diff --git a/lua/u.lua b/lua/u.lua
index 4632dc5..0740f24 100644
--- a/lua/u.lua
+++ b/lua/u.lua
@@ -6,8 +6,8 @@ local M = {}
 
 local MAX_COL = vim.v.maxcol
 
---- @param bufnr number
---- @param lnum number 1-based
+--- @param bufnr integer
+--- @param lnum integer 1-based
 local function line_text(bufnr, lnum)
   return vim.api.nvim_buf_get_lines(bufnr, lnum - 1, lnum, false)[1]
 end
@@ -73,7 +73,10 @@ function Pos.from10(bufnr, lnum1, col0, off) return Pos.new(bufnr, lnum1, col0 +
 
 function Pos.invalid() return Pos.new(0, 0, 0, 0) end
 
-function Pos.__lt(a, b) return a.lnum < b.lnum or (a.lnum == b.lnum and a.col < b.col) end
+function Pos.__lt(a, b)
+  return a.bufnr == b.bufnr
+    and (a.lnum < b.lnum or (a.lnum == b.lnum and a.col < b.col))
+end
 function Pos.__le(a, b) return a < b or a == b end
 function Pos.__eq(a, b)
   return getmetatable(a) == Pos
@@ -240,8 +243,14 @@ function Pos:find_next(dir, predicate)
 end
 
 --- Finds the matching bracket/paren for the current position.
---- @param max_chars? number|nil
---- @param invocations? u.Pos[]
+---
+--- Algorithm: Scans forward (for openers) or backward (for closers) until we find
+--- a matching character. When encountering a nested bracket of the same type, we
+--- recursively find its match first, then continue scanning. This handles deeply
+--- nested structures correctly.
+---
+--- @param max_chars? number|nil Safety limit to prevent infinite loops
+--- @param invocations? u.Pos[] Tracks positions to prevent infinite recursion
 --- @return u.Pos|nil
 function Pos:find_match(max_chars, invocations)
   if invocations == nil then invocations = {} end
@@ -317,6 +326,10 @@ end
 -- Range class (forward declared for Extmark)
 --------------------------------------------------------------------------------
 
+--- @class u.Range
+--- @field start u.Pos
+--- @field stop u.Pos|nil
+--- @field mode 'v'|'V'
 local Range = {}
 
 --------------------------------------------------------------------------------
@@ -406,14 +419,14 @@ function Range.__tostring(self)
     end
   end
 
-  local _1 = posstr(self.start)
-  local _2 = posstr(self.stop)
+  local start_str = posstr(self.start)
+  local stop_str = posstr(self.stop)
   return string.format(
     'Range{bufnr=%d, mode=%s, start=%s, stop=%s}',
     self.start.bufnr,
     self.mode,
-    _1,
-    _2
+    start_str,
+    stop_str
   )
 end
 
@@ -499,25 +512,25 @@ end
 --- @param opts? { bufnr?: number, contains_cursor?: boolean, pos?: u.Pos, user_defined?: boolean }
 --- @return u.Range|nil
 function Range.from_motion(motion, opts)
-  -- Options handling:
+  -- SECTION: Normalize options
   opts = opts or {}
   if opts.bufnr == nil or opts.bufnr == 0 then opts.bufnr = vim.api.nvim_get_current_buf() end
   if opts.contains_cursor == nil then opts.contains_cursor = false end
   if opts.user_defined == nil then opts.user_defined = false end
 
-  -- Extract some information from the motion:
+  -- SECTION: Parse motion string
   --- @type 'a'|'i', string
   local scope, motion_rest = motion:sub(1, 1), motion:sub(2)
   local is_txtobj = scope == 'a' or scope == 'i'
   local is_quote_txtobj = is_txtobj and vim.tbl_contains({ "'", '"', '`' }, motion_rest)
 
