Add a "Set default SIM" entry next to the existing "Unset default SIM"

Start by reading cab_contacts.xml, cab_recent_calls.xml and menu_recent_item_options.xml alongside the existing cab_remove_default_sim behavior; the issue also points to ContactsAdapter and Config.saveCustomSIM(). Run assembleFossDebug, detekt and lintFossDebug. Done means the new menu entry opens a SIM picker, saves the choice for one number or the selected contacts, and appears only when multiple SIMs are available.

Checklist

• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the request will be dismissed otherwise.
• This issue contains only one feature request.
• I have read and understood the contribution guidelines.

Feature description

In the contact, favourite and call log menus, the SIM related entries are "Call from SIM 1 / SIM 2", which place a single call without remembering anything, and "Unset default SIM". Nothing in those menus sets a default SIM for a number.

I would like to add a "Set default SIM" entry there, opening the list of available SIMs with the current preference preselected and storing the choice for that number. It places no call — it is the counterpart of the entry that already removes the preference.

In the contact and favourite lists, where selecting several items is already supported, it would also apply to a multi-selection, so a whole group of people can be assigned to the same SIM at once.

Why do you want this feature?

As far as I can tell, the only place where a preferred SIM can be created today is the "remember my choice" checkbox in the SIM picker dialog, and that dialog only appears when long pressing the dialpad call button, or when no default outgoing phone account is set at system level.

Someone who calls from the contact list or the call log - which is how I use the app - therefore never encounters it, and concludes that per-contact SIM preferences do not exist. That is what happened to me: I was about to request the feature before discovering it was already there, behind a long press on the dialpad.

These menus cannot help them find it, because the only entry that hints at the feature is conditional on already having used it: "Unset default SIM" is shown exclusively when a preference exists for that number. It is visible only to users who already found the dialpad shortcut - the ones who do not need the hint - and permanently invisible to everyone else.

Adding the entry that creates a preference, right where the entry that removes one already lives, closes that loop.

Additional information

I have a working implementation and would be happy to open a pull request:

• a showSetDefaultSIMDialog() helper, reusing RadioGroupDialog and the existing Config.saveCustomSIM();
• a cab_set_default_sim entry next to cab_remove_default_sim in cab_contacts.xml, cab_recent_calls.xml and menu_recent_item_options.xml, shown only when areMultipleSIMsAvailable();
• in ContactsAdapter, the entry stays visible for a multi-selection and applies the SIM to the primary number of each selected contact; the current SIM is then preselected only when all of them already share it;
• one new string and a CHANGELOG entry.

70 lines, no new setting, no change to any existing behaviour. assembleFossDebug, detekt and lintFossDebug pass. Tested on a dual-SIM Pixel 8 Pro (Android 17), app version 1.11.1.

I did consider having "Call from SIM 1 / SIM 2" offer to remember the choice instead of adding an entry, but that would either put a confirmation step in front of an action that is instant today, or double the number of SIM entries in the menu. A separate entry keeps the two intentions apart: one places a call, the other sets a preference. Happy to implement it differently if you prefer.

Related threads: in #375 and FossifyOrg/General-Discussion#353 the answer was that per-number SIMs already exist, but that the option only shows up once the system-wide preferred SIM is unset. Since #50 added the long press on the dialpad call button, which opens the SIM picker regardless of that setting, and since a stored per-number SIM now takes precedence over the system default when calling, the preference works for everyone: it is only hard to create. This request is about that part. #155, closed as a duplicate of #50, asked to set a default SIM for many contacts at once, which the multi-selection part would cover.

This replaces #912, which I had created without the issue form by mistake.

The implementation and this report were written with AI assistance; I reviewed both and tested the change on my own device.