Merge 10298f4533 into 7121983c45

feat(treesitter): vertical conceal for conceal nodes
TSHighlighter now places marks for conceal_lines metadata. A new internal decor provider callback _on_conceal_line was added that instructs the highlighter to place conceal_lines marks whenever the editor needs to know whether a line is concealed. The bundled markdown queries use `conceal_lines` metadata to conceal code block fence lines.
2024-12-19 02:34:59 -07:00 · 2024-12-18 14:40:43 +00:00 · 2024-12-12 18:33:52 +01:00 · 2024-12-12 18:32:39 +01:00
30 changed files with 688 additions and 157 deletions
--- a/runtime/doc/api.txt
+++ b/runtime/doc/api.txt
@ -2772,6 +2772,10 @@ nvim_buf_set_extmark({buffer}, {ns_id}, {line}, {col}, {opts})
                    When a character is supplied it is used as |:syn-cchar|.
                    "hl_group" is used as highlight for the cchar if provided,
                    otherwise it defaults to |hl-Conceal|.
+                  • conceal_lines: string which should be either empty or a
+                    single character. When provided, lines in the range are
+                    not drawn at all; the next unconcealed line is drawn
+                    instead.
                  • spell: boolean indicating that spell checking should be
                    performed within this extmark
                  • ui_watched: boolean that indicates the mark should be
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@ -178,6 +178,7 @@ API

 • |nvim__ns_set()| can set properties for a namespace
 • |vim.json.encode()| has an option to enable forward slash escaping
+• New |nvim_buf_set_extmark()| flag `conceal_lines` to conceal an entire line.

 DEFAULTS

@ -303,6 +304,8 @@ TREESITTER
 • |treesitter-directive-trim!| can trim all whitespace (not just empty lines)
  from both sides of a node.
 • |vim.treesitter.get_captures_at_pos()| now returns the `id` of each capture
+• Bundled markdown highlight queries use `conceal_lines` metadata to conceal
+  code block fence lines vertically.

 TUI

--- a/runtime/doc/treesitter.txt
+++ b/runtime/doc/treesitter.txt
@ -493,10 +493,10 @@ capture marks comments as to be checked: >query
 There is also `@nospell` which disables spellchecking regions with `@spell`.

                                                *treesitter-highlight-conceal*
-Treesitter highlighting supports |conceal| via the `conceal` metadata. By
-convention, nodes to be concealed are captured as `@conceal`, but any capture
-can be used. For example, the following query can be used to hide code block
-delimiters in Markdown: >query
+Treesitter highlighting supports |conceal| via the `conceal` and `conceal_lines`
+metadata. By convention, nodes to be concealed are captured as `@conceal`, but
+any capture can be used. For example, the following query can be used to hide
+code block delimiters in Markdown: >query

    (fenced_code_block_delimiter @conceal (#set! conceal ""))
 <
@ -507,7 +507,13 @@ still highlighted the same as other operators: >query

    "!=" @operator (#set! conceal "≠")
 <
-Conceals specified in this way respect 'conceallevel'.
+To conceal an entire line (do not draw it at all), a query with `conceal_lines`
+metadata can be used: >query
+
+    ((comment) @comment @spell
+      (#set! conceal_lines ""))
+<
+Conceals specified in this way respect 'conceallevel' and 'concealcursor'.

                                               *treesitter-highlight-priority*
 Treesitter uses |nvim_buf_set_extmark()| to set highlights with a default
--- a/runtime/lua/vim/_meta/api.lua
+++ b/runtime/lua/vim/_meta/api.lua
@ -686,6 +686,9 @@ function vim.api.nvim_buf_line_count(buffer) end
 ---     When a character is supplied it is used as `:syn-cchar`.
 ---     "hl_group" is used as highlight for the cchar if provided,
 ---     otherwise it defaults to `hl-Conceal`.
+--- - conceal_lines: string which should be either empty or a single
+---     character. When provided, lines in the range are not drawn
+---     at all; the next unconcealed line is drawn instead.
 --- - spell: boolean indicating that spell checking should be
 ---     performed within this extmark
 --- - ui_watched: boolean that indicates the mark should be drawn
--- a/runtime/lua/vim/_meta/api_keysets.lua
+++ b/runtime/lua/vim/_meta/api_keysets.lua
@ -234,6 +234,7 @@ error('Cannot require a meta file')
 --- @field on_end? fun(_: "end", tick: integer)
 --- @field _on_hl_def? fun(_: "hl_def")
 --- @field _on_spell_nav? fun(_: "spell_nav")
+--- @field _on_conceal_line? fun(_: "conceal_line")

 --- @class vim.api.keyset.set_extmark
 --- @field id? integer
@ -263,6 +264,7 @@ error('Cannot require a meta file')
 --- @field line_hl_group? integer|string
 --- @field cursorline_hl_group? integer|string
 --- @field conceal? string
+--- @field conceal_lines? string
 --- @field spell? boolean
 --- @field ui_watched? boolean
 --- @field undo_restore? boolean
--- a/runtime/lua/vim/treesitter/highlighter.lua
+++ b/runtime/lua/vim/treesitter/highlighter.lua
@ -67,6 +67,8 @@ end
 --- This state is kept during rendering across each line update.
 ---@field private _highlight_states vim.treesitter.highlighter.State[]
 ---@field private _queries table<string,vim.treesitter.highlighter.Query>
+---@field  _conceal_line boolean?
+---@field  _conceal_checked table<integer, boolean>
 ---@field tree vim.treesitter.LanguageTree
 ---@field private redraw_count integer
 local TSHighlighter = {
@ -114,7 +116,7 @@ function TSHighlighter.new(tree, opts)

  self.bufnr = source
  self.redraw_count = 0
-  self._highlight_states = {}
+  self._conceal_checked = {}
  self._queries = {}

  -- Queries for a specific language can be overridden by a custom
@ -122,6 +124,7 @@ function TSHighlighter.new(tree, opts)
  if opts.queries then
    for lang, query_string in pairs(opts.queries) do
      self._queries[lang] = TSHighlighterQuery.new(lang, query_string)
+      self._conceal_line = self._conceal_line or self._queries[lang]:query().conceal_line
    end
  end

@ -140,7 +143,7 @@ function TSHighlighter.new(tree, opts)
  -- immediately afterwards will not error.
  if vim.g.syntax_on ~= 1 then
    vim.cmd.runtime({ 'syntax/synload.vim', bang = true })
-    vim.api.nvim_create_augroup('syntaxset', { clear = false })
+    api.nvim_create_augroup('syntaxset', { clear = false })
  end

  vim._with({ buf = self.bufnr }, function()
@ -148,6 +151,7 @@ function TSHighlighter.new(tree, opts)
  end)

  self.tree:parse()
+  self:set_decoration_provider()

  return self
 end
@ -160,6 +164,7 @@ function TSHighlighter:destroy()
  if api.nvim_buf_is_loaded(self.bufnr) then
    vim.bo[self.bufnr].spelloptions = self.orig_spelloptions
    vim.b[self.bufnr].ts_highlight = nil
+    api.nvim_buf_clear_namespace(self.bufnr, ns, 0, -1)
    if vim.g.syntax_on == 1 then
      api.nvim_exec_autocmds('FileType', { group = 'syntaxset', buffer = self.bufnr })
    end
@ -185,10 +190,14 @@ function TSHighlighter:prepare_highlight_states(srow, erow)
      return
    end

-    local highlighter_query = self:get_query(tree:lang())
+    local hl_query = self:get_query(tree:lang())
+    if hl_query:query().conceal_line and not self._conceal_line then
+      self._conceal_line = true
+      self:set_decoration_provider()
+    end

    -- Some injected languages may not have highlight queries.
-    if not highlighter_query:query() then
+    if not hl_query:query() then
      return
    end

@ -198,7 +207,7 @@ function TSHighlighter:prepare_highlight_states(srow, erow)
      tstree = tstree,
      next_row = 0,
      iter = nil,
-      highlighter_query = highlighter_query,
+      highlighter_query = hl_query,
    })
  end)
 end
@ -220,7 +229,10 @@ end
 ---@param changes Range6[]
 function TSHighlighter:on_changedtree(changes)
  for _, ch in ipairs(changes) do
-    api.nvim__redraw({ buf = self.bufnr, range = { ch[1], ch[4] + 1 }, flush = false })
+    api.nvim__redraw({ buf = self.bufnr, range = { ch[1], ch[4] }, flush = false })
+    for i = ch[1], self._conceal_line and ch[4] or 0 do
+      self._conceal_checked[i] = false
+    end
  end
 end

@ -279,8 +291,10 @@ end
 ---@param self vim.treesitter.highlighter
 ---@param buf integer
 ---@param line integer
---@param is_spell_nav boolean
-local function on_line_impl(self, buf, line, is_spell_nav)
+---@param on_spell boolean
+---@param on_conceal boolean
+local function on_line_impl(self, buf, line, on_spell, on_conceal)
+  self._conceal_checked[line] = true
  self:for_each_highlight_state(function(state)
    local root_node = state.tstree:root()
    local root_start_row, _, root_end_row, _ = root_node:range()
@ -326,7 +340,7 @@ local function on_line_impl(self, buf, line, is_spell_nav)

        local url = get_url(match, buf, capture, metadata)

