEnv(env)
	if err != nil {
		return err
	}
	if !ok {
		return nil
	}
	values := strings.Fields(raw)
	hasNone := false
	for _, value := range values {
		if !validOIDCPromptValues[value] {
			return fmt.Errorf(
				"invalid value for %s (%q): must be a space-delimited combination of none, login, consent, select_account",
				env, raw,
			)
		}
		hasNone = hasNone || value == "none"
	}
	if hasNone && len(values) > 1 {
		return fmt.Errorf("invalid value for %s (%q): none must not be combined with other values", env, raw)
	}
	*target = raw
	return nil
}

I think its worth doing, it protects gotify admins from faulty configs and protects OIDC IdP system from some injection vectors.

I've decided against including this, as the existing list already missed the create prompt type.