Format-on-save doesn't work, but calling `:lua vim.lsp.buf.format()` does about lsp-format.nvim HOT 1 CLOSED

Problem solved, it seems. For posterity:

null-ls's .setup has its own on_attach handler, which (apparently?) doesn't use lspconfig's on_attach. So files that were not handled by null-ls used lsp-format correctly, but files that are handled by null-ls did not.

I made my null-ls.lua file look like this:

local null_ls = require("null-ls")

null_ls.setup({
  sources = {
    null_ls.builtins.formatting.black,
    null_ls.builtins.formatting.isort,
    null_ls.builtins.formatting.stylua,
  },
  on_attach = function(client, _)
    require("lsp-format").on_attach(client)
  end,
})

and now it seems everything uses lsp-format as it should 🙂

from lsp-format.nvim.