feat(conflict): add virtual text formatting and action lines (#101)

## Problem

Conflict resolution virtual text only showed plain "current" /
"incoming"
labels with no keymap hints. Users had no way to discover available
resolution keymaps without reading docs.

## Solution

Default virtual text labels now include keymap hints: `(current — doo)`
and
`(incoming — dot)`. A new `format_virtual_text` config option lets users
customize or hide labels entirely. A new `show_actions` option (off by
default) renders a codelens-style action line above each `<<<<<<<`
marker
listing all enabled resolution keymaps. Merge diff views also gain hunk
hints on `@@` header lines showing available keymaps.

New config fields: `conflict.format_virtual_text` (function|nil),
`conflict.show_actions` (boolean). New highlight group:
`DiffsConflictActions`.

README.md

@@ -9,18 +9,12 @@ syntax highlighting.
 
 ## Features
 
-- Treesitter syntax highlighting in `:Git` diffs and commit views
+- Treesitter syntax highlighting in fugitive diffs and commit views
-- Diff header highlighting (`diff --git`, `index`, `---`, `+++`)
+- Character-level intra-line diff highlighting
-- `:Gdiffsplit` / `:Gvdiffsplit` syntax through diff backgrounds
+- `:Gdiff` unified diff against any revision
-- `:Gdiff` unified diff against any git revision with syntax highlighting
+- Background-only diff colors for `&diff` buffers
-- Fugitive status buffer keymaps (`du`/`dU`) for unified diffs
+- Inline merge conflict detection, highlighting, and resolution
-- Background-only diff colors for any `&diff` buffer (`:diffthis`, `vimdiff`)
+- Vim syntax fallback, context padding, configurable blend/debounce
-- Vim syntax fallback for languages without a treesitter parser
-- Hunk header context highlighting (`@@ ... @@ function foo()`)
-- Character-level (intra-line) diff highlighting for changed characters
-- Inline merge conflict detection, highlighting, and resolution keymaps
-- Configurable debouncing, max lines, diff prefix concealment, blend alpha, and
-  highlight overrides
 
 ## Requirements
 

doc/diffs.nvim.txt

@@ -85,6 +85,7 @@ Configuration is done via `vim.g.diffs`. Set this before the plugin loads:
         enabled = true,
         disable_diagnostics = true,
         show_virtual_text = true,
+        show_actions = false,
         keymaps = {
           ours = 'doo',
           theirs = 'dot',
@@ -416,6 +417,7 @@ Configuration: ~
         enabled = true,
         disable_diagnostics = true,
         show_virtual_text = true,
+        show_actions = false,
         keymaps = {
           ours = 'doo',
           theirs = 'dot',
@@ -442,9 +444,32 @@ Configuration: ~
                              diagnostics alone.
 
         {show_virtual_text}  (boolean, default: true)
-                             Show virtual text labels (" current" and
+                             Show `(current)` and `(incoming)` labels at
-                             " incoming") at the end of `<<<<<<<` and
+                             the end of `<<<<<<<` and `>>>>>>>` marker
-                             `>>>>>>>` marker lines.
+                             lines. Also controls hunk hints in merge
+                             diff views.
+
+        {format_virtual_text} (function|nil, default: nil)
+                             Custom formatter for virtual text labels.
+                             Receives `(side, keymap)` where `side` is
+                             `"ours"` or `"theirs"` and `keymap` is the
+                             configured keymap string or `false`. Return
+                             a string (label text without parens) or
+                             `nil` to hide the label. Example: >lua
+                                 format_virtual_text = function(side, keymap)
+                                   if keymap then
+                                     return side .. ' [' .. keymap .. ']'
+                                   end
+                                   return side
+                                 end
+<
+
+        {show_actions}       (boolean, default: false)
+                             Show a codelens-style action line above each
+                             `<<<<<<<` marker listing available resolution
+                             keymaps. Renders as virtual lines using the
+                             `DiffsConflictActions` highlight group.
+                             Only keymaps that are not `false` appear.
 
         {keymaps}            (table, default: see above)
                              Buffer-local keymaps for conflict resolution
@@ -687,6 +712,10 @@ Conflict highlights: ~
                                                       *DiffsConflictBaseNr*
     DiffsConflictBaseNr Line number for base content lines (diff3).
 
