diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2a0df4a..dcf5dcb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,34 +9,41 @@ jobs:
 
     strategy:
       matrix:
-        nvim: [v0.9.1, nightly]
+        nvim: [nightly]
+
+    env:
+      RIPGREP_VERSION: "14.1.0"
+      VIM: ~/.local/share/nvim/share/nvim/runtime
 
     steps:
       - uses: actions/checkout@v3
 
-      - name: Set Envs
+      - name: Add PATH
         run: |
-          echo "VIM=~/.local/share/nvim/share/nvim/runtime" >> $GITHUB_ENV
-          echo "PATH=~/.local/share/nvim/bin:$PATH" >> $GITHUB_ENV
+          echo "$HOME/.local/share/nvim/bin" >> $GITHUB_PATH
+          echo "$HOME/.local/share/ripgrep" >> $GITHUB_PATH
 
       - name: Cache Dependencies
         id: cache
-        uses: actions/cache@v3
+        uses: actions/cache@v4
         with:
-          path: ~/.local/share/nvim
-          key: ${{ runner.os }}-nvim-${{ matrix.nvim }}
+          key: ${{ runner.os }}-nvim-${{ matrix.nvim }}-rg-${{ env.RIPGREP_VERSION }}
+          path: |
+            ~/.local/share/nvim
+            ~/.local/share/ripgrep
 
       - name: Install Dependencies
         if: steps.cache.outputs.cache-hit != 'true'
         run: |
-          mkdir -p ~/.local/share/nvim/
+          mkdir -p ~/.local/share/{nvim,ripgrep}
+          curl -sL "https://github.com/BurntSushi/ripgrep/releases/download/$RIPGREP_VERSION/ripgrep-$RIPGREP_VERSION-x86_64-unknown-linux-musl.tar.gz" | tar xzf - --strip-components=1 -C ~/.local/share/ripgrep
           curl -sL "https://github.com/neovim/neovim/releases/download/${{ matrix.nvim }}/nvim-linux64.tar.gz" | tar xzf - --strip-components=1 -C ~/.local/share/nvim/
           git clone --depth 1 https://github.com/nvim-treesitter/nvim-treesitter.git ~/.local/share/nvim/site/pack/vendor/start/nvim-treesitter
           git clone --depth 1 https://github.com/nvim-lua/plenary.nvim ~/.local/share/nvim/site/pack/vendor/start/plenary.nvim
-          ln -s $(pwd) ~/.local/share/nvim/site/pack/vendor/start
-          nvim --headless -c 'TSInstallSync python javascript lua rust go' -c 'q'
+          ln -s $PWD ~/.local/share/nvim/site/pack/vendor/start
+          nvim --headless '+TSInstallSync python javascript lua rust go' +q
           
