feat(tui): handle kitty key events in libtermkey (#31727)

Enable key event reporting in the kitty keyboard protocol. This causes
supporting terminals to send key events for presses, repeats, and key
releases. For now we ignore release events, but eventually we will
support users mapping those.

5 files changed, 40 insertions, 5 deletions

diff --git a/src/nvim/tui/input.c b/src/nvim/tui/input.c
index bf00a6a82e..9d901e94ce 100644
--- a/src/nvim/tui/input.c
+++ b/src/nvim/tui/input.c
@@ -431,6 +431,15 @@ 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
diff --git a/src/nvim/tui/termkey/driver-csi.c b/src/nvim/tui/termkey/driver-csi.c
index ac2459beb2..3f54c874d1 100644
--- a/src/nvim/tui/termkey/driver-csi.c
+++ b/src/nvim/tui/termkey/driver-csi.c
@@ -177,9 +177,21 @@ 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) {
+        switch (subparam) {
+        case 1:
+          key->event = TERMKEY_EVENT_PRESS;
+          break;
+        case 2:
+          key->event = TERMKEY_EVENT_REPEAT;
+          break;
+        case 3:
+          key->event = TERMKEY_EVENT_RELEASE;
+          break;
+        default:
+          // Invalid event
+          return TERMKEY_RES_NONE;
+        }
       }
 
       key->modifiers = args[1] - 1;
diff --git a/src/nvim/tui/termkey/termkey.c b/src/nvim/tui/termkey/termkey.c
index f5736e9b69..8c4a91e736 100644
--- a/src/nvim/tui/termkey/termkey.c
+++ b/src/nvim/tui/termkey/termkey.c
@@ -834,6 +834,9 @@ 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);
diff --git a/src/nvim/tui/termkey/termkey_defs.h b/src/nvim/tui/termkey/termkey_defs.h
index 7c218ba7c2..09d3a5615a 100644
--- a/src/nvim/tui/termkey/termkey_defs.h
+++ b/src/nvim/tui/termkey/termkey_defs.h
@@ -123,6 +123,12 @@ typedef enum {
   TERMKEY_MOUSE_RELEASE,
 } TermKeyMouseEvent;
 
+typedef enum {
+  TERMKEY_EVENT_PRESS,
+  TERMKEY_EVENT_REPEAT,
+  TERMKEY_EVENT_RELEASE,
+} TermKeyEvent;
+
 enum {
   TERMKEY_KEYMOD_SHIFT = 1 << 0,
   TERMKEY_KEYMOD_ALT   = 1 << 1,
@@ -163,6 +169,8 @@ 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 693b45e80e..f4337d5011 100644
--- a/src/nvim/tui/tui.c
+++ b/src/nvim/tui/tui.c
@@ -296,7 +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"));
@@ -311,7 +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"));