Merge remote-tracking branch 'upstream/master' into mix_20240309HEADrahm

12 files changed, 180 insertions, 78 deletions

diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index 98dd7b4b45..1f73f2d135 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -8,7 +8,6 @@
 #include "nvim/api/private/helpers.h"
 #include "nvim/event/loop.h"
 #include "nvim/event/rstream.h"
-#include "nvim/event/stream.h"
 #include "nvim/macros_defs.h"
 #include "nvim/main.h"
 #include "nvim/map_defs.h"
@@ -160,12 +159,16 @@ void tinput_init(TermInput *input, Loop *loop)
   // initialize a timer handle for handling ESC with libtermkey
   uv_timer_init(&loop->uv, &input->timer_handle);
   input->timer_handle.data = input;
+
+  uv_timer_init(&loop->uv, &input->bg_query_timer);
+  input->bg_query_timer.data = input;
 }
 
 void tinput_destroy(TermInput *input)
 {
   map_destroy(int, &kitty_key_map);
   uv_close((uv_handle_t *)&input->timer_handle, NULL);
+  uv_close((uv_handle_t *)&input->bg_query_timer, NULL);
   rstream_may_close(&input->read_stream);
   termkey_destroy(input->tk);
 }
@@ -179,6 +182,7 @@ void tinput_stop(TermInput *input)
 {
   rstream_stop(&input->read_stream);
   uv_timer_stop(&input->timer_handle);
+  uv_timer_stop(&input->bg_query_timer);
 }
 
 static void tinput_done_event(void **argv)
@@ -383,6 +387,10 @@ static void forward_mouse_event(TermInput *input, TermKeyKey *key)
     len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Middle");
   } else if (button == 3) {
     len += (size_t)snprintf(buf + len, sizeof(buf) - len, "Right");
+  } else if (button == 8) {
+    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "X1");
+  } else if (button == 9) {
+    len += (size_t)snprintf(buf + len, sizeof(buf) - len, "X2");
   }
 
   switch (ev) {
@@ -427,6 +435,15 @@ static void tk_getkeys(TermInput *input, bool force)
   TermKeyResult result;
 
   while ((result = tk_getkey(input->tk, &key, force)) == TERMKEY_RES_KEY) {
+    // Only press and repeat events are handled for now
+    switch (key.event) {
+    case TERMKEY_EVENT_PRESS:
+    case TERMKEY_EVENT_REPEAT:
+      break;
+    default:
+      continue;
+    }
+
     if (key.type == TERMKEY_TYPE_UNICODE && !key.modifiers) {
       forward_simple_utf8(input, &key);
     } else if (key.type == TERMKEY_TYPE_UNICODE
@@ -474,6 +491,13 @@ static void tinput_timer_cb(uv_timer_t *handle)
   tinput_flush(input);
 }
 
+static void bg_query_timer_cb(uv_timer_t *handle)
+  FUNC_ATTR_NONNULL_ALL
+{
+  TermInput *input = handle->data;
+  tui_query_bg_color(input->tui_data);
+}
+
 /// Handle focus events.
 ///
 /// If the upcoming sequence of bytes in the input stream matches the termcode
@@ -660,6 +684,33 @@ static void handle_unknown_csi(TermInput *input, const TermKeyKey *key)
       }
     }
     break;
+  case 'n':
+    // Device Status Report (DSR)
+    if (nparams == 2) {
+      int args[2];
+      for (size_t i = 0; i < ARRAY_SIZE(args); i++) {
+        if (termkey_interpret_csi_param(params[i], &args[i], NULL, NULL) != TERMKEY_RES_KEY) {
+          return;
+        }
+      }
+
+      if (args[0] == 997) {
+        // Theme update notification
+        // https://github.com/contour-terminal/contour/blob/master/docs/vt-extensions/color-palette-update-notifications.md
+        // The second argument tells us whether the OS theme is set to light
+        // mode or dark mode, but all we care about is the background color of
+        // the terminal emulator. We query for that with OSC 11 and the response
+        // is handled by the autocommand created in _defaults.lua. The terminal
+        // may send us multiple notifications all at once so we use a timer to
+        // coalesce the queries.
+        if (uv_timer_get_due_in(&input->bg_query_timer) > 0) {
+          return;
+        }
+
+        uv_timer_start(&input->bg_query_timer, bg_query_timer_cb, 100, 0);
+      }
+    }
+    break;
   default:
     break;
   }
diff --git a/src/nvim/tui/input.h b/src/nvim/tui/input.h
index 4c2baf908e..e48982f9a4 100644
--- a/src/nvim/tui/input.h
+++ b/src/nvim/tui/input.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <uv.h>
 