       - name: Run tests
         run: |
-          nvim --version
-          nvim --headless -c 'PlenaryBustedDirectory tests/'
+          nvim --version | head -1 && rg --version | head -1
+          nvim --headless '+PlenaryBustedDirectory tests/'
diff --git a/.neoconf.json b/.neoconf.json
new file mode 100644
index 0000000..39b80bd
--- /dev/null
+++ b/.neoconf.json
@@ -0,0 +1,20 @@
+{
+  "neodev": {
+    "library": {
+      "enabled": true,
+      "plugins": ["plenary.nvim"]
+    }
+  },
+  "neoconf": {
+    "plugins": {
+      "lua_ls": {
+        "enabled": true
+      }
+    }
+  },
+  "lspconfig": {
+    "lua_ls": {
+      "Lua.format.enable": false
+    }
+  }
+}
diff --git a/lua/ssr.lua b/lua/ssr.lua
deleted file mode 100644
index a32cfe4..0000000
--- a/lua/ssr.lua
+++ /dev/null
@@ -1,471 +0,0 @@
-local api = vim.api
-local ts = vim.treesitter
-local fn = vim.fn
-local keymap = vim.keymap
-local highlight = vim.highlight
-local ParseContext = require("ssr.parse").ParseContext
-local search = require("ssr.search").search
-local replace = require("ssr.search").replace
-local u = require "ssr.utils"
-
-local M = {}
-
----@class Config
-local config = {
-  border = "rounded",
-  min_width = 50,
-  min_height = 5,
-  max_width = 120,
-  max_height = 25,
-  adjust_window = true,
-  keymaps = {
-    close = "q",
-    next_match = "n",
-    prev_match = "N",
-    replace_confirm = "<cr>",
-    replace_all = "<leader><cr>",
-  },
-}
-
--- Set config options.
----@param cfg Config?
-function M.setup(cfg)
-  if cfg then
-    config = vim.tbl_deep_extend("force", config, cfg)
-  end
-end
-
----@type table<window, Ui>
-local win_uis = {}
-
----@class Ui
----@field ns number
----@field cur_search_ns number
----@field augroup number
----@field ui_buf buffer
----@field extmarks {status: number, search: number, replace: number}
----@field origin_win window
----@field lang string
----@field parse_context ParseContext
----@field buf_matches table<buffer, Match[]>
-local Ui = {}
-
----@return Ui?
-function Ui.new()
-  local self = setmetatable({}, { __index = Ui })
-
-  self.origin_win = api.nvim_get_current_win()
-  local origin_buf = api.nvim_win_get_buf(self.origin_win)
-  local lang = ts.language.get_lang(vim.bo[origin_buf].filetype)
-  if not lang then
-    return u.notify("Treesitter language not found")
-  end
-  self.lang = lang
-
-  local origin_node = u.node_for_range(origin_buf, self.lang, u.get_selection(self.origin_win))
-  if not origin_node then
-    return u.notify("Treesitter parser not found, please try to install it with :TSInstall " .. self.lang)
-  end
-  if origin_node:has_error() then
-    return u.notify "You have syntax errors in the selected node"
-  end
-  local parse_context = ParseContext.new(origin_buf, origin_node)
-  if not parse_context then
-    return u.notify "Can't find a proper context to parse the pattern"
-  end
-  self.parse_context = parse_context
-
-  self.buf_matches = {}
-  self.ns = api.nvim_create_namespace("ssr_" .. self.origin_win) -- TODO
-  self.cur_search_ns = api.nvim_create_namespace("ssr_cur_match_" .. self.origin_win)
-  self.augroup = api.nvim_create_augroup("ssr_augroup_" .. self.origin_win, {})
-
-  -- Init ui buffer
-  self.ui_buf = api.nvim_create_buf(false, true)
-  vim.bo[self.ui_buf].filetype = "ssr"
-
-  local placeholder = ts.get_node_text(origin_node, origin_buf)
-  placeholder = "\n\n" .. placeholder .. "\n\n"
-  placeholder = vim.split(placeholder, "\n")
-  u.remove_indent(placeholder, u.get_indent(origin_buf, origin_node:start()))
-  api.nvim_buf_set_lines(self.ui_buf, 0, -1, true, placeholder)
-  -- Enable syntax highlights
-  ts.start(self.ui_buf, self.lang)
-
-  local function virt_text(row, text)
-    return api.nvim_buf_set_extmark(self.ui_buf, self.ns, row, 0, { virt_text = text, virt_text_pos = "overlay" })
-  end
-  self.extmarks = {
-    status = virt_text(0, { { "[SSR]", "Comment" }, { " (Press ? for help)", "Comment" } }),
-    search = virt_text(1, { { "SEARCH:", "String" } }),
-    replace = virt_text(#placeholder - 2, { { "REPLACE:", "String" } }),
-  }
-
-  local function map(key, func)
-    keymap.set("n", key, function()
-      func(self)
-    end, { buffer = self.ui_buf, nowait = true })
-  end
-  map(config.keymaps.replace_confirm, self.replace_confirm)
-  map(config.keymaps.replace_all, self.replace_all)
-  map(config.keymaps.next_match, function()
-    self:goto_match(self:next_match_idx())
-  end)
-  map(config.keymaps.prev_match, function()
-    self:goto_match(self:prev_match_idx())
-  end)
-
-  -- Open float window
-  local width, height = u.get_win_size(placeholder, config)
-  local ui_win = api.nvim_open_win(self.ui_buf, true, {
-    relative = "win",
-    anchor = "NE",
-    row = 1,
-    col = api.nvim_win_get_width(0) - 1,
-    style = "minimal",
-    border = config.border,
-    width = width,
-    height = height,
-  })
-  u.set_cursor(ui_win, 2, 0)
-  fn.matchadd("Title", [[$\w\+]])
-
-  map(config.keymaps.close, function()
-    api.nvim_win_close(ui_win, false)
-  end)
-
-  api.nvim_create_autocmd({ "TextChanged", "TextChangedI" }, {
-    group = self.augroup,
-    buffer = self.ui_buf,
-    callback = function()
-      if config.adjust_window then
-        local lines = api.nvim_buf_get_lines(self.ui_buf, 0, -1, true)
-        local width, height = u.get_win_size(lines, config)
-        if api.nvim_win_get_width(ui_win) ~= width then
-          api.nvim_win_set_width(ui_win, width)
-        end
-        if api.nvim_win_get_height(ui_win) ~= height then
-          api.nvim_win_set_height(ui_win, height)
-        end
-      end
-      self:search()
-    end,
-  })
-
-  -- SSR window is bound to the original window (not buffer!), which is the same behavior as IDEs and browsers.
-  api.nvim_create_autocmd("BufWinEnter", {
-    group = self.augroup,
-    callback = function(event)
-      if event.buf == self.ui_buf then
-        return
-      end
-
-      local win = api.nvim_get_current_win()
-      if win == ui_win then
-        -- Prevent accidentally opening another file in the ssr window.
-        -- Adapted from neo-tree.nvim.
-        vim.schedule(function()
-          api.nvim_win_set_buf(ui_win, self.ui_buf)
-          local name = api.nvim_buf_get_name(event.buf)
-          api.nvim_win_call(self.origin_win, function()
-            pcall(api.nvim_buf_delete, event.buf, {})
-            if name ~= "" then
-              vim.cmd.edit(name)
-            end
-          end)
-          api.nvim_set_current_win(self.origin_win)
-        end)
-        return
-      elseif win ~= self.origin_win then
-        return
-      end
-
-      if ts.language.get_lang(vim.bo[event.buf].filetype) ~= self.lang then
-        return self:set_status "N/A"
-      end
-      self:search()
-    end,
-  })
-
-  api.nvim_create_autocmd("WinClosed", {
-    group = self.augroup,
-    buffer = self.ui_buf,
-    callback = function()
-      win_uis[self.origin_win] = nil
-      api.nvim_clear_autocmds { group = self.augroup }
-      api.nvim_buf_delete(self.ui_buf, {})
-      for buf in pairs(self.buf_matches) do
-        api.nvim_buf_clear_namespace(buf, self.ns, 0, -1)
-        api.nvim_buf_clear_namespace(buf, self.cur_search_ns, 0, -1)
-      end
-    end,
-  })
-
-  win_uis[self.origin_win] = self
-  return self
-end
-
-function Ui:search()
-  local pattern = self:get_input()
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  self.buf_matches[buf] = {}
-  api.nvim_buf_clear_namespace(buf, self.ns, 0, -1)
-  api.nvim_buf_clear_namespace(buf, self.cur_search_ns, 0, -1)
-
-  local start = vim.loop.hrtime()
-  local node, source = self.parse_context:parse(pattern)
-  if node:has_error() then
-    return self:set_status "Error"
-  end
-  self.buf_matches[buf] = search(buf, node, source, self.ns)
-  local elapsed = (vim.loop.hrtime() - start) / 1E6
-  for _, match in ipairs(self.buf_matches[buf]) do
-    local start_row, start_col, end_row, end_col = match.range:get()
-    highlight.range(buf, self.ns, "Search", { start_row, start_col }, { end_row, end_col }, {})
-  end
-  self:set_status(string.format("%d found in %dms", #self.buf_matches[buf], elapsed))
-end
-
-function Ui:next_match_idx()
-  local cursor_row, cursor_col = u.get_cursor(self.origin_win)
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  for idx, matches in pairs(self.buf_matches[buf]) do
-    local start_row, start_col = matches.range:get()
-    if start_row > cursor_row or (start_row == cursor_row and start_col > cursor_col) then
-      return idx
-    end
-  end
-  return 1
-end
-
-function Ui:prev_match_idx()
-  local cursor_row, cursor_col = u.get_cursor(self.origin_win)
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  local matches = self.buf_matches[buf]
-  for idx = #matches, 1, -1 do
-    local start_row, start_col = matches[idx].range:get()
-    if start_row < cursor_row or (start_row == cursor_row and start_col < cursor_col) then
-      return idx
-    end
-  end
-  return #matches
-end
-
-function Ui:goto_match(match_idx)
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  api.nvim_buf_clear_namespace(buf, self.cur_search_ns, 0, -1)
-  local matches = self.buf_matches[buf]
-  local start_row, start_col, end_row, end_col = matches[match_idx].range:get()
-  u.set_cursor(self.origin_win, start_row, start_col)
-  highlight.range(
-    buf,
-    self.cur_search_ns,
-    "CurSearch",
-    { start_row, start_col },
-    { end_row, end_col },
-    { priority = vim.highlight.priorities.user + 100 }
-  )
-  api.nvim_buf_set_extmark(buf, self.cur_search_ns, start_row, start_col, {
-    virt_text_pos = "eol",
-    virt_text = { { string.format("[%d/%d]", match_idx, #matches), "DiagnosticVirtualTextInfo" } },
-  })
-end
-
-function Ui:replace_all()
-  self:search()
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  local matches = self.buf_matches[buf]
-  if #matches == 0 then
-    return self:set_status "pattern not found"
-  end
-  local _, template = self:get_input()
-  local start = vim.loop.hrtime()
-  for _, match in ipairs(matches) do
-    replace(buf, match, template)
-  end
-  local elapsed = (vim.loop.hrtime() - start) / 1E6
-  self:set_status(string.format("%d replaced in %dms", #matches, elapsed))
-end
-
-function Ui:replace_confirm()
-  self:search()
-  local buf = api.nvim_win_get_buf(self.origin_win)
-  local matches = self.buf_matches[buf]
-  if #matches == 0 then
-    return self:set_status "pattern not found"
-  end
-
-  local confirm_buf = api.nvim_create_buf(false, true)
-  vim.bo[confirm_buf].filetype = "ssr_confirm"
-  local choices = {
-    "• Yes",
-    "• No",
-    "──────────────",
-    "• All",
-    "• Quit",
-    "• Last replace",
-  }
-  local separator_idx = 3
-  api.nvim_buf_set_lines(confirm_buf, 0, -1, true, choices)
-  for idx = 0, #choices - 1 do
-    if idx + 1 ~= separator_idx then
-      api.nvim_buf_set_extmark(confirm_buf, self.ns, idx, 4, { hl_group = "Underlined", end_row = idx, end_col = 5 })
-    end
-  end
-
-  local function open_confirm_win(match_idx)
-    self:goto_match(match_idx)
-    local _, _, end_row, end_col = matches[match_idx].range:get()
-    local cfg = {
-      relative = "win",
-      win = self.origin_win,
-      bufpos = { end_row, end_col },
-      style = "minimal",
-      border = config.border,
-      width = 14,
-      height = 6,
-    }
-    if vim.fn.has "nvim-0.9" == 1 then
-      cfg.title = "Replace?"
-      cfg.title_pos = "center"
-    end
-    return api.nvim_open_win(confirm_buf, true, cfg)
-  end
-
-  local match_idx = 1
-  local replaced = 0
-  local cursor = 1
-  local _, template = self:get_input()
-  self:set_status(string.format("replacing 0/%d", #matches))
-
-  while match_idx <= #matches do
-    local confirm_win = open_confirm_win(match_idx)
-
-    ---@type string
-    local key
-    while true do
-      -- Draw a fake cursor because cursor is not shown correctly when blocking on `getchar()`.
-      api.nvim_buf_clear_namespace(confirm_buf, self.cur_search_ns, 0, -1)
-      api.nvim_buf_set_extmark(
-        confirm_buf,
-        self.cur_search_ns,
-        cursor - 1,
-        0,
-        { virt_text = { { "•", "Cursor" } }, virt_text_pos = "overlay" }
-      )
-      api.nvim_buf_set_extmark(confirm_buf, self.cur_search_ns, cursor - 1, 0, { line_hl_group = "CursorLine" })
-      vim.cmd.redraw()
-
-      local ok, char = pcall(vim.fn.getcharstr)
-      key = ok and vim.fn.keytrans(char) or ""
-      if key == "j" then
-        if cursor == separator_idx - 1 then -- skip separator
-          cursor = separator_idx + 1
-        elseif cursor == #choices then -- wrap
-          cursor = 1
-        else
-          cursor = cursor + 1
-        end
-      elseif key == "k" then
-        if cursor == separator_idx + 1 then -- skip separator
-          cursor = separator_idx - 1
-        elseif cursor == 1 then -- wrap
-          cursor = #choices
-        else
-          cursor = cursor - 1
-        end
-      elseif vim.tbl_contains({ "<C-E>", "<C-Y>", "<C-U>", "<C-D>", "<C-F>", "<C-B>" }, key) then
-        fn.win_execute(self.origin_win, string.format('execute "normal! \\%s"', key))
-      else
-        break
-      end
-    end
-
-    if key == "<CR>" then
-      key = ({ "y", "n", "", "a", "q", "l" })[cursor]
-    end
-
-    if key == "y" then
-      replace(buf, matches[match_idx], template)
-      replaced = replaced + 1
-      match_idx = match_idx + 1
-    elseif key == "n" then
-      match_idx = match_idx + 1
-    elseif key == "a" then
-      for i = match_idx, #matches do
-        replace(buf, matches[i], template)
-      end
-      replaced = replaced + #matches + 1 - match_idx
-      match_idx = #matches + 1
-    elseif key == "l" then
-      replace(buf, matches[match_idx], template)
-      replaced = replaced + 1
-      match_idx = #matches + 1
-    elseif key == "q" or key == "<ESC>" or key == "" then
-      match_idx = #matches + 1
-    end
-    api.nvim_win_close(confirm_win, false)
-    self:set_status(string.format("replacing %d/%d", replaced, #matches))
-  end
-
-  api.nvim_buf_delete(confirm_buf, {})
-  api.nvim_buf_clear_namespace(buf, self.cur_search_ns, 0, -1)
-  self:set_status(string.format("%d/%d replaced", replaced, #matches))
-end
-
-function Ui:get_input()
-  local lines = api.nvim_buf_get_lines(self.ui_buf, 0, -1, true)
-  local pattern_pos = api.nvim_buf_get_extmark_by_id(self.ui_buf, self.ns, self.extmarks.search, {})[1]
-  local template_pos = api.nvim_buf_get_extmark_by_id(self.ui_buf, self.ns, self.extmarks.replace, {})[1]
-  local pattern = vim.trim(table.concat(lines, "\n", pattern_pos + 2, template_pos))
-  local template = vim.trim(table.concat(lines, "\n", template_pos + 1, #lines))
-  return pattern, template
-end
-
----@param status string
-function Ui:set_status(status)
-  api.nvim_buf_set_extmark(self.ui_buf, self.ns, 0, 0, {
-    id = self.extmarks.status,
-    virt_text = {
-      { "[SSR] ", "Comment" },
-      { status },
-      { " (Press ? for help)", "Comment" },
-    },
-    virt_text_pos = "overlay",
-  })
-end
-
----@param win window?
----@return Ui?
-function Ui.from_win(win)
-  if win == nil or win == 0 then
-    win = api.nvim_get_current_win()
-  end
-  local ui = win_uis[win]
-  if not ui then
-    return u.notify "No open SSR window"
-  end
-  return ui
-end
-
-function M.open()
-  return Ui.new()
-end
-
--- Replace all matches.
-function M.replace_all()
-  local ui = Ui.from_win()
-  if ui then
-    ui:replace_all()
-  end
-end
-
--- Confirm each match.
-function M.replace_confirm()
-  local ui = Ui.from_win()
-  if ui then
-    ui:replace_confirm()
-  end
-end
-
-return M
diff --git a/lua/ssr/config.lua b/lua/ssr/config.lua
new file mode 100644
index 0000000..7326c92
--- /dev/null
+++ b/lua/ssr/config.lua
@@ -0,0 +1,24 @@
+local M = {}
+
+---@class Config
+M.opts = {
+  border = "rounded",
+  min_width = 50,
+  max_width = 120,
+  min_height = 6,
+  max_height = 25,
+  adjust_window = true,
+  keymaps = {
+    close = "q",
+    next_match = "n",
+    prev_match = "N",
+    replace_confirm = "<cr>",
+    replace_all = "<leader><cr>",
+  },
+}
+
+function M.set(config)
+  M.opts = vim.tbl_deep_extend("force", M.opts, config)
+end
+
+return M
diff --git a/lua/ssr/file.lua b/lua/ssr/file.lua
new file mode 100644
index 0000000..d43b416
--- /dev/null
+++ b/lua/ssr/file.lua
@@ -0,0 +1,147 @@
+local api = vim.api
+local ts = vim.treesitter
+local uv = vim.uv or vim.loop
+
+-- File contents and it's parsed tree
+-- Unloaded buffers are read with libuv because loading a vim buffer can be up to 100x slower.
+---@class ssr.File
+---@field path string
+---@field source string | buffer
+---@field tree vim.treesitter.LanguageTree
+-- Only if `source` is file content
+---@field lines? string[]
+---@field mtime? { nsec: integer, sec: integer }
+local File = {}
+
+---@type table<string, ssr.File>
+local cache = {}
+
+---@param path string
+---@return ssr.File?
+function File.new(path)
+  -- First check if the file is already opened as a buffer.
+  local buf = vim.fn.bufnr(path)
+  if buf ~= -1 then
+    cache[path] = nil
+    if vim.bo[buf].filetype == "" then
+      local ft = vim.filetype.match { buf = buf }
+      api.nvim_buf_call(buf, function()
+        vim.cmd("noautocmd setlocal filetype=" .. ft)
+      end)
+    end
+    return setmetatable({
+      path = path,
+      source = buf,
+      tree = ts.get_parser(buf),
+    }, { __index = File })
+  end
+
+  local fd = uv.fs_open(path, "r", 438)
+  if not fd then
+    return
+  end
+  local stat = uv.fs_fstat(fd) ---@cast stat -?
+  local self = cache[path]
+  if self then
+    if stat.mtime.sec == self.mtime.sec and stat.mtime.nsec == self.mtime.nsec then
+      uv.fs_close(fd)
+      return self
+    else
+      cache[path] = nil
+    end
+  end
+  local source = uv.fs_read(fd, stat.size, 0) --[[@as string]]
+  uv.fs_close(fd)
+  local lines = vim.split(source, "\n", { plain = true })
+  local ft = vim.filetype.match { filename = path, contents = lines } -- not work for .ts
+  if not ft then
+    return
+  end
+  local lang = ts.language.get_lang(ft)
+  if not lang then
+    return
+  end
+  local has_parser, tree = pcall(ts.get_string_parser, source, lang)
+  if not has_parser then
+    return
+  end
+  tree:parse(true)
+  self = setmetatable({
+    path = path,
+    source = source,
+    tree = tree,
+    filetype = ft,
+    lines = lines,
+    mtime = stat.mtime,
+  }, { __index = File })
+  cache[path] = self
+  return self
+end
+
+---@param line integer
+---@return string
+function File:get_line(line)
+  if type(self.source) == "number" then
+    return api.nvim_buf_get_lines(self.source --[[@as integer]], line, line + 1, true)[1]
+  end
+  return self.lines[line + 1]
+end
+
+---@return integer
+function File:load_buf()
+  if type(self.source) == "integer" then
+    return self.source --[[@as integer]]
+  end
+  local buf = vim.fn.bufadd(self.path)
+  self.source = buf
+  vim.fn.bufload(buf)
+  -- api.nvim_buf_call(buf, function()
+  --   vim.cmd("noautocmd setlocal filetype=" .. self.filetype)
+  -- end)
+  self.lines = nil
+  self.mtime = nil
+  cache[self.path] = nil
+  return buf
+end
+
+---@param dir string
+---@param regex string
+---@param on_file fun(file: ssr.File)
+---@param on_end fun()
+---@return nil
+function File.grep(dir, regex, on_file, on_end)
+  vim.system(
+    { "rg", "--line-buffered", "--files-with-matches", "--multiline", regex, dir },
+    {
+      text = true,
+      stdout = vim.schedule_wrap(function(err, files)
+        if err then
+          error(files)
+        end
+        if not files then
+          on_end()
+          return
+        end
+        for _, path in ipairs(vim.split(files, "\n", { plain = true, trimempty = true })) do
+          local file = File.new(path)
+          if file then
+            on_file(file)
+          end
+        end
+      end),
+    },
+    vim.schedule_wrap(function(obj)
+      if obj.code == 1 then -- no match was found
+        on_end()
+      elseif obj.code ~= 0 then
+        error(obj.stderr)
+      end
+    end)
+  )
+end
+
+function File.clear_cache()
+  cache = {}
+end
+
+return File
diff --git a/lua/ssr/init.lua b/lua/ssr/init.lua
new file mode 100644
index 0000000..63b3880
--- /dev/null
+++ b/lua/ssr/init.lua
@@ -0,0 +1,15 @@
+local M = {}
+
+--- Set config options. Optional.
+---@param config Config?
+function M.setup(config)
+  if config then
+    require("ssr.config").set(config)
+  end
+end
+
+function M.open()
+  require("ssr.ui").new()
+end
+
+return M
diff --git a/lua/ssr/parse.lua b/lua/ssr/parse_context.lua
similarity index 65%
rename from lua/ssr/parse.lua
rename to lua/ssr/parse_context.lua
index 2e78f40..9e341f3 100644
--- a/lua/ssr/parse.lua
+++ b/lua/ssr/parse_context.lua
@@ -1,8 +1,7 @@
 local ts = vim.treesitter
-local wildcard_prefix = require("ssr.search").wildcard_prefix
-
-local M = {}
+local u = require "ssr.utils"
 
