ComfyFactorio/modules/backpack_research.lua

-- backpack research -- researching mining efficiency increases your backpack capacity (inventory slots)

local Event = require 'utils.event'

local function on_research_finished(event)
    event.research.force.character_inventory_slots_bonus = game.forces.player.mining_drill_productivity_bonus * 100
end

Event.add(defines.events.on_research_finished, on_research_finished)