+                                                    *DiffsConflictActions*
+    DiffsConflictActions Dimmed foreground (no bold) for the codelens-style
+                        action line shown when `show_actions` is true.
+
 Diff mode window highlights: ~
 These are used for |winhighlight| remapping in `&diff` windows.
 

lua/diffs/conflict.lua

@@ -92,6 +92,17 @@ local function parse_buffer(bufnr)
   return M.parse(lines)
 end
 
+---@param side string
+---@param config diffs.ConflictConfig
+---@return string?
+local function get_virtual_text_label(side, config)
+  if config.format_virtual_text then
+    local keymap = side == 'ours' and config.keymaps.ours or config.keymaps.theirs
+    return config.format_virtual_text(side, keymap)
+  end
+  return side == 'ours' and 'current' or 'incoming'
+end
+
 ---@param bufnr integer
 ---@param regions diffs.ConflictRegion[]
 ---@param config diffs.ConflictConfig
@@ -107,10 +118,37 @@ local function apply_highlights(bufnr, regions, config)
     })
 
     if config.show_virtual_text then
-      pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, region.marker_ours, 0, {
+      local ours_label = get_virtual_text_label('ours', config)
-        virt_text = { { ' (current)', 'DiffsConflictMarker' } },
+      if ours_label then
-        virt_text_pos = 'eol',
+        pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, region.marker_ours, 0, {
-      })
+          virt_text = { { ' (' .. ours_label .. ')', 'DiffsConflictMarker' } },
+          virt_text_pos = 'eol',
+        })
+      end
+    end
+
+    if config.show_actions then
+      local parts = {}
+      local actions = {
+        { 'Current', config.keymaps.ours },
+        { 'Incoming', config.keymaps.theirs },
+        { 'Both', config.keymaps.both },
+        { 'None', config.keymaps.none },
+      }
+      for _, action in ipairs(actions) do
+        if action[2] then
+          if #parts > 0 then
+            table.insert(parts, { ' \226\148\130 ', 'DiffsConflictActions' })
+          end
+          table.insert(parts, { ('%s (%s)'):format(action[1], action[2]), 'DiffsConflictActions' })
+        end
+      end
+      if #parts > 0 then
+        pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, region.marker_ours, 0, {
+          virt_lines = { parts },
+          virt_lines_above = true,
+        })
+      end
     end
 
     for line = region.ours_start, region.ours_end - 1 do
@@ -176,10 +214,13 @@ local function apply_highlights(bufnr, regions, config)
     })
 
     if config.show_virtual_text then
-      pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, region.marker_theirs, 0, {
+      local theirs_label = get_virtual_text_label('theirs', config)
-        virt_text = { { ' (incoming)', 'DiffsConflictMarker' } },
+      if theirs_label then
-        virt_text_pos = 'eol',
+        pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, region.marker_theirs, 0, {
-      })
+          virt_text = { { ' (' .. theirs_label .. ')', 'DiffsConflictMarker' } },
+          virt_text_pos = 'eol',
+        })
+      end
     end
   end
 end

lua/diffs/init.lua

@@ -41,6 +41,8 @@
 ---@field enabled boolean
 ---@field disable_diagnostics boolean
 ---@field show_virtual_text boolean
+---@field format_virtual_text? fun(side: string, keymap: string|false): string?
+---@field show_actions boolean
 ---@field keymaps diffs.ConflictKeymaps
 
 ---@class diffs.Config
@@ -128,6 +130,7 @@ local default_config = {
     enabled = true,
     disable_diagnostics = true,
     show_virtual_text = true,
+    show_actions = false,
     keymaps = {
       ours = 'doo',
       theirs = 'dot',
@@ -276,6 +279,7 @@ local function compute_highlight_groups()
   vim.api.nvim_set_hl(0, 'DiffsConflictTheirs', { default = true, bg = blended_theirs })
   vim.api.nvim_set_hl(0, 'DiffsConflictBase', { default = true, bg = blended_base })
   vim.api.nvim_set_hl(0, 'DiffsConflictMarker', { default = true, fg = 0x808080, bold = true })
+  vim.api.nvim_set_hl(0, 'DiffsConflictActions', { default = true, fg = 0x808080 })
   vim.api.nvim_set_hl(
     0,
     'DiffsConflictOursNr',
@@ -390,6 +394,8 @@ local function init()
       ['conflict.enabled'] = { opts.conflict.enabled, 'boolean', true },
       ['conflict.disable_diagnostics'] = { opts.conflict.disable_diagnostics, 'boolean', true },
       ['conflict.show_virtual_text'] = { opts.conflict.show_virtual_text, 'boolean', true },
+      ['conflict.format_virtual_text'] = { opts.conflict.format_virtual_text, 'function', true },
+      ['conflict.show_actions'] = { opts.conflict.show_actions, 'boolean', true },
       ['conflict.keymaps'] = { opts.conflict.keymaps, 'table', true },
     })
 

lua/diffs/merge.lua

@@ -338,6 +338,43 @@ function M.goto_prev(bufnr)
   vim.api.nvim_win_set_cursor(0, { candidates[#candidates].start_line + 1, 0 })
 end
 