-        if hl and end_row >= line and (not is_spell_nav or spell ~= nil) then
+        if hl and end_row >= line and not on_conceal and (not on_spell or spell ~= nil) then
          api.nvim_buf_set_extmark(buf, ns, start_row, start_col, {
            end_line = end_row,
            end_col = end_col,
@ -338,6 +352,16 @@ local function on_line_impl(self, buf, line, is_spell_nav)
            url = url,
          })
        end
+
+        if
+          (metadata.conceal_lines or metadata[capture] and metadata[capture].conceal_lines)
+          and #api.nvim_buf_get_extmarks(buf, ns, { start_row, 0 }, { start_row, 0 }, {}) == 0
+        then
+          api.nvim_buf_set_extmark(buf, ns, start_row, 0, {
+            end_line = end_row,
+            conceal_lines = '',
+          })
+        end
      end

      if start_row > line then
@ -357,7 +381,7 @@ function TSHighlighter._on_line(_, _win, buf, line, _)
    return
  end

-  on_line_impl(self, buf, line, false)
+  on_line_impl(self, buf, line, false, false)
 end

 ---@private
@ -376,17 +400,45 @@ function TSHighlighter._on_spell_nav(_, _, buf, srow, _, erow, _)
  self:prepare_highlight_states(srow, erow)

  for row = srow, erow do
-    on_line_impl(self, buf, row, true)
+    on_line_impl(self, buf, row, true, false)
  end
  self._highlight_states = highlight_states
 end

 ---@private
---@param _win integer
+---@param buf integer
+---@param row integer
+function TSHighlighter._on_conceal_line(_, _, buf, row)
+  local self = TSHighlighter.active[buf]
+  if not self or self._conceal_checked[row] then
+    return
+  end
+
+  -- Do not affect potentially populated highlight state.
+  local highlight_states = self._highlight_states
+  self:prepare_highlight_states(row, row)
+  on_line_impl(self, buf, row, false, true)
+  self._highlight_states = highlight_states
+end
+
+---@private
+--- Clear conceal_lines marks whenever we redraw for a buffer change. Marks are
+--- added back as either the _conceal_line or on_win callback comes across them.
+function TSHighlighter._on_buf(_, buf)
+  local self = TSHighlighter.active[buf]
+  if not self then
+    return
+  end
+
+  api.nvim_buf_clear_namespace(buf, ns, 0, -1)
+  self._conceal_checked = {}
+end
+
+---@private
 ---@param buf integer
 ---@param topline integer
 ---@param botline integer
-function TSHighlighter._on_win(_, _win, buf, topline, botline)
+function TSHighlighter._on_win(_, _, buf, topline, botline)
  local self = TSHighlighter.active[buf]
  if not self then
    return false
@ -397,10 +449,15 @@ function TSHighlighter._on_win(_, _win, buf, topline, botline)
  return true
 end

-api.nvim_set_decoration_provider(ns, {
-  on_win = TSHighlighter._on_win,
-  on_line = TSHighlighter._on_line,
-  _on_spell_nav = TSHighlighter._on_spell_nav,
-})
+---@private
+function TSHighlighter:set_decoration_provider()
+  api.nvim_set_decoration_provider(ns, {
+    on_win = TSHighlighter._on_win,
+    on_line = TSHighlighter._on_line,
+    _on_spell_nav = TSHighlighter._on_spell_nav,
+    _on_conceal_line = self._conceal_line and TSHighlighter._on_conceal_line or nil,
+    on_buf = self._conceal_line and TSHighlighter._on_buf or nil,
+  })
+end

 return TSHighlighter
--- a/runtime/lua/vim/treesitter/query.lua
+++ b/runtime/lua/vim/treesitter/query.lua
@ -11,6 +11,7 @@ local M = {}
 ---@field lang string name of the language for this parser
 ---@field captures string[] list of (unique) capture names defined in query
 ---@field info vim.treesitter.QueryInfo contains information used in the query (e.g. captures, predicates, directives)
+---@field conceal_line boolean whether this query sets conceal_lines metadata.
 ---@field query TSQuery userdata query object
 local Query = {}
 Query.__index = Query
@ -30,6 +31,17 @@ function Query.new(lang, ts_query)
    patterns = query_info.patterns,
  }
  self.captures = self.info.captures
+
+  -- Instruct highlighter to place marks when query contains conceal_lines metadata.
+  for _, preds in pairs(self.info.patterns) do
+    for _, pred in ipairs(preds) do
+      if vim.deep_equal(pred, { 'set!', 'conceal_lines', '' }) then
+        self.conceal_line = true
+        break
+      end
+    end
+  end
+
  return self
 end

--- a/runtime/queries/markdown/highlights.scm
+++ b/runtime/queries/markdown/highlights.scm
@ -49,12 +49,12 @@

 (fenced_code_block
  (fenced_code_block_delimiter) @markup.raw.block
-  (#set! conceal ""))
+  (#set! conceal_lines ""))

 (fenced_code_block
  (info_string
    (language) @label
-    (#set! conceal "")))
+    (#set! conceal_lines "")))

 (link_destination) @markup.link.url

--- a/src/nvim/api/extmark.c
+++ b/src/nvim/api/extmark.c
@ -475,6 +475,9 @@ Array nvim_buf_get_extmarks(Buffer buffer, Integer ns_id, Object start, Object e
 ///                   When a character is supplied it is used as |:syn-cchar|.
 ///                   "hl_group" is used as highlight for the cchar if provided,
 ///                   otherwise it defaults to |hl-Conceal|.
+///               - conceal_lines: string which should be either empty or a single
+///                   character. When provided, lines in the range are not drawn
+///                   at all; the next unconcealed line is drawn instead.
 ///               - spell: boolean indicating that spell checking should be
 ///                   performed within this extmark
 ///               - ui_watched: boolean that indicates the mark should be drawn
@ -575,6 +578,11 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
    }
  }

+  if (HAS_KEY(opts, set_extmark, conceal_lines)) {
+    hl.flags |= kSHConcealLines;
+    has_hl = true;
+  }
+
  if (HAS_KEY(opts, set_extmark, virt_text)) {
    virt_text.data.virt_text = parse_virt_text(opts->virt_text, err, &virt_text.width);
    if (ERROR_SET(err)) {
@ -793,6 +801,10 @@ Integer nvim_buf_set_extmark(Buffer buffer, Integer ns_id, Integer line, Integer
      }
    }

+    if (hl.flags & kSHConcealLines) {
+      decor_flags |= MT_FLAG_DECOR_CONCEAL_LINES;
+    }
+
    DecorInline decor = DECOR_INLINE_INIT;
    if (decor_alloc || decor_indexed != DECOR_ID_INVALID || url != NULL
        || schar_high(hl.conceal_char)) {
@ -1052,6 +1064,7 @@ void nvim_set_decoration_provider(Integer ns_id, Dict(set_decoration_provider) *
    { "on_end", &opts->on_end, &p->redraw_end },
    { "_on_hl_def", &opts->_on_hl_def, &p->hl_def },
    { "_on_spell_nav", &opts->_on_spell_nav, &p->spell_nav },
+    { "_on_conceal_line", &opts->_on_conceal_line, &p->conceal_line },
    { NULL, NULL, NULL },
  };

--- a/src/nvim/api/keysets_defs.h
+++ b/src/nvim/api/keysets_defs.h
@ -20,6 +20,7 @@ typedef struct {
  LuaRefOf(("end" _, Integer tick)) on_end;
  LuaRefOf(("hl_def" _)) _on_hl_def;
  LuaRefOf(("spell_nav" _)) _on_spell_nav;
+  LuaRefOf(("conceal_line" _)) _on_conceal_line;
 } Dict(set_decoration_provider);

 typedef struct {
@ -51,6 +52,7 @@ typedef struct {
  HLGroupID line_hl_group;
  HLGroupID cursorline_hl_group;
  String conceal;
+  String conceal_lines;
  Boolean spell;
  Boolean ui_watched;
  Boolean undo_restore;
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@ -811,6 +811,7 @@ typedef struct {
  uint16_t wl_size;             // height in screen lines
  char wl_valid;                // true values are valid for text in buffer
  char wl_folded;               // true when this is a range of folded lines
+  linenr_T wl_foldend;          // last buffer line number for folded line
  linenr_T wl_lastlnum;         // last buffer line number for logical line
 } wline_T;

--- a/src/nvim/change.c
+++ b/src/nvim/change.c
@ -206,9 +206,10 @@ static void changed_lines_invalidate_win(win_T *wp, linenr_T lnum, colnr_T col,
        } else if (xtra != 0) {
          // line below change
          wp->w_lines[i].wl_lnum += xtra;
+          wp->w_lines[i].wl_foldend += xtra;
          wp->w_lines[i].wl_lastlnum += xtra;
        }
-      } else if (wp->w_lines[i].wl_lastlnum >= lnum) {
+      } else if (wp->w_lines[i].wl_foldend >= lnum) {
        // change somewhere inside this range of folded lines,
        // may need to be redrawn
        wp->w_lines[i].wl_valid = false;
--- a/src/nvim/decoration.c
+++ b/src/nvim/decoration.c
@ -12,6 +12,7 @@
 #include "nvim/buffer_defs.h"
 #include "nvim/change.h"
 #include "nvim/decoration.h"
+#include "nvim/decoration_provider.h"
 #include "nvim/drawscreen.h"
 #include "nvim/extmark.h"
 #include "nvim/fold.h"
@ -125,6 +126,13 @@ void decor_redraw_sh(buf_T *buf, int row1, int row2, DecorSignHighlight sh)
      redraw_buf_range_later(buf, row1 + 1, row2 + 1);
    }
  }
+  if (sh.flags & kSHConcealLines) {
+    FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+      if (wp->w_buffer == buf) {
+        changed_window_setting(wp);
+      }
+    }
+  }
  if (sh.flags & kSHUIWatched) {
    redraw_buf_line_later(buf, row1 + 1, false);
  }
@ -833,8 +841,56 @@ int sign_item_cmp(const void *p1, const void *p2)
  return 0;
 }

