fix: correct 13 bugs across .vimrc, install.sh, and docs

.vimrc:
- Fix syntax=OFF no-op in large file handler (syntax= is correct)
- Fix <leader>rG broken -F flag (new RgWord command with -F before --)
- Fix :Gdiff → :Gdiffsplit (fugitive v3+ compat)
- Fix go_def_mode/go_info_mode conflicting with go_gopls_enabled=0
- Fix <leader>m prefix collision with mt/mp (renamed to <leader>ms)
- Wrap PlugInstall autocmd in augroup (prevent doubling on re-source)

install.sh:
- Guard against empty version string in hadolint/marksman downloads
- Add HAS_SUDO check in _do_binary_apt before sudo mv
- Add PlugClean warning when existing plugins directory is non-empty
- Fix pkg_install brew-first priority (macOS-only now, Linux fallback)
- Fix menu double-draw flicker on first render
- Fix Fedora deselected tools not tracked in SKIPPED array

docs:
- Remove nonexistent nvm install step from README
- Fix TOC description (side window, not quickfix) in README/QUICKSTART
- Fix TTY detection description (add dumb, empty, builtin)
- Add missing ,cd and ,wa mappings to README
- Remove dead CoC formatOnSaveFiletypes from coc-settings.json

.vimrc

@@ -96,7 +96,10 @@ let data_dir = has('nvim') ? stdpath('data') . '/site' : '~/.vim'
 if empty(glob(data_dir . '/autoload/plug.vim'))
     silent execute '!curl -fLo '.data_dir.'/autoload/plug.vim --create-dirs '
         \ . 'https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim'
+    augroup PlugBootstrap
+        autocmd!
         autocmd VimEnter * PlugInstall --sync | source $MYVIMRC
+    augroup END
 endif
 
 call plug#begin('~/.vim/plugged')
@@ -358,7 +361,7 @@ endfunction
 map <C-p>     :call <SID>SmartFiles()<CR>
 map <leader>b :Buffers<CR>
 map <leader>rg :Rg<CR>
-map <leader>rG :Rg -F <C-r><C-w><CR>
+map <leader>rG :RgWord<CR>
 map <leader>rt :Tags<CR>
 map <leader>gF :GFiles<CR>
 
@@ -384,6 +387,19 @@ else
     command! -bang GFiles call fzf#vim#gitfiles('', fzf#vim#with_preview(), <bang>0)
 endif
 
+" RgWord: fixed-string search for word under cursor (flags before --)
+if g:is_tty
+    command! -bang -nargs=* RgWord
+        \ call fzf#vim#grep(
+        \   'rg --column --line-number --no-heading --color=always --smart-case -F -- '
+        \   .shellescape(expand('<cword>')), 1, <bang>0)
+else
+    command! -bang -nargs=* RgWord
+        \ call fzf#vim#grep(
+        \   'rg --column --line-number --no-heading --color=always --smart-case -F -- '
+        \   .shellescape(expand('<cword>')), 1, fzf#vim#with_preview(), <bang>0)
+endif
+
 " ============================================================================
 " => GitGutter
 " ============================================================================
@@ -450,8 +466,8 @@ nmap <silent> <leader>aD :ALEDetail<cr>
 " vim-lsp (gopls) handles all Go intelligence; disable vim-go's own LSP layer
 let g:go_gopls_enabled            = 0
 let g:go_code_completion_enabled  = 0
-let g:go_def_mode                 = 'gopls'
-let g:go_info_mode                = 'gopls'
+let g:go_def_mode                 = 'godef'
+let g:go_info_mode                = 'godef'
 let g:go_fmt_autosave             = 0  " ALE handles format-on-save
 let g:go_imports_autosave         = 0
 let g:go_highlight_types          = 1
@@ -903,7 +919,7 @@ nnoremap <leader>cp :let @+ = expand("%:p")<CR>:echo "Copied: " . expand("%:p")<
 nnoremap <leader>cf :let @+ = expand("%:t")<CR>:echo "Copied: " . expand("%:t")<CR>
 
