Problem: Argument type mismatches are excluded from EmmyLua checks.

Solution: Correct runtime annotations and calls, document local checker
workarounds, and enable the diagnostic.

AI-assisted

Problem: Command inputs and parsed modifiers have different optional
fields, and completion window IDs are annotated as floating-point
values.

Solution: Separate modifier input and return types, correct integer IDs,
and update the metadata generators and their output.

AI-assisted

AI-assisted

Make gen_helptags.lua call help.lua instead of keeping its own tag
parser. Builds and :helptags now use the same code.

Allow the shared code to run without Neovim, and fail the build when tag
generation reports an error.

AI-assisted

Problem: Watcher failures are reported inconsistently, and callers
cannot detect when a watcher is no longer usable.

Solution: Route startup and event failures and unexpected inotifywait
exits through an optional on_error callback. Log to nvim-watch.log by
default. Ignore disappearing child directories and exits caused by
cancellation. Let LSP log failures and notify once per message, using
INFO for missing roots and ERROR otherwise, without interrupting
registration.

AI-assisted

Problem: Nvim has many Lua APIs that start callback-driven work: timers,
jobs, libuv handles, and other event-loop tasks. Callers that need to
sequence or cancel that work have to build their own coroutine wrappers,
task bookkeeping, and cleanup rules. This makes async control flow hard
to share, test, and document.

Solution: Add `vim.async`, a structured-concurrency module vendored from
async.nvim. It provides task handles, await/pawait helpers,
sleep/timeout helpers, completion-order iteration, and semaphores on top
of Nvim's event loop.

The API follows the same broad model as Trio: async work has an owner,
tasks are awaited explicitly, and cancellation is cooperative. Include
generated vimdoc with an introductory overview and examples, a news
entry, and functional tests for the new module.

AI-assisted

Problem: there should be exactly one cell of padding between sections,
and exactly one cell of minimum padding between the left and the right.
- Spaces between sections waste space when a section is empty.
  According to a comment in #33036, this was the reason to avoid `%k`
  and implement the keymap section with a vim expression, but other
  sections still have this problem.
- The diagnostics section wastes space because it is not entirely empty
  when there are diagnostics in another buffer.
- The terminal exit code section can touch the right side, e.g. the
  ruler, even though it belongs to the left side.
Solution:
- Use auto-hiding item groups (`%(` without width fields) to get rid of
  unneeded spaces when a section shows no information.
  This simplifies the 'showcmd' and 'keymap' sections in particular.
- As a slight simplification, `term_exitcode` is moved into the flags
  section since it is formatted with square brackets like a flag.
- Count the diagnostics for the current buffer specifically.
- Ensure at least one cell of padding between the left and the right
  side by adding a space next to the separator `%=`.

Problem: some sections are implemented with `%{%`, even though
reevaluation of the expression result is not needed.
This leads to otherwise needless %-escaping in `progress_status`.
Solution: use `%{` instead.

Problem: `%{` and `%{%` (without items) replace spaces with fillchars.
This looks out-of-place inside the terminal exit code section, and in
contrast to all other sections, the 'busy' section is surrounded by
fillchars, which looks inconsistent, and with some terminal-font
combinations, ◐ overlaps the fillchar, e.g. Alacritty & JetBrains Mono.
Solution: use non-breaking spaces U+202F to avoid fillchar substitution.

Problem: sections that appear/disappear frequently can make otherwise
more stable sections jump around a lot.
Solution: sort the sections on the right roughly by volatility:
'showcmd' in first place, 'keymap' next to the ruler.

Problem:
Cannot assign Lua functions/closures to "func" ('completefunc',
'tagfun', …) or "expr" ('foldexpr', 'indentexpr', …) options.

Solution:
- Store "func"/"expr" options as `Callback` instead of string.
- Delete oceans of copy-pasted code.
- BREAKING: LuaRef returned via RPC/Vimscript is now represented as
  `"<Lua N: file:line>"` (like what `:map` shows) instead of `nil`.
- Note: `man.vim` still uses `v:lua` string, bc it's a vimscript ftplugin.

Helped-by: Lewis Russell <lewis6991@gmail.com>

Problem:
The bundled `zip` plugin is implemented in Vimscript, making it harder to
maintain and build on with Nvim's Lua runtime infrastructure.

Solution:
Add an opt-out `zip.lua` browser backed by `nvim.dir`, and disable the legacy
Vimscript implementation by moving it to `pack/dist/opt/zip/`. Load it with
`:packadd zip`.