@@ -32,6 +33,7 @@ typedef struct {
   TermKey *tk;
   TermKey_Terminfo_Getstr_Hook *tk_ti_hook_fn;  ///< libtermkey terminfo hook
   uv_timer_t timer_handle;
+  uv_timer_t bg_query_timer;  ///< timer used to batch background color queries
   Loop *loop;
   RStream read_stream;
   TUIData *tui_data;
diff --git a/src/nvim/tui/termkey/driver-csi.c b/src/nvim/tui/termkey/driver-csi.c
index 28c7eaccfd..d427be50ff 100644
--- a/src/nvim/tui/termkey/driver-csi.c
+++ b/src/nvim/tui/termkey/driver-csi.c
@@ -1,11 +1,10 @@
 #include <assert.h>
-#include <stdio.h>
+#include <stdint.h>
 #include <string.h>
 
 #include "nvim/memory.h"
 #include "nvim/tui/termkey/driver-csi.h"
 #include "nvim/tui/termkey/termkey-internal.h"
-#include "nvim/tui/termkey/termkey.h"
 #include "nvim/tui/termkey/termkey_defs.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
@@ -32,11 +31,20 @@ static TermKeyResult handle_csi_ss3_full(TermKey *tk, TermKeyKey *key, int cmd,
 
   if (nparams > 1 && params[1].param != NULL) {
     int arg = 0;
-    result = termkey_interpret_csi_param(params[1], &arg, NULL, NULL);
+    int subparam = 0;
+    size_t nsubparams = 1;
+    result = termkey_interpret_csi_param(params[1], &arg, &subparam, &nsubparams);
     if (result != TERMKEY_RES_KEY) {
       return result;
     }
 
+    if (nsubparams > 0) {
+      key->event = parse_key_event(subparam);
+      if (key->event == TERMKEY_EVENT_UNKNOWN) {
+        return TERMKEY_RES_NONE;
+      }
+    }
+
     key->modifiers = arg - 1;
   } else {
     key->modifiers = 0;
@@ -104,11 +112,20 @@ static TermKeyResult handle_csifunc(TermKey *tk, TermKeyKey *key, int cmd, TermK
   int args[3];
 
   if (nparams > 1 && params[1].param != NULL) {
-    result = termkey_interpret_csi_param(params[1], &args[1], NULL, NULL);
+    int subparam = 0;
+    size_t nsubparams = 1;
+    result = termkey_interpret_csi_param(params[1], &args[1], &subparam, &nsubparams);
     if (result != TERMKEY_RES_KEY) {
       return result;
     }
 
+    if (nsubparams > 0) {
+      key->event = parse_key_event(subparam);
+      if (key->event == TERMKEY_EVENT_UNKNOWN) {
+        return TERMKEY_RES_NONE;
+      }
+    }
+
     key->modifiers = args[1] - 1;
   } else {
     key->modifiers = 0;
@@ -178,9 +195,11 @@ static TermKeyResult handle_csi_u(TermKey *tk, TermKeyKey *key, int cmd, TermKey
         return TERMKEY_RES_ERROR;
       }
 
-      if (nsubparams > 0 && subparam != 1) {
-        // Not a press event. Ignore for now
-        return TERMKEY_RES_NONE;
+      if (nsubparams > 0) {
+        key->event = parse_key_event(subparam);
+        if (key->event == TERMKEY_EVENT_UNKNOWN) {
+          return TERMKEY_RES_NONE;
+        }
       }
 
       key->modifiers = args[1] - 1;
@@ -308,6 +327,12 @@ TermKeyResult termkey_interpret_mouse(TermKey *tk, const TermKeyKey *key, TermKe
     btn = code + 4 - 64;
     break;
 