 " Scratch markdown buffer
-map <leader>m :e ~/buffer.md<cr>
+nnoremap <leader>ms :e ~/buffer.md<cr>
 
 " Auto-create parent directories on save
 function! s:MkNonExDir(file, buf)
@@ -930,7 +946,7 @@ nnoremap <leader>gs :Git status<CR>
 nnoremap <leader>gc :Git commit<CR>
 nnoremap <leader>gp :Git push<CR>
 nnoremap <leader>gl :Git pull<CR>
-nnoremap <leader>gd :Gdiff<CR>
+nnoremap <leader>gd :Gdiffsplit<CR>
 nnoremap <leader>gb :Git blame<CR>
 
 " ============================================================================
@@ -967,7 +983,7 @@ function! LargeFileSettings()
     setlocal undolevels=-1
     setlocal eventignore+=FileType
     setlocal noswapfile
-    setlocal syntax=OFF
+    setlocal syntax=
     let b:ale_enabled = 0
     echo "Large file (>10 MB): syntax, undo, and linting disabled."
 endfunction
@@ -977,7 +993,7 @@ if g:is_tty
         autocmd!
         autocmd BufReadPre *
             \ if !empty(expand('<afile>')) && getfsize(expand('<afile>')) > 512000 |
-            \     setlocal syntax=OFF |
+            \     setlocal syntax= |
             \ endif
     augroup END
 

QUICKSTART.md

@@ -142,7 +142,7 @@ K               Show documentation
 | Key | Action |
 |-----|--------|
 | `,mp` | Open live preview in browser |
-| `,mt` | Table of contents |
+| `,mt` | Table of contents (side window) |
 | `zr` / `zm` | Unfold / fold all headings |
 
 Formatting in the buffer is live: `**bold**` renders as bold,

README.md

@@ -86,11 +86,10 @@ cd ~/.vim && ./install.sh
 3. Backs up existing `~/.vimrc`, then symlinks `~/.vimrc → ~/.vim/.vimrc`
 4. Installs vim-plug and runs `:PlugInstall`
 5. Offers to install system tools (ripgrep, fzf, ctags, shellcheck, hadolint, marksman)
-6. Offers to install Node.js via nvm (for npm formatters — optional)
-7. Offers to install npm formatters (prettier, eslint, etc.)
-8. Offers to install Python formatters/linters (black, isort, flake8, etc.)
-9. Offers to install Go tools (gopls, goimports, staticcheck)
-10. Offers to append vim-tmux-navigator bindings to `~/.tmux.conf`
+6. Offers to install npm formatters (prettier, eslint, etc.) — requires Node.js
+7. Offers to install Python formatters/linters (black, isort, flake8, etc.)
+8. Offers to install Go tools (gopls, goimports, staticcheck)
+9. Offers to append vim-tmux-navigator bindings to `~/.tmux.conf`
 
 **Supported platforms:** macOS (Homebrew), Debian/Ubuntu (apt), Arch (pacman), Fedora (dnf).
 
@@ -150,10 +149,12 @@ Press `,?` at any time to open the built-in cheat sheet.
 | `,E` | Open netrw in vertical split |
 | `,b` | Search open buffers (FZF) |
 | `,rg` | Project-wide search (ripgrep + FZF) |
-| `,rG` | Ripgrep for word under cursor |
+| `,rG` | Ripgrep word under cursor (fixed-string) |
 | `,,` | Switch to last file |
 | `,l` / `,h` | Next / previous buffer |
 | `,bd` | Close current buffer (preserves window layout) |
+| `,wa` | Save all open buffers |
+| `,cd` | Change working directory to current file's directory |
 
 ### Code Intelligence (vim-lsp)
 
@@ -179,7 +180,7 @@ Press `,?` at any time to open the built-in cheat sheet.
 | Key | Action |
 |-----|--------|
 | `,mp` | Open live preview in browser (previm) |
-| `,mt` | Table of contents |
+| `,mt` | Table of contents (side window) |
 | `zr` / `zm` | Unfold / fold all headings |
 
