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/commands.lua

@@ -248,18 +248,24 @@ register_session_commands = function()
     local state = require("reviewthem.session.state")
     local session = state.get_active()
     local ui_mod = require("reviewthem.ui")
-    local context = ui_mod.get_cursor_context()
+
+    -- Resolve selected buffer rows to file linenos via the line map: buffer
+    -- rows include padding and header lines, so adding the row delta to the
+    -- start lineno would overshoot the hunk.
+    local context
+    if cmd.range == 2 then
+      context = ui_mod.get_range_context(cmd.line1, cmd.line2)
+    else
+      context = ui_mod.get_cursor_context()
+    end
 
     if not context then
       vim.notify("Place cursor on a diff line to add a comment.", vim.log.levels.WARN)
       return
     end
 
-    local start_line = context.lineno
-    local end_line = context.lineno
-    if cmd.range == 2 then
-      end_line = start_line + (cmd.line2 - cmd.line1)
-    end
+    local start_line = context.start_lineno
+    local end_line = context.end_lineno
 
     local prefix = context.hunk_line.type == "add" and "+" or
                    context.hunk_line.type == "remove" and "-" or " "

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/init.lua

@@ -31,6 +31,14 @@ M.get_cursor_context = function()
   return split.get_cursor_context()
 end
 
+--- Get context for a range of buffer rows.
+---@param row1 number
+---@param row2 number
+---@return table|nil
+M.get_range_context = function(row1, row2)
+  return split.get_range_context(row1, row2)
+end
+
 --- Show a specific file.
 ---@param session ReviewSession
 ---@param file DiffFile

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 +85,120 @@ 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
+  local function take(ch)
+    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
+  -- 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. The
+  -- pattern cannot match continuation bytes at the start of the string, so
+  -- take that run separately first.
+  local head = line:match("^[\128-\191]+")
+  if head then
+    take(head)
+  end
+  for ch in line:sub(head and #head + 1 or 1):gmatch("[^\128-\191][\128-\191]*") do
+    take(ch)
+  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", "    ")
+  -- Remaining control chars are drawn caret-notated by virt_lines (^X, two
+  -- cells) but measured as one cell by nvim_strwidth; make the caret form
+  -- literal so measured and drawn widths agree.
+  normalized = normalized:gsub("[%z\1-\9\11-\31\127]", function(c)
+    local b = c:byte()
+    return b == 127 and "^?" or ("^" .. string.char(b + 64))
+  end)
+  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