+-- The context in which user input (pattern or template) will be parsed correctly.
 ---@class ParseContext
 ---@field lang string
 ---@field before string
@@ -10,18 +9,24 @@ local M = {}
 ---@field pad_rows integer
 ---@field pad_cols integer
 local ParseContext = {}
-ParseContext.__index = ParseContext
-M.ParseContext = ParseContext
 
--- Create a context in which `origin_node` (and user input) will be parsed correctly.
----@param buf buffer
+---@param lang string
+---@return ParseContext
+function ParseContext.empty(lang)
+  return setmetatable({
+    lang = lang,
+    before = "",
+    after = "",
+    pad_rows = 0,
+    pad_cols = 0,
+  }, { __index = ParseContext })
+end
+
+---@param buf integer
+---@param lang string
 ---@param origin_node TSNode
 ---@return ParseContext?
-function ParseContext.new(buf, origin_node)
-  local lang = ts.language.get_lang(vim.bo[buf].filetype)
-  if not lang then
-    return
-  end
+function ParseContext.new(buf, lang, origin_node)
   local self = setmetatable({ lang = lang }, { __index = ParseContext })
 
   local origin_start_row, origin_start_col, origin_start_byte = origin_node:start()
@@ -48,8 +53,8 @@ function ParseContext.new(buf, origin_node)
     if end_row == start_row then
       end_col = end_col + start_col
     end
-    local node_in_context = root:named_descendant_for_range(start_row, start_col, end_row, end_col)
-    if node_in_context and node_in_context:type() == origin_node:type() and node_in_context:sexpr() == origin_sexpr then
+    local node_in_context = root:named_descendant_for_range(start_row, start_col, end_row, end_col) --[[@as TSNode]]
+    if node_in_context:type() == origin_node:type() and node_in_context:sexpr() == origin_sexpr then
       local context_start_byte
       self.start_row, self.start_col, context_start_byte = context_node:start()
       self.before = context_text:sub(1, origin_start_byte - context_start_byte)
@@ -63,17 +68,17 @@ function ParseContext.new(buf, origin_node)
   end
 end
 
--- Parse search pattern to syntax tree in proper context.
----@param pattern string
----@return TSNode?, string
-function ParseContext:parse(pattern)
+-- Parse code to TS node.
+---@param code string
+---@return TSNode, string
+function ParseContext:parse(code)
   -- Replace named wildcard $name to identifier __ssr_var_name to avoid syntax error.
-  pattern = pattern:gsub("%$([_%a%d]+)", wildcard_prefix .. "%1")
-  local context_text = self.before .. pattern .. self.after
-  local root = ts.get_string_parser(context_text, self.lang):parse()[1]:root()
-  local lines = vim.split(pattern, "\n")
-  local node = root:named_descendant_for_range(self.pad_rows, self.pad_cols, self.pad_rows + #lines - 1, #lines[#lines])
-  return node, context_text
+  code = code:gsub("%$([_%a%d]+)", u.wildcard_prefix .. "%1")
+  local source = self.before .. code .. self.after
+  local root = ts.get_string_parser(source, self.lang):parse()[1]:root()
+  local lines = vim.split(code, "\n")
+  local node = root:named_descendant_for_range(self.pad_rows, self.pad_cols, self.pad_rows + #lines - 1, #lines[#lines]) --[[@as TSNode]]
+  return node, source
 end
 
