Fix zt to consider context.vim's context height

autoload/smooth_scroll.vim

@@ -15,13 +15,13 @@ set cpo&vim
 " Scroll the screen up
 function! smooth_scroll#up(dist)
   let move_only = max([0, &scrolloff - (line('w$') - line("."))])
-  call s:smooth_scroll('u', a:dist - l:move_only, 1)
+  call s:smooth_scroll('u', max([0, a:dist - l:move_only]), 1)
 endfunction
 
 " Scroll the screen down
 function! smooth_scroll#down(dist)
   let move_only = max([0, &scrolloff - (line(".") - line('w0'))])
-  call s:smooth_scroll('d', a:dist - l:move_only, 1)
+  call s:smooth_scroll('d', max([0, a:dist - l:move_only]), 1)
 endfunction
 
 " Scroll to the center
@@ -54,12 +54,15 @@ function! smooth_scroll#top(visual)
   endif
   let saved_mode=mode()
 
+  call s:prepare_context_top_scroll()
   let cur_top = line('w0') + &scrolloff
   let target_top = line('.')
-  let num_down =  l:target_top - l:cur_top
+  let context_height = s:context_height()
+  let num_down =  l:target_top - l:cur_top - l:context_height
   if l:num_down > 0
     call s:smooth_scroll('d', l:num_down, 0)
   endif
+  call s:update_context_after_top_scroll()
 
   " Restore visual mode
   if l:saved_mode == "v" || l:saved_mode == "V"
@@ -91,11 +94,58 @@ endfunction
 " Functions
 " ==============================================================================
 
+function! s:context_active() abort
+  if !exists('g:context') || type(g:context) != v:t_dict
+    return 0
+  endif
+  if get(g:context, 'presenter', '') ==# 'preview'
+    return 0
+  endif
+  if !exists('w:context') || type(w:context) != v:t_dict || get(w:context, 'enabled', get(g:context, 'enabled', 1)) == 0
+    return 0
+  endif
+  if get(g:context, 'enabled', 1) == 0
+    return 0
+  endif
+  if get(get(g:context, 'filetype_blacklist', {}), &filetype, 0) || get(get(g:context, 'buftype_blacklist', {}), &buftype, 0)
+    return 0
+  endif
+
+  return 1
+endfunction
+
+function! s:context_height() abort
+  if !s:context_active()
+    return 0
+  endif
+
+  let l:height = len(get(w:context, 'lines', []))
+
+  " Make room for context.vim's separator line when a context popup is visible.
+  return l:height > 0 ? l:height + get(g:context, 'show_border', 0) : 0
+endfunction
+
+function! s:prepare_context_top_scroll() abort
+  if s:context_active()
+    let w:context.force_fix_strategy = 'scroll'
+  endif
+endfunction
+
+function! s:update_context_after_top_scroll() abort
+  if exists('*context#update') && s:context_active()
+    silent! call context#update('smooth-scroll-zt')
+  endif
+endfunction
+
 " Scroll the window smoothly
 " dir: Direction of the scroll. 'd' is downwards, 'u' is upwards
 " dist: Distance, or the total number of lines to scroll
 " move: when 1, move the cursor too
 function! s:smooth_scroll(dir, dist, move)
+  if a:dist <= 0
+    return
+  endif
+
   let move_cmd=''
   if a:move == 1
     if a:dir ==# 'd'