+---@param bufnr integer
+---@param config diffs.ConflictConfig
+local function apply_hunk_hints(bufnr, config)
+  if not config.show_virtual_text then
+    return
+  end
+
+  local hunks = M.parse_hunks(bufnr)
+  for _, hunk in ipairs(hunks) do
+    if M.is_resolved(bufnr, hunk.index) then
+      add_resolved_virtual_text(bufnr, hunk)
+    else
+      local parts = {}
+      local actions = {
+        { 'current', config.keymaps.ours },
+        { 'incoming', config.keymaps.theirs },
+        { 'both', config.keymaps.both },
+        { 'none', config.keymaps.none },
+      }
+      for _, action in ipairs(actions) do
+        if action[2] then
+          if #parts > 0 then
+            table.insert(parts, { ' | ', 'Comment' })
+          end
+          table.insert(parts, { ('%s: %s'):format(action[2], action[1]), 'Comment' })
+        end
+      end
+      if #parts > 0 then
+        pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, hunk.start_line, 0, {
+          virt_text = parts,
+          virt_text_pos = 'eol',
+        })
+      end
+    end
+  end
+end
+
 ---@param bufnr integer
 ---@param config diffs.ConflictConfig
 function M.setup_keymaps(bufnr, config)
@@ -358,6 +395,8 @@ function M.setup_keymaps(bufnr, config)
     end
   end
 
+  apply_hunk_hints(bufnr, config)
+
   vim.api.nvim_create_autocmd('BufWipeout', {
     buffer = bufnr,
     callback = function()

spec/conflict_spec.lua

@@ -6,6 +6,7 @@ local function default_config(overrides)
     enabled = true,
     disable_diagnostics = false,
     show_virtual_text = true,
+    show_actions = false,
     keymaps = {
       ours = 'doo',
       theirs = 'dot',
@@ -685,4 +686,158 @@ describe('conflict', function()
       helpers.delete_buffer(bufnr)
     end)
   end)
+
+  describe('virtual text formatting', function()
+    after_each(function()
+      conflict.detach(vim.api.nvim_get_current_buf())
+    end)
+
+    it('default labels show current and incoming without keymaps', function()
+      local bufnr = create_file_buffer({
+        '<<<<<<< HEAD',
+        'local x = 1',
+        '=======',
+        'local x = 2',
+        '>>>>>>> feature',
+      })
+
+      conflict.attach(bufnr, default_config())
+
+      local extmarks = get_extmarks(bufnr)
+      local labels = {}
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text then
+          table.insert(labels, mark[4].virt_text[1][1])
+        end
+      end
+      assert.are.equal(2, #labels)
+      assert.are.equal(' (current)', labels[1])
+      assert.are.equal(' (incoming)', labels[2])
+
+      helpers.delete_buffer(bufnr)
+    end)
+
+    it('uses custom format_virtual_text function', function()
+      local bufnr = create_file_buffer({
+        '<<<<<<< HEAD',
+        'local x = 1',
+        '=======',
+        'local x = 2',
+        '>>>>>>> feature',
+      })
+
+      conflict.attach(
+        bufnr,
+        default_config({
+          format_virtual_text = function(side)
+            return side == 'ours' and 'OURS' or 'THEIRS'
+          end,
+        })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local labels = {}
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text then
+          table.insert(labels, mark[4].virt_text[1][1])
+        end
+      end
+      assert.are.equal(2, #labels)
+      assert.are.equal(' (OURS)', labels[1])
+      assert.are.equal(' (THEIRS)', labels[2])
+
+      helpers.delete_buffer(bufnr)
+    end)
+
+    it('hides label when format_virtual_text returns nil', function()
+      local bufnr = create_file_buffer({
+        '<<<<<<< HEAD',
+        'local x = 1',
+        '=======',
+        'local x = 2',
+        '>>>>>>> feature',
+      })
+
+      conflict.attach(
+        bufnr,
+        default_config({
+          format_virtual_text = function()
+            return nil
+          end,
+        })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      local virt_text_count = 0
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text then
+          virt_text_count = virt_text_count + 1
+        end
+      end
+      assert.are.equal(0, virt_text_count)
+
+      helpers.delete_buffer(bufnr)
+    end)
+  end)
+
+  describe('action lines', function()
+    after_each(function()
+      conflict.detach(vim.api.nvim_get_current_buf())
+    end)
+
+    it('adds virt_lines when show_actions is true', function()
+      local bufnr = create_file_buffer({
+        '<<<<<<< HEAD',
+        'local x = 1',
+        '=======',
+        'local x = 2',
+        '>>>>>>> feature',
+      })
+
+      conflict.attach(bufnr, default_config({ show_actions = true }))
+
+      local extmarks = get_extmarks(bufnr)
+      local virt_lines_count = 0
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_lines then
+          virt_lines_count = virt_lines_count + 1
+        end
+      end
+      assert.are.equal(1, virt_lines_count)
+
+      helpers.delete_buffer(bufnr)
+    end)
+
+    it('omits disabled keymaps from action line', function()
+      local bufnr = create_file_buffer({
+        '<<<<<<< HEAD',
+        'local x = 1',
+        '=======',
+        'local x = 2',
+        '>>>>>>> feature',
+      })
+
+      conflict.attach(
+        bufnr,
+        default_config({ show_actions = true, keymaps = { both = false, none = false } })
+      )
+
+      local extmarks = get_extmarks(bufnr)
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_lines then
+          local line = mark[4].virt_lines[1]
+          local text = ''
+          for _, chunk in ipairs(line) do
+            text = text .. chunk[1]
+          end
+          assert.is_truthy(text:find('Current'))
+          assert.is_truthy(text:find('Incoming'))
+          assert.is_falsy(text:find('Both'))
+          assert.is_falsy(text:find('None'))
+        end
+      end
+
+      helpers.delete_buffer(bufnr)
+    end)
+  end)
 end)