 ### Git (vim-fugitive)
@@ -253,7 +254,7 @@ No Node.js required. Uses `open` (macOS) or `xdg-open` (Linux).
 ### Table of contents
 
 ```vim
-,mt    " open TOC in a quickfix window — press Enter to jump to heading
+,mt    " open TOC in a side window — press Enter to jump to heading
 ```
 
 ---
@@ -307,7 +308,7 @@ bind-key -n 'C-l' if-shell "$is_vim" 'send-keys C-l' 'select-pane -R'
 
 ### TTY / SSH Support
 
-Detected automatically when `$TERM` is `linux` or `screen`. In TTY mode:
+Detected automatically when `$TERM` is unset, `dumb`, `linux`, `screen`, or contains `builtin`. In TTY mode:
 
 - True colour and cursorline disabled
 - FZF preview windows disabled

coc-settings.json

@@ -6,8 +6,5 @@
       "filetypes": ["markdown"],
       "rootPatterns": [".git", ".marksman.toml"]
     }
-  },
-  "coc.preferences.formatOnSaveFiletypes": [
-    "markdown"
-  ]
+  }
 }

install.sh

@@ -72,10 +72,11 @@ safe_download() {
 # ── Cross-platform package install helper ─────────────────────────────────────
 pkg_install() {
     local brew_pkg="${1:-}" apt_pkg="${2:-}" pac_pkg="${3:-}" dnf_pkg="${4:-}"
-    if   [[ $HAS_BREW   -eq 1 && -n "$brew_pkg" ]]; then brew install "$brew_pkg" >/dev/null 2>&1
+    if   [[ $OS == "macos" && $HAS_BREW -eq 1 && -n "$brew_pkg" ]]; then brew install "$brew_pkg" >/dev/null 2>&1
     elif [[ $HAS_APT    -eq 1 && -n "$apt_pkg"  && $HAS_SUDO -eq 1 ]]; then sudo apt-get install -y "$apt_pkg" >/dev/null 2>&1
     elif [[ $HAS_PACMAN -eq 1 && -n "$pac_pkg"  && $HAS_SUDO -eq 1 ]]; then sudo pacman -S --noconfirm "$pac_pkg" >/dev/null 2>&1
     elif [[ $HAS_DNF    -eq 1 && -n "$dnf_pkg"  && $HAS_SUDO -eq 1 ]]; then sudo dnf install -y "$dnf_pkg" >/dev/null 2>&1
+    elif [[ $HAS_BREW   -eq 1 && -n "$brew_pkg" ]]; then brew install "$brew_pkg" >/dev/null 2>&1
     else return 1
     fi
 }
@@ -164,11 +165,14 @@ _menu_checkbox() {
     local _key _esc _i
 
     tput civis 2>/dev/null   # hide cursor
-    _menu_draw
+    local _first=1
 
     while true; do
+        if [[ $_first -eq 0 ]]; then
             tput cuu "$_lines" 2>/dev/null   # move back to top of menu
+        fi
         _menu_draw
+        _first=0
 
         IFS= read -r -s -n1 _key </dev/tty
         if [[ $_key == $'\x1b' ]]; then
@@ -412,6 +416,9 @@ _vim_run() {
         vim --not-a-term "$@" 2>/dev/null
     fi
 }
+if [[ -d "$HOME/.vim/plugged" ]] && [[ -n "$(ls -A "$HOME/.vim/plugged" 2>/dev/null)" ]]; then
+    warn "PlugClean: removing plugins not listed in .vimrc from ~/.vim/plugged"
+fi
 _vim_run +'PlugClean!' +qall || true  # remove plugins no longer in vimrc; ignore exit code (none expected)
 _vim_run +'PlugInstall --sync' +qall || true  # fzf post-install hook may exit non-zero; harmless
 
