feat: display review comments inline in the diff view

Makefile

@@ -0,0 +1,5 @@
+.PHONY: test
+
+# Headless functional checks. Requires Neovim >= 0.10.0 on PATH.
+test:
+	nvim --headless -l tests/inline_comments_spec.lua

README.md

@@ -11,6 +11,7 @@ This project is inspired by [ReviewIt](https://github.com/yoshiko-pg/reviewit) -
 - **Split diff view** — Side-by-side old/new comparison with syntax highlighting
 - **File tree sidebar** — Browse changed files, track review progress
 - **Line-level comments** — Floating input window, supports multi-line ranges
+- **Inline comment display** — Comments are rendered as virtual text blocks right below the commented lines
 - **Session management** — Named sessions persisted as JSON, pause and resume anytime
 - **Markdown export** — Copy review output to clipboard, ready for coding agents
 - **Context-aware commands** — Only relevant commands are available at each stage
@@ -140,6 +141,7 @@ All options are optional — defaults are shown below:
 ```lua
 require("reviewthem").setup({
   comment_sign = "💬",        -- sign shown on commented lines
+  inline_comments = true,     -- show comment text inline below commented lines
   file_tree_width = 30,       -- sidebar width in columns
   auto_save = true,           -- auto-save session on changes
   keymaps = {

doc/reviewthem.txt

@@ -70,6 +70,7 @@ Call the setup function with optional configuration: >lua
 
     require("reviewthem").setup({
       comment_sign = "💬",
+      inline_comments = true,
       file_tree_width = 30,
       auto_save = true,
       keymaps = {
@@ -186,6 +187,13 @@ comment_sign~
     Default: "💬"
     Sign displayed at the end of commented lines in the diff view.
 
+inline_comments~
+    Default: true
+    Render the full comment text inline below the commented line in the
+    diff view using virtual lines. Blank filler lines are added to the
+    opposite pane so both sides stay aligned. Set to false to only show
+    the comment_sign indicator.
+
 file_tree_width~
     Default: 30
     Width of the file tree sidebar in columns.

lua/reviewthem/config.lua

@@ -2,6 +2,7 @@ local M = {}
 
 M.defaults = {
   comment_sign = "💬",
+  inline_comments = true,
   file_tree_width = 30,
   auto_save = true,
   keymaps = {

lua/reviewthem/diff/renderer.lua

@@ -14,6 +14,8 @@ M.setup_highlights = function()
     ReviewThemLineNrNew = { default = true, fg = "#60e060" },
     ReviewThemLineNrContext = { default = true, link = "LineNr" },
     ReviewThemCommentSign = { default = true, fg = "#f0c060" },
+    ReviewThemInlineComment = { default = true, link = "Comment" },
+    ReviewThemInlineCommentBorder = { default = true, link = "NonText" },
     ReviewThemSeparator = { default = true, fg = "#555555" },
     ReviewThemPadding = { default = true, bg = "#1a1a2a" },
   }
@@ -83,6 +85,104 @@ M.add_comment_sign = function(bufnr, line_idx, sign)
   })
 end
 
+--- Wrap a single line of text by display width, safe for multibyte text.
+---@param line string
+---@param max_width number
+---@return string[]
+local function wrap_line(line, max_width)
+  if max_width < 1 then
+    max_width = 1
+  end
+  if line == "" or vim.api.nvim_strwidth(line) <= max_width then
+    return { line }
+  end
+
+  local wrapped = {}
+  local current = ""
+  local current_width = 0
+  -- Iterate over characters: any non-continuation byte starts a new one, so
+  -- bytes that are not valid UTF-8 are kept instead of being dropped.
+  for ch in line:gmatch("[^\128-\191][\128-\191]*") do
+    local w = vim.api.nvim_strwidth(ch)
+    if current_width + w > max_width and current ~= "" then
+      table.insert(wrapped, current)
+      current = ""
+      current_width = 0
+    end
+    current = current .. ch
+    current_width = current_width + w
+  end
+  if current ~= "" then
+    table.insert(wrapped, current)
+  end
+  return wrapped
+end
+
+--- Split comment text into display lines: tabs are expanded and CR is treated
+--- as a line break, so widths measured by wrap_line match what is drawn.
+---@param text string
+---@return string[]
+local function comment_display_lines(text)
+  local normalized = text:gsub("\r\n", "\n"):gsub("\r", "\n"):gsub("\t", "    ")
+  return vim.split(normalized, "\n", { plain = true })
+end
+
+--- Render comment blocks inline below a buffer line using virt_lines.
+--- Multiple comments are stacked in order.