-static const uint32_t sign_filter[4] = {[kMTMetaSignText] = kMTFilterSelect,
-                                        [kMTMetaSignHL] = kMTFilterSelect };
+static const uint32_t conceal_filter[kMTMetaCount] = {[kMTMetaConcealLines] = kMTFilterSelect };
+
+bool decor_conceal_line(win_T *wp, int row, bool check_cursor)
+{
+  if (wp->w_p_cole < 2
+      || (!check_cursor && ((row + 1 == wp->w_cursor.lnum) && !conceal_cursor_line(wp)))) {
+    return false;
+  }
+
+  size_t keys = wp->w_buffer->b_marktree->n_keys;
+  if (!buf_meta_total(wp->w_buffer, kMTMetaConcealLines)) {
+    decor_providers_invoke_conceal_line(wp, row);
+    return wp->w_buffer->b_marktree->n_keys > keys;
+  }
+
+  MTPair pair;
+  MarkTreeIter itr[1];
+  marktree_itr_get_overlap(wp->w_buffer->b_marktree, row, 0, itr);
+  while (marktree_itr_step_overlap(wp->w_buffer->b_marktree, itr, &pair)) {
+    if (mt_conceal_lines(pair.start) && ns_in_win(pair.start.ns, wp)) {
+      return true;
+    }
+  }
+
+  marktree_itr_step_out_filter(wp->w_buffer->b_marktree, itr, conceal_filter);
+
+  while (itr->x) {
+    MTKey mark = marktree_itr_current(itr);
+    if (mark.pos.row > row) {
+      break;
+    }
+    if (mt_conceal_lines(mark) && ns_in_win(pair.start.ns, wp)) {
+      return true;
+    }
+    marktree_itr_next_filter(wp->w_buffer->b_marktree, itr, row + 1, 0, conceal_filter);
+  }
+
+  decor_providers_invoke_conceal_line(wp, row);
+  return wp->w_buffer->b_marktree->n_keys > keys;
+}
+
+bool win_lines_concealed(win_T *wp)
+{
+  return hasAnyFolding(wp)
+         || (wp->w_p_cole >= 2
+             && (conceal_provider || buf_meta_total(wp->w_buffer, kMTMetaConcealLines)));
+}
+
+static const uint32_t sign_filter[kMTMetaCount] = {[kMTMetaSignText] = kMTFilterSelect,
+                                                   [kMTMetaSignHL] = kMTFilterSelect };

 /// Return the sign attributes on the currently refreshed row.
 ///
@ -856,7 +912,7 @@ void decor_redraw_signs(win_T *wp, buf_T *buf, int row, SignTextAttrs sattrs[],
  // TODO(bfredl): integrate with main decor loop.
  marktree_itr_get_overlap(buf->b_marktree, row, 0, itr);
  while (marktree_itr_step_overlap(buf->b_marktree, itr, &pair)) {
-    if (!mt_invalid(pair.start) && mt_decor_sign(pair.start)) {
+    if (!mt_invalid(pair.start) && mt_decor_sign(pair.start) && ns_in_win(pair.start.ns, wp)) {
      DecorSignHighlight *sh = decor_find_sign(mt_decor(pair.start));
      num_text += (sh->text[0] != NUL);
      kv_push(signs, ((SignItem){ sh, pair.start.id }));
@ -923,7 +979,7 @@ DecorSignHighlight *decor_find_sign(DecorInline decor)
  }
 }

-static const uint32_t signtext_filter[4] = {[kMTMetaSignText] = kMTFilterSelect };
+static const uint32_t signtext_filter[kMTMetaCount] = {[kMTMetaSignText] = kMTFilterSelect };

 /// Count the number of signs in a range after adding/removing a sign, or to
 /// (re-)initialize a range in "b_signcols.count".
@ -1018,7 +1074,7 @@ bool decor_redraw_eol(win_T *wp, DecorState *state, int *eol_attr, int eol_col)
  return has_virt_pos;
 }

-static const uint32_t lines_filter[4] = {[kMTMetaLines] = kMTFilterSelect };
+static const uint32_t lines_filter[kMTMetaCount] = {[kMTMetaLines] = kMTFilterSelect };

 /// @param apply_folds Only count virtual lines that are not in folds.
 int decor_virt_lines(win_T *wp, int start_row, int end_row, VirtLines *lines, bool apply_folds)
@ -1049,7 +1105,8 @@ int decor_virt_lines(win_T *wp, int start_row, int end_row, VirtLines *lines, bo
          int mrow = mark.pos.row;
          int draw_row = mrow + (above ? 0 : 1);
          if (draw_row >= start_row && draw_row < end_row
-              && (!apply_folds || !hasFolding(wp, mrow + 1, NULL, NULL))) {
+              && (!apply_folds || !(hasFolding(wp, mrow + 1, NULL, NULL)
+                                    || decor_conceal_line(wp, mrow, false)))) {
            virt_lines += (int)kv_size(vt->data.virt_lines);
            if (lines) {
              kv_splice(*lines, vt->data.virt_lines);
@ -1116,6 +1173,10 @@ void decor_to_dict_legacy(Dict *dict, DecorInline decor, bool hl_name, Arena *ar
    PUT_C(*dict, "conceal", CSTR_TO_ARENA_OBJ(arena, buf));
  }

+  if (sh_hl.flags & kSHConcealLines) {
+    PUT_C(*dict, "conceal_lines", STRING_OBJ(cstr_as_string("")));
+  }
+
  if (sh_hl.flags & kSHSpellOn) {
    PUT_C(*dict, "spell", BOOLEAN_OBJ(true));
  } else if (sh_hl.flags & kSHSpellOff) {
--- a/src/nvim/decoration_defs.h
+++ b/src/nvim/decoration_defs.h
@ -46,6 +46,7 @@ enum {
  kSHSpellOn = 16,
  kSHSpellOff = 32,
  kSHConceal = 64,
+  kSHConcealLines = 128,
 };

 typedef struct {
@ -143,6 +144,7 @@ typedef struct {
  LuaRef redraw_end;
  LuaRef hl_def;
  LuaRef spell_nav;
+  LuaRef conceal_line;
  int hl_valid;
  bool hl_cached;

--- a/src/nvim/decoration_provider.c
+++ b/src/nvim/decoration_provider.c
@ -30,7 +30,7 @@ static kvec_t(DecorProvider) decor_providers = KV_INITIAL_VALUE;
 #define DECORATION_PROVIDER_INIT(ns_id) (DecorProvider) \
  { ns_id, kDecorProviderDisabled, LUA_NOREF, LUA_NOREF, \
    LUA_NOREF, LUA_NOREF, LUA_NOREF, \
-    LUA_NOREF, -1, false, false, 0 }
+    LUA_NOREF, LUA_NOREF, -1, false, false, 0 }

 static void decor_provider_error(DecorProvider *provider, const char *name, const char *msg)
 {
@ -92,6 +92,21 @@ void decor_providers_invoke_spell(win_T *wp, int start_row, int start_col, int e
  }
 }

+void decor_providers_invoke_conceal_line(win_T *wp, int row)
+{
+  for (size_t i = 0; i < kv_size(decor_providers); i++) {
+    DecorProvider *p = &kv_A(decor_providers, i);
+    if (p->state != kDecorProviderDisabled && p->conceal_line != LUA_NOREF) {
+      conceal_provider = true;
+      MAXSIZE_TEMP_ARRAY(args, 4);
+      ADD_C(args, INTEGER_OBJ(wp->handle));
+      ADD_C(args, INTEGER_OBJ(wp->w_buffer->handle));
+      ADD_C(args, INTEGER_OBJ(row));
+      decor_provider_invoke((int)i, "conceal_line", p->conceal_line, args, true);
+    }
+  }
+}
+
 /// For each provider invoke the 'start' callback
 ///
 /// @param[out] providers Decoration providers
@ -264,6 +279,7 @@ void decor_provider_clear(DecorProvider *p)
  NLUA_CLEAR_REF(p->redraw_line);
  NLUA_CLEAR_REF(p->redraw_end);
  NLUA_CLEAR_REF(p->spell_nav);
+  NLUA_CLEAR_REF(p->conceal_line);
  p->state = kDecorProviderDisabled;
 }

--- a/src/nvim/decoration_provider.h
+++ b/src/nvim/decoration_provider.h
@ -7,6 +7,7 @@
 #include "nvim/types_defs.h"  // IWYU pragma: keep

 EXTERN bool provider_active INIT( = false);
+EXTERN bool conceal_provider INIT( = false);

 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "decoration_provider.h.generated.h"
--- a/src/nvim/diff.c
+++ b/src/nvim/diff.c
@ -24,6 +24,7 @@
 #include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/diff.h"
 #include "nvim/drawscreen.h"
 #include "nvim/errors.h"
@ -2082,7 +2083,7 @@ int diff_check_with_linestatus(win_T *wp, linenr_T lnum, int *linestatus)
  }

  // A closed fold never has filler lines.
-  if (hasFolding(wp, lnum, NULL, NULL)) {
+  if (hasFolding(wp, lnum, NULL, NULL) || decor_conceal_line(wp, lnum - 1, false)) {
    return 0;
  }

