Add gutter signs support

README.md

@@ -102,6 +102,7 @@ https://github.com/user-attachments/assets/64c41f01-dffe-4318-bce4-16eec8de356e
       jump_to_first_change = true,        -- Auto-scroll to first change when opening a diff: false to stay at same line
       highlight_added_deleted_files = false, -- Tint full contents of added, untracked, and deleted files
       highlight_priority = 100,           -- Priority for line-level diff highlights (increase to override LSP highlights)
+      gutter_signs = false,                -- Gutter +/- signs; see Gutter signs below
       compute_moves = false,              -- Detect moved code blocks (opt-in, matches VSCode experimental.showMoves)
       compact_context_lines = 3,          -- Number of context lines around hunks in compact mode
       compact_sync_folds = true,          -- Sync fold open/close across panes (mirrors Vim diff mode behavior)
@@ -317,6 +318,39 @@ require("codediff").setup({
 
 The C library will be downloaded automatically on first use. No `build` step needed!
 
+### Gutter signs
+
+```lua
+-- Disabled by default; existing move annotations remain.
+gutter_signs = false
+
+-- Enabled defaults.
+gutter_signs = {
+  insert_text = "＋",
+  delete_text = "－",
+  highlight_numbers = true,
+  changed_priority = 100,
+  unchanged_priority = nil,
+}
+
+-- Hide other Neovim signs with lower priorities.
+gutter_signs = {
+  changed_priority = 100,
+  unchanged_priority = 7,
+}
+```
+
+Set this under `diff`. `insert_text` and `delete_text` must each occupy one or two display cells, as measured by `strdisplaywidth()`, because Neovim limits sign text to two display cells. The fullwidth defaults each occupy two display cells. A rejected sign is skipped with a warning and the rest of the diff still renders.
+
+CodeDiff uses persistent Neovim signs and does not modify `signcolumn` or `statuscolumn`. This example keeps a sign column and places signs after line numbers:
+
+```lua
+vim.opt.signcolumn = "yes"
+vim.opt.statuscolumn = "%C%=%l %s"
+```
+
+`signcolumn = "yes:2"` allows a second sign on each line. Changed signs use priority 100 by default. An unchanged blocker at priority 99 can hide lower-priority Gitsigns, remote signs, diagnostics, or other signs across unchanged lines while the changed signs still win. Gutter signs require Neovim 0.10 or newer, because a sign extmark spanning several lines only decorates every line from 0.10 on. When enabled, they appear in every window displaying a buffer used by an active CodeDiff view. CodeDiff removes them when the view is suspended or closed.
+
 ### Managing Library Installation
 
 The plugin automatically manages the C library installation:
@@ -742,8 +776,18 @@ The plugin defines highlight groups matching VSCode's diff colors:
 - `CodeDiffCharInsert` - Deep/dark green for inserted characters
 - `CodeDiffCharDelete` - Deep/dark red for deleted characters
 - `CodeDiffFiller` - Gray foreground for non-empty filler line patterns
-- `CodeDiffLineMove` - Background for moved code lines (derived from DiffChange)
-- `CodeDiffMoveTo` - Sign column and annotation color for move indicators
+- `CodeDiffLineMove` - Background for moved lines (derived from DiffChange)
+- `CodeDiffCharMove` - Character-level highlight for moved text
+- `CodeDiffMoveFrom` - Sign/annotation color for move source
+- `CodeDiffMoveTo` - Sign/annotation color for move destination
+- `CodeDiffHelpSection` - Section headings in keymap help (links to Statement)
+- `CodeDiffHelpKey` - Key bindings in keymap help (links to Special)
+- `CodeDiffHelpSep` - Separators in keymap help (links to NonText)
+- `CodeDiffHelpDesc` - Descriptions in keymap help (links to Normal)
+- `CodeDiffGutterInsert` - Gutter insert sign (defaults to `CodeDiffLineInsert`)
+- `CodeDiffGutterDelete` - Gutter delete sign (defaults to `CodeDiffLineDelete`)
+- `CodeDiffGutterInsertNumber` - Gutter insert line number (defaults to `CodeDiffCharInsert`)
+- `CodeDiffGutterDeleteNumber` - Gutter delete line number (defaults to `CodeDiffCharDelete`)
 - `CodeDiffExplorerStatFiles` - Explorer file counts
 - `CodeDiffExplorerStatInsertions` - Explorer insertion counts
 - `CodeDiffExplorerStatDeletions` - Explorer deletion counts