+---@param bufnr number
+---@param line_idx number  0-indexed anchor line
+---@param comments Comment[]
+---@param sign string
+---@param max_width number  maximum display width for comment text lines
+---@return number  number of virtual lines added
+M.add_inline_comments = function(bufnr, line_idx, comments, sign, max_width)
+  local virt_lines = {}
+  for _, comment in ipairs(comments) do
+    local range = comment.start_line == comment.end_line and ("L" .. comment.start_line)
+      or ("L" .. comment.start_line .. "-" .. comment.end_line)
+    table.insert(virt_lines, {
+      { "  ┌─ ", "ReviewThemInlineCommentBorder" },
+      { sign .. " " .. range, "ReviewThemInlineComment" },
+      { " ─", "ReviewThemInlineCommentBorder" },
+    })
+    for _, text_line in ipairs(comment_display_lines(comment.text)) do
+      for _, chunk in ipairs(wrap_line(text_line, max_width)) do
+        table.insert(virt_lines, {
+          { "  │ ", "ReviewThemInlineCommentBorder" },
+          { chunk, "ReviewThemInlineComment" },
+        })
+      end
+    end
+    table.insert(virt_lines, { { "  └─", "ReviewThemInlineCommentBorder" } })
+  end
+
+  vim.api.nvim_buf_set_extmark(bufnr, ns, line_idx, 0, {
+    virt_lines = virt_lines,
+    priority = 20,
+  })
+  return #virt_lines
+end
+
+--- Add blank virtual lines below a buffer line.
+--- Used to mirror the height of an inline comment block in the opposite pane so
+--- the two split buffers keep the same screen rows.
+---@param bufnr number
+---@param line_idx number  0-indexed anchor line
+---@param count number  number of blank lines (no-op when <= 0)
+M.add_filler_lines = function(bufnr, line_idx, count)
+  if count <= 0 then
+    return
+  end
+  local virt_lines = {}
+  for _ = 1, count do
+    table.insert(virt_lines, { { "", "ReviewThemInlineCommentBorder" } })
+  end
+  vim.api.nvim_buf_set_extmark(bufnr, ns, line_idx, 0, {
+    virt_lines = virt_lines,
+    priority = 20,
+  })
+end
+
 --- Add a file header decoration.
 ---@param bufnr number
 ---@param line_idx number  0-indexed

lua/reviewthem/diff/split.lua

@@ -124,21 +124,54 @@ local function build_split_content(file)
   return old_lines, new_lines, old_map, new_map
 end
 
+---@type table<number, number> Last wrap width used per buffer, to skip no-op refreshes
+local wrap_widths = {}
+
+--- Wrap width for inline comment text: keep blocks readable without
+--- overflowing the window.
+---@param bufnr number
+---@return number
+local function compute_wrap_width(bufnr)
+  local winid = vim.fn.bufwinid(bufnr)
+  local win_width = winid ~= -1 and vim.api.nvim_win_get_width(winid) or vim.o.columns
+  return math.max(20, math.min(80, win_width - 10))
+end
+
 --- Apply decorations to a split buffer.
 ---@param bufnr number
 ---@param line_map table[]
 ---@param session ReviewSession
+---@return table<number, number> inline_heights  virt_lines count per 0-indexed row
 local function apply_split_decorations(bufnr, line_map, session)
   renderer.clear(bufnr)
 
+  local config = require("reviewthem.config").get()
+
   local comment_lookup = {}
+  local inline_lookup = {}
   for _, c in ipairs(session.comments) do
     for l = c.start_line, c.end_line do
       comment_lookup[c.file .. ":" .. c.side .. ":" .. l] = true
     end
+    if config.inline_comments then
+      local key = c.file .. ":" .. c.side .. ":" .. c.end_line
+      inline_lookup[key] = inline_lookup[key] or {}
+      table.insert(inline_lookup[key], c)
+    end
+  end
+  for _, list in pairs(inline_lookup) do
+    table.sort(list, function(a, b)
+      if a.start_line ~= b.start_line then
+        return a.start_line < b.start_line
+      end
+      return tostring(a.id) < tostring(b.id)
+    end)
   end
 
-  local config = require("reviewthem.config").get()
+  local wrap_width = compute_wrap_width(bufnr)
+  wrap_widths[bufnr] = wrap_width
+
+  local inline_heights = {}
 
   for i, entry in ipairs(line_map) do
     local line_idx = i - 1
@@ -152,12 +185,78 @@ local function apply_split_decorations(bufnr, line_map, session)
       if comment_lookup[key] then
         renderer.add_comment_sign(bufnr, line_idx, config.comment_sign)
       end
+      local inline_comments = inline_lookup[key]
+      if inline_comments then
+        inline_heights[line_idx] =
+          renderer.add_inline_comments(bufnr, line_idx, inline_comments, config.comment_sign, wrap_width)
+      end
     elseif entry.type == "padding" then
       vim.api.nvim_buf_set_extmark(bufnr, renderer.get_namespace(), line_idx, 0, {
         line_hl_group = "ReviewThemPadding",
       })
     end
   end
+
+  return inline_heights
+end
+
+--- Decorate both panes of the current view.