--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@ -148,6 +148,11 @@ void conceal_check_cursor_line(void)
  }

  redrawWinline(curwin, curwin->w_cursor.lnum);
+
+  // Concealed line visibility toggled.
+  if (decor_conceal_line(curwin, curwin->w_cursor.lnum - 1, true)) {
+    changed_window_setting(curwin);
+  }
  // Need to recompute cursor column, e.g., when starting Visual mode
  // without concealing.
  curs_columns(curwin, true);
@ -1622,7 +1627,7 @@ static void win_update(win_T *wp)
      }
    }

-    if (mod_top != 0 && hasAnyFolding(wp)) {
+    if (mod_top != 0 && (win_lines_concealed(wp))) {
      // A change in a line can cause lines above it to become folded or
      // unfolded.  Find the top most buffer line that may be affected.
      // If the line was previously folded and displayed, get the first
@ -1719,12 +1724,12 @@ static void win_update(win_T *wp)
                       && wp->w_topfill > wp->w_old_topfill))) {
      // New topline is above old topline: May scroll down.
      int j;
-      if (hasAnyFolding(wp)) {
-        // count the number of lines we are off, counting a sequence
-        // of folded lines as one
+      if (win_lines_concealed(wp)) {
+        // Count the number of lines we are off, counting a sequence
+        // of folded lines as one, and skip concealed lines.
        j = 0;
        for (linenr_T ln = wp->w_topline; ln < wp->w_lines[0].wl_lnum; ln++) {
-          j++;
+          j += !decor_conceal_line(wp, ln - 1, false);
          if (j >= wp->w_grid.rows - 2) {
            break;
          }
@ -2109,6 +2114,28 @@ static void win_update(win_T *wp)
        top_to_mod = false;
      }

+      // When lines are folded, display one line for all of them.
+      // Otherwise, display normally (can be several display lines when
+      // 'wrap' is on).
+      foldinfo_T foldinfo = wp->w_p_cul && lnum == wp->w_cursor.lnum
+                            ? cursorline_fi : fold_info(wp, lnum);
+
+      // Concealed line: continue to next line on the same row.
+      if (decor_conceal_line(wp, lnum - 1, false)) {
+        if (wp == curwin && lnum == curwin->w_cursor.lnum) {
+          conceal_cursor_used = conceal_cursor_line(curwin);
+        }
+        if (idx > 0) {
+          wp->w_lines[idx - 1].wl_lastlnum = lnum + foldinfo.fi_lines - 1;
+        }
+        if (lnum == mod_top && lnum < mod_bot) {
+          mod_top += foldinfo.fi_lines ? foldinfo.fi_lines : 1;
+        }
+        lnum += foldinfo.fi_lines ? foldinfo.fi_lines : 1;
+        spv.spv_capcol_lnum = 0;
+        continue;
+      }
+
      // When at start of changed lines: May scroll following lines
      // up or down to minimize redrawing.
      // Don't do this when the change continues until the end.
@ -2158,8 +2185,10 @@ static void win_update(win_T *wp)
          // rows, and may insert/delete lines
          int j = idx;
          for (l = lnum; l < mod_bot; l++) {
+            linenr_T first = l;
+            int prev_rows = new_rows;
            if (hasFolding(wp, l, NULL, &l)) {
-              new_rows++;
+              new_rows += !decor_conceal_line(wp, first - 1, false);
            } else if (l == wp->w_topline) {
              int n = plines_win_nofill(wp, l, false) + wp->w_topfill
                      - adjust_plines_for_skipcol(wp);
@ -2168,7 +2197,8 @@ static void win_update(win_T *wp)
            } else {
              new_rows += plines_win(wp, l, true);
            }
-            j++;
+            // Do not increment when height was 0 (for a concealed line).
+            j += (prev_rows != new_rows);
            if (new_rows > wp->w_grid.rows - row - 2) {
              // it's getting too much, must redraw the rest
              new_rows = 9999;
@ -2250,12 +2280,6 @@ static void win_update(win_T *wp)
        }
      }

-      // When lines are folded, display one line for all of them.
-      // Otherwise, display normally (can be several display lines when
-      // 'wrap' is on).
-      foldinfo_T foldinfo = wp->w_p_cul && lnum == wp->w_cursor.lnum
-                            ? cursorline_fi : fold_info(wp, lnum);
-
      if (foldinfo.fi_lines == 0
          && idx < wp->w_lines_valid
          && wp->w_lines[idx].wl_valid
@ -2290,11 +2314,13 @@ static void win_update(win_T *wp)

        if (foldinfo.fi_lines == 0) {
          wp->w_lines[idx].wl_folded = false;
+          wp->w_lines[idx].wl_foldend = lnum;
          wp->w_lines[idx].wl_lastlnum = lnum;
          did_update = DID_LINE;
        } else {
          foldinfo.fi_lines--;
          wp->w_lines[idx].wl_folded = true;
+          wp->w_lines[idx].wl_foldend = lnum + foldinfo.fi_lines;
          wp->w_lines[idx].wl_lastlnum = lnum + foldinfo.fi_lines;
          did_update = DID_FOLD;
        }
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@ -15,6 +15,7 @@
 #include "nvim/change.h"
 #include "nvim/charset.h"
 #include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/digraph.h"
 #include "nvim/drawscreen.h"
 #include "nvim/edit.h"
@ -2577,15 +2578,15 @@ int oneleft(void)
  return OK;
 }

-/// Move the cursor up "n" lines in window "wp".
-/// Takes care of closed folds.
-void cursor_up_inner(win_T *wp, linenr_T n)
+/// Move the cursor up "n" lines in window "wp". Takes care of closed folds.
+/// Skips over concealed lines when "skip_conceal" is true.
+void cursor_up_inner(win_T *wp, linenr_T n, bool skip_conceal)
 {
  linenr_T lnum = wp->w_cursor.lnum;

  if (n >= lnum) {
    lnum = 1;
-  } else if (hasAnyFolding(wp)) {
+  } else if (win_lines_concealed(wp)) {
    // Count each sequence of folded lines as one logical line.

    // go to the start of the current fold
@ -2594,6 +2595,7 @@ void cursor_up_inner(win_T *wp, linenr_T n)
    while (n--) {
      // move up one line
      lnum--;
+      n += skip_conceal && decor_conceal_line(wp, lnum - 1, true);
      if (lnum <= 1) {
        break;
      }
@ -2619,7 +2621,7 @@ int cursor_up(linenr_T n, bool upd_topline)
  if (n > 0 && curwin->w_cursor.lnum <= 1) {
    return FAIL;
  }
-  cursor_up_inner(curwin, n);
+  cursor_up_inner(curwin, n, false);

  // try to advance to the column we want to be at
  coladvance(curwin, curwin->w_curswant);
@ -2631,16 +2633,16 @@ int cursor_up(linenr_T n, bool upd_topline)
  return OK;
 }

-/// Move the cursor down "n" lines in window "wp".
-/// Takes care of closed folds.
-void cursor_down_inner(win_T *wp, int n)
+/// Move the cursor down "n" lines in window "wp". Takes care of closed folds.
+/// Skips over concealed lines when "skip_conceal" is true.
+void cursor_down_inner(win_T *wp, int n, bool skip_conceal)
 {
  linenr_T lnum = wp->w_cursor.lnum;
  linenr_T line_count = wp->w_buffer->b_ml.ml_line_count;

  if (lnum + n >= line_count) {
    lnum = line_count;
-  } else if (hasAnyFolding(wp)) {
+  } else if (win_lines_concealed(wp)) {
    linenr_T last;

    // count each sequence of folded lines as one logical line
@ -2650,6 +2652,7 @@ void cursor_down_inner(win_T *wp, int n)
      } else {
        lnum++;
      }
+      n += skip_conceal && decor_conceal_line(wp, lnum - 1, true);
      if (lnum >= line_count) {
        break;
      }
@ -2671,7 +2674,7 @@ int cursor_down(int n, bool upd_topline)
  if (n > 0 && lnum >= curwin->w_buffer->b_ml.ml_line_count) {
    return FAIL;
  }
-  cursor_down_inner(curwin, n);
+  cursor_down_inner(curwin, n, false);

  // try to advance to the column we want to be at
  coladvance(curwin, curwin->w_curswant);
--- a/src/nvim/fold.c
+++ b/src/nvim/fold.c
@ -194,7 +194,7 @@ bool hasFoldingWin(win_T *const win, const linenr_T lnum, linenr_T *const firstp
    const int x = find_wl_entry(win, lnum);
    if (x >= 0) {
      first = win->w_lines[x].wl_lnum;
-      last = win->w_lines[x].wl_lastlnum;
+      last = win->w_lines[x].wl_foldend;
      had_folded = win->w_lines[x].wl_folded;
    }
  }
@ -971,7 +971,7 @@ int find_wl_entry(win_T *win, linenr_T lnum)
      if (lnum < win->w_lines[i].wl_lnum) {
        return -1;
      }
-      if (lnum <= win->w_lines[i].wl_lastlnum) {
+      if (lnum <= win->w_lines[i].wl_foldend) {
        return i;
      }
    }
--- a/src/nvim/marktree.c
+++ b/src/nvim/marktree.c
@ -250,7 +250,7 @@ static inline void split_node(MarkTree *b, MTNode *x, const int i, MTKey next)
  refkey(b, x, i);
  x->n++;