VERSION

@@ -1 +1 @@
-2.66.0
+2.67.0

doc/codediff.txt

@@ -246,6 +246,7 @@ Setup entry point:
       jump_to_first_change = true,
       highlight_added_deleted_files = false,
       highlight_priority = 100,
+      gutter_signs = false,
       compute_moves = false,
       compact_context_lines = 3,
       compact_sync_folds = true,
@@ -443,6 +444,53 @@ Example: replace only group rows and right-align the file count:
   })
 <
 
+==============================================================================
+GUTTER SIGNS                                         *codediff-gutter-signs*
+
+Gutter signs are disabled by default and require Neovim 0.10+, because a sign
+extmark spanning several lines only decorates every line from 0.10 on. When
+enabled, they appear in every window displaying a buffer used by an active
+CodeDiff view. CodeDiff removes them when the view is suspended or closed.
+
+>lua
+  -- Disabled by default; existing move annotations remain.
+  gutter_signs = false
+
+  -- Enabled defaults.
+  gutter_signs = {
+    insert_text = "＋",
+    delete_text = "－",
+    highlight_numbers = true,
+    changed_priority = 100,
+    unchanged_priority = nil,
+  }
+
+  -- Hide other Neovim signs with lower priorities.
+  gutter_signs = {
+    changed_priority = 100,
+    unchanged_priority = 7,
+  }
+<
+
+Place `gutter_signs` under `diff`. `insert_text` and `delete_text` must each
+occupy one or two display cells, as measured by strdisplaywidth(), because
+Neovim limits sign text to two display cells. The fullwidth defaults each
+occupy two display cells. A rejected sign is skipped with a warning and the
+rest of the diff still renders.
+
+CodeDiff does not modify signcolumn or statuscolumn. This example keeps a sign
+column and places signs after line numbers:
+
+>lua
+  vim.opt.signcolumn = "yes"
+  vim.opt.statuscolumn = "%C%=%l %s"
+<
+
+`signcolumn = "yes:2"` allows a second sign on each line. Changed signs use
+priority 100 by default. An unchanged blocker at priority 99 can hide
+lower-priority Gitsigns, remote signs, diagnostics, debugger signs, and other
+signs across unchanged lines while changed signs still win.
+
 ==============================================================================
 HIGHLIGHT GROUPS                                     *codediff-highlight-groups*
 
@@ -460,6 +508,10 @@ CodeDiff defines highlight groups matching VSCode's diff colors:
 - CodeDiffHelpKey - key bindings in keymap help (links to Special)
 - CodeDiffHelpSep - separators in keymap help (links to NonText)
 - CodeDiffHelpDesc - descriptions in keymap help (links to Normal)
+- CodeDiffGutterInsert - Gutter insert sign (defaults to CodeDiffLineInsert)
+- CodeDiffGutterDelete - Gutter delete sign (defaults to CodeDiffLineDelete)
+- CodeDiffGutterInsertNumber - Gutter insert line number (defaults to CodeDiffCharInsert)
+- CodeDiffGutterDeleteNumber - Gutter delete line number (defaults to CodeDiffCharDelete)
 
 Default behavior:
 - Uses DiffAdd and DiffDelete for line-level highlights

doc/tags

@@ -8,6 +8,7 @@ codediff-events	codediff.txt	/*codediff-events*
 codediff-explorer-line-formatters	codediff.txt	/*codediff-explorer-line-formatters*
 codediff-explorer-line-statistics	codediff.txt	/*codediff-explorer-line-statistics*
 codediff-filler-text	codediff.txt	/*codediff-filler-text*
+codediff-gutter-signs	codediff.txt	/*codediff-gutter-signs*
 codediff-highlight-groups	codediff.txt	/*codediff-highlight-groups*
 codediff-history	codediff.txt	/*codediff-history*
 codediff-history-line-range	codediff.txt	/*codediff-history-line-range*

lua/codediff/config.lua

@@ -46,6 +46,7 @@ M.defaults = {
     jump_to_first_change = true, -- Auto-scroll to first change when opening a diff: true = jump to first hunk, false = stay at same line
     highlight_added_deleted_files = false, -- Tint the full contents of added, untracked, and deleted files
     highlight_priority = 100, -- Priority for line-level diff highlights (increase to override LSP highlights)
+    gutter_signs = false, -- Gutter +/- signs; optionally block lower-priority signs on unchanged lines
     compute_moves = false, -- Detect moved code blocks (opt-in, may increase diff computation time)
     compact_context_lines = 3, -- Number of context lines around hunks in compact mode
     compact_sync_folds = true, -- Sync fold open/close across panes in compact mode (mirrors Vim diff mode behavior)

lua/codediff/ui/core.lua

@@ -4,6 +4,7 @@ local M = {}
 local config = require("codediff.config")
 local highlights = require("codediff.ui.highlights")
 local filler_renderer = require("codediff.ui.filler")
+local gutter_signs = require("codediff.ui.gutter_signs")
 local compat = require("codediff.core.compat")
 