+  case 128:
+  case 129:
+    *event = drag ? TERMKEY_MOUSE_DRAG : TERMKEY_MOUSE_PRESS;
+    btn = code + 8 - 128;
+    break;
+
   default:
     *event = TERMKEY_MOUSE_UNKNOWN;
   }
@@ -419,6 +444,20 @@ TermKeyResult termkey_interpret_modereport(TermKey *tk, const TermKeyKey *key, i
 
 #define CHARAT(i) (tk->buffer[tk->buffstart + (i)])
 
+static TermKeyEvent parse_key_event(int n)
+{
+  switch (n) {
+  case 1:
+    return TERMKEY_EVENT_PRESS;
+  case 2:
+    return TERMKEY_EVENT_REPEAT;
+  case 3:
+    return TERMKEY_EVENT_RELEASE;
+  default:
+    return TERMKEY_EVENT_UNKNOWN;
+  }
+}
+
 static TermKeyResult parse_csi(TermKey *tk, size_t introlen, size_t *csi_len,
                                TermKeyCsiParam params[], size_t *nargs, unsigned *commandp)
 {
@@ -529,7 +568,7 @@ TermKeyResult termkey_interpret_csi_param(TermKeyCsiParam param, int *paramp, in
     if (c == ':') {
       if (length == 0) {
         *paramp = arg;
-      } else {
+      } else if (subparams != NULL) {
         subparams[length - 1] = arg;
       }
 
@@ -544,7 +583,7 @@ TermKeyResult termkey_interpret_csi_param(TermKeyCsiParam param, int *paramp, in
 
   if (length == 0) {
     *paramp = arg;
-  } else {
+  } else if (subparams != NULL) {
     subparams[length - 1] = arg;
   }
 
diff --git a/src/nvim/tui/termkey/driver-csi.h b/src/nvim/tui/termkey/driver-csi.h
index 0abd8b5c2e..644cc9d58b 100644
--- a/src/nvim/tui/termkey/driver-csi.h
+++ b/src/nvim/tui/termkey/driver-csi.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/tui/termkey/termkey_defs.h"
+#include "nvim/tui/termkey/termkey_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "tui/termkey/driver-csi.h.generated.h"
diff --git a/src/nvim/tui/termkey/driver-ti.c b/src/nvim/tui/termkey/driver-ti.c
index 745ee9902f..e402f93e93 100644
--- a/src/nvim/tui/termkey/driver-ti.c
+++ b/src/nvim/tui/termkey/driver-ti.c
@@ -1,16 +1,16 @@
-#include <ctype.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
-#include <sys/types.h>
 #include <unibilium.h>
+#include <uv.h>
 
 #include "nvim/memory.h"
 #include "nvim/tui/termkey/driver-ti.h"
 #include "nvim/tui/termkey/termkey-internal.h"
-#include "nvim/tui/termkey/termkey.h"
+#include "nvim/tui/termkey/termkey_defs.h"
 
 #ifndef _WIN32
 # include <unistd.h>
diff --git a/src/nvim/tui/termkey/driver-ti.h b/src/nvim/tui/termkey/driver-ti.h
index df9bd72d5b..6dbcb11344 100644
--- a/src/nvim/tui/termkey/driver-ti.h
+++ b/src/nvim/tui/termkey/driver-ti.h
@@ -1,6 +1,6 @@
 #pragma once
 
-#include "nvim/tui/termkey/termkey_defs.h"
+#include "nvim/tui/termkey/termkey_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "tui/termkey/driver-ti.h.generated.h"
diff --git a/src/nvim/tui/termkey/termkey-internal.h b/src/nvim/tui/termkey/termkey-internal.h
index 107591f950..97fae939c5 100644
--- a/src/nvim/tui/termkey/termkey-internal.h
+++ b/src/nvim/tui/termkey/termkey-internal.h
@@ -47,7 +47,7 @@ struct TermKey {
   int canonflags;
   unsigned char *buffer;
   size_t buffstart;  // First offset in buffer
-  size_t buffcount;  // NUMBER of entires valid in buffer
+  size_t buffcount;  // NUMBER of entries valid in buffer
   size_t buffsize;   // Total malloc'ed size
   size_t hightide;   // Position beyond buffstart at which peekkey() should next start
                      // normally 0, but see also termkey_interpret_csi
diff --git a/src/nvim/tui/termkey/termkey.c b/src/nvim/tui/termkey/termkey.c
index e6440118f3..eabde2f9f7 100644
--- a/src/nvim/tui/termkey/termkey.c
+++ b/src/nvim/tui/termkey/termkey.c
@@ -1,9 +1,9 @@
 #include <ctype.h>
 #include <errno.h>
-#include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
 