-  -- Capture the original state of the buffer for restoration later.
+  -- SECTION: Capture original state for restoration
   local original_state = {
     winview = vim.fn.winsaveview(),
-    regquote = vim.fn.getreg '"',
+    unnamed_register = vim.fn.getreg '"',
     cursor = vim.fn.getpos '.',
-    pos_lbrack = vim.fn.getpos "'[",
-    pos_rbrack = vim.fn.getpos "']",
+    mark_lbracket = vim.fn.getpos "'[",
+    mark_rbracket = vim.fn.getpos "']",
     opfunc = vim.go.operatorfunc,
     prev_captured_range = _G.Range__from_motion_opfunc_captured_range,
     prev_mode = vim.fn.mode(),
@@ -526,6 +539,7 @@ function Range.from_motion(motion, opts)
   --- @type u.Range|nil
   _G.Range__from_motion_opfunc_captured_range = nil
 
+  -- SECTION: Execute motion and capture result
   vim.api.nvim_buf_call(opts.bufnr, function()
     if opts.pos ~= nil then opts.pos:save_to_pos '.' end
 
@@ -545,19 +559,19 @@ function Range.from_motion(motion, opts)
   end)
   local captured_range = _G.Range__from_motion_opfunc_captured_range
 
-  -- Restore original state:
+  -- SECTION: Restore state
   vim.fn.winrestview(original_state.winview)
-  vim.fn.setreg('"', original_state.regquote)
+  vim.fn.setreg('"', original_state.unnamed_register)
   vim.fn.setpos('.', original_state.cursor)
-  vim.fn.setpos("'[", original_state.pos_lbrack)
-  vim.fn.setpos("']", original_state.pos_rbrack)
+  vim.fn.setpos("'[", original_state.mark_lbracket)
+  vim.fn.setpos("']", original_state.mark_rbracket)
   if original_state.prev_mode ~= 'n' then original_state.vinf:set_visual_selection() end
   vim.go.operatorfunc = original_state.opfunc
   _G.Range__from_motion_opfunc_captured_range = original_state.prev_captured_range
 
   if not captured_range then return nil end
 
-  -- Fixup the bounds:
+  -- SECTION: Fixup edge cases (quote text objects, 'it' tag)
   if
     -- I have no idea why, but when yanking `i"`, the stop-mark is
     -- placed on the ending quote. For other text-objects, the stop-
@@ -573,6 +587,7 @@ function Range.from_motion(motion, opts)
     captured_range.stop = captured_range.stop:find_next(-1, motion_rest) or captured_range.stop
   end
 
+  -- SECTION: Validate cursor containment
   if
     opts.contains_cursor and not captured_range:contains(Pos.new(unpack(original_state.cursor)))
   then
@@ -873,14 +888,14 @@ function Range:sub(i, j)
 
   local start = get_pos(i)
   if not start then
-    -- start is inalid, so return an empty range:
+    -- start is invalid, so return an empty range:
     return Range.new(self.start, nil, self.mode)
   end
 
   local stop
   if j then stop = get_pos(j) end
   if not stop then
-    -- stop is inalid, so return an empty range:
+    -- stop is invalid, so return an empty range:
     return Range.new(start, nil, self.mode)
   end
   return Range.new(start, stop, 'v')
@@ -896,8 +911,6 @@ end
 function Range:text() return vim.fn.join(self:lines(), '\n') end
 
 --- @param l number
--- luacheck: ignore
---- @return { line: string, idx0: { start: number, stop: number }, lnum: number, range: fun():u.Range, text: fun():string }|nil
 function Range:line(l)
   if l < 0 then l = self:line_count() + l + 1 end
   if l > self:line_count() then return end
@@ -1043,6 +1056,9 @@ end
 -- opkeymap
 --------------------------------------------------------------------------------
 
+-- NOTE: These must be global because Neovim's 'operatorfunc' option only
+-- accepts VimScript expressions (v:lua.FunctionName), not direct Lua
+-- references. This is a Neovim API limitation.
 --- @type fun(range: u.Range): nil|(fun():any)
 local __U__OpKeymapOpFunc_rhs = nil
 
@@ -1238,7 +1254,6 @@ local utils = {}
 ---   -- Perform search and replace...
 --- end, { nargs = 2, range = true })
 --- ```
--- luacheck: ignore
 function utils.ucmd(name, cmd, opts)
   opts = opts or {}
   local cmd2 = cmd