-return M
+return ParseContext
diff --git a/lua/ssr/range.lua b/lua/ssr/range.lua
new file mode 100644
index 0000000..cacd0d0
--- /dev/null
+++ b/lua/ssr/range.lua
@@ -0,0 +1,50 @@
+local api = vim.api
+local u = require "ssr.utils"
+
+---@class ssr.Range
+---@field start_row integer
+---@field start_col integer
+---@field end_row integer
+---@field end_col integer
+local Range = {}
+
+---@param node TSNode
+---@return ssr.Range
+function Range.from_node(node)
+  local start_row, start_col, end_row, end_col = node:range()
+  return setmetatable({
+    start_row = start_row,
+    start_col = start_col,
+    end_row = end_row,
+    end_col = end_col,
+  }, { __index = Range })
+end
+
+---@param other ssr.Range
+---@return boolean
+function Range:before(other)
+  return self.end_row < other.start_row or (self.end_row == other.start_row and self.end_col <= other.start_col)
+end
+
+---@param other ssr.Range
+---@return boolean
+function Range:inside(other)
+  return (
+    (self.start_row > other.start_row or (self.start_row == other.start_row and self.start_col > other.start_col))
+    and (self.end_row < other.end_row or (self.end_row == other.end_row and self.end_col <= other.end_col))
+  )
+end
+
+-- Extmark-based ranges automatically adjust as buffer contents change.
+---@param buf integer
+---@return integer
+function Range:to_extmark(buf)
+  return api.nvim_buf_set_extmark(buf, u.namespace, self.start_row, self.start_col, {
+    end_row = self.end_row,
+    end_col = self.end_col,
+    right_gravity = false,
+    end_right_gravity = true,
+  })
+end
+
+return Range
diff --git a/lua/ssr/replace.lua b/lua/ssr/replace.lua
new file mode 100644
index 0000000..9f96f4d
--- /dev/null
+++ b/lua/ssr/replace.lua
@@ -0,0 +1,59 @@
+local api = vim.api
+local u = require "ssr.utils"
+
+local M = {}
+
+---@class ssr.PinnedMatch
+---@field buf integer
+---@field range integer
+---@field captures integer[]
+M.PinnedMatch = {}
+
+-- Convert `ssr.SearchResults` to extmark-based version.
+---@param matches ssr.Matches
+---@return ssr.PinnedMatch[]
+function M.pin_matches(matches)
+  local res = {}
+  for _, row in ipairs(matches) do
+    local buf = row.file:load_buf()
+    for _, match in ipairs(row.matches) do
+      local pinned = { buf = buf, range = match.range:to_extmark(buf), captures = {} }
+      for var, range in pairs(match.captures) do
+        pinned.captures[var] = range:to_extmark(buf)
+      end
+      table.insert(res, pinned)
+    end
+  end
+  return res
+end
+
+---@param buf integer
+---@param id integer
+---@return integer, number, number, number
+local function get_extmark_range(buf, id)
+  local extmark = api.nvim_buf_get_extmark_by_id(buf, u.namespace, id, { details = true })
+  return extmark[1], extmark[2], extmark[3].end_row, extmark[3].end_col
+end
+
+--- Render template and replace one match.
+---@param match ssr.PinnedMatch
+---@param template string
+function M.replace(match, template)
+  -- Render templates with captured nodes.
+  local replacement = template:gsub("()%$([_%a%d]+)", function(pos, var)
+    local start_row, start_col, end_row, end_col = get_extmark_range(match.buf, match.captures[var])
+    local capture_lines = api.nvim_buf_get_text(match.buf, start_row, start_col, end_row, end_col, {})
+    u.remove_indent(capture_lines, u.get_indent(match.buf, start_row))
+    local var_lines = vim.split(template:sub(1, pos), "\n")
+    local var_line = var_lines[#var_lines]
+    local template_indent = var_line:match "^%s*"
+    u.add_indent(capture_lines, template_indent)
+    return table.concat(capture_lines, "\n")
+  end)
+  replacement = vim.split(replacement, "\n")
+  local start_row, start_col, end_row, end_col = get_extmark_range(match.buf, match.range)
+  u.add_indent(replacement, u.get_indent(match.buf, start_row))
+  api.nvim_buf_set_text(match.buf, start_row, start_col, end_row, end_col, replacement)
+end
+
+return M
diff --git a/lua/ssr/search.lua b/lua/ssr/search.lua
index ec6cdcc..6cd986a 100644
--- a/lua/ssr/search.lua
+++ b/lua/ssr/search.lua
@@ -1,57 +1,15 @@
-local api = vim.api
 local ts = vim.treesitter
+local Range = require "ssr.range"
 local u = require "ssr.utils"
 
-local M = {}
-
-M.wildcard_prefix = "__ssr_var_"
-
----@class Match
----@field range ExtmarkRange
----@field captures ExtmarkRange[]
-
----@class ExtmarkRange
----@field ns number
----@field buf buffer
----@field extmark number
-local ExtmarkRange = {}
-M.ExtmarkRange = ExtmarkRange
-
----@param ns number
----@param buf buffer
----@param node TSNode
----@return ExtmarkRange
-function ExtmarkRange.new(ns, buf, node)
-  local start_row, start_col, end_row, end_col = node:range()
-  return setmetatable({
-    ns = ns,
-    buf = buf,
-    extmark = api.nvim_buf_set_extmark(buf, ns, start_row, start_col, {
-      end_row = end_row,
-      end_col = end_col,
-      right_gravity = false,
-      end_right_gravity = true,
-    }),
-  }, { __index = ExtmarkRange })
-end
-
----@return number, number, number, number
-function ExtmarkRange:get()
-  local extmark = api.nvim_buf_get_extmark_by_id(self.buf, self.ns, self.extmark, { details = true })
-  return extmark[1], extmark[2], extmark[3].end_row, extmark[3].end_col
-end
-
 -- Compare if two captured trees can match.
--- The check is loose because users want to match different types of node.
+-- The check is loose because we want to match different types of node.
 -- e.g. converting `{ foo: foo }` to shorthand `{ foo }`.
 ts.query.add_predicate("ssr-tree-match?", function(match, _pattern, buf, pred)
-  ---@param node1 TSNode?
-  ---@param node2 TSNode?
+  ---@param node1 TSNode
+  ---@param node2 TSNode
   ---@return boolean
   local function tree_match(node1, node2)
-    if not node1 or not node2 then
-      return false
-    end
     if node1:named() ~= node2:named() then
       return false
     end
@@ -62,33 +20,38 @@ ts.query.add_predicate("ssr-tree-match?", function(match, _pattern, buf, pred)
       return false
     end
     for i = 0, node1:child_count() - 1 do
-      if not tree_match(node1:child(i), node2:child(i)) then
+      if
+        not tree_match(node1:child(i) --[[@as TSNode]], node2:child(i) --[[@as TSNode]])
+      then
         return false
       end
     end
     return true
   end
   return tree_match(match[pred[2]], match[pred[3]])
-end, true)
+end, { force = true })
 
 -- Build a TS sexpr represting the node.
+-- This function is more strict than `TSNode:sexpr()` by also requiring leaf nodes to match text.
 ---@param node TSNode
 ---@param source string
----@return string, table<string, number>
+---@return string sexpr
+---@return table<string, integer> wildcards
+---@return string rough_regex
 local function build_sexpr(node, source)
-  ---@type table<string, number>
+  ---@type table<string, integer>
   local wildcards = {}
+  local rough_regex = ""
   local next_idx = 1
 
-  -- This function is more strict than `tsnode:sexpr()` by also requiring leaf nodes to match text.
   ---@param node TSNode
   ---@return string
   local function build(node)
     local text = ts.get_node_text(node, source)
 
     -- Special identifier __ssr_var_name is a named wildcard.
-    -- Handle this early to make sure wildcard captures largest node.
-    local var = text:match("^" .. M.wildcard_prefix .. "([_%a%d]+)$")
+    -- Handle this early to make sure wildcard captures the largest node.
+    local var = text:match("^" .. u.wildcard_prefix .. "([_%a%d]+)$")
     if var then
       if not wildcards[var] then
         wildcards[var] = next_idx
@@ -104,6 +67,9 @@ local function build_sexpr(node, source)
 
     -- Leaf nodes (keyword, identifier, literal and symbol) should match text.
     if node:named_child_count() == 0 then
+      if #text > #rough_regex then -- TODO build an actual regex
+        rough_regex = text
+      end
       local sexpr = string.format("(%s) @_%d (#eq? @_%d %s)", node:type(), next_idx, next_idx, u.to_ts_query_str(text))
       next_idx = next_idx + 1
       return sexpr
@@ -134,76 +100,74 @@ local function build_sexpr(node, source)
   end
 
   local sexpr = string.format("(%s) @all", build(node))
-  return sexpr, wildcards
+  rough_regex = u.regex_escape(rough_regex)
+  return sexpr, wildcards, rough_regex
 end
 
----@param buf buffer
----@param node TSNode
----@param source string
----@return Match[]
-function M.search(buf, node, source, ns)
-  local sexpr, wildcards = build_sexpr(node, source)
-  local parse_query = ts.query.parse or ts.parse_query
-  local lang = ts.language.get_lang(vim.bo[buf].filetype)
-  if not lang then
-    return {}
+---@class ssr.Searcher
+---@field lang string
+---@field query vim.treesitter.Query
+---@field wildcards table<string, integer>
+---@field rough_regex string
+local Searcher = {}
+
+---@param lang string
+---@param pattern string
+---@param parse_context ParseContext
+---@return ssr.Searcher?
+function Searcher.new(lang, pattern, parse_context)
+  local node, source = parse_context:parse(pattern)
+  if node:has_error() then
+    return
   end
+  local sexpr, wildcards, rough_regex = build_sexpr(node, source)
+  local parse_query = ts.query.parse or ts.parse_query
   local query = parse_query(lang, sexpr)
+  return setmetatable({
+    lang = lang,
+    query = query,
+    wildcards = wildcards,
+    rough_regex = rough_regex,
+  }, { __index = Searcher })
+end
+
+-- A single match, including its captures.
+---@class ssr.Match
+---@field range ssr.Range
+---@field captures table<string, ssr.Range>
+
+---@param file ssr.File
+---@return ssr.Match[]
+function Searcher:search(file)
+  ---@type ssr.Match[]
   local matches = {}
-  local has_parser, parser = pcall(ts.get_parser, buf, lang)
-  if not has_parser then
-    return {}
-  end
-  local root = parser:parse(true)[1]:root()
-  for _, nodes in query:iter_matches(root, buf, 0, -1) do
-    ---@type table<string, ExtmarkRange>
-    local captures = {}
-    for var, idx in pairs(wildcards) do
-      captures[var] = ExtmarkRange.new(ns, buf, nodes[idx])
+  file.tree:for_each_tree(function(tree, lang_tree) -- must called :parse(true)
+    if lang_tree:lang() ~= self.lang then
+      return
     end
-    local match = { range = ExtmarkRange.new(ns, buf, nodes[#nodes]), captures = captures }
-    table.insert(matches, match)
-  end
+    for _, nodes in self.query:iter_matches(tree:root(), file.source, 0, -1) do
+      local range = Range.from_node(nodes[#nodes])
+      local captures = {}
+      for var, idx in pairs(self.wildcards) do
+        captures[var] = Range.from_node(nodes[idx])
+      end
+      table.insert(matches, { range = range, captures = captures })
+    end
+  end)
 
   -- Sort matches from
   --  buffer top to bottom, to make goto next/prev match intuitive
   --  inner to outer for recursive matches, to make replacing correct
-  ---@param match1 { range: ExtmarkRange, captures: table<string, ExtmarkRange>}
-  ---@param match2 { range: ExtmarkRange, captures: table<string, ExtmarkRange>}
+  ---@param match1 ssr.Match
+  ---@param match2 ssr.Match
   ---@return boolean
   table.sort(matches, function(match1, match2)
-    local start_row1, start_col1, end_row1, end_col1 = match1.range:get()
-    local start_row2, start_col2, end_row2, end_col2 = match2.range:get()
-    if end_row1 < start_row2 or (end_row1 == start_row2 and end_col1 <= start_col2) then
+    if match1.range:before(match2.range) then
       return true
     end
-    return (start_row1 > start_row2 or (start_row1 == start_row2 and start_col1 > start_col2))
-      and (end_row1 < end_row2 or (end_row1 == end_row2 and end_col1 <= end_col2))
+    return match1.range:inside(match2.range)
   end)
-
   return matches
 end
 