+#include "nvim/macros_defs.h"
 #include "nvim/mbyte.h"
 #include "nvim/memory.h"
 #include "nvim/tui/termkey/driver-csi.h"
@@ -13,9 +13,10 @@
 #include "nvim/tui/termkey/termkey_defs.h"
 
 #ifndef _WIN32
-# include <poll.h>
-# include <strings.h>
-# include <unistd.h>
+// Include these directly instead of <termios.h> which is system-dependent. #31704
+# include <poll.h>  // IWYU pragma: keep
+# include <strings.h>  // IWYU pragma: keep
+# include <unistd.h>  // IWYU pragma: keep
 #else
 # include <io.h>
 #endif
@@ -633,40 +634,13 @@ static void eat_bytes(TermKey *tk, size_t count)
   tk->buffcount -= count;
 }
 
-// TODO(dundargoc): we should be able to replace this with utf_char2bytes from mbyte.c
 int fill_utf8(int codepoint, char *str)
 {
-  int nbytes = utf_char2len(codepoint);
-
+  int nbytes = utf_char2bytes(codepoint, str);
   str[nbytes] = 0;
-
-  // This is easier done backwards
-  int b = nbytes;
-  while (b > 1) {
-    b--;
-    str[b] = (char)0x80 | (codepoint & 0x3f);
-    codepoint >>= 6;
-  }
-
-  switch (nbytes) {
-  case 1:
-    str[0] = (codepoint & 0x7f); break;
-  case 2:
-    str[0] = (char)0xc0 | (codepoint & 0x1f); break;
-  case 3:
-    str[0] = (char)0xe0 | (codepoint & 0x0f); break;
-  case 4:
-    str[0] = (char)0xf0 | (codepoint & 0x07); break;
-  case 5:
-    str[0] = (char)0xf8 | (codepoint & 0x03); break;
-  case 6:
-    str[0] = (char)0xfc | (codepoint & 0x01); break;
-  }
-
   return nbytes;
 }
 
-#define UTF8_INVALID 0xFFFD
 static TermKeyResult parse_utf8(const unsigned char *bytes, size_t len, int *cp, size_t *nbytep)
 {
   unsigned nbytes;
@@ -680,7 +654,7 @@ static TermKeyResult parse_utf8(const unsigned char *bytes, size_t len, int *cp,
     return TERMKEY_RES_KEY;
   } else if (b0 < 0xc0) {
     // Starts with a continuation byte - that's not right
-    *cp = UTF8_INVALID;
+    *cp = UNICODE_INVALID;
     *nbytep = 1;
     return TERMKEY_RES_KEY;
   } else if (b0 < 0xe0) {
@@ -699,7 +673,7 @@ static TermKeyResult parse_utf8(const unsigned char *bytes, size_t len, int *cp,
     nbytes = 6;
     *cp = b0 & 0x01;
   } else {
-    *cp = UTF8_INVALID;
+    *cp = UNICODE_INVALID;
     *nbytep = 1;
     return TERMKEY_RES_KEY;
   }
@@ -713,7 +687,7 @@ static TermKeyResult parse_utf8(const unsigned char *bytes, size_t len, int *cp,
 
     cb = bytes[b];
     if (cb < 0x80 || cb >= 0xc0) {
-      *cp = UTF8_INVALID;
+      *cp = UNICODE_INVALID;
       *nbytep = b;
       return TERMKEY_RES_KEY;
     }
@@ -724,14 +698,14 @@ static TermKeyResult parse_utf8(const unsigned char *bytes, size_t len, int *cp,
 
   // Check for overlong sequences
   if ((int)nbytes > utf_char2len(*cp)) {
-    *cp = UTF8_INVALID;
+    *cp = UNICODE_INVALID;
   }
 
   // Check for UTF-16 surrogates or invalid *cps
   if ((*cp >= 0xD800 && *cp <= 0xDFFF)
       || *cp == 0xFFFE
       || *cp == 0xFFFF) {
-    *cp = UTF8_INVALID;
+    *cp = UNICODE_INVALID;
   }
 