+--- Inline comment blocks only exist on the side they belong to, so the opposite
+--- pane gets blank filler lines of the same height. Without them the panes would
+--- drift apart on screen: 'scrollbind' syncs buffer lines, not screen rows.
+---@param session ReviewSession
+local function apply_both_decorations(session)
+  local old_bufnr = view_state.old_bufnr
+  local new_bufnr = view_state.new_bufnr
+  local old_valid = old_bufnr ~= nil and vim.api.nvim_buf_is_valid(old_bufnr)
+  local new_valid = new_bufnr ~= nil and vim.api.nvim_buf_is_valid(new_bufnr)
+
+  local old_heights = old_valid and apply_split_decorations(old_bufnr, view_state.line_map_old, session) or {}
+  local new_heights = new_valid and apply_split_decorations(new_bufnr, view_state.line_map_new, session) or {}
+
+  if not (old_valid and new_valid) then
+    return
+  end
+
+  -- Both line maps are built in lockstep, so a row index means the same
+  -- position in either pane.
+  for line_idx, height in pairs(old_heights) do
+    renderer.add_filler_lines(new_bufnr, line_idx, height - (new_heights[line_idx] or 0))
+  end
+  for line_idx, height in pairs(new_heights) do
+    renderer.add_filler_lines(old_bufnr, line_idx, height - (old_heights[line_idx] or 0))
+  end
+end
+
+local RESIZE_AUGROUP = "ReviewThemSplitResize"
+
+--- Re-render decorations when a pane resize changes the inline comment wrap
+--- width. Registered once per render; the augroup is cleared on re-register.
+local function setup_resize_refresh()
+  local group = vim.api.nvim_create_augroup(RESIZE_AUGROUP, { clear = true })
+  vim.api.nvim_create_autocmd({ "WinResized", "VimResized" }, {
+    group = group,
+    callback = function()
+      local session = view_state.session
+      if not session then
+        return
+      end
+      local changed = false
+      for _, bufnr in ipairs({ view_state.old_bufnr, view_state.new_bufnr }) do
+        if bufnr and vim.api.nvim_buf_is_valid(bufnr) and wrap_widths[bufnr] ~= compute_wrap_width(bufnr) then
+          changed = true
+        end
+      end
+      if not changed then
+        return
+      end
+      vim.schedule(function()
+        if view_state.session then
+          M.refresh_decorations(view_state.session)
+        end
+      end)
+    end,
+  })
 end
 
 --- Prevent accidental close of diff buffer windows.
@@ -278,11 +377,7 @@ M.render_file = function(session, file, old_winnr, new_winnr)
     })
   end
 
-  -- Apply decorations
-  apply_split_decorations(old_bufnr, old_map, session)
-  apply_split_decorations(new_bufnr, new_map, session)
-
-  -- Update state
+  -- Update state (decorations below need both line maps for pane alignment)
   view_state.old_bufnr = old_bufnr
   view_state.new_bufnr = new_bufnr
   view_state.old_winnr = old_winnr
@@ -291,17 +386,18 @@ M.render_file = function(session, file, old_winnr, new_winnr)
   view_state.line_map_new = new_map
   view_state.current_file = file.path
   view_state.session = session
+
+  -- Apply decorations
+  apply_both_decorations(session)
+
+  -- Re-wrap inline comments when the panes change width
+  setup_resize_refresh()
 end
 
 --- Refresh decorations for the current split view.
 ---@param session ReviewSession
 M.refresh_decorations = function(session)
-  if view_state.old_bufnr and vim.api.nvim_buf_is_valid(view_state.old_bufnr) then
-    apply_split_decorations(view_state.old_bufnr, view_state.line_map_old, session)
-  end
-  if view_state.new_bufnr and vim.api.nvim_buf_is_valid(view_state.new_bufnr) then
-    apply_split_decorations(view_state.new_bufnr, view_state.line_map_new, session)
-  end
+  apply_both_decorations(session)
 end
 
 --- Get context info for cursor position in either split buffer.
@@ -362,11 +458,13 @@ end
 --- Close split view buffers.
 M.close = function()
   closing_intentionally = true
+  pcall(vim.api.nvim_del_augroup_by_name, RESIZE_AUGROUP)
   for _, bufnr in ipairs({ view_state.old_bufnr, view_state.new_bufnr }) do
     if bufnr and vim.api.nvim_buf_is_valid(bufnr) then
       vim.api.nvim_buf_delete(bufnr, { force = true })
     end
   end
+  wrap_widths = {}
   view_state.old_bufnr = nil
   view_state.new_bufnr = nil
   view_state.old_winnr = nil