The default vanilla  gameplay always restore armor fully after end of mission, this mod introduce partial restoration. So carefully not to send the same mech over multiple missions to end up as glass cannon. Yang aware of that but he has only two hands and busy with Triple-F, he does promise that you will see all mechs fully armored when you step into mechbay next morning.

At the end of mission, if your armor below the maxPercentageArmorRestore value (50%), than repair happen with allowance of percentageArmorRestorePerMission value (50%) but cap at the maxPercentageArmorRestore value. The useStockArmorValue value default to true as it is routine task to repair stock armor configuration.

The frame color of the mech tonnage info will set to light grey if less than 100%, medgrey if less than 80% and dark grey if less than 60%. The paperdoll info of the mech will always display the color depth based on the armor availability.

mod json setting:
        "percentageArmorRestorePerMission" : 50, // percentage of armor to be restored after each mission
        "maxPercentageArmorRestore" : 50,             // the maximum restored value allowed, no armor repaired if armor more than the threshold
        "useStockArmorValue" : true                          // restored based on stock value, set to false for user assigned value

Requires ModTek, and thanks to Mpstark.