   *nbytep = nbytes;
@@ -833,6 +807,9 @@ static TermKeyResult peekkey(TermKey *tk, TermKeyKey *key, int force, size_t *nb
     return TERMKEY_RES_ERROR;
   }
 
+  // Press is the default event type.
+  key->event = TERMKEY_EVENT_PRESS;
+
 #ifdef DEBUG
   fprintf(stderr, "getkey(force=%d): buffer ", force);
   print_buffer(tk);
@@ -958,9 +935,9 @@ static TermKeyResult peekkey_simple(TermKey *tk, TermKeyKey *key, int force, siz
     if (res == TERMKEY_RES_AGAIN && force) {
       // There weren't enough bytes for a complete UTF-8 sequence but caller
       // demands an answer. About the best thing we can do here is eat as many
-      // bytes as we have, and emit a UTF8_INVALID. If the remaining bytes
+      // bytes as we have, and emit a UNICODE_INVALID. If the remaining bytes
       // arrive later, they'll be invalid too.
-      codepoint = UTF8_INVALID;
+      codepoint = UNICODE_INVALID;
       *nbytep = tk->buffcount;
       res = TERMKEY_RES_KEY;
     }
diff --git a/src/nvim/tui/termkey/termkey.h b/src/nvim/tui/termkey/termkey.h
index 21ed141346..5cf9894cac 100644
--- a/src/nvim/tui/termkey/termkey.h
+++ b/src/nvim/tui/termkey/termkey.h
@@ -1,9 +1,9 @@
 #pragma once
 
-#include <stdint.h>
-#include <stdlib.h>
+#include <stdint.h>  // IWYU pragma: keep
+#include <stdlib.h>  // IWYU pragma: keep
 
-#include "nvim/tui/termkey/termkey_defs.h"
+#include "nvim/tui/termkey/termkey_defs.h"  // IWYU pragma: keep
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "tui/termkey/termkey.h.generated.h"
diff --git a/src/nvim/tui/termkey/termkey_defs.h b/src/nvim/tui/termkey/termkey_defs.h
index 7c218ba7c2..87d3f63447 100644
--- a/src/nvim/tui/termkey/termkey_defs.h
+++ b/src/nvim/tui/termkey/termkey_defs.h
@@ -123,6 +123,13 @@ typedef enum {
   TERMKEY_MOUSE_RELEASE,
 } TermKeyMouseEvent;
 
+typedef enum {
+  TERMKEY_EVENT_UNKNOWN,
+  TERMKEY_EVENT_PRESS,
+  TERMKEY_EVENT_REPEAT,
+  TERMKEY_EVENT_RELEASE,
+} TermKeyEvent;
+
 enum {
   TERMKEY_KEYMOD_SHIFT = 1 << 0,
   TERMKEY_KEYMOD_ALT   = 1 << 1,
@@ -163,6 +170,8 @@ typedef struct {
 
   int modifiers;
 
+  TermKeyEvent event;
+
   // Any Unicode character can be UTF-8 encoded in no more than 6 bytes, plus
   // terminating NUL
   char utf8[7];
diff --git a/src/nvim/tui/tui.c b/src/nvim/tui/tui.c
index 2839a665da..31f95a1006 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -1,9 +1,9 @@
 // Terminal UI functions. Invoked (by ui_client.c) on the UI process.
 