 -- Namespace references
@@ -285,6 +286,7 @@ function M.render_diff(left_bufnr, right_bufnr, original_lines, modified_lines,
   vim.api.nvim_buf_clear_namespace(right_bufnr, ns_highlight, 0, -1)
   vim.api.nvim_buf_clear_namespace(left_bufnr, ns_filler, 0, -1)
   vim.api.nvim_buf_clear_namespace(right_bufnr, ns_filler, 0, -1)
+  gutter_signs.set_changed_ranges(left_bufnr, right_bufnr, lines_diff.changes)
 
   local total_left_fillers = 0
   local total_right_fillers = 0
@@ -358,6 +360,7 @@ end
 function M.render_whole_file(bufnr, side)
   vim.api.nvim_buf_clear_namespace(bufnr, ns_highlight, 0, -1)
   vim.api.nvim_buf_clear_namespace(bufnr, ns_filler, 0, -1)
+  gutter_signs.set_whole_file(bufnr, side)
 
   if not config.options.diff.highlight_added_deleted_files then
     return
@@ -398,6 +401,7 @@ function M.render_single_buffer(bufnr, diff, side)
   -- Clear existing highlights
   vim.api.nvim_buf_clear_namespace(bufnr, ns_highlight, 0, -1)
   vim.api.nvim_buf_clear_namespace(bufnr, ns_filler, 0, -1)
+  gutter_signs.clear_buffer(bufnr)
 
   -- Get buffer lines for character highlight calculations
   local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
@@ -463,6 +467,8 @@ function M.render_merge_view(left_bufnr, right_bufnr, base_to_left_diff, base_to
   vim.api.nvim_buf_clear_namespace(right_bufnr, ns_highlight, 0, -1)
   vim.api.nvim_buf_clear_namespace(right_bufnr, ns_filler, 0, -1)
   vim.api.nvim_buf_clear_namespace(right_bufnr, ns_conflict, 0, -1)
+  gutter_signs.clear_buffer(left_bufnr)
+  gutter_signs.clear_buffer(right_bufnr)
 
   -- Get buffer lines for character highlight calculations
   local left_lines = vim.api.nvim_buf_get_lines(left_bufnr, 0, -1, false)