-  uint32_t meta_inc[4];
+  uint32_t meta_inc[kMTMetaCount];
  meta_describe_key(meta_inc, x->key[i]);
  for (int m = 0; m < kMTMetaCount; m++) {
    // y used contain all of z and x->key[i], discount those
@ -451,6 +451,7 @@ static void meta_describe_key_inc(uint32_t *meta_inc, MTKey *k)
    meta_inc[kMTMetaLines] += (k->flags & MT_FLAG_DECOR_VIRT_LINES) ? 1 : 0;
    meta_inc[kMTMetaSignHL] += (k->flags & MT_FLAG_DECOR_SIGNHL) ? 1 : 0;
    meta_inc[kMTMetaSignText] += (k->flags & MT_FLAG_DECOR_SIGNTEXT) ? 1 : 0;
+    meta_inc[kMTMetaConcealLines] += (k->flags & MT_FLAG_DECOR_CONCEAL_LINES) ? 1 : 0;
  }
 }

@ -505,10 +506,10 @@ void marktree_put_key(MarkTree *b, MTKey k)
    r = s;
  }

-  uint32_t meta_inc[4];
+  uint32_t meta_inc[kMTMetaCount];
  meta_describe_key(meta_inc, k);
  marktree_putp_aux(b, r, k, meta_inc);
-  for (int m = 0; m < 4; m++) {
+  for (int m = 0; m < kMTMetaCount; m++) {
    b->meta_root[m] += meta_inc[m];
  }
  b->n_keys++;
@ -579,7 +580,7 @@ uint64_t marktree_del_itr(MarkTree *b, MarkTreeIter *itr, bool rev)
  assert(x->level == 0);
  MTKey intkey = x->key[itr->i];

-  uint32_t meta_inc[4];
+  uint32_t meta_inc[kMTMetaCount];
  meta_describe_key(meta_inc, intkey);
  if (x->n > itr->i + 1) {
    memmove(&x->key[itr->i], &x->key[itr->i + 1],
@ -776,7 +777,7 @@ uint64_t marktree_del_itr(MarkTree *b, MarkTreeIter *itr, bool rev)

 void marktree_revise_meta(MarkTree *b, MarkTreeIter *itr, MTKey old_key)
 {
-  uint32_t meta_old[4], meta_new[4];
+  uint32_t meta_old[kMTMetaCount], meta_new[kMTMetaCount];
  meta_describe_key(meta_old, old_key);
  meta_describe_key(meta_new, rawkey(itr));

@ -1038,7 +1039,7 @@ static MTNode *merge_node(MarkTree *b, MTNode *p, int i)
    relative(p->key[i - 1].pos, &x->key[x->n].pos);
  }

-  uint32_t meta_inc[4];
+  uint32_t meta_inc[kMTMetaCount];
  meta_describe_key(meta_inc, x->key[x->n]);

  memmove(&x->key[x->n + 1], y->key, (size_t)y->n * sizeof(MTKey));
@ -1128,9 +1129,9 @@ static void pivot_right(MarkTree *b, MTPos p_pos, MTNode *p, const int i)
  p->key[i] = x->key[x->n - 1];
  refkey(b, p, i);

-  uint32_t meta_inc_y[4];
+  uint32_t meta_inc_y[kMTMetaCount];
  meta_describe_key(meta_inc_y, y->key[0]);
-  uint32_t meta_inc_x[4];
+  uint32_t meta_inc_x[kMTMetaCount];
  meta_describe_key(meta_inc_x, p->key[i]);

  for (int m = 0; m < kMTMetaCount; m++) {
@ -1214,9 +1215,9 @@ static void pivot_left(MarkTree *b, MTPos p_pos, MTNode *p, int i)
  p->key[i] = y->key[0];
  refkey(b, p, i);

-  uint32_t meta_inc_x[4];
+  uint32_t meta_inc_x[kMTMetaCount];
  meta_describe_key(meta_inc_x, x->key[x->n]);
-  uint32_t meta_inc_y[4];
+  uint32_t meta_inc_y[kMTMetaCount];
  meta_describe_key(meta_inc_y, p->key[i]);
  for (int m = 0; m < kMTMetaCount; m++) {
    p->meta[i][m] += meta_inc_x[m];
@ -1619,8 +1620,13 @@ bool marktree_itr_next_filter(MarkTree *b, MarkTreeIter *itr, int stop_row, int
  return marktree_itr_check_filter(b, itr, stop_row, stop_col, meta_filter);
 }

-const uint32_t meta_map[4] = { MT_FLAG_DECOR_VIRT_TEXT_INLINE, MT_FLAG_DECOR_VIRT_LINES,
-                               MT_FLAG_DECOR_SIGNHL, MT_FLAG_DECOR_SIGNTEXT };
+const uint32_t meta_map[kMTMetaCount] = {
+  MT_FLAG_DECOR_VIRT_TEXT_INLINE,
+  MT_FLAG_DECOR_VIRT_LINES,
+  MT_FLAG_DECOR_SIGNHL,
+  MT_FLAG_DECOR_SIGNTEXT,
+  MT_FLAG_DECOR_CONCEAL_LINES
+};
 static bool marktree_itr_check_filter(MarkTree *b, MarkTreeIter *itr, int stop_row, int stop_col,
                                      MetaFilter meta_filter)
 {
@ -1860,9 +1866,9 @@ static void swap_keys(MarkTree *b, MarkTreeIter *itr1, MarkTreeIter *itr2, Damag
                                   itr2->i, itr1->i }));
    }

-    uint32_t meta_inc_1[4];
+    uint32_t meta_inc_1[kMTMetaCount];
    meta_describe_key(meta_inc_1, rawkey(itr1));
-    uint32_t meta_inc_2[4];
+    uint32_t meta_inc_2[kMTMetaCount];
    meta_describe_key(meta_inc_2, rawkey(itr2));

    if (memcmp(meta_inc_1, meta_inc_2, sizeof(meta_inc_1)) != 0) {
@ -2373,7 +2379,7 @@ size_t marktree_check_node(MarkTree *b, MTNode *x, MTPos *last, bool *last_right
    *last = x->key[x->n - 1].pos;
  }

-  uint32_t meta_node[4];
+  uint32_t meta_node[kMTMetaCount];
  meta_describe_node(meta_node, x);
  for (int m = 0; m < kMTMetaCount; m++) {
    assert(meta_node_ref[m] == meta_node[m]);
--- a/src/nvim/marktree.h
+++ b/src/nvim/marktree.h
@ -34,6 +34,7 @@
 #define MT_FLAG_DECOR_SIGNHL (((uint16_t)1) << 10)
 #define MT_FLAG_DECOR_VIRT_LINES (((uint16_t)1) << 11)
 #define MT_FLAG_DECOR_VIRT_TEXT_INLINE (((uint16_t)1) << 12)
+#define MT_FLAG_DECOR_CONCEAL_LINES (((uint16_t)1) << 13)

 // These _must_ be last to preserve ordering of marks
 #define MT_FLAG_RIGHT_GRAVITY (((uint16_t)1) << 14)
@ -43,8 +44,8 @@
                             | MT_FLAG_DECOR_SIGNHL | MT_FLAG_DECOR_VIRT_LINES \
                             | MT_FLAG_DECOR_VIRT_TEXT_INLINE)

-#define MT_FLAG_EXTERNAL_MASK (MT_FLAG_DECOR_MASK | MT_FLAG_NO_UNDO \
-                               | MT_FLAG_INVALIDATE | MT_FLAG_INVALID)
+#define MT_FLAG_EXTERNAL_MASK (MT_FLAG_DECOR_MASK | MT_FLAG_NO_UNDO | MT_FLAG_INVALIDATE \
+                               | MT_FLAG_INVALID | MT_FLAG_DECOR_CONCEAL_LINES)

 // this is defined so that start and end of the same range have adjacent ids
 #define MARKTREE_END_FLAG ((uint64_t)1)
@ -108,6 +109,11 @@ static inline bool mt_decor_sign(MTKey key)
  return key.flags & (MT_FLAG_DECOR_SIGNTEXT | MT_FLAG_DECOR_SIGNHL);
 }

+static inline bool mt_conceal_lines(MTKey key)
+{
+  return key.flags & MT_FLAG_DECOR_CONCEAL_LINES;
+}
+
 static inline uint16_t mt_flags(bool right_gravity, bool no_undo, bool invalidate, bool decor_ext)
 {
  return (uint16_t)((right_gravity ? MT_FLAG_RIGHT_GRAVITY : 0)
--- a/src/nvim/marktree_defs.h
+++ b/src/nvim/marktree_defs.h
@ -22,13 +22,12 @@ typedef struct {
 } MTPos;
 #define MTPos(r, c) ((MTPos){ .row = (r), .col = (c) })

-// Currently there are four counts, which makes for a uint32_t[4] per node
-// which makes for nice autovectorization into a single XMM or NEON register
 typedef enum {
  kMTMetaInline,
  kMTMetaLines,
  kMTMetaSignHL,
  kMTMetaSignText,
+  kMTMetaConcealLines,
  kMTMetaCount,  // sentinel, must be last
 } MetaIndex;