 #include <assert.h>
+#include <inttypes.h>
 #include <signal.h>
 #include <stdbool.h>
-#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -22,8 +22,6 @@
 #include "nvim/event/stream.h"
 #include "nvim/globals.h"
 #include "nvim/grid.h"
-#include "nvim/grid_defs.h"
-#include "nvim/highlight.h"
 #include "nvim/highlight_defs.h"
 #include "nvim/log.h"
 #include "nvim/macros_defs.h"
@@ -107,7 +105,7 @@ struct TUIData {
   bool busy, is_invisible, want_invisible;
   bool cork, overflow;
   bool set_cursor_color_as_str;
-  bool cursor_color_changed;
+  bool cursor_has_color;
   bool is_starting;
   bool did_set_grapheme_cluster_mode;
   FILE *screenshot;
@@ -241,16 +239,19 @@ void tui_handle_term_mode(TUIData *tui, TermMode mode, TermModeState state)
       tui->unibi_ext.sync = (int)unibi_add_ext_str(tui->ut, "Sync",
                                                    "\x1b[?2026%?%p1%{1}%-%tl%eh%;");
       break;
-    case kTermModeResizeEvents:
-      signal_watcher_stop(&tui->winch_handle);
-      tui_set_term_mode(tui, mode, true);
-      break;
     case kTermModeGraphemeClusters:
       if (!is_set) {
         tui_set_term_mode(tui, mode, true);
         tui->did_set_grapheme_cluster_mode = true;
       }
       break;
+    case kTermModeThemeUpdates:
+      tui_set_term_mode(tui, mode, true);
+      break;
+    case kTermModeResizeEvents:
+      signal_watcher_stop(&tui->winch_handle);
+      tui_set_term_mode(tui, mode, true);
+      break;
     }
   }
 }
@@ -295,7 +296,10 @@ void tui_set_key_encoding(TUIData *tui)
 {
   switch (tui->input.key_encoding) {
   case kKeyEncodingKitty:
-    out(tui, S_LEN("\x1b[>1u"));
+    // Progressive enhancement flags:
+    //   0b01   (1) Disambiguate escape codes
+    //   0b10   (2) Report event types
+    out(tui, S_LEN("\x1b[>3u"));
     break;
   case kKeyEncodingXterm:
     out(tui, S_LEN("\x1b[>4;2m"));
@@ -310,7 +314,7 @@ static void tui_reset_key_encoding(TUIData *tui)
 {
   switch (tui->input.key_encoding) {
   case kKeyEncodingKitty:
-    out(tui, S_LEN("\x1b[<1u"));
+    out(tui, S_LEN("\x1b[<u"));
     break;
   case kKeyEncodingXterm:
     out(tui, S_LEN("\x1b[>4;0m"));
@@ -320,6 +324,18 @@ static void tui_reset_key_encoding(TUIData *tui)
   }
 }
 
+/// Write the OSC 11 sequence to the terminal emulator to query the current
+/// background color.
+///
+/// The response will be handled by the TermResponse autocommand created in
+/// _defaults.lua.
+void tui_query_bg_color(TUIData *tui)
+  FUNC_ATTR_NONNULL_ALL
+{
+  out(tui, S_LEN("\x1b]11;?\x07"));
+  flush_buf(tui);
+}
+
 /// Enable the alternate screen and emit other control sequences to start the TUI.
 ///
 /// This is also called when the TUI is resumed after being suspended. We reinitialize all state
@@ -336,7 +352,7 @@ static void terminfo_start(TUIData *tui)
   tui->cork = false;
   tui->overflow = false;
   tui->set_cursor_color_as_str = false;
-  tui->cursor_color_changed = false;
+  tui->cursor_has_color = false;
   tui->showing_mode = SHAPE_IDX_N;
   tui->unibi_ext.enable_mouse = -1;
   tui->unibi_ext.disable_mouse = -1;
@@ -438,14 +454,13 @@ static void terminfo_start(TUIData *tui)
   // Enable bracketed paste
   unibi_out_ext(tui, tui->unibi_ext.enable_bracketed_paste);
 
-  // Query support for mode 2026 (Synchronized Output). Some terminals also
-  // support an older DCS sequence for synchronized output, but we will only use
-  // mode 2026.
+  // Query support for private DEC modes that Nvim can take advantage of.
   // Some terminals (such as Terminal.app) do not support DECRQM, so skip the query.
   if (!nsterm) {
     tui_request_term_mode(tui, kTermModeSynchronizedOutput);
-    tui_request_term_mode(tui, kTermModeResizeEvents);
     tui_request_term_mode(tui, kTermModeGraphemeClusters);
+    tui_request_term_mode(tui, kTermModeThemeUpdates);
+    tui_request_term_mode(tui, kTermModeResizeEvents);
   }
 
