TUI: kitty keyboard protocol, word movement and deletion keys

Query CSI ? u at startup and push the disambiguate flag on the alternate
screen when the terminal answers; CSI u reports are mapped back to legacy
input (Shift/Ctrl+Enter insert a newline, Ctrl+Backspace deletes a word).
Ctrl/Alt+Left/Right move by word, Ctrl/Alt+Delete delete the next word.
Our define_key codes move above the range ncurses uses for terminfo
extended keys.

src/keymap.c

@@ -291,6 +291,70 @@ const char *cst_key_name(int code, char *buf, size_t n) {
   return buf;
 }
 
+/* Shift on a US layout; the kitty report names the unshifted key. */
+static int us_shift(int c) {
+  static const char PLAIN[] = "`1234567890-=[]\\;',./";
+  static const char SHIFTED[] = "~!@#$%^&*()_+{}|:\"<>?";
+  if (c >= 'a' && c <= 'z')
+    return c - 'a' + 'A';
+  const char *p = c > 0 && c < 0x80 ? strchr(PLAIN, c) : NULL;
+  return p ? SHIFTED[p - PLAIN] : c;
+}
+
+/* The control character xterm sends for ctrl+c, or c when there is none. */
+static int ctrl_char(int c) {
+  if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
+    return c & 0x1f;
+  switch (c) {
+  case ' ': case '2': case '@': return 0;
+  case '3': case '[': return 27;
+  case '4': case '\\': return 28;
+  case '5': case ']': return 29;
+  case '6': case '^': return 30;
+  case '7': case '-': case '_': case '/': return 31;
+  case '8': case '?': return 127;
+  default: return c;
+  }
+}
+
+int cst_key_from_kitty(int cp, int mods, int out[2]) {
+  int shift = mods & 1, alt = mods & 2, ctrl = mods & 4;
+  if (mods & ~7)
+    return 0; /* super, hyper, meta, caps/num lock: not ours */
+  int c;
+  switch (cp) {
+  case 13:
+    if (!mods)
+      return out[0] = 13, 1;
+    out[0] = 27, out[1] = 13; /* newline */
+    return 2;
+  case 127:
+    if (!alt && !ctrl)
+      return out[0] = 127, 1;
+    out[0] = 27, out[1] = 127; /* delete word */
+    return 2;
+  case 9:
+    if (shift && !alt && !ctrl)
+      return out[0] = CST_K_BTAB, 1;
+    c = 9;
+    break;
+  case 27:
+    c = 27;
+    break;
+  default:
+    if (cp < ' ' || cp > 0x10FFFF)
+      return 0;
+    c = shift ? us_shift(cp) : cp;
+    if (ctrl)
+      c = ctrl_char(c);
+    break;
+  }
+  if (!alt)
+    return out[0] = c, 1;
+  out[0] = 27, out[1] = c;
+  return 2;
+}
+
 /* "ctrl+x n", "<leader> n" or "f2" → keys; returns the count (0 on error). */
 static int parse_seq(const cst_keymap_t *km, const char *s, int keys[2]) {
   int n = 0;