---- Render template and replace one match.
----@param buf buffer
----@param match Match
----@param template string
-function M.replace(buf, match, template)
-  -- Render templates with captured nodes.
-  local replace = template:gsub("()%$([_%a%d]+)", function(pos, var)
-    local start_row, start_col, end_row, end_col = match.captures[var]:get()
-    local lines = api.nvim_buf_get_text(buf, start_row, start_col, end_row, end_col, {})
-    u.remove_indent(lines, u.get_indent(buf, start_row))
-    local var_lines = vim.split(template:sub(1, pos), "\n")
-    local var_line = var_lines[#var_lines]
-    local template_indent = var_line:match "^%s*"
-    u.add_indent(lines, template_indent)
-    return table.concat(lines, "\n")
-  end)
-  replace = vim.split(replace, "\n")
-  local start_row, start_col, end_row, end_col = match.range:get()
-  u.add_indent(replace, u.get_indent(buf, start_row))
-  api.nvim_buf_set_text(buf, start_row, start_col, end_row, end_col, replace)
-end
-
-return M
+return Searcher
diff --git a/lua/ssr/ui/confirm_win.lua b/lua/ssr/ui/confirm_win.lua
new file mode 100644
index 0000000..e02fa19
--- /dev/null
+++ b/lua/ssr/ui/confirm_win.lua
@@ -0,0 +1,139 @@
+local api = vim.api
+
+---@class ConfirmWin
+local ConfirmWin = {}
+
+function ConfirmWin.new() end
+
+function ConfirmWin:open()
+  local buf = api.nvim_win_get_buf(self.origin_win)
+  local matches = self.matches[buf]
+  if #matches == 0 then
+    return self:set_status "pattern not found"
+  end
+
+  local confirm_buf = api.nvim_create_buf(false, true)
+  vim.bo[confirm_buf].filetype = "ssr_confirm"
+  local choices = {
+    "• Yes",
+    "• No",
+    "──────────────",
+    "• All",
+    "• Quit",
+    "• Last replace",
+  }
+  local separator_idx = 3
+  api.nvim_buf_set_lines(confirm_buf, 0, -1, true, choices)
+  for idx = 0, #choices - 1 do
+    if idx + 1 ~= separator_idx then
+      api.nvim_buf_set_extmark(
+        confirm_buf,
+        u.namespace,
+        idx,
+        4,
+        { hl_group = "Underlined", end_row = idx, end_col = 5 }
+      )
+    end
+  end
+
+  local function open_confirm_win(match_idx)
+    self:goto_match(match_idx)
+    local _, _, end_row, end_col = matches[match_idx].range:get()
+    local cfg = {
+      relative = "win",
+      win = self.origin_win,
+      bufpos = { end_row, end_col },
+      style = "minimal",
+      border = config.options.border,
+      width = 14,
+      height = 6,
+    }
+    if vim.fn.has "nvim-0.9" == 1 then
+      cfg.title = "Replace?"
+      cfg.title_pos = "center"
+    end
+    return api.nvim_open_win(confirm_buf, true, cfg)
+  end
+
+  local match_idx = 1
+  local replaced = 0
+  local cursor = 1
+  local _, template = self:get_input()
+  self:set_status(string.format("replacing 0/%d", #matches))
+
+  while match_idx <= #matches do
+    local confirm_win = open_confirm_win(match_idx)
+
+    ---@type string
+    local key
+    while true do
+      -- Draw a fake cursor because cursor is not shown correctly when blocking on `getchar()`.
+      api.nvim_buf_clear_namespace(confirm_buf, u.cur_search_ns, 0, -1)
+      api.nvim_buf_set_extmark(
+        confirm_buf,
+        u.cur_search_ns,
+        cursor - 1,
+        0,
+        { virt_text = { { "•", "Cursor" } }, virt_text_pos = "overlay" }
+      )
+      api.nvim_buf_set_extmark(confirm_buf, u.cur_search_ns, cursor - 1, 0, { line_hl_group = "CursorLine" })
+      vim.cmd.redraw()
+
+      local ok, char = pcall(vim.fn.getcharstr)
+      key = ok and vim.fn.keytrans(char) or ""
+      if key == "j" then
+        if cursor == separator_idx - 1 then -- skip separator
+          cursor = separator_idx + 1
+        elseif cursor == #choices then -- wrap
+          cursor = 1
+        else
+          cursor = cursor + 1
+        end
+      elseif key == "k" then
+        if cursor == separator_idx + 1 then -- skip separator
+          cursor = separator_idx - 1
+        elseif cursor == 1 then -- wrap
+          cursor = #choices
+        else
+          cursor = cursor - 1
+        end
+      elseif vim.tbl_contains({ "<C-E>", "<C-Y>", "<C-U>", "<C-D>", "<C-F>", "<C-B>" }, key) then
+        vim.fn.win_execute(self.origin_win, string.format('execute "normal! \\%s"', key))
+      else
+        break
+      end
+    end
+
+    if key == "<CR>" then
+      key = ({ "y", "n", "", "a", "q", "l" })[cursor]
+    end
+
+    if key == "y" then
+      replace(buf, matches[match_idx], template)
+      replaced = replaced + 1
+      match_idx = match_idx + 1
+    elseif key == "n" then
+      match_idx = match_idx + 1
+    elseif key == "a" then
+      for i = match_idx, #matches do
+        replace(buf, matches[i], template)
+      end
+      replaced = replaced + #matches + 1 - match_idx
+      match_idx = #matches + 1
+    elseif key == "l" then
+      replace(buf, matches[match_idx], template)
+      replaced = replaced + 1
+      match_idx = #matches + 1
+    elseif key == "q" or key == "<ESC>" or key == "" then
+      match_idx = #matches + 1
+    end
+    api.nvim_win_close(confirm_win, false)
+    self:set_status(string.format("replacing %d/%d", replaced, #matches))
+  end
+
+  api.nvim_buf_delete(confirm_buf, {})
+  api.nvim_buf_clear_namespace(buf, u.cur_search_ns, 0, -1)
+  self:set_status(string.format("%d/%d replaced", replaced, #matches))
+end
+
+return ConfirmWin
diff --git a/lua/ssr/ui/init.lua b/lua/ssr/ui/init.lua
new file mode 100644
index 0000000..a5ad74b
--- /dev/null
+++ b/lua/ssr/ui/init.lua
@@ -0,0 +1,123 @@
+local api = vim.api
+local ts = vim.treesitter
+local config = require "ssr.config"
+local ParseContext = require "ssr.parse_context"
+local Searcher = require "ssr.search"
+local replace = require("ssr.replace").replace
+local pin_matches = require("ssr.replace").pin_matches
+local File = require "ssr.file"
+local MainWin = require "ssr.ui.main_win"
+local u = require "ssr.utils"
+
+---@alias ssr.Matches { file: ssr.File, matches: ssr.Match[] }[]
+
+---@class Ui
+---@field lang string
+---@field parse_context ParseContext
+---@field matches ssr.Matches
+---@field last_pattern string
+---@field main_win MainWin
+local Ui = {}
+
+---@return Ui?
+function Ui.new()
+  local self = setmetatable({ matches = {} }, { __index = Ui })
+
+  -- Pre-checks
+  local origin_win = api.nvim_get_current_win()
+  local origin_buf = api.nvim_win_get_buf(origin_win)
+  local lang = ts.language.get_lang(vim.bo[origin_buf].filetype)
+  if not lang then
+    return u.notify(string.format("Treesitter language not found for filetype '%s'", vim.bo[origin_buf].filetype))
+  end
+  self.lang = lang
+  local origin_node = u.node_for_range(origin_buf, self.lang, u.get_selection(origin_win))
+  if not origin_node then
+    return u.notify("Treesitter parser not found, please try to install it with :TSInstall " .. self.lang)
+  end
+  if origin_node:has_error() then
+    return u.notify "You have syntax errors in the selected node"
+  end
+  local parse_context = ParseContext.new(origin_buf, self.lang, origin_node)
+  if not parse_context then
+    return u.notify "Can't find a proper context to parse the pattern"
+  end
+  self.parse_context = parse_context
+
+  local placeholder = vim.split(ts.get_node_text(origin_node, origin_buf), "\n", { plain = true })
+  u.remove_indent(placeholder, u.get_indent(origin_buf, origin_node:start()))
+
+  self.main_win = MainWin.new(lang, placeholder, { "" }, origin_win)
+
+  self.main_win:on({ "InsertLeave", "TextChanged" }, function()
+    self:search()
+  end)
+
+  self.main_win:on_key(config.opts.keymaps.replace_all, function()
+    self:replace_all()
+  end)
+
+  self:search()
+  return self
+end
+
+function Ui:search()
+  local pattern = self.main_win:get_input()
+  if pattern == self.last_pattern then
+    return
+  end
+  self.last_pattern = pattern
+
+  self.matches = {}
+  local found = 0
+  local matched_files = 0
+  local start = vim.loop.hrtime()
+  local searcher = Searcher.new(self.lang, pattern, self.parse_context)
+  if not searcher then
+    return self:set_status "Error"
+  end
+
+  File.grep(vim.loop.cwd(), searcher.rough_regex, function(file)
+    local matches = searcher:search(file)
+    if #matches == 0 then
+      return
+    end
+    found = found + #matches
+    matched_files = matched_files + 1
+    table.insert(self.matches, { file = file, matches = matches })
+  end, function()
+    local elapsed = (vim.loop.hrtime() - start) / 1E6
+    self.main_win.result_list:set(self.matches)
+    self:set_status(string.format("%d found in %d files (%dms)", found, matched_files, elapsed))
+  end)
+end
+
+function Ui:replace_all()
+  if #self.matches == 0 then
+    return self:set_status "pattern not found"
+  end
+  local _, template = self.main_win:get_input()
+  local start = vim.loop.hrtime()
+  local pinned = pin_matches(self.matches)
+  for _, match in ipairs(pinned) do
+    replace(match, template)
+  end
+  local elapsed = (vim.loop.hrtime() - start) / 1E6
+  self:set_status(string.format("%d replaced in %d files (%dms)", #self.matches, 0, elapsed))
+end
+
+---@param status string
+---@return nil
+function Ui:set_status(status)
+  api.nvim_buf_set_extmark(self.main_win.buf, u.namespace, 0, 0, {
+    id = self.main_win.extmarks.status,
+    virt_text = {
+      { "[SSR] ", "Comment" },
+      { status },
+      { " (Press ? for help)", "Comment" },
+    },
+    virt_text_pos = "overlay",
+  })
+end
+
+return Ui
diff --git a/lua/ssr/ui/main_win.lua b/lua/ssr/ui/main_win.lua
new file mode 100644
index 0000000..b81a830
--- /dev/null
+++ b/lua/ssr/ui/main_win.lua
@@ -0,0 +1,241 @@
+local api = vim.api
+local ts = vim.treesitter
+local config = require "ssr.config"
+local ResultList = require "ssr.ui.result_list"
+local u = require "ssr.utils"
+
+---@class MainWin
+---@field buf integer
+---@field win integer
+---@field origin_win integer
+---@field lang string
+---@field last_pattern string[]
+---@field last_template string[]
+---@field result_list ResultList
+local MainWin = {}
+
+function MainWin.new(lang, pattern, template, origin_win)
+  local self = setmetatable({
+    lang = lang,
+    last_pattern = pattern,
+    last_template = template,
+    origin_win = origin_win,
+  }, { __index = MainWin })
+
+  self.buf = api.nvim_create_buf(false, true)
+  vim.bo[self.buf].filetype = "ssr"
+
+  local lines = self:render()
+  self:open_win(u.get_win_size(lines))
+
+  self.result_list = ResultList.new(self.buf, self.win, self.extmarks.results)
+
+  self:setup_autocmds()
+  self:setup_keymaps()
+
+  return self
+end
+
+---@private
+function MainWin:render()
+  ts.stop(self.buf)
+  api.nvim_buf_clear_namespace(self.buf, u.namespace, 0, -1)
+
+  local lines = {
+    "", -- [SSR]
+    "```" .. self.lang, -- SEARCH:
+  }
+  vim.list_extend(lines, self.last_pattern)
+  table.insert(lines, "") -- REPLACE:
+  vim.list_extend(lines, self.last_template)
+  table.insert(lines, "```") -- RESULTS:
+  api.nvim_buf_set_lines(self.buf, 0, -1, true, lines)
+
+  -- Enable syntax highlights for input area.
+  local parser = ts.get_parser(self.buf, "markdown")
+  parser:parse(true)
+  parser:for_each_tree(function(tree, lang_tree)
+    if tree:root():start() == 2 then
+      ts.highlighter.new(lang_tree)
+    end
+  end)
+
+  local function virt_text(row, text)
+    return api.nvim_buf_set_extmark(self.buf, u.namespace, row, 0, { virt_text = text, virt_text_pos = "overlay" })
+  end
+  self.extmarks = {
+    status = virt_text(0, { { "[SSR]", "Comment" }, { " (Press ? for help)", "Comment" } }),
+    search = virt_text(1, { { "SEARCH:           ", "String" } }), -- Extra spaces to cover too long language name.