   // Don't use DECRQSS in screen or tmux, as they behave strangely when receiving it.
@@ -493,6 +508,10 @@ static void terminfo_start(TUIData *tui)
 /// Disable the alternate screen and prepare for the TUI to close.
 static void terminfo_stop(TUIData *tui)
 {
+  // Disable theme update notifications. We do this first to avoid getting any
+  // more notifications after we reset the cursor and any color palette changes.
+  tui_set_term_mode(tui, kTermModeThemeUpdates, false);
+
   // Destroy output stuff
   tui_mode_change(tui, NULL_STRING, SHAPE_IDX_N);
   tui_mouse_off(tui);
@@ -509,6 +528,7 @@ static void terminfo_stop(TUIData *tui)
   if (tui->did_set_grapheme_cluster_mode) {
     tui_set_term_mode(tui, kTermModeGraphemeClusters, false);
   }
+
   // May restore old title before exiting alternate screen.
   tui_set_title(tui, NULL_STRING);
   if (ui_client_exit_status == 0) {
@@ -521,7 +541,7 @@ static void terminfo_stop(TUIData *tui)
     // Exit alternate screen.
     unibi_out(tui, unibi_exit_ca_mode);
   }
-  if (tui->cursor_color_changed) {
+  if (tui->cursor_has_color) {
     unibi_out_ext(tui, tui->unibi_ext.reset_cursor_color);
   }
   // Disable bracketed paste
@@ -1302,11 +1322,12 @@ static void tui_set_mode(TUIData *tui, ModeShape mode)
         UNIBI_SET_NUM_VAR(tui->params[0], aep.rgb_bg_color);
       }
       unibi_out_ext(tui, tui->unibi_ext.set_cursor_color);
-      tui->cursor_color_changed = true;
+      tui->cursor_has_color = true;
     }
-  } else if (c.id == 0) {
+  } else if (c.id == 0 && (tui->want_invisible || tui->cursor_has_color)) {
     // No cursor color for this mode; reset to default.
     tui->want_invisible = false;
+    tui->cursor_has_color = false;
     unibi_out_ext(tui, tui->unibi_ext.reset_cursor_color);
   }
 
@@ -1319,7 +1340,7 @@ static void tui_set_mode(TUIData *tui, ModeShape mode)
   case SHAPE_VER:
     shape = 5; break;
   }
-  UNIBI_SET_NUM_VAR(tui->params[0], shape + (int)(c.blinkon == 0));
+  UNIBI_SET_NUM_VAR(tui->params[0], shape + (int)(c.blinkon == 0 || c.blinkoff == 0));
   unibi_out_ext(tui, tui->unibi_ext.set_cursor_style);
 }
 
@@ -2273,6 +2294,7 @@ static void augment_terminfo(TUIData *tui, const char *term, int vte_version, in
   bool putty = terminfo_is_term_family(term, "putty");
   bool screen = terminfo_is_term_family(term, "screen");
   bool tmux = terminfo_is_term_family(term, "tmux") || !!os_getenv("TMUX");
+  bool st = terminfo_is_term_family(term, "st");
   bool iterm = terminfo_is_term_family(term, "iterm")
                || terminfo_is_term_family(term, "iterm2")
                || terminfo_is_term_family(term, "iTerm.app")
@@ -2357,9 +2379,10 @@ static void augment_terminfo(TUIData *tui, const char *term, int vte_version, in
       // would use a tmux control sequence and an extra if(screen) test.
       tui->unibi_ext.set_cursor_color =
         (int)unibi_add_ext_str(ut, NULL, TMUX_WRAP(tmux, "\033]Pl%p1%06x\033\\"));
-    } else if ((xterm || hterm || rxvt || tmux || alacritty)
+    } else if ((xterm || hterm || rxvt || tmux || alacritty || st)
                && (vte_version == 0 || vte_version >= 3900)) {
       // Supported in urxvt, newer VTE.
+      // Supported in st, but currently missing in ncurses definitions. #32217
       tui->unibi_ext.set_cursor_color = (int)unibi_add_ext_str(ut, "ext.set_cursor_color",
                                                                "\033]12;%p1%s\007");
     }
diff --git a/src/nvim/tui/tui_defs.h b/src/nvim/tui/tui_defs.h
index bd99d6b0ad..5d6f027bf7 100644
--- a/src/nvim/tui/tui_defs.h
+++ b/src/nvim/tui/tui_defs.h
@@ -5,6 +5,7 @@ typedef struct TUIData TUIData;
 typedef enum {
   kTermModeSynchronizedOutput = 2026,
   kTermModeGraphemeClusters = 2027,
+  kTermModeThemeUpdates = 2031,
   kTermModeResizeEvents = 2048,
 } TermMode;