lua/codediff/ui/gutter_signs.lua

@@ -0,0 +1,177 @@
+local M = {}
+
+local config = require("codediff.config")
+
+local namespace = vim.api.nvim_create_namespace("codediff-gutter-signs")
+-- A sign extmark spanning several rows only decorates every row from 0.10 on.
+-- Older versions decorate start_row alone, so ranges there are drawn per line.
+local has_ranged_signs = vim.fn.has("nvim-0.10") == 1
+local default_move_priority = 250
+local default_options = {
+  insert_text = "＋",
+  delete_text = "－",
+  highlight_numbers = true,
+  changed_priority = 100,
+}
+local signs = {
+  original = {
+    text_option = "delete_text",
+    hl_group = "CodeDiffGutterDelete",
+    number_hl_group = "CodeDiffGutterDeleteNumber",
+  },
+  modified = {
+    text_option = "insert_text",
+    hl_group = "CodeDiffGutterInsert",
+    number_hl_group = "CodeDiffGutterInsertNumber",
+  },
+  unchanged = { text = "  ", hl_group = "Normal" },
+  move_single = { text = "─", hl_group = "CodeDiffMoveTo" },
+  move_first = { text = "┌", hl_group = "CodeDiffMoveTo" },
+  move_middle = { text = "│", hl_group = "CodeDiffMoveTo" },
+  move_last = { text = "└", hl_group = "CodeDiffMoveTo" },
+}
+
+local get_options = function()
+  local options = config.options.diff.gutter_signs
+  if type(options) ~= "table" then
+    return nil
+  end
+  if not has_ranged_signs then
+    vim.notify_once("[codediff] diff.gutter_signs requires Neovim 0.10 or newer", vim.log.levels.WARN)
+    return nil
+  end
+  return vim.tbl_extend("force", default_options, options)
+end
+
+local get_changed_sign = function(side, options)
+  local sign = signs[side]
+  return {
+    text = options[sign.text_option],
+    hl_group = sign.hl_group,
+    number_hl_group = options.highlight_numbers and sign.number_hl_group or nil,
+  }
+end
+
+local set_extmark = function(bufnr, row, opts)
+  -- Neovim rejects sign text wider than two cells and out-of-range priorities.
+  -- Without this guard a bad option aborts the whole diff render.
+  local ok = pcall(vim.api.nvim_buf_set_extmark, bufnr, namespace, row, 0, opts)
+  if not ok then
+    vim.notify_once("[codediff] diff.gutter_signs could not place a sign, check insert_text, delete_text and priorities", vim.log.levels.WARN)
+  end
+  return ok
+end
+
+local set_sign_range = function(bufnr, range, sign, priority)
+  if not bufnr or not vim.api.nvim_buf_is_valid(bufnr) or not range or range.end_line <= range.start_line then
+    return
+  end
+
+  local line_count = vim.api.nvim_buf_line_count(bufnr)
+  local start_row = math.max(range.start_line - 1, 0)
+  local end_row = math.min(range.end_line - 1, line_count)
+  if end_row <= start_row then
+    return
+  end
+
+  set_extmark(bufnr, start_row, {
+    end_row = end_row - 1,
+    end_col = 0,
+    sign_text = sign.text,
+    sign_hl_group = sign.hl_group,
+    number_hl_group = sign.number_hl_group,
+    priority = priority,
+    strict = false,
+  })
+end
+
+local set_whole_buffer_sign = function(bufnr, sign, priority, tracks_appends)
+  if not bufnr or not vim.api.nvim_buf_is_valid(bufnr) then
+    return
+  end
+
+  local line_count = vim.api.nvim_buf_line_count(bufnr)
+  set_extmark(bufnr, 0, {
+    end_row = tracks_appends and line_count or line_count - 1,
+    end_col = 0,
+    right_gravity = false,
+    end_right_gravity = tracks_appends,
+    sign_text = sign.text,
+    sign_hl_group = sign.hl_group,
+    number_hl_group = sign.number_hl_group,
+    priority = priority,
+    strict = false,
+  })
+end
+
+M.clear_buffer = function(bufnr)
+  if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
+    vim.api.nvim_buf_clear_namespace(bufnr, namespace, 0, -1)
+  end
+end
+
+M.set_changed_ranges = function(left_bufnr, right_bufnr, changes)
+  M.clear_buffer(left_bufnr)
+  M.clear_buffer(right_bufnr)
+
+  local options = get_options()
+  if not options then
+    return
+  end
+
+  if options.unchanged_priority then
+    set_whole_buffer_sign(left_bufnr, signs.unchanged, options.unchanged_priority, false)
+    set_whole_buffer_sign(right_bufnr, signs.unchanged, options.unchanged_priority, false)
+  end
+
+  local priority = options.changed_priority
+  local original_sign = get_changed_sign("original", options)
+  local modified_sign = get_changed_sign("modified", options)
+  for _, change in ipairs(changes or {}) do
+    set_sign_range(left_bufnr, change.original, original_sign, priority)
+    set_sign_range(right_bufnr, change.modified, modified_sign, priority)
+  end
+end
+
+local move_sign = function(line, first, last)
+  if first == last then
+    return signs.move_single
+  end
+  if line == first then
+    return signs.move_first
+  end
+  if line == last then
+    return signs.move_last
+  end
+  return signs.move_middle
+end
+
+M.set_move_range = function(bufnr, first, last)
+  if last < first then
+    return
+  end
+
+  -- A moved line is also a changed line, so the move glyph has to outrank the
+  -- changed sign instead of tying with it and depending on extmark creation order.
+  local options = get_options()
+  local priority = options and math.max(options.changed_priority + 1, default_move_priority) or default_move_priority
+
+  -- One sign per line, as move rendering has always done: a single ranged
+  -- extmark would decorate only its first row before Neovim 0.10.
+  for line = first, last do
+    set_sign_range(bufnr, { start_line = line, end_line = line + 1 }, move_sign(line, first, last), priority)
+  end
+end
+
+M.set_whole_file = function(bufnr, side)
+  M.clear_buffer(bufnr)
+
+  local options = get_options()
+  if not options then
+    return
+  end
+
+  set_whole_buffer_sign(bufnr, get_changed_sign(side, options), options.changed_priority, true)
+end
+
+return M