+    replace = virt_text(#lines - 3, { { "REPLACE:", "String" } }),
+    results = virt_text(#lines - 1, { { "RESULTS:", "String" } }),
+  }
+
+  return lines
+end
+
+---@private
+function MainWin:check(lines)
+  if #lines < 6 then
+    return false
+  end
+
+  local function get_index(extmark)
+    return api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, extmark, {})[1] + 1
+  end
+
+  return get_index(self.extmarks.status) == 1
+    and lines[1] == ""
+    and get_index(self.extmarks.search) == 2
+    and lines[2] == "```" .. self.lang
+    and lines[get_index(self.extmarks.replace)] == ""
+    and lines[get_index(self.extmarks.results)] == "```"
+end
+
+---@private
+function MainWin:open_win(width, height)
+  self.win = api.nvim_open_win(self.buf, true, {
+    relative = "editor",
+    anchor = "NE",
+    row = 0,
+    col = vim.o.columns - 1,
+    style = "minimal",
+    border = config.opts.border,
+    width = width,
+    height = height,
+  })
+  vim.wo[self.win].wrap = false
+  if vim.fn.has "nvim-0.10" == 1 then
+    vim.wo[self.win].winfixbuf = true
+  end
+  u.set_cursor(self.win, 2, 0)
+  vim.fn.matchadd("Title", [[$\w\+]])
+end
+
+function MainWin:on(event, func)
+  api.nvim_create_autocmd(event, {
+    group = u.augroup,
+    buffer = self.buf,
+    callback = func,
+  })
+end
+
+---@private
+function MainWin:setup_autocmds()
+  self:on({ "TextChanged", "TextChangedI" }, function()
+    local lines = api.nvim_buf_get_lines(self.buf, 0, -1, true)
+    if not self:check(lines) then
+      self:render()
+      self.result_list.extmark = self.extmarks.results
+      self.result_list:set {}
+      u.set_cursor(self.win, 2, 0)
+    end
+    if not config.opts.adjust_window then
+      return
+    end
+    local width, height = u.get_win_size(lines)
+    if api.nvim_win_get_width(self.win) ~= width then
+      api.nvim_win_set_width(self.win, width)
+    end
+    if api.nvim_win_get_height(self.win) ~= height then
+      api.nvim_win_set_height(self.win, height)
+    end
+  end)
+
+  self:on("BufWinEnter", function(event)
+    if event.buf == self.buf then
+      return
+    end
+    local win = api.nvim_get_current_win()
+    if win ~= self.win then
+      return
+    end
+    -- Prevent accidentally opening another file in the ssr window.
+    -- Adapted from neo-tree.nvim.
+    vim.schedule(function()
+      api.nvim_win_set_buf(self.win, self.buf)
+      local name = api.nvim_buf_get_name(event.buf)
+      api.nvim_win_call(self.origin_win, function()
+        pcall(api.nvim_buf_delete, event.buf, {})
+        if name ~= "" then
+          vim.cmd.edit(name)
+        end
+      end)
+      api.nvim_set_current_win(self.origin_win)
+    end)
+  end)
+
+  self:on("WinClosed", function()
+    api.nvim_clear_autocmds { group = u.augroup }
+    api.nvim_buf_delete(self.buf, {})
+  end)
+end
+
+function MainWin:on_key(key, func)
+  vim.keymap.set("n", key, func, { buffer = self.buf, nowait = true })
+end
+
+---@private
+function MainWin:setup_keymaps()
+  self:on_key(config.opts.keymaps.close, function()
+    api.nvim_win_close(self.win, false)
+  end)
+
+  self:on_key("gg", function()
+    u.set_cursor(self.win, 2, 0)
+  end)
+
+  self:on_key("j", function()
+    local cursor = u.get_cursor(self.win)
+    for _, extmark in ipairs { self.extmarks.replace, self.extmarks.results } do
+      local skip_pos = api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, extmark, {})[1]
+      if cursor == skip_pos - 1 then
+        return pcall(u.set_cursor, self.win, skip_pos + 1, 0)
+      end
+    end
+    vim.fn.feedkeys("j", "n")
+  end)
+
+  self:on_key("k", function()
+    local cursor = u.get_cursor(self.win)
+    if cursor <= 2 then
+      return u.set_cursor(self.win, 2, 0)
+    end
+    for _, extmark in ipairs { self.extmarks.replace, self.extmarks.results } do
+      local skip_pos = api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, extmark, {})[1]
+      if cursor == skip_pos + 1 then
+        return pcall(u.set_cursor, self.win, skip_pos - 1, 0)
+      end
+    end
+    vim.fn.feedkeys("k", "n")
+  end)
+
+  self:on_key("l", function()
+    local cursor = u.get_cursor(self.win)
+    if cursor < self.result_list:get_start() then
+      return vim.fn.feedkeys("l", "n")
+    end
+    self.result_list:set_folded(false)
+  end)
+
+  self:on_key("h", function()
+    local cursor = u.get_cursor(self.win)
+    if cursor < self.result_list:get_start() then
+      return vim.fn.feedkeys("h", "n")
+    end
+    self.result_list:set_folded(true)
+  end)
+end
+
+function MainWin:get_input()
+  local pattern_pos = api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, self.extmarks.search, {})[1]
+  local template_pos = api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, self.extmarks.replace, {})[1]
+  local results_pos = api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, self.extmarks.results, {})[1]
+  local lines = api.nvim_buf_get_lines(self.buf, 0, results_pos, true)
+  local pattern = vim.list_slice(lines, pattern_pos + 2, template_pos)
+  local template = vim.list_slice(lines, template_pos + 2)
+  self.last_pattern = pattern
+  self.last_template = template
+  return vim.trim(table.concat(pattern, "\n")), vim.trim(table.concat(template, "\n"))
+end
+
+return MainWin
diff --git a/lua/ssr/ui/result_list.lua b/lua/ssr/ui/result_list.lua
new file mode 100644
index 0000000..815e6b5
--- /dev/null
+++ b/lua/ssr/ui/result_list.lua
@@ -0,0 +1,205 @@
+local api = vim.api
+local config = require "ssr.config"
+local u = require "ssr.utils"
+
+-- List item per line
+---@class Item
+---@field fold_idx integer which fold this line belongs to, 1-based
+---@field match_idx integer which match this line belongs to, 0-based, 0 for filename
+
+-- A foldable region that may span multiple lines
+---@class Fold
+---@field folded boolean
+---@field filename string
+---@field path string
+---@field preview_lines string[]
+local Fold = {}
+
+---@param folded boolean
+---@param file ssr.File
+---@param matches ssr.Match[]
+---@return Fold
+function Fold.new(folded, file, matches)
+  local preview_lines = {}
+  for _, match in ipairs(matches) do
+    local line = file:get_line(match.range.start_row)
+    line = line:gsub("^%s*", "")
+    table.insert(preview_lines, "│ " .. line)
+  end
+  return setmetatable({
+    folded = folded,
+    filename = vim.fn.fnamemodify(file.path, ":t"),
+    path = vim.fn.fnamemodify(file.path, ":~:.:h"),
+    preview_lines = preview_lines,
+  }, { __index = Fold })
+end
+
+function Fold:len()
+  if self.folded then
+    return 1
+  end
+  return 1 + #self.preview_lines
+end
+
+---@private
+function Fold:get_lines()
+  if self.folded then
+    return { string.format(" %s %s %d", self.filename, self.path, #self.preview_lines) }
+  end
+  local lines = { string.format(" %s %s %d", self.filename, self.path, #self.preview_lines) }
+  vim.list_extend(lines, self.preview_lines)
+  return lines
+end
+
+function Fold:highlight(buf, row)
+  local col = 4 -- "" is 3 bytes, plus 1 space
+  api.nvim_buf_add_highlight(buf, u.namespace, "Directory", row, col, col + #self.filename)
+  col = col + #self.filename + 1
+  api.nvim_buf_add_highlight(buf, u.namespace, "Comment", row, col, col + #self.path)
+  col = col + #self.path + 1
+  api.nvim_buf_add_highlight(buf, u.namespace, "Number", row, col, col + #(tostring(self.preview_lines)))
+end
+
+---@class ResultList
+---@field buf integer
+---@field win integer
+---@field extmark integer
+---@field folds Fold[]
+---@field items Item[]
+local ResultList = {}
+
+function ResultList.new(buf, win, extmark)
+  local self = setmetatable({
+    buf = buf,
+    win = win,
+    extmark = extmark,
+    folds = {},
+    items = {},
+  }, { __index = ResultList })
+
+  vim.keymap.set("n", config.opts.keymaps.next_match, function()
+    self:next_match()
+  end, { buffer = self.buf, nowait = true })
+  vim.keymap.set("n", config.opts.keymaps.prev_match, function()
+    self:prev_match()
+  end, { buffer = self.buf, nowait = true })
+
+  return self
+end
+
+---@private
+function ResultList:get_start()
+  return api.nvim_buf_get_extmark_by_id(self.buf, u.namespace, self.extmark, {})[1] + 1
+end
+
+---@params matches ssr.Matches
+function ResultList:set(matches)
+  self.folds = {}
+  self.items = {}
+  local start = self:get_start()
+  api.nvim_buf_clear_namespace(self.buf, u.namespace, start, -1)
+
+  local lines = {}
+  for fold_idx, row in ipairs(matches) do
+    local fold = Fold.new(fold_idx ~= 1, row.file, row.matches)
+    table.insert(self.folds, fold)
+    for match_idx, line in ipairs(fold:get_lines()) do
+      table.insert(lines, line)
+      table.insert(self.items, { fold_idx = fold_idx, match_idx = match_idx - 1 })
+    end
+  end
+  api.nvim_buf_set_lines(self.buf, start, -1, true, lines)
+
+  for _, fold in ipairs(self.folds) do
+    fold:highlight(self.buf, start)
+    start = start + fold:len()
+  end
+end
+
+---@param folded boolean
+---@param cursor integer?
+function ResultList:set_folded(folded, cursor)
+  local result_start = self:get_start()
+  cursor = cursor or u.get_cursor(self.win) - result_start
+  local item = self.items[cursor + 1] -- +1 beacause `cursor` is 0-based
+  local fold = self.folds[item.fold_idx]
+  if fold.folded == folded then
+    return
+  end
+
+  local start = cursor - item.match_idx -- like C macro `container_of`
+  local end_ = start + fold:len()
+  fold.folded = folded
+  local lines = fold:get_lines()
+  local items = {}
+  for i = 0, #lines - 1 do
+    table.insert(items, { fold_idx = item.fold_idx, match_idx = i })
+  end
+  u.list_replace(self.items, start, end_, items)
+  start = result_start + start
+  end_ = result_start + end_
+  api.nvim_buf_set_lines(self.buf, start, end_, true, lines)
+  fold:highlight(self.buf, start)
+  if folded then
+    u.set_cursor(self.win, start, 0)
+  end
+end
+
+function ResultList:next_match()
+  local cursor = u.get_cursor(self.win)
+  local result_start = self:get_start()
+  cursor = cursor > result_start and cursor - result_start or 0
+  local item = self.items[cursor + 1] -- +1: lua index
+  if not item then
+    return
+  end
+  if item.match_idx == 0 then
+    self:set_folded(false, cursor)
+  end
+  cursor = cursor + 1
+  item = self.items[cursor + 1]
+  if not item then
+    return
+  end
+  if item.match_idx == 0 then
+    self:set_folded(false, cursor)
+    cursor = cursor + 1
+  end
+  return u.set_cursor(self.win, cursor + result_start, 0)
+end
+
+function ResultList:prev_match()
+  local cursor = u.get_cursor(self.win)
+  local result_start = self:get_start()
+  if cursor <= result_start then
+    if #self.items == 0 then
+      return
+    end
+    self:set_folded(false, #self.items - 1)
+    return u.set_cursor(self.win, result_start + #self.items - 1, 0)
+  end
+
+  cursor = cursor - result_start
+  local item = self.items[cursor + 1]
+  if not item then
+    return
+  end
+  if item.match_idx <= 1 then
+    cursor = cursor - item.match_idx - 1
+    item = self.items[cursor + 1]
+    if not item then
+      return
+    end
+    local fold = self.folds[item.fold_idx]
+    if fold.folded then
+      self:set_folded(false, cursor)
+      cursor = cursor + #fold.preview_lines
+    end
+    return u.set_cursor(self.win, result_start + cursor, 0)
+  end
+
+  cursor = cursor - 1
+  return u.set_cursor(self.win, cursor + result_start, 0)
+end
+
+return ResultList
diff --git a/lua/ssr/utils.lua b/lua/ssr/utils.lua
index 099ed92..fa0efb1 100644
--- a/lua/ssr/utils.lua
+++ b/lua/ssr/utils.lua
@@ -1,8 +1,14 @@
 local api = vim.api
 local ts = vim.treesitter
+local config = require "ssr.config"
 
