nvim: migrate copilot to native 0.12 inline completion

nix/home/common.nix

@@ -325,6 +325,7 @@
     markdown-oxide
     ncdu
     neovim
+    copilot-language-server
     nerd-fonts.hack
     nodejs
     nvd

nvim/lsp/copilot.lua

@@ -0,0 +1 @@
+return require("lsps.copilot")

nvim/lua/lsps/copilot.lua

@@ -0,0 +1,117 @@
+local function sign_in(bufnr, client)
+  client:request('signIn', vim.empty_dict(), function(err, result)
+    if err then
+      vim.notify(err.message, vim.log.levels.ERROR)
+      return
+    end
+    if result.command then
+      vim.fn.setreg('+', result.userCode)
+      vim.fn.setreg('*', result.userCode)
+      local ok = vim.fn.confirm(
+        'Copied one-time code to clipboard.\nOpen browser to sign in?',
+        '&Yes\n&No'
+      )
+      if ok == 1 then
+        client:exec_cmd(result.command, { bufnr = bufnr }, function(cmd_err, cmd_result)
+          if cmd_err then
+            vim.notify(cmd_err.message, vim.log.levels.ERROR)
+            return
+          end
+          if cmd_result.status == 'OK' then
+            vim.notify('Signed in as ' .. cmd_result.user)
+          end
+        end)
+      end
+    elseif result.status == 'PromptUserDeviceFlow' then
+      vim.notify('Enter code ' .. result.userCode .. ' at ' .. result.verificationUri)
+    elseif result.status == 'AlreadySignedIn' then
+      vim.notify('Already signed in as ' .. result.user)
+    end
+  end)
+end
+
+local function sign_out(_, client)
+  client:request('signOut', vim.empty_dict(), function(err, result)
+    if err then
+      vim.notify(err.message, vim.log.levels.ERROR)
+      return
+    end
+    if result.status == 'NotSignedIn' then
+      vim.notify('Not signed in.')
+    end
+  end)
+end
+
+--- Truncate insert_text via a transform function, skip the server-side accept command.
+local function partial_accept(transform)
+  return function(item)
+    local text = type(item.insert_text) == 'string' and item.insert_text
+      or tostring(item.insert_text.value)
+    local partial = transform(text)
+    if not partial or partial == '' then return item end
+    item.insert_text = partial
+    item.command = nil
+    return item
+  end
+end
+
+local accept_word = partial_accept(function(text)
+  local word = vim.fn.matchstr(text, [[\k\+\s\?]])
+  return word ~= '' and word or text:sub(1, 1)
+end)
+
+local accept_line = partial_accept(function(text)
+  return text:match('^[^\n]*')
+end)
+
+return {
+  cmd = { 'copilot-language-server', '--stdio' },
+  root_markers = { '.git' },
+  init_options = {
+    editorInfo = {
+      name = 'Neovim',
+      version = tostring(vim.version()),
+    },
+    editorPluginInfo = {
+      name = 'Neovim',
+      version = tostring(vim.version()),
+    },
+  },
+  on_attach = function(client, bufnr)
+    vim.api.nvim_buf_create_user_command(bufnr, 'CopilotSignIn', function()
+      sign_in(bufnr, client)
+    end, { desc = 'Sign in to GitHub Copilot' })
+    vim.api.nvim_buf_create_user_command(bufnr, 'CopilotSignOut', function()
+      sign_out(bufnr, client)
+    end, { desc = 'Sign out of GitHub Copilot' })
+
+    if not client:supports_method(vim.lsp.protocol.Methods.textDocument_inlineCompletion, bufnr) then
+      return
+    end
+
+    vim.lsp.inline_completion.enable(true, { bufnr = bufnr })
+    local ic = vim.lsp.inline_completion
+    local map = vim.keymap.set
+
+    map('i', '<A-S-s>', function() ic.get() end,
+      { buffer = bufnr, desc = 'Copilot: accept suggestion' })
+
+    map('i', '<A-S-w>', function() ic.get({ on_accept = accept_word }) end,
+      { buffer = bufnr, desc = 'Copilot: accept word' })
+
+    map('i', '<A-S-q>', function() ic.get({ on_accept = accept_line }) end,
+      { buffer = bufnr, desc = 'Copilot: accept line' })
+
+    map('i', '<A-S-d>', function() ic.select() end,
+      { buffer = bufnr, desc = 'Copilot: next suggestion' })
+
+    map('i', '<A-S-a>', function() ic.select({ count = -1 }) end,
+      { buffer = bufnr, desc = 'Copilot: previous suggestion' })
+
+    map('n', '<leader>cc', function()
+      local enabled = ic.is_enabled({ bufnr = bufnr })
+      ic.enable(not enabled, { bufnr = bufnr })
+      vim.notify('Copilot: ' .. (not enabled and 'ON' or 'OFF'))
+    end, { buffer = bufnr, desc = 'Toggle Copilot' })
+  end,
+}