--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@ -17,6 +17,7 @@
 #include "nvim/buffer.h"
 #include "nvim/buffer_defs.h"
 #include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/diff.h"
 #include "nvim/drawscreen.h"
 #include "nvim/edit.h"
@ -318,14 +319,13 @@ void update_topline(win_T *wp)
        halfheight = 2;
      }
      int64_t n;
-      if (hasAnyFolding(wp)) {
+      if (win_lines_concealed(wp)) {
        // Count the number of logical lines between the cursor and
        // topline + p_so (approximation of how much will be
        // scrolled).
        n = 0;
-        for (linenr_T lnum = wp->w_cursor.lnum;
-             lnum < wp->w_topline + *so_ptr; lnum++) {
-          n++;
+        for (linenr_T lnum = wp->w_cursor.lnum; lnum < wp->w_topline + *so_ptr; lnum++) {
+          n += !decor_conceal_line(wp, lnum, false);
          // stop at end of file or when we know we are far off
          assert(wp->w_buffer != 0);
          if (lnum >= wp->w_buffer->b_ml.ml_line_count || n >= halfheight) {
@ -367,7 +367,7 @@ void update_topline(win_T *wp)
    assert(wp->w_buffer != 0);
    if (wp->w_botline <= wp->w_buffer->b_ml.ml_line_count) {
      if (wp->w_cursor.lnum < wp->w_botline) {
-        if ((wp->w_cursor.lnum >= wp->w_botline - *so_ptr || hasAnyFolding(wp))) {
+        if ((wp->w_cursor.lnum >= wp->w_botline - *so_ptr || win_lines_concealed(wp))) {
          lineoff_T loff;

          // Cursor is (a few lines) above botline, check if there are
@ -399,13 +399,12 @@ void update_topline(win_T *wp)
      }
      if (check_botline) {
        int line_count = 0;
-        if (hasAnyFolding(wp)) {
+        if (win_lines_concealed(wp)) {
          // Count the number of logical lines between the cursor and
          // botline - p_so (approximation of how much will be
          // scrolled).
-          for (linenr_T lnum = wp->w_cursor.lnum;
-               lnum >= wp->w_botline - *so_ptr; lnum--) {
-            line_count++;
+          for (linenr_T lnum = wp->w_cursor.lnum; lnum >= wp->w_botline - *so_ptr; lnum--) {
+            line_count += !decor_conceal_line(wp, lnum - 1, false);
            // stop at end of file or when we know we are far off
            if (lnum <= 0 || line_count > wp->w_height_inner + 1) {
              break;
@ -462,7 +461,7 @@ static int scrolljump_value(win_T *wp)
 static bool check_top_offset(win_T *wp)
 {
  int so = get_scrolloff_value(wp);
-  if (wp->w_cursor.lnum < wp->w_topline + so || hasAnyFolding(wp)) {
+  if (wp->w_cursor.lnum < wp->w_topline + so || win_lines_concealed(wp)) {
    lineoff_T loff;
    loff.lnum = wp->w_cursor.lnum;
    loff.fill = 0;
@ -506,6 +505,13 @@ void check_cursor_moved(win_T *wp)
  if (wp->w_cursor.lnum != wp->w_valid_cursor.lnum) {
    wp->w_valid &= ~(VALID_WROW|VALID_WCOL|VALID_VIRTCOL
                     |VALID_CHEIGHT|VALID_CROW|VALID_TOPLINE);
+
+    // Concealed line visibility toggled.
+    if (wp->w_p_cole >= 2 && !conceal_cursor_line(wp)
+        && (decor_conceal_line(wp, wp->w_cursor.lnum - 1, true)
+            || decor_conceal_line(wp, wp->w_valid_cursor.lnum - 1, true))) {
+      changed_window_setting(wp);
+    }
    wp->w_valid_cursor = wp->w_cursor;
    wp->w_valid_leftcol = wp->w_leftcol;
    wp->w_valid_skipcol = wp->w_skipcol;
@ -1341,13 +1347,14 @@ bool scrolldown(win_T *wp, linenr_T line_count, int byfold)
        // A sequence of folded lines only counts for one logical line
        linenr_T first;
        if (hasFolding(wp, wp->w_topline, &first, NULL)) {
-          done++;
+          done += !decor_conceal_line(wp, first - 1, false);
          if (!byfold) {
            todo -= wp->w_topline - first - 1;
          }
          wp->w_botline -= wp->w_topline - first;
          wp->w_topline = first;
        } else {
+          todo += decor_conceal_line(wp, wp->w_topline - 1, false);
          if (do_sms) {
            int size = win_linetabsize(wp, wp->w_topline,
                                       ml_get_buf(wp->w_buffer, wp->w_topline), MAXCOL);
@ -1391,12 +1398,8 @@ bool scrolldown(win_T *wp, linenr_T line_count, int byfold)
  while (wrow >= wp->w_height_inner && wp->w_cursor.lnum > 1) {
    linenr_T first;
    if (hasFolding(wp, wp->w_cursor.lnum, &first, NULL)) {
-      wrow--;
-      if (first == 1) {
-        wp->w_cursor.lnum = 1;
-      } else {
-        wp->w_cursor.lnum = first - 1;
-      }
+      wrow -= !decor_conceal_line(wp, wp->w_cursor.lnum - 1, false);
+      wp->w_cursor.lnum = MAX(first - 1, 1);
    } else {
      wrow -= plines_win(wp, wp->w_cursor.lnum--, true);
    }
@ -1424,7 +1427,7 @@ bool scrollup(win_T *wp, linenr_T line_count, bool byfold)
  linenr_T botline = wp->w_botline;
  bool do_sms = wp->w_p_wrap && wp->w_p_sms;

-  if (do_sms || (byfold && hasAnyFolding(wp)) || win_may_fill(wp)) {
+  if (do_sms || (byfold && win_lines_concealed(wp)) || win_may_fill(wp)) {
    int width1 = wp->w_width_inner - win_col_off(wp);
    int width2 = width1 + win_col_off2(wp);
    int size = 0;
@ -1439,6 +1442,7 @@ bool scrollup(win_T *wp, linenr_T line_count, bool byfold)
    // the line, then advance to the next line.
    // folding: count each sequence of folded lines as one logical line.
    for (int todo = line_count; todo > 0; todo--) {
+      todo += decor_conceal_line(wp, wp->w_topline - 1, false);
      if (wp->w_topfill > 0) {
        wp->w_topfill--;
      } else {
@ -1495,10 +1499,8 @@ bool scrollup(win_T *wp, linenr_T line_count, bool byfold)

  check_topfill(wp, false);

-  if (hasAnyFolding(wp)) {
-    // Make sure w_topline is at the first of a sequence of folded lines.
-    hasFolding(wp, wp->w_topline, &wp->w_topline, NULL);
-  }
+  // Make sure w_topline is at the first of a sequence of folded lines.
+  hasFolding(wp, wp->w_topline, &wp->w_topline, NULL);

  wp->w_valid &= ~(VALID_WROW|VALID_CROW|VALID_BOTLINE);
  if (wp->w_cursor.lnum < wp->w_topline) {
@ -1702,8 +1704,8 @@ static void topline_back_winheight(win_T *wp, lineoff_T *lp, int winheight)
    if (lp->lnum < 1) {
      lp->height = MAXCOL;
    } else if (hasFolding(wp, lp->lnum, &lp->lnum, NULL)) {
-      // Add a closed fold
-      lp->height = 1;
+      // Add a closed fold unless concealed.
+      lp->height = !decor_conceal_line(wp, lp->lnum - 1, false);
    } else {
      lp->height = plines_win_nofill(wp, lp->lnum, winheight);
    }
@ -1732,8 +1734,8 @@ static void botline_forw(win_T *wp, lineoff_T *lp)
    if (lp->lnum > wp->w_buffer->b_ml.ml_line_count) {
      lp->height = MAXCOL;
    } else if (hasFolding(wp, lp->lnum, NULL, &lp->lnum)) {
-      // Add a closed fold
-      lp->height = 1;
+      // Add a closed fold unless concealed.
+      lp->height = !decor_conceal_line(wp, lp->lnum - 1, false);
    } else {
      lp->height = plines_win_nofill(wp, lp->lnum, true);
    }
@ -1785,9 +1787,8 @@ void scroll_cursor_top(win_T *wp, int min_scroll, int always)
  // Check if the lines from "top" to "bot" fit in the window.  If they do,
  // set new_topline and advance "top" and "bot" to include more lines.
  while (top > 0) {
-    int i = hasFolding(wp, top, &top, NULL)
-            ? 1  // count one logical line for a sequence of folded lines
-            : plines_win_nofill(wp, top, true);
+    int i = plines_win_nofill(wp, top, true);
+    hasFolding(wp, top, &top, NULL);
    if (top < wp->w_topline) {
      scrolled += i;
    }
@ -1799,12 +1800,7 @@ void scroll_cursor_top(win_T *wp, int min_scroll, int always)

    used += i;
    if (extra + i <= off && bot < wp->w_buffer->b_ml.ml_line_count) {
-      if (hasFolding(wp, bot, NULL, &bot)) {
-        // count one logical line for a sequence of folded lines
-        used++;
-      } else {
-        used += plines_win(wp, bot, true);
-      }
+      used += plines_win_full(wp, bot, &bot, NULL, true, true);
    }
    if (used > wp->w_height_inner) {
      break;
@ -2265,7 +2261,7 @@ void cursor_correct(win_T *wp)
  linenr_T cln = wp->w_cursor.lnum;  // Cursor Line Number
  if (cln >= wp->w_topline + above_wanted
      && cln < wp->w_botline - below_wanted
-      && !hasAnyFolding(wp)) {
+      && !win_lines_concealed(wp)) {
    return;
  }

