Is it possible to make snippets take precedence over completion?

[unphased]

I'd love to be able to use Tab to control snippy only if a snippy context is valid.

I'm using it with cmp and so far the only way to make things behave sanely is to configure snippy to go forward and backward on ctrl+tab and ctrl+shift+tab, this way no conflict with the cmp popup menu where tab and shift+tab serve to move forward and back in the menu.

Well I want to eliminate having to think about ctrl.

I tried stuff like

vim.cmd[[
function! SnippyBinds()
  imap <expr> <Tab> snippy#can_expand_or_advance() ? '<Plug>(snippy-expand-or-advance)' : '<Tab>'
  imap <expr> <S-Tab> snippy#can_jump(-1) ? '<Plug>(snippy-previous)' : '<S-Tab>'
  smap <expr> <Tab> snippy#can_jump(1) ? '<Plug>(snippy-next)' : '<Tab>'
  smap <expr> <S-Tab> snippy#can_jump(-1) ? '<Plug>(snippy-previous)' : '<S-Tab>'
  xmap <Tab> <Plug>(snippy-cut-text)
endfun
augroup SnippyAuGroup
  autocmd!
  autocmd VimEnter * call SnippyBinds()
augroup END
]]

but no matter what I did nvim does report that the tab key is bound to cmp.utils.keymap.set_map... so my autocmd shenanigans to try to give this snippy binding precedence over cmp is not working.

But anyway this thought process does bring up a reasonable conflict -- what if in the course of typing out one of my snippet regions I want to use tab completion? So even the notion of always prioritizing the Tab input to snippy requires some logic.

The logic that I would like to have is to make tab prioritize snippy but I can use a backup (like ctrl+tab) to send that as input to the completion menu.

I don't think this is possible to implement but I would still like to know if anyone could explain exactly why and where the limitations are.

For now I will keep using completely separate binds. I already had to use such a workflow (separate key binding to manipulate snippet state from completion menu state) in my pre-nvim, pre-lua config, where I used coc.nvim and coc-snippets. I was hopeful I could make progress beyond that, but alas.

[unphased]

I was able to make progress! By adding logic in cmp's own mapping config for <Tab>. This is obvious in hindsight! I should be able to implement exactly what I described above. Also epic is I'm able to merely type l<Tab> to immediately expand the l snippet that I have. Having the ability to do that without needing the cmp menu to even appear is wonderful.

[unphased]

There is one problem with how I have it so far, which is that whenever cmp's cmp.select_next_item() happens, IF THE SNIPPET has a back-reference e.g. ${2:${VISUAL}$1} then the automation used to fill that in appears to be causing the cmp menu to behave badly (act as though I typed in the selected item).

That looks like it's definitely worthy of its own ticket.