--- a/runtime/indent/context.vim
+++ b/runtime/indent/context.vim
@@ -1,36 +1,65 @@
-" ConTeXt indent file
-" Language: ConTeXt typesetting engine
-" Maintainer: Nicola Vitacolonna <nvitacolonna@gmail.com>
-" Last Change:  2016 Oct 15
+vim9script
+
+# Language:           ConTeXt typesetting engine
+# Maintainer:         Nicola Vitacolonna <nvitacolonna@gmail.com>
+# Former Maintainers: Nikolai Weibull <now@bitwi.se>
+# Latest Revision:    2022 Aug 12
 
 if exists("b:did_indent")
   finish
 endif
 
-if !get(b:, 'context_metapost', get(g:, 'context_metapost', 1))
-  finish
-endif
-
-" Load MetaPost indentation script
+# Load MetaPost indentation script (this will also set b:did_indent)
 runtime! indent/mp.vim
 
-let s:keepcpo= &cpo
-set cpo&vim
+setlocal indentexpr=ConTeXtIndent()
+
+b:undo_indent = "setl indentexpr<"
 
-setlocal indentexpr=GetConTeXtIndent()
+def PrevNotComment(l: number): number
+  var prevlnum = prevnonblank(l)
+
+  while prevlnum > 0 && getline(prevlnum) =~# '^\s*%'
+    prevlnum = prevnonblank(prevlnum - 1)
+  endwhile
 
-let b:undo_indent = "setl indentexpr<"
+  return prevlnum
+enddef
 
-function! GetConTeXtIndent()
-  " Use MetaPost rules inside MetaPost graphic environments
+def FindPair(pstart: string, pmid: string, pend: string): number
+  cursor(v:lnum, 1)
+  return indent(searchpair(pstart, pmid, pend, 'bWn',
+    'synIDattr(synID(line("."), col("."), 0), "name") =~? "string\\|comment"'))
+enddef
+
+def ConTeXtIndent(): number
+  # Use MetaPost rules inside MetaPost graphic environments
   if len(synstack(v:lnum, 1)) > 0 &&
-        \ synIDattr(synstack(v:lnum, 1)[0], "name") ==# 'contextMPGraphic'
-    return GetMetaPostIndent()
+    synIDattr(synstack(v:lnum, 1)[0], "name") ==# 'contextMPGraphic'
+    return g:MetaPostIndent()
   endif
+
+  const prevlnum = PrevNotComment(v:lnum - 1)
+  const prevind  = indent(prevlnum)
+  const prevline = getline(prevlnum)
+  const currline = getline(v:lnum)
+
+  # If the current line starts with ], match indentation.
+  if currline =~# '^\s*\]'
+    return FindPair('\[', '', '\]')
+  endif
+
+  # If the current line starts with }, match indentation.
+  if currline =~# '^\s*}'
+    return FindPair('{', '', '}')
+  endif
+
+  # If the previous line ends with [ or { (possibly followed by a comment) then indent.
+  if prevline =~# '[{[]\s*\%(%.*\)\=$'
+    return prevind + shiftwidth()
+  endif
+
   return -1
-endfunc
+enddef
 
-let &cpo = s:keepcpo
-unlet s:keepcpo
-
-" vim:sw=2
+# vim: sw=2 fdm=marker