How can I limit a Weblate check/autofix on the file format (i.a. Android, iOS)

We use Weblate in our mobile app CI environment. So far everything is awesome. Weblate runs in a docker environment (v4.1)

Now I want to improve the workflow.

I managed to create custom checks, these validate the use of Android/iOS placeholders (see sample below). Now the translator needs to know which platform he is working with to use the correct placeholder and dismiss the false-positive check.

Placeholder in use right now are %1$@ for iOS and %1$s for Android

My question:

Is there a better/general approach how I can teach my translators how to write placeholders?
How can I write my check based on the file format (or translation file suffix, i.e .xml, .strings)? So I know, this is an android/xml file, and the placeholder should be %1$s NOT %1$@

Sample check

class iOSPlaceholderCheck(TargetCheck):
    # Used as identifier for check, should be unique
    # Has to be shorter than 50 characters
    check_id = "iOSPlaceholder"

    # Short name used to display failing check
    name = _("iOS placeholder")

    # Description for failing check
    description = _("Your translation contains an iOS placeholder")

    # Real check code
    def check_single(self, source, target, unit):
        if "%1$@" in target:
            return True
...

thanks in advance

Solution

I can see few approaches:

In case these formats are generic to the file format, file a feature request so that it's included in future Weblate releases
In case this affects just few strings, you can define the placeholders, you can utilize generic placeholders check in Weblate and let Weblate check and highlight them
To limit check triggering only on some components, you can use translation flags, these can be set at component level
In case you want to write custom check, it should probably also check if the format string is present in the source string, so something like:

if "%1$@" not in source:
    return False
return "%1$@" not in target