@ -2290,19 +2286,12 @@ void cursor_correct(win_T *wp)
  int below = wp->w_filler_rows;  // screen lines below botline
  while ((above < above_wanted || below < below_wanted) && topline < botline) {
    if (below < below_wanted && (below <= above || above >= above_wanted)) {
-      if (hasFolding(wp, botline, &botline, NULL)) {
-        below++;
-      } else {
-        below += plines_win(wp, botline, true);
-      }
+      below += plines_win_full(wp, botline, &botline, NULL, true, true);
      botline--;
    }
    if (above < above_wanted && (above < below || below >= below_wanted)) {
-      if (hasFolding(wp, topline, NULL, &topline)) {
-        above++;
-      } else {
-        above += plines_win_nofill(wp, topline, true);
-      }
+      above += plines_win_nofill(wp, topline, true);
+      hasFolding(wp, topline, NULL, &topline);

      // Count filler lines below this line as context.
      if (topline < botline) {
@ -2456,7 +2445,8 @@ int pagescroll(Direction dir, int count, bool half)
    int curscount = count;
    // Adjust count so as to not reveal end of buffer lines.
    if (dir == FORWARD
-        && (curwin->w_topline + curwin->w_height_inner + count > buflen || hasAnyFolding(curwin))) {
+        && (curwin->w_topline + curwin->w_height_inner + count > buflen
+            || win_lines_concealed(curwin))) {
      int n = plines_correct_topline(curwin, curwin->w_topline, NULL, false, NULL);
      if (n - count < curwin->w_height_inner && curwin->w_topline < buflen) {
        n += plines_m_win(curwin, curwin->w_topline + 1, buflen, curwin->w_height_inner + count);
@ -2474,13 +2464,14 @@ int pagescroll(Direction dir, int count, bool half)
      curwin->w_curswant = prev_curswant;
    }

-    // Move the cursor the same amount of screen lines.
+    // Move the cursor the same amount of screen lines, skipping over
+    // concealed lines as those were not included in "curscount".
    if (curwin->w_p_wrap) {
-      nv_screengo(&oa, dir, curscount);
+      nv_screengo(&oa, dir, curscount, true);
    } else if (dir == FORWARD) {
-      cursor_down_inner(curwin, curscount);
+      cursor_down_inner(curwin, curscount, true);
    } else {
-      cursor_up_inner(curwin, curscount);
+      cursor_up_inner(curwin, curscount, true);
    }
  } else {
    // Scroll [count] times 'window' or current window height lines.
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@ -24,6 +24,7 @@
 #include "nvim/charset.h"
 #include "nvim/cmdhist.h"
 #include "nvim/cursor.h"
+#include "nvim/decoration.h"
 #include "nvim/diff.h"
 #include "nvim/digraph.h"
 #include "nvim/drawscreen.h"
@ -2486,7 +2487,7 @@ bool find_decl(char *ptr, size_t len, bool locally, bool thisblock, int flags_ar
 /// 'dist' must be positive.
 ///
 /// @return  true if able to move cursor, false otherwise.
-bool nv_screengo(oparg_T *oap, int dir, int dist)
+bool nv_screengo(oparg_T *oap, int dir, int dist, bool skip_conceal)
 {
  int linelen = linetabsize(curwin, curwin->w_cursor.lnum);
  bool retval = true;
@ -2548,7 +2549,7 @@ bool nv_screengo(oparg_T *oap, int dir, int dist)
            retval = false;
            break;
          }
-          cursor_up_inner(curwin, 1);
+          cursor_up_inner(curwin, 1, skip_conceal);

          linelen = linetabsize(curwin, curwin->w_cursor.lnum);
          if (linelen > width1) {
@ -2573,7 +2574,7 @@ bool nv_screengo(oparg_T *oap, int dir, int dist)
            retval = false;
            break;
          }
-          cursor_down_inner(curwin, 1);
+          cursor_down_inner(curwin, 1, skip_conceal);
          curwin->w_curswant %= width2;

          // Check if the cursor has moved below the number display
@ -3616,12 +3617,11 @@ static void nv_scroll(cmdarg_T *cap)
    if (cap->count1 - 1 >= curwin->w_cursor.lnum) {
      curwin->w_cursor.lnum = 1;
    } else {
-      if (hasAnyFolding(curwin)) {
+      if (win_lines_concealed(curwin)) {
        // Count a fold for one screen line.
-        for (n = cap->count1 - 1; n > 0
-             && curwin->w_cursor.lnum > curwin->w_topline; n--) {
-          hasFolding(curwin, curwin->w_cursor.lnum,
-                     &curwin->w_cursor.lnum, NULL);
+        for (n = cap->count1 - 1; n > 0 && curwin->w_cursor.lnum > curwin->w_topline; n--) {
+          hasFolding(curwin, curwin->w_cursor.lnum, &curwin->w_cursor.lnum, NULL);
+          n += decor_conceal_line(curwin, curwin->w_cursor.lnum, true);
          if (curwin->w_cursor.lnum > curwin->w_topline) {
            curwin->w_cursor.lnum--;
          }
@ -3634,8 +3634,7 @@ static void nv_scroll(cmdarg_T *cap)
    if (cap->cmdchar == 'M') {
      int used = 0;
      // Don't count filler lines above the window.
-      used -= win_get_fill(curwin, curwin->w_topline)
-              - curwin->w_topfill;
+      used -= win_get_fill(curwin, curwin->w_topline) - curwin->w_topfill;
      validate_botline(curwin);  // make sure w_empty_rows is valid
      int half = (curwin->w_height_inner - curwin->w_empty_rows + 1) / 2;
      for (n = 0; curwin->w_topline + n < curbuf->b_ml.ml_line_count; n++) {
@ -3658,10 +3657,11 @@ static void nv_scroll(cmdarg_T *cap)
      }
    } else {  // (cap->cmdchar == 'H')
      n = cap->count1 - 1;
-      if (hasAnyFolding(curwin)) {
+      if (win_lines_concealed(curwin)) {
        // Count a fold for one screen line.
        lnum = curwin->w_topline;
-        while (n-- > 0 && lnum < curwin->w_botline - 1) {
+        while ((decor_conceal_line(curwin, lnum - 1, true) || n-- > 0)
+               && lnum < curwin->w_botline - 1) {
          hasFolding(curwin, lnum, NULL, &lnum);
          lnum++;
        }
@ -5316,7 +5316,7 @@ static void nv_g_dollar_cmd(cmdarg_T *cap)
          curwin->w_cursor.col--;
        }
      }
-    } else if (nv_screengo(oap, FORWARD, cap->count1 - 1) == false) {
+    } else if (nv_screengo(oap, FORWARD, cap->count1 - 1, false) == false) {
      clearopbeep(oap);
    }
  } else {
@ -5443,7 +5443,7 @@ static void nv_g_cmd(cmdarg_T *cap)
      oap->motion_type = kMTLineWise;
      i = cursor_down(cap->count1, oap->op_type == OP_NOP);
    } else {
-      i = nv_screengo(oap, FORWARD, cap->count1);
+      i = nv_screengo(oap, FORWARD, cap->count1, false);
    }
    if (!i) {
      clearopbeep(oap);
@ -5457,7 +5457,7 @@ static void nv_g_cmd(cmdarg_T *cap)
      oap->motion_type = kMTLineWise;
      i = cursor_up(cap->count1, oap->op_type == OP_NOP);
    } else {
-      i = nv_screengo(oap, BACKWARD, cap->count1);
+      i = nv_screengo(oap, BACKWARD, cap->count1, false);
    }
    if (!i) {
      clearopbeep(oap);
--- a/src/nvim/plines.c
+++ b/src/nvim/plines.c
@ -80,7 +80,7 @@ int linetabsize(win_T *wp, linenr_T lnum)
  return win_linetabsize(wp, lnum, ml_get_buf(wp->w_buffer, lnum), MAXCOL);
 }

-static const uint32_t inline_filter[4] = {[kMTMetaInline] = kMTFilterSelect };
+static const uint32_t inline_filter[kMTMetaCount] = {[kMTMetaInline] = kMTFilterSelect };

 /// Prepare the structure passed to charsize functions.
 ///
@ -749,6 +749,10 @@ int plines_win(win_T *wp, linenr_T lnum, bool limit_winheight)
 /// @param limit_winheight  when true limit to window height
 int plines_win_nofill(win_T *wp, linenr_T lnum, bool limit_winheight)
 {
+  if (decor_conceal_line(wp, lnum - 1, false)) {
+    return 0;
+  }
+
  if (!wp->w_p_wrap) {
    return 1;
  }
@ -885,6 +889,11 @@ int plines_win_full(win_T *wp, linenr_T lnum, linenr_T *const nextp, bool *const
  if (foldedp != NULL) {
    *foldedp = folded;
  }
+
+  if (decor_conceal_line(wp, lnum - 1, false)) {
+    return 0;
+  }
+
  return ((folded ? 1 : plines_win_nofill(wp, lnum, limit_winheight)) +
          (lnum == wp->w_topline ? wp->w_topfill : win_get_fill(wp, lnum)));
 }
@ -963,8 +972,8 @@ int64_t win_text_height(win_T *const wp, const linenr_T start_lnum, const int64_

  if (start_vcol >= 0) {
    linenr_T lnum_next = lnum;
-    const bool folded = hasFolding(wp, lnum, &lnum, &lnum_next);
-    height_cur_nofill = folded ? 1 : plines_win_nofill(wp, lnum, false);
+    hasFolding(wp, lnum, &lnum, &lnum_next);
+    height_cur_nofill = plines_win_nofill(wp, lnum, false);
    height_sum_nofill += height_cur_nofill;
    const int64_t row_off = (start_vcol < width1 || width2 <= 0)
                            ? 0
@ -975,9 +984,9 @@ int64_t win_text_height(win_T *const wp, const linenr_T start_lnum, const int64_

  while (lnum <= end_lnum) {
    linenr_T lnum_next = lnum;
-    const bool folded = hasFolding(wp, lnum, &lnum, &lnum_next);
+    hasFolding(wp, lnum, &lnum, &lnum_next);
    height_sum_fill += win_get_fill(wp, lnum);
-    height_cur_nofill = folded ? 1 : plines_win_nofill(wp, lnum, false);
+    height_cur_nofill = plines_win_nofill(wp, lnum, false);
    height_sum_nofill += height_cur_nofill;
    lnum = lnum_next + 1;
  }
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@ -6465,9 +6465,9 @@ void win_fix_scroll(bool resize)