src/tui.c

@@ -127,9 +127,90 @@ static int cst_clock_gettime_mono(struct timespec *ts) {
 #define COMP_MAX 8
 #define TODO_PANEL_MAX 6
 #define ASK_OPTS_MAX 9
-/* Bracketed paste markers, bound with define_key() above KEY_MAX. */
-#define KEY_PASTE_BEGIN (KEY_MAX + 1)
-#define KEY_PASTE_END (KEY_MAX + 2)
+/* Our define_key() codes. ncurses numbers the terminfo extended keys (kLFT5,
+ * kDC3, ...) from KEY_MAX up, and key codes must fit in 16 bits, so stay well
+ * clear of the first and below the second. */
+#define KEY_OWN_BASE (KEY_MAX + 0x1000)
+/* Bracketed paste markers. */
+#define KEY_PASTE_BEGIN (KEY_OWN_BASE + 1)
+#define KEY_PASTE_END (KEY_OWN_BASE + 2)
+/* Kitty keyboard protocol: the reply to CSI ? u, and CSI cp;1+mods u reports
+ * bound as KEY_KITTY_BASE + cp * 8 + mods for ASCII code points. */
+#define KEY_KITTY_REPLY (KEY_OWN_BASE + 3)
+#define KEY_KITTY_BASE (KEY_OWN_BASE + 16)
+#define KITTY_CP_END 128
+
+#ifdef NCURSES_VERSION
+static int g_kitty_on;
+
+/* Bind the reports and ask whether the terminal speaks the protocol; the
+ * flags are pushed once the reply arrives (see tui_wget_wch). */
+static void kitty_init(void) {
+  char seq[24];
+  for (int f = 0; f < 32; f++) {
+    snprintf(seq, sizeof(seq), "\033[?%du", f);
+    define_key(seq, KEY_KITTY_REPLY);
+  }
+  for (int cp = 9; cp < KITTY_CP_END; cp++) {
+    if (cp != 9 && cp != 13 && cp != 27 && cp < ' ')
+      continue;
+    if (cp == 27)
+      define_key("\033[27u", KEY_KITTY_BASE + cp * 8);
+    for (int m = 1; m < 8; m++) {
+      snprintf(seq, sizeof(seq), "\033[%d;%du", cp, m + 1);
+      define_key(seq, KEY_KITTY_BASE + cp * 8 + m);
+    }
+  }
+  printf("\033[?u");
+  fflush(stdout);
+}
+
+/* Pop our flags before leaving; harmless if they were never pushed. */
+static void kitty_restore(void) {
+  if (g_kitty_on) {
+    printf("\033[<u");
+    fflush(stdout);
+    g_kitty_on = 0;
+  }
+}
+#endif
+
+/* wget_wch() that turns kitty key reports back into legacy input. */
+static int tui_wget_wch(WINDOW *w, wint_t *wch) {
+  for (;;) {
+    int rc = wget_wch(w, wch);
+#ifdef NCURSES_VERSION
+    if (rc != KEY_CODE_YES)
+      return rc;
+    if (*wch == KEY_KITTY_REPLY) {
+      if (!g_kitty_on) {
+        /* disambiguate: Esc, alt+x, ctrl+x, shift+enter... as CSI u */
+        printf("\033[>1u");
+        fflush(stdout);
+        g_kitty_on = 1;
+      }
+      continue;
+    }
+    int k = (int)*wch - KEY_KITTY_BASE;
+    if (k < 0 || k >= KITTY_CP_END * 8)
+      return rc;
+    int out[2];
+    int n = cst_key_from_kitty(k / 8, k % 8, out);
+    if (n == 0)
+      continue;
+    if (n == 2)
+      unget_wch((wchar_t)out[1]);
+    if (out[0] == CST_K_BTAB) {
+      *wch = KEY_BTAB;
+      return KEY_CODE_YES;
+    }
+    *wch = (wint_t)out[0];
+    return OK;
+#else
+    return rc;
+#endif
+  }
+}
 
 /* Color pair indices */
 enum {
@@ -3411,7 +3492,7 @@ static int picker_run(tui_t *t, const char *title, char items[][128], int n,
     wrefresh(dlg);
 
     wint_t wch = 0;
-    int rc = wget_wch(dlg, &wch);
+    int rc = tui_wget_wch(dlg, &wch);
     if (rc == ERR)
       continue;
     if (rc == KEY_CODE_YES) {
@@ -3542,7 +3623,7 @@ static int secret_input_run(tui_t *t, const char *title, const char *hint,
     refresh();
 
     wint_t wch = 0;
-    int r = get_wch(&wch);
+    int r = tui_wget_wch(stdscr, &wch);
     if (r == ERR)
       continue;
     if (r == KEY_CODE_YES) {
@@ -5634,8 +5715,10 @@ static int run_keys_panel(tui_t *t, int busy, int *quit) {
       "Edit     cancel the turn / close popups       esc",
       "Edit     clear input, twice to quit           ctrl+c",
       "Edit     quit on an empty prompt              ctrl+d",
-      "Edit     move by char / word / line           ← → alt+b alt+f ctrl+a ctrl+e",
-      "Edit     delete word / to start / to end      ctrl+w ctrl+u ctrl+k",
+      "Edit     new line (kitty keyboard terminals)  shift+enter ctrl+enter",
+      "Edit     move by char / word / line           ← → ctrl+← → alt+b alt+f ctrl+a ctrl+e",
+      "