spec/merge_spec.lua

@@ -6,6 +6,7 @@ local function default_config(overrides)
     enabled = true,
     disable_diagnostics = false,
     show_virtual_text = true,
+    show_actions = false,
     keymaps = {
       ours = 'doo',
       theirs = 'dot',
@@ -617,6 +618,65 @@ describe('merge', function()
     end)
   end)
 
+  describe('hunk hints', function()
+    it('adds keymap hints on hunk header lines', function()
+      local d_bufnr = create_diff_buffer({
+        'diff --git a/file.lua b/file.lua',
+        '--- a/file.lua',
+        '+++ b/file.lua',
+        '@@ -1,1 +1,1 @@',
+        '-local x = 1',
+        '+local x = 2',
+      })
+
+      merge.setup_keymaps(d_bufnr, default_config())
+
+      local extmarks =
+        vim.api.nvim_buf_get_extmarks(d_bufnr, merge.get_namespace(), 0, -1, { details = true })
+      local hint_marks = {}
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text then
+          local text = ''
+          for _, chunk in ipairs(mark[4].virt_text) do
+            text = text .. chunk[1]
+          end
+          table.insert(hint_marks, { line = mark[2], text = text })
+        end
+      end
+      assert.are.equal(1, #hint_marks)
+      assert.are.equal(3, hint_marks[1].line)
+      assert.is_truthy(hint_marks[1].text:find('doo'))
+      assert.is_truthy(hint_marks[1].text:find('dot'))
+
+      helpers.delete_buffer(d_bufnr)
+    end)
+
+    it('does not add hints when show_virtual_text is false', function()
+      local d_bufnr = create_diff_buffer({
+        'diff --git a/file.lua b/file.lua',
+        '--- a/file.lua',
+        '+++ b/file.lua',
+        '@@ -1,1 +1,1 @@',
+        '-local x = 1',
+        '+local x = 2',
+      })
+
+      merge.setup_keymaps(d_bufnr, default_config({ show_virtual_text = false }))
+
+      local extmarks =
+        vim.api.nvim_buf_get_extmarks(d_bufnr, merge.get_namespace(), 0, -1, { details = true })
+      local virt_text_count = 0
+      for _, mark in ipairs(extmarks) do
+        if mark[4] and mark[4].virt_text then
+          virt_text_count = virt_text_count + 1
+        end
+      end
+      assert.are.equal(0, virt_text_count)
+
+      helpers.delete_buffer(d_bufnr)
+    end)
+  end)
+
   describe('fugitive integration', function()
     it('parse_file_line returns status for unmerged files', function()
       local fugitive = require('diffs.fugitive')