fix(runtime)!: move "tohtml" to pack/dist/opt/ #34557

Problem:
The "tohtml" plugin is loaded by default.

Solution:
- Move it to `pack/dist/opt/nvim.tohtml/`, it is an "opt-in" plugin now.
- Document guidelines.
- Also revert the `plugin/` locations of `spellfile.lua` and `net.lua`.
  That idea was not worth the trouble, it will be too much re-education
  for too little gain.

1 files changed, 45 insertions, 0 deletions

diff --git a/runtime/plugin/net.lua b/runtime/plugin/net.lua
new file mode 100644
index 0000000000..e23c55a115
--- /dev/null
+++ b/runtime/plugin/net.lua
@@ -0,0 +1,45 @@
+vim.g.loaded_remote_file_loader = true
+
+--- Callback for BufReadCmd on remote URLs.
+--- @param ev { buf: integer }
+local function on_remote_read(ev)
+  if vim.fn.executable('curl') ~= 1 then
+    vim.api.nvim_echo({
+      { 'Warning: `curl` not found; remote URL loading disabled.', 'WarningMsg' },
+    }, true, {})
+    return true
+  end
+
+  local bufnr = ev.buf
+  local url = vim.api.nvim_buf_get_name(bufnr)
+  local view = vim.fn.winsaveview()
+
+  vim.api.nvim_echo({ { 'Fetching ' .. url .. ' …', 'MoreMsg' } }, true, {})
+
+  vim.net.request(
+    url,
+    { retry = 3 },
+    vim.schedule_wrap(function(err, content)
+      if err then
+        vim.notify('Failed to fetch ' .. url .. ': ' .. tostring(err), vim.log.levels.ERROR)
+        vim.fn.winrestview(view)
+        return
+      end
+
+      local lines = vim.split(content.body, '\n', { plain = true })
+      vim.api.nvim_buf_set_lines(bufnr, 0, -1, true, lines)
+      vim.api.nvim_exec_autocmds('BufRead', { group = 'filetypedetect', buffer = bufnr })
+      vim.bo[bufnr].modified = false
+
+      vim.fn.winrestview(view)
+      vim.api.nvim_echo({ { 'Loaded ' .. url, 'Normal' } }, true, {})
+    end)
+  )
+end
+
+vim.api.nvim_create_autocmd('BufReadCmd', {
+  group = vim.api.nvim_create_augroup('nvim.net.remotefile', {}),
+  pattern = { 'http://*', 'https://*' },
+  desc = 'Edit remote files (:edit https://example.com)',
+  callback = on_remote_read,
+})