diff --git a/runtime/doc/editing.txt b/runtime/doc/editing.txt
index 51332571aa..f2437588d1 100644
--- a/runtime/doc/editing.txt
+++ b/runtime/doc/editing.txt
@@ -1209,9 +1209,8 @@ ZZ			Write current file, if modified, and close the current
 ZQ			Quit without checking for changes (same as ":q!").
 
 							*ZR*
-[count]ZR		Mapped to |:restart|. |default-mappings|
-			If a [count] is given, restarts without checking for
-			changes (same as ":restart +qall!").
+[count]ZR		Performs |:restart|. If a [count] is given, restarts
+			without checking for changes (":restart +qall!").
 
 MULTIPLE WINDOWS AND BUFFERS				*window-exit*
 
diff --git a/runtime/doc/gui.txt b/runtime/doc/gui.txt
index 41743b0a7f..63da98d72f 100644
--- a/runtime/doc/gui.txt
+++ b/runtime/doc/gui.txt
@@ -69,7 +69,7 @@ Restart Nvim
 
                                                 *:restart*
 :restart [+cmd] [command]
-                Restarts Nvim.
+                Restarts Nvim. See also |ZR|.
 
                 1. Stops Nvim using `:qall` (or |+cmd|, if given).
                 2. Starts a new Nvim server using the same |v:argv| (except
@@ -88,9 +88,6 @@ Restart Nvim
                 Note: If no attached UI implements the "restart" UI event,
                 this command will lead to a dangling server process.
 
-                Also see |ZR|.
-
-
 ------------------------------------------------------------------------------
 Connect UI to a different server
 
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 4feaf4f1b8..9b45d01e11 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -115,8 +115,7 @@ BUILD
 
 DEFAULTS
 
-• Mappings:
-  • |ZR| in Normal mode to |:restart|
+• todo
 
 DIAGNOSTICS
 
@@ -126,6 +125,7 @@ EDITOR
 
 • |gf| and |<cfile>| support `file://…` URIs.
 • |:log| opens log files.
+• |ZR| restarts Nvim (|:restart|).
 
 EVENTS
 
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index e05d1893d1..d738638575 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -171,7 +171,6 @@ you never want any default mappings, call |:mapclear| early in your config.
 - Treesitter defaults |treesitter-defaults|
   - |v_an| |v_in|
   - |v_]n| |v_[n|
-- |ZR|
 
 DEFAULT AUTOCOMMANDS
                                                         *default-autocmds*
@@ -389,6 +388,7 @@ Input/Mappings:
 Normal commands:
 - |gO| shows a filetype-defined "outline" of the current buffer.
 - |Q| replays the last recorded macro instead of switching to Ex mode (|gQ|).
+- |ZR| performs |:restart|
 
 Options:
 
diff --git a/runtime/lua/vim/_core/defaults.lua b/runtime/lua/vim/_core/defaults.lua
index efe390d8ee..27165bbb04 100644
--- a/runtime/lua/vim/_core/defaults.lua
+++ b/runtime/lua/vim/_core/defaults.lua
@@ -482,14 +482,6 @@ do
       end
     end, { desc = 'Select child (inner) node' })
   end
-
-  -- Z layer mappings
-  do
-    vim.keymap.set('n', 'ZR', function()
-      local args = vim.v.count >= 1 and { '+qall!' } or nil
-      cmd({ cmd = 'restart', args = args })
-    end, { desc = ':help ZR' })
-  end
 end
 
 --- Default menus
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 9860937612..7a5a238df2 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -3299,6 +3299,15 @@ static void nv_Zet(cmdarg_T *cap)
     do_cmdline_cmd("q!");
     break;
 
+  // "ZR": restart. With count, restart without checking for changes.
+  case 'R':
+    if (cap->count0 >= 1) {
+      do_cmdline_cmd("restart +qall!");
+    } else {
+      do_cmdline_cmd("restart");
+    }
+    break;
+
   default:
     clearopbeep(cap->oap);
   }
diff --git a/test/client/uv_stream.lua b/test/client/uv_stream.lua
index 220938307a..464f52a609 100644
--- a/test/client/uv_stream.lua
+++ b/test/client/uv_stream.lua
@@ -122,7 +122,9 @@ function SocketStream:read_stop()
 end
 
 function SocketStream:close()
-  uv.close(self._socket)
+  if not self._socket:is_closing() then
+    uv.close(self._socket)
+  end
 end
 
 --- Stream over child process stdio.
diff --git a/test/functional/terminal/tui_spec.lua b/test/functional/terminal/tui_spec.lua
index 5d6b264578..5ada3ebd0a 100644
--- a/test/functional/terminal/tui_spec.lua
+++ b/test/functional/terminal/tui_spec.lua
@@ -10,7 +10,6 @@ local Screen = require('test.functional.ui.screen')
 local tt = require('test.functional.testterm')
 
 local eq = t.eq
-local pcall_err = t.pcall_err
 local feed_data = tt.feed_data
 local clear = n.clear
 local command = n.command
@@ -208,10 +207,74 @@ describe('TUI :restart', function()
   before_each(n.clear)
   after_each(n.check_close)
 
+  ---@param exp boolean Restart expected
+  ---@param sess table Session
+  ---@param addr string
+  local function assert_restarted(exp, sess, addr)
+    local s = sess
+    retry(nil, 5000, function()
+      if exp then
+        s:close()
+        s = n.connect(addr)
+      end
+
+      -- Cheesy but reliable: :restart drops "-- [files…]", so empty v:argf means restart happened.
+      -- TODO(justinmk): add `v:startreason`, `v:starttime`
+      local _, argf = s:request('nvim_eval', 'v:argf')
+      ok(vim.tbl_count(argf) == (exp and 0 or 1), exp and 'empty v:argf' or 'nonempty v:argf', argf)
+    end)
+  end
+
   it('validation', function()
     eq('Vim(restart):E481: No range allowed: :1restart', t.pcall_err(n.command, ':1restart'))
   end)
 
+  it('ZR', function()
+    -- Just exercise ZR, don't need to test all :restart functionality here.
+    t.skip(is_os('win'), 'FIXME: --listen not preserved by :restart on Windows #38539')
+    local server_pipe = new_pipename()
+    local server_session
+    finally(function()
+      if server_session and not server_session.closed then
+        server_session:close()
+      end
+    end)
+    local screen = tt.setup_child_nvim({
+      '-u',
+      'NONE',
+      '-i',
+      'NONE',
+      '--listen',
+      server_pipe,
+      '--cmd',
+      'set notermguicolors',
+      '--',
+      'file1.txt', -- XXX: see comment in assert_restarted()
+    }, {
+      env = vim.tbl_extend('force', env_notermguicolors, {
+        -- Ignore logs, because assert_restarted may log "connection refused" while it retries.
+        NVIM_LOG_FILE = testlog,
+      }),
+    })
+    finally(function()
+      os.remove(testlog)
+    end)
+    screen:expect({ any = 'file1%.txt' })
+
+    server_session = n.connect(server_pipe)
+    assert_restarted(false, server_session, server_pipe)
+
+    -- ZR on modified buffer fails with E37.
+    tt.feed_data('ifoo\027')
+    tt.feed_data('ZR')
+    screen:expect({ any = 'E37' })
+
+    -- [count]ZR discards unsaved changes.
+    tt.feed_data('1ZR')
+
+    assert_restarted(true, server_session, server_pipe)
+  end)
+
   it('works', function()
     local server_pipe = new_pipename()
     local screen = tt.setup_child_nvim({