 local M = {}
 
+M.wildcard_prefix = "__ssr_var_"
+M.namespace = api.nvim_create_namespace "ssr_ns"
+M.cur_search_ns = api.nvim_create_namespace "ssr_cur_search_ns"
+M.augroup = api.nvim_create_augroup("ssr_augroup", {})
+
 -- Send a notification titled SSR.
 ---@param msg string
 ---@return nil
@@ -11,14 +17,14 @@ function M.notify(msg)
 end
 
 -- Get (0,0)-indexed cursor position.
----@param win window
+---@param win integer
 function M.get_cursor(win)
   local cursor = api.nvim_win_get_cursor(win)
   return cursor[1] - 1, cursor[2]
 end
 
 -- Set (0,0)-indexed cursor position.
----@param win window
+---@param win integer
 ---@param row integer
 ---@param col integer
 function M.set_cursor(win, row, col)
@@ -26,8 +32,8 @@ function M.set_cursor(win, row, col)
 end
 
 -- Get selected region, works in many modes.
----@param win window
----@return number, number, number, number
+---@param win integer
+---@return integer, number, number, number
 function M.get_selection(win)
   local mode = api.nvim_get_mode().mode
   local cursor_row, cursor_col = M.get_cursor(win)
@@ -54,12 +60,12 @@ function M.get_selection(win)
 end
 
 -- Get smallest node for the range.
----@param buf buffer
+---@param buf integer
 ---@param lang string
----@param start_row number
----@param start_col number
----@param end_row number
----@param end_col number
+---@param start_row integer
+---@param start_col integer
+---@param end_row integer
+---@param end_col integer
 ---@return TSNode?
 function M.node_for_range(buf, lang, start_row, start_col, end_row, end_col)
   local has_parser, parser = pcall(ts.get_parser, buf, lang)
@@ -68,8 +74,8 @@ function M.node_for_range(buf, lang, start_row, start_col, end_row, end_col)
   end
 end
 
----@param buf buffer
----@param row number
+---@param buf integer
+---@param row integer
 function M.get_indent(buf, row)
   local line = api.nvim_buf_get_lines(buf, row, row + 1, true)[1]
   return line:match "^%s*"
@@ -103,14 +109,13 @@ end
 
 -- Compute window size to show giving lines.
 ---@param lines string[]
----@param config Config
----@return number
----@return number
-function M.get_win_size(lines, config)
-  ---@param i number
-  ---@param min number
-  ---@param max number
-  ---@return number
+---@return integer
+---@return integer
+function M.get_win_size(lines)
+  ---@param i integer
+  ---@param min integer
+  ---@param max integer
+  ---@return integer
   local function clamp(i, min, max)
     return math.min(math.max(i, min), max)
   end
@@ -122,9 +127,74 @@ function M.get_win_size(lines, config)
     end
   end
 
-  width = clamp(width, config.min_width, config.max_width)
-  local height = clamp(#lines, config.min_height, config.max_height)
+  width = clamp(width, config.opts.min_width, config.opts.max_width)
+  local height = clamp(#lines, config.opts.min_height, config.opts.max_height)
   return width, height
 end
 
+-- https://github.com/rust-lang/regex/blob/17284451f10aa06c6c42e622e3529b98513901a8/regex-syntax/src/lib.rs#L272
+local regex_meta_chars = {
+  ["\\"] = true,
+  ["."] = true,
+  ["+"] = true,
+  ["*"] = true,
+  ["?"] = true,
+  ["("] = true,
+  [")"] = true,
+  ["|"] = true,
+  ["["] = true,
+  ["]"] = true,
+  ["{"] = true,
+  ["}"] = true,
+  ["^"] = true,
+  ["$"] = true,
+  ["#"] = true,
+  ["&"] = true,
+  ["-"] = true,
+  ["~"] = true,
+}
+
+---@param s string
+---@return string
+function M.regex_escape(s)
+  local escaped = s:gsub(".", function(ch)
+    return regex_meta_chars[ch] and "\\" .. ch or ch
+  end)
+  return escaped
+end
+
+---@generic T
+---@param list T[]
+---@param f fun(T): -1 | 0 | 1
+---@return integer?
+function M.binary_search_by(list, f)
+  local left = 1
+  local right = #list + 1
+  while left < right do
+    local mid = math.floor((left + right) / 2)
+    local cmp = f(list[mid])
+    if cmp < 0 then
+      left = mid + 1
+    elseif cmp > 0 then
+      right = mid
+    else
+      return mid
+    end
+  end
+end
+
+---@generic T
+---@param list table<T>
+---@param start integer 0-based
+---@param end_ integer exclusive
+---@param replacement table<T>
+function M.list_replace(list, start, end_, replacement)
+  for _ = start + 1, end_ do
+    table.remove(list, start + 1)
+  end
+  for i = start + 1, start + #replacement do
+    table.insert(list, i, replacement[i - start])
+  end
+end
+
 return M
diff --git a/tests/ssr_spec.lua b/tests/ssr_spec.lua
index f6fcd17..bbe5683 100644
--- a/tests/ssr_spec.lua
+++ b/tests/ssr_spec.lua
@@ -1,99 +1,101 @@
-local u = require "ssr.utils"
-local ParseContext = require("ssr.parse").ParseContext
 local ts = vim.treesitter
-local search = require("ssr.search").search
-local replace = require("ssr.search").replace
+local uv = vim.uv or vim.loop
+local ParseContext = require "ssr.parse_context"
+local Searcher = require "ssr.search"
+local pin_matches = require("ssr.replace").pin_matches
+local replace = require("ssr.replace").replace
+local File = require "ssr.file"
 