        // Add difference in height and row to botline.
        if (diff > 0) {
-          cursor_down_inner(wp, diff);
+          cursor_down_inner(wp, diff, false);
        } else {
-          cursor_up_inner(wp, -diff);
+          cursor_up_inner(wp, -diff, false);
        }

        // Scroll to put the new cursor position at the bottom of the
@ -6514,11 +6514,11 @@ static void win_fix_cursor(bool normal)
  linenr_T lnum = wp->w_cursor.lnum;

  wp->w_cursor.lnum = wp->w_topline;
-  cursor_down_inner(wp, so);
+  cursor_down_inner(wp, so, false);
  linenr_T top = wp->w_cursor.lnum;

  wp->w_cursor.lnum = wp->w_botline - 1;
-  cursor_up_inner(wp, so);
+  cursor_up_inner(wp, so, false);
  linenr_T bot = wp->w_cursor.lnum;

  wp->w_cursor.lnum = lnum;
@ -6612,7 +6612,7 @@ void scroll_to_fraction(win_T *wp, int prev_height)
        hasFolding(wp, lnum, &lnum, NULL);
        if (lnum == 1) {
          // first line in buffer is folded
-          line_size = 1;
+          line_size = !decor_conceal_line(wp, lnum - 1, false);
          sline--;
          break;
        }
--- a/test/functional/api/extmark_spec.lua
+++ b/test/functional/api/extmark_spec.lua
@ -1552,6 +1552,7 @@ describe('API/extmarks', function()
  it('can get details', function()
    set_extmark(ns, marks[1], 0, 0, {
      conceal = 'c',
+      conceal_lines = '',
      cursorline_hl_group = 'Statement',
      end_col = 0,
      end_right_gravity = true,
@ -1586,6 +1587,7 @@ describe('API/extmarks', function()
      0,
      {
        conceal = 'c',
+        conceal_lines = '',
        cursorline_hl_group = 'Statement',
        end_col = 0,
        end_right_gravity = true,
--- a/test/functional/treesitter/highlight_spec.lua
+++ b/test/functional/treesitter/highlight_spec.lua
@ -1119,14 +1119,16 @@ describe('treesitter highlighting (markdown)', function()
    })
  end)

-  it('works with spellchecked and smoothscrolled topline', function()
-    insert([[
+  local code_block = [[
 - $f(0)=\sum_{k=1}^{\infty}\frac{2}{\pi^{2}k^{2}}+\lim_{w \to 0}x$.

 ```c
 printf('Hello World!');
 ```
-    ]])
+    ]]
+
+  it('works with spellchecked and smoothscrolled topline', function()
+    insert(code_block)
    command('set spell smoothscroll')
    feed('gg<C-E>')
    screen:add_extra_attr_ids({ [100] = { undercurl = true, special = Screen.colors.Red } })
@ -1141,6 +1143,105 @@ printf('Hello World!');
      ]],
    })
  end)
+
+  it('works with concealed lines', function()
+    insert(code_block)
+    screen:expect({
+      grid = [[
+                                                |
+        {18:```}{15:c}                                    |
+        {25:printf}{16:(}{26:'Hello World!'}{16:);}                 |
+        {18:```}                                     |
+           ^                                     |
+                                                |
+      ]],
+    })
+    feed('ggj')
+    command('set number conceallevel=3')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }^                                    |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  6 }                                    |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  3 }{18:^```}{15:c}                                |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  4 }{25:^printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  6 }                                    |
+                                                |
+      ]],
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+        {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+        {8:  2 }                                    |
+        {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+        {8:  5 }{18:^```}                                 |
+                                                |
+      ]],
+    })
+    -- Concealed lines highlight until changed botline
+    screen:try_resize(screen._width, 16)
+    feed('y3k30P:<Esc><C-F><C-B>')
+    screen:expect([[
+      {8:  1 }{16:- }$f(0)=\sum_{k=1}^{\infty}\frac{2}{|
+      {8:    }\pi^{2}k^{2}}+\lim_{w \to 0}x$.     |
+      {8:  2 }                                    |
+      {8:  4 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:  6 }                                    |
+      {8:  8 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 10 }                                    |
+      {8: 12 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 14 }                                    |
+      {8: 16 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 18 }                                    |
+      {8: 20 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 22 }                                    |
+      {8: 24 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8: 25 }{18:^```}                                 |
+                                              |
+    ]])
+    feed('G')
+    screen:expect([[
+      {8: 98 }                                    |
+      {8:100 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:102 }                                    |
+      {8:104 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:106 }                                    |
+      {8:108 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:110 }                                    |
+      {8:112 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:114 }                                    |
+      {8:116 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:118 }                                    |
+      {8:120 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:122 }                                    |
+      {8:124 }{25:printf}{16:(}{26:'Hello World!'}{16:);}             |
+      {8:126 }   ^                                 |
+                                              |
+    ]])
+  end)
 end)

 it('starting and stopping treesitter highlight in init.lua works #29541', function()
--- a/test/functional/ui/decorations_spec.lua
+++ b/test/functional/ui/decorations_spec.lua
@ -2495,6 +2495,209 @@ describe('extmark decorations', function()
                                                        |
    ]])
  end)
+
+  it ('conceal_lines', function()
+    insert(example_text)
+    exec('set number conceallevel=3')
+    feed('ggj')
+    local not_concealed = {
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  2 }^    local text, hl_id_cell, count = unpack(ite|
+        {2:    }m)                                            |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  4 }        hl_id = hl_id_cell                    |
+        {2:  5 }    end                                       |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|
+                                                          |
+      ]]
+    }
+    screen:expect(not_concealed)
+    api.nvim_buf_set_extmark(0, ns, 1, 0, { conceal_lines = "" })
+    screen:expect_unchanged()
+    feed('j')
+    local concealed = {
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }^    if hl_id_cell ~= nil then                 |
+        {2:  4 }        hl_id = hl_id_cell                    |
+        {2:  5 }    end                                       |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*3
+                                                          |
+      ]]
+    }
+    screen:expect(concealed)
+    feed('k')
+    screen:expect(not_concealed)
+    exec('set concealcursor=n')
+    screen:expect(concealed)
+    api.nvim_buf_set_extmark(0, ns, 3, 0, { conceal_lines = "" })
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }^    if hl_id_cell ~= nil then                 |
+        {2:  5 }    end                                       |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*4
+                                                          |
+      ]]
+    })
+    feed('kjj')
+    screen:expect_unchanged()
+    api.nvim_buf_set_extmark(0, ns, 4, 0, { conceal_lines = "" })
+    feed('kjjjC')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  5 }^                                              |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*4
+        {24:-- INSERT --}                                      |
+      ]]
+    })
+    feed('<esc>')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  6 }^    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*5
+                                                          |
+      ]]
+    })
+    feed('kji')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  5 }^                                              |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*4
+        {24:-- INSERT --}                                      |
+      ]]
+    })
+    feed('conceal text')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  5 }conceal text^                                  |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*4
+        {24:-- INSERT --}                                      |
+      ]]
+    })
+    feed('<esc>')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  6 }    for _ =^ 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*5
+                                                          |
+      ]]
+    })
+    feed('ggzfj')
+    screen:expect({
+      grid = [[
+        {2:  1 }{33:^+--  2 lines: for _,item in ipairs(items) do··}|
+        {2:  3 }    if hl_id_cell ~= nil then                 |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*5
+                                                          |
+      ]]
+    })
+    feed('j')
+    screen:expect({
+      grid = [[
+        {2:  1 }{33:+--  2 lines: for _,item in ipairs(items) do··}|
+        {2:  3 }^    if hl_id_cell ~= nil then                 |
+        {2:  6 }    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*5
+                                                          |
+      ]]
+    })
+    feed('ggzdjzfj')
+    screen:expect({
+      grid = [[
+        {2:  1 }for _,item in ipairs(items) do                |
+        {2:  6 }^    for _ = 1, (count or 1) do                |
+        {2:  7 }        local cell = line[colpos]             |
+        {2:  8 }        cell.text = text                      |
+        {2:  9 }        cell.hl_id = hl_id                    |
+        {2: 10 }        colpos = colpos+1                     |
+        {2: 11 }    end                                       |
+        {2: 12 }end                                           |
+        {1:~                                                 }|*6
+                                                          |
+      ]]
+    })
+    feed('jj')
+    screen:expect_unchanged()
+  end)
 end)

 describe('decorations: inline virtual text', function()