vim-patch:9.2.0750: completion: 'autocompletedelay' deferral leaks state

Problem:  After 'autocompletedelay' was made non-blocking, the deferred
          popup can misbehave: a pending autocomplete survives leaving
          Insert mode and then keeps waking the editor in Normal mode,
          the deferral is recorded into registers while recording a
          macro, the popup appears an extra 'updatetime' late when
          'autocompletedelay' is larger and a CursorHoldI autocommand
          exists, CursorHoldI can fire twice without an intervening
          keypress, and an open balloon is dismissed (after v9.2.0739)
Solution: Treat the deferral like CursorHold: only keep it pending in
          Insert mode and not while recording, with pending typeahead,
          or when completion is already active; drop it when Insert mode
          ends; measure the delay from when the user typed so a
          CursorHold in between does not push the popup back; and do not
          let the deferral re-enable CursorHoldI or dismiss the balloon.
          (Hirohito Higashi).

closes: vim/vim#20669

1f0f14bc2f

Co-authored-by: Hirohito Higashi <h.east.727@gmail.com>
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/nvim/edit.c

@@ -372,6 +372,8 @@ static void insert_enter(InsertState *s)
     // and return false, causing `state_enter` to be called again.
   } while (!ins_esc(&s->count, s->cmdchar, s->nomove));
 
+  // Drop a pending autocomplete so it does not outlive Insert mode.
+  ins_compl_clear_autocomplete_delay();
   // Always update o_lnum, so that a "CTRL-O ." that adds a line
   // still puts the cursor back after the inserted text.
   if (ins_at_eol) {
@@ -1327,8 +1329,9 @@ static void insert_do_cindent(InsertState *s)
 
 static void insert_handle_key_post(InsertState *s)
 {
-  // If typed something may trigger CursorHoldI again.
-  if (s->c != K_EVENT
+  // If typed something may trigger CursorHoldI again; K_COMPLETE_DELAY is
+  // injected, not typed.
+  if (s->c != K_EVENT && s->c != K_COMPLETE_DELAY
       // but not in CTRL-X mode, a script can't restore the state
       && ctrl_x_mode_normal()) {
     did_cursorhold = false;

src/nvim/os/input.c

@@ -149,7 +149,13 @@ int input_get(uint8_t *buf, int maxlen, int ms, int tb_change_cnt, MultiQueue *e
     // When an autocomplete is pending, wake at the sooner of
     // 'autocompletedelay' and 'updatetime' so the delay does not postpone
     // CursorHold.  Once CursorHold has fired, only the delay is left.
-    bool delay_pending = ins_compl_autocomplete_pending() && p_acl > 0;
+    // Gate the injection like trigger_cursorhold() so the deferred key
+    // cannot fire while recording or outside Insert mode.
+    bool delay_pending = ins_compl_autocomplete_pending() && p_acl > 0
+                         && reg_recording == 0
+                         && typebuf.tb_len == 0
+                         && !ins_compl_active()
+                         && (get_real_state() & MODE_INSERT) != 0;
     // Measure the delay from when it was armed (the keystroke), so a
     // CursorHold returning in between does not push the popup back.
     int64_t wait_time = p_ut - cursorhold_time;

test/old/testdir/test_ins_complete.vim

@@ -6114,6 +6114,24 @@ func Test_autocompletedelay_ctrl_k()
   call Run_test_autocompletedelay_ctrl_k(150, 500)
 endfunc
 
+func Test_autocompletedelay_no_record()
+  " The K_COMPLETE_DELAY pseudo key must not be recorded into a register while
+  " recording a macro, like K_CURSORHOLD.
+  new
+  call setline(1, 'foobar')
+  set autocomplete autocompletedelay=100
+
+  let @a = ''
+  " Type a char that arms the delay, idle past 'autocompletedelay' so a
+  " K_COMPLETE_DELAY would be injected, then end Insert mode and stop recording.
+  call timer_start(200, { -> feedkeys("\<Esc>q", 't') })
+  call feedkeys("qaSf", 'tx!')
+  call assert_equal("Sf\<Esc>", @a)
+
+  set autocomplete& autocompletedelay&
+  bwipe!
+endfunc
+
 " Preinsert longest prefix when autocomplete
 func Test_autocomplete_longest()
   func GetLine()