Behaviour for library-level bot initialization hooks.

Modules implementing this behaviour are called once during bot startup, before the user's ExGram.Handler.init/1 callback. Use this to set up storage tables, register processes, or inject data into every context.

Return values

• :ok - hook succeeded, no extra data
• {:ok, map()} - hook succeeded, merge map into extra_info (which flows into every ExGram.Cnt.extra)
• {:error, reason} - hook failed, the bot will not start

Registration

Register hooks in your bot module using the on_bot_init/1-2 macro (available via use ExGram.Bot):

defmodule MyBot do
  use ExGram.Bot, name: :my_bot

  on_bot_init(MyLibrary.Initializer, some_opt: :value)
  # ...
end

Libraries that provide a use macro should emit on_bot_init/1-2 calls automatically, so end-users don't need to wire anything manually.

Execution order

Hooks run in declaration order, before the user's ExGram.Handler.init/1 callback. Each hook receives the accumulated extra_info from all previous hooks via the extra_info: key in init_opts.