diff --git a/src/nvim/api/vim.c b/src/nvim/api/vim.c
index fe263d051d..037a4d75fd 100644
--- a/src/nvim/api/vim.c
+++ b/src/nvim/api/vim.c
@@ -1586,6 +1586,7 @@ Array nvim_get_api_info(uint64_t channel_id, Arena *arena)
 ///
 /// @param attributes Arbitrary string:string map of informal client properties.
 ///     Suggested keys:
+///     - "pid":     Process id.
 ///     - "website": Client homepage URL (e.g. GitHub repository)
 ///     - "license": License description ("Apache 2", "GPLv3", "MIT", …)
 ///     - "logo":    URI or path to image, preferably small logo or icon.
@@ -1644,9 +1645,8 @@ void nvim_set_client_info(uint64_t channel_id, String name, Dictionary version,
 ///                 the key will still be present if a pty is used (e.g. for
 ///                 conpty on Windows).
 ///    -  "buffer"  (optional) Buffer with connected |terminal| instance.
-///    -  "client"  (optional) Info about the peer (client on the other end of
-///                 the RPC channel), if provided by it via
-///                 |nvim_set_client_info()|.
+///    -  "client"  (optional) Info about the peer (client on the other end of the RPC channel),
+///                 which it provided via |nvim_set_client_info()|.
 ///
 Dictionary nvim_get_chan_info(uint64_t channel_id, Integer chan, Arena *arena, Error *err)
   FUNC_API_SINCE(4)
diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index 3eb8d4ba2e..98dd7b4b45 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -464,7 +464,7 @@ static void tinput_timer_cb(uv_timer_t *handle)
 {
   TermInput *input = handle->data;
   // If the raw buffer is not empty, process the raw buffer first because it is
-  // processing an incomplete bracketed paster sequence.
+  // processing an incomplete bracketed paste sequence.
   size_t size = rstream_available(&input->read_stream);
   if (size) {
     size_t consumed = handle_raw_buffer(input, true, input->read_stream.read_pos, size);
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 314d322a68..587124fab0 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -182,9 +182,10 @@ bool ui_override(void)
   return false;
 }
 
-bool ui_active(void)
+/// Gets the number of UIs connected to this server.
+size_t ui_active(void)
 {
-  return ui_count > 0;
+  return ui_count;
 }
 
 void ui_refresh(void)
@@ -197,7 +198,7 @@ void ui_refresh(void)
   int height = INT_MAX;
   bool ext_widgets[kUIExtCount];
   bool inclusive = ui_override();
-  memset(ext_widgets, ui_active(), ARRAY_SIZE(ext_widgets));
+  memset(ext_widgets, !!ui_active(), ARRAY_SIZE(ext_widgets));
 
   for (size_t i = 0; i < ui_count; i++) {
     RemoteUI *ui = uis[i];
diff --git a/src/nvim/ui_client.c b/src/nvim/ui_client.c
index cfa79b9d8c..6bfcadebf2 100644
--- a/src/nvim/ui_client.c
+++ b/src/nvim/ui_client.c
@@ -81,12 +81,15 @@ uint64_t ui_client_start_server(int argc, char **argv)
   return channel->id;
 }
 
+/// Attaches this client to the UI channel, and sets its client info.
 void ui_client_attach(int width, int height, char *term, bool rgb)
 {
+  //
+  // nvim_ui_attach
+  //
   MAXSIZE_TEMP_ARRAY(args, 3);
   ADD_C(args, INTEGER_OBJ(width));
   ADD_C(args, INTEGER_OBJ(height));
-
   MAXSIZE_TEMP_DICT(opts, 9);
   PUT_C(opts, "rgb", BOOLEAN_OBJ(rgb));
   PUT_C(opts, "ext_linegrid", BOOLEAN_OBJ(true));
@@ -94,7 +97,6 @@ void ui_client_attach(int width, int height, char *term, bool rgb)
   if (term) {
     PUT_C(opts, "term_name", CSTR_AS_OBJ(term));
   }
-
   PUT_C(opts, "term_colors", INTEGER_OBJ(t_colors));
   if (!ui_client_is_remote) {
     PUT_C(opts, "stdin_tty", BOOLEAN_OBJ(stdin_isatty));
@@ -108,6 +110,36 @@ void ui_client_attach(int width, int height, char *term, bool rgb)
 
   rpc_send_event(ui_client_channel_id, "nvim_ui_attach", args);
   ui_client_attached = true;
+
+  //
+  // nvim_set_client_info
+  //
+  MAXSIZE_TEMP_ARRAY(args2, 5);
+  ADD_C(args2, CSTR_AS_OBJ("nvim-tui"));            // name
+  Object m = api_metadata();
+  Dictionary version = { 0 };
+  assert(m.data.dictionary.size > 0);
+  for (size_t i = 0; i < m.data.dictionary.size; i++) {
+    if (strequal(m.data.dictionary.items[i].key.data, "version")) {
+      version = m.data.dictionary.items[i].value.data.dictionary;
+      break;
+    } else if (i + 1 == m.data.dictionary.size) {
+      abort();
+    }
+  }
+  ADD_C(args2, DICTIONARY_OBJ(version));            // version
+  ADD_C(args2, CSTR_AS_OBJ("ui"));                  // type
+  // We don't send api_metadata.functions as the "methods" because:
+  // 1. it consumes memory.
+  // 2. it is unlikely to be useful, since the peer can just call `nvim_get_api`.
+  // 3. nvim_set_client_info expects a dict instead of an array.
+  ADD_C(args2, ARRAY_OBJ((Array)ARRAY_DICT_INIT));  // methods
+  MAXSIZE_TEMP_DICT(info, 9);                       // attributes
+  PUT_C(info, "website", CSTR_AS_OBJ("https://neovim.io"));
+  PUT_C(info, "license", CSTR_AS_OBJ("Apache 2"));
+  PUT_C(info, "pid", INTEGER_OBJ(os_get_pid()));
+  ADD_C(args2, DICTIONARY_OBJ(info));               // attributes
+  rpc_send_event(ui_client_channel_id, "nvim_set_client_info", args2);
 }
 
 void ui_client_detach(void)