@@ -558,6 +565,10 @@ _do_binary_apt() {
     if command -v "$check" >/dev/null 2>&1; then
         ok "$name (already installed)"; return
     fi
+    if [[ $HAS_SUDO -ne 1 ]]; then
+        fail "$name — sudo not available, cannot install to /usr/local/bin"
+        FAILED+=("$name"); return
+    fi
     if safe_download "$url" "$tmp"; then
         chmod +x "$tmp" && sudo mv "$tmp" /usr/local/bin/"$check"
         ok "$name"; INSTALLED+=("$name")
@@ -583,20 +594,38 @@ elif [[ $HAS_APT -eq 1 ]]; then
     _do_sys "shellcheck"      shellcheck "$_I_SHELLCHECK" "" shellcheck      "" ""
 
     # hadolint: no apt package — binary from GitHub releases
+    if [[ $_I_HADOLINT -ge 0 ]] && _selected "$_I_HADOLINT"; then
         HARCH=$(arch_github)
         HVER=$(curl -fsSL https://api.github.com/repos/hadolint/hadolint/releases/latest \
                | grep '"tag_name"' | cut -d'"' -f4 2>/dev/null) || HVER=""
+        if [[ -z "$HVER" ]]; then
+            fail "hadolint — could not determine latest release version"
+            FAILED+=("hadolint")
+        else
             _do_binary_apt "hadolint" hadolint "$_I_HADOLINT" \
                 "https://github.com/hadolint/hadolint/releases/download/${HVER}/hadolint-Linux-${HARCH}" \
                 /tmp/chopsticks-hadolint
+        fi
+    else
+        skip "hadolint"; SKIPPED+=("hadolint")
+    fi
 
     # marksman: no apt package — binary from GitHub releases
+    if [[ $_I_MARKSMAN -ge 0 ]] && _selected "$_I_MARKSMAN"; then
         MARCH=$(arch_linux_x64)
         MVER=$(curl -fsSL https://api.github.com/repos/artempyanykh/marksman/releases/latest \
                | grep '"tag_name"' | cut -d'"' -f4 2>/dev/null) || MVER=""
+        if [[ -z "$MVER" ]]; then
+            fail "marksman — could not determine latest release version"
+            FAILED+=("marksman")
+        else
             _do_binary_apt "marksman" marksman "$_I_MARKSMAN" \
                 "https://github.com/artempyanykh/marksman/releases/download/${MVER}/marksman-linux-${MARCH}" \
                 /tmp/chopsticks-marksman
+        fi
+    else
+        skip "marksman"; SKIPPED+=("marksman")
+    fi
 
 elif [[ $HAS_PACMAN -eq 1 ]]; then
     _do_sys "ripgrep"         rg         "$_I_RIPGREP"    "" "" ripgrep    ""
@@ -610,16 +639,22 @@ elif [[ $HAS_DNF -eq 1 ]]; then
     _do_sys "ripgrep"         rg         "$_I_RIPGREP"    "" "" "" ripgrep
     _do_sys "fzf"             fzf        "$_I_FZF"        "" "" "" fzf
     _do_sys "shellcheck"      shellcheck "$_I_SHELLCHECK" "" "" "" ShellCheck
-    if [[ $_I_CTAGS -ge 0 ]] && _selected "$_I_CTAGS"; then
+    if [[ $_I_CTAGS -ge 0 ]]; then
+        if _selected "$_I_CTAGS"; then
             skip "universal-ctags — Fedora: install manually: sudo dnf install ctags"
+        fi
         SKIPPED+=("universal-ctags")
     fi
-    if [[ $_I_HADOLINT -ge 0 ]] && _selected "$_I_HADOLINT"; then
+    if [[ $_I_HADOLINT -ge 0 ]]; then
+        if _selected "$_I_HADOLINT"; then
             skip "hadolint — Fedora: install manually: https://github.com/hadolint/hadolint/releases"
+        fi
         SKIPPED+=("hadolint")
     fi
-    if [[ $_I_MARKSMAN -ge 0 ]] && _selected "$_I_MARKSMAN"; then
+    if [[ $_I_MARKSMAN -ge 0 ]]; then
+        if _selected "$_I_MARKSMAN"; then
             skip "marksman — Fedora: install manually: https://github.com/artempyanykh/marksman/releases"
+        fi
         SKIPPED+=("marksman")
     fi
 else