+---@type string[]
 local tests = {}
 
+---@param s string
 local function t(s)
   table.insert(tests, s)
 end
 
-t [[ python operators
-<a + b>
-a - b
-====
+t [[ operators
 a + b ==>> (+ a b)
+==== t.py
+a + b
+a - b
 ====
 (+ a b)
 a - b
 ]]
 
-t [[ python complex string
-<"""
+t [[ complex string
+"""
 line 1
 \r\n\a\?\\
 'a'"'"'b'
-""">
-====
+""" ==>> x
+==== t.py
 """
 line 1
 \r\n\a\?\\
 'a'"'"'b'
 """
-==>>
-x
 ====
 x
 ]]
 
-t [[ javascript keywords
-<let a = 1>
-const a = 1
-====
+t [[ keywords
 let a = 1 ==>> x
+==== t.js
+let a = 1
+const a = 1
 ====
 x
 const a = 1
 ]]
 
-t [[ lua func args
-<f(1, 2, 3)>
-f(1, 3)
-====
+t [[ func args
 f(1, 3) ==>> x
+==== t.lua
+f(1, 2, 3)
+f(1, 3)
 ====
 f(1, 2, 3)
 x
 ]]
 
-t [[ lua recursive 1
-<f(f(f(0)))>
-====
+t [[ recursive 1
 f($a) ==>> $a.f()
+==== recursive.lua
+f(f(f(0)))
 ====
 0.f().f().f()
 ]]
 
-t [[ rust recursive 2
-f(f(<f(0, 1)>, 2), 3)
-====
+t [[ recursive 2
 f($a, $b) ==>> $a.f($b)
+==== t.rs
+f(f(f(0, 1), 2), 3)
 ====
 0.f(1).f(2).f(3)
 ]]
 
-t [[ rust recursive 3
-f(3, f(2, <f(1, 0)>))
-====
+t [[ recursive 3
 f($a, $b) ==>> $a.f($b)
+==== t.rs
+f(3, f(2, f(1, 0)))
 ====
 3.f(2.f(1.f(0)))
 ]]
 
-t [[ python indent 1
-def f():
-    <if foo:
-        if bar:
-            pass>
-====
+t [[ indent 1
 if $a:
     $b
 ==>>
 if $a:
     if True:
         $b
+==== t.py
+def f():
+    if foo:
+        if bar:
+            pass
 ====
 def f():
     if foo:
@@ -103,18 +105,18 @@ def f():
                     pass
 ]]
 
-t [[ python indent 2
-def f():
-    if len(a) != 0:
-        do_a(a)
-        <if len(b) != 0:
-            do_b(b)>
-====
+t [[ indent 2
 if len($a) != 0:
     $b
 ==>>
 if $a:
     $b
+==== t.py
+def f():
+    if len(a) != 0:
+        do_a(a)
+        if len(b) != 0:
+            do_b(b)
 ====
 def f():
     if a:
@@ -123,59 +125,45 @@ def f():
             do_b(b)
 ]]
 
-t [[ rust question mark
-let foo = <bar().await?>;
-====
+t [[ question mark
 $a? ==>> try!($a)
+==== t.rs
+let foo = bar().await?;
 ====
 let foo = try!(bar().await);
 ]]
 
-t [[ rust rust-analyzer ssr example
-String::from(<foo(y + 5, z)>)
-====
+t [[ rust-analyzer ssr example
 foo($a, $b) ==>> ($a).foo($b)
+==== t.rs
+String::from(foo(y + 5, z))
 ====
 String::from((y + 5).foo(z))
 ]]
 
-t [[ go parse Go := in function
-func main() {
-    <commit, _ := os.LookupEnv("GITHUB_SHA")>
-}
-====
-$a, _ := os.LookupEnv($b)
-==>>
-$a := os.Getenv($b)
-====
-func main() {
-    commit := os.Getenv("GITHUB_SHA")
-}
-]]
-
-t [[ go match Go if err
+t [[ match Go if err
+if err != nil { panic(err) } ==>> x
+==== t.go
 fn main() {
-    <if err != nil {
+    if err != nil {
         panic(err)
-    }>
+    }
 }
 ====
-if err != nil { panic(err) } ==>> x
-====
 fn main() {
     x
 }
 ]]
 
-t [[ rust reused wildcard: compound assignments
-<idx = idx + 1>;
+t [[ reused wildcard: compound assignments
+$a = $a + $b; ==>> $a += $b;
+==== t.rs
+idx = idx + 1;
 bar = foo + idx;
 *foo.bar() = * foo . bar () + 1;
 (foo + bar) = (foo + bar) + 1;
 (foo + bar) = (foo - bar) + 1;
 ====
-$a = $a + $b ==>> $a += $b
-====
 idx += 1;
 bar = foo + idx;
 *foo.bar() += 1;
@@ -183,18 +171,18 @@ bar = foo + idx;
 (foo + bar) = (foo - bar) + 1;
 ]]
 
-t [[ python reused wildcard: indent
-def f():
-    <if await foo.bar(baz):
-        if await foo.bar(baz):
-            pass>
-====
+t [[ reused wildcard: indent
 if $foo:
     if $foo:
         $body
 ==>>
 if $foo:
     $body
+==== t.py
+def f():
+    if await foo.bar(baz):
+        if await foo.bar(baz):
+            pass
 ====
 def f():
     if await foo.bar(baz):
@@ -202,74 +190,102 @@ def f():
 ]]
 
 -- two `foo`s have different type: `property_identifier` and `identifier`
-t [[ javascript reused wildcard: match different node types 1
-<{ foo: foo }>
-{ foo: bar }
-====
+t [[ reused wildcard: match different node types 1
 { $a: $a } ==>> { $a }
+==== t.js
+{ foo: foo }
+{ foo: bar }
 ====
 { foo }
 { foo: bar }
 ]]
 
-t [[ lua reused wildcard: match different node types 2
-<local api = vim.api>
-local a = vim.api
-====
+t [[ reused wildcard: match different node types 2
 local $a = vim.$a ==>> x
+==== t.lua
+local api = vim.api
+local a = vim.api
 ====
 x
 local a = vim.api
 ]]
 
+t [[ multiple files
+local $a = vim.$a ==>> _G.g_$a = vim.$a
+
+==== t.lua
+local api = vim.api
+local fn = vim.fn
+====
+_G.g_api = vim.api
+_G.g_fn = vim.fn
+
+==== README.md
+# Example
+```lua
+local F = vim.F
+local uv = vim.uv
+```
+====
+# Example
+```lua
+_G.g_F = vim.F
+_G.g_uv = vim.uv
+```
+]]
+
 describe("", function()
   -- Plenary runs nvim with `--noplugin` argument.
-  -- Make sure nvim-treesitter is loaded, which populates vim.treesitter's ft_to_lang table.
+  -- Load nvim-treesitter to make `ts.language.get_lang()` work.
   require "nvim-treesitter"
 
   for _, s in ipairs(tests) do
-    local ft, desc, content, pattern, template, expected =
-      s:match "^ (%a-) (.-)\n(.-)%s?====%s?(.-)%s?==>>%s?(.-)%s?====%s?(.-)%s?$"
-    content = vim.split(content, "\n")
-    expected = vim.split(expected, "\n")
-    local start_row, start_col, end_row, end_col
-    for idx, line in ipairs(content) do
-      local col = line:find "<"
-      if col then
-        start_row = idx - 1
-        start_col = col - 1
-      end
-      line = line:gsub("<", "")
-      col = line:find ">"
-      if col then
-        end_row = idx - 1
-        end_col = col - 1
-      end
-      line = line:gsub(">", "")
-      content[idx] = line
-    end
-
+    local desc, pattern, template, rest = s:match "^ (.-)\n(.-)%s?==>>%s?(.-)\n%s*==(.-)$"
     it(desc, function()
-      local ns = vim.api.nvim_create_namespace ""
-      local buf = vim.api.nvim_create_buf(false, true)
-      vim.bo[buf].filetype = ft
-      vim.api.nvim_buf_set_lines(buf, 0, -1, true, content)
-      local lang = ts.language.get_lang(vim.bo[buf].filetype)
-      assert(lang, "language not found")
-      local origin_node = u.node_for_range(buf, lang, start_row, start_col, end_row, end_col)
+      local dir = vim.fn.tempname()
+      assert(uv.fs_mkdir(dir, 448))
+
+      local expected_files = {}
+      local lang
+      for fname, before, after in (rest .. "=="):gmatch "== (.-)\n(.-)====\n(.-)%s*==" do
+        after = after .. "\n" -- Vim always adds a \n to files.
+        fname = vim.fs.joinpath(dir, fname)
+        local fd = assert(uv.fs_open(fname, "w", 438))
+        assert(uv.fs_write(fd, before) > 0)
+        assert(uv.fs_close(fd))
+        expected_files[fname] = after
+        lang = lang or assert(ts.language.get_lang(vim.filetype.match { filename = fname }))
+      end
 
-      local parse_context = ParseContext.new(buf, origin_node)
-      assert(parse_context)
-      local node, source = parse_context:parse(pattern)
-      local matches = search(buf, node, source, ns)
+      local empty_context = ParseContext.empty(lang)
+      local searcher = assert(Searcher.new(lang, pattern, empty_context))
+      ---@type ssr.SearchResults
+      local results = {}
+      local done = false
+      File.grep(dir, searcher.rough_regex, function(file)
+        local matches = searcher:search(file)
+        assert(#matches > 0)
+        table.insert(results, { file = file, matches = matches })
+      end, function()
+        done = true
+      end)
+      vim.wait(1000, function()
+        return done
+      end)
 
-      for _, match in ipairs(matches) do
-        replace(buf, match, template)
+      local pinned_matches = pin_matches(results)
+      for _, match in ipairs(pinned_matches) do
+        replace(match, template)
       end
 
-      local actual = vim.api.nvim_buf_get_lines(buf, 0, -1, true)
-      vim.api.nvim_buf_delete(buf, {})
-      assert.are.same(expected, actual)
+      vim.cmd "silent wa"
+      for fname, expected in pairs(expected_files) do
+        local fd = assert(uv.fs_open(fname, "r", 438))
+        local stat = assert(uv.fs_fstat(fd))
+        local actual = uv.fs_read(fd, stat.size, 0)
+        uv.fs_close(fd)
+        assert.are.same(expected, actual)
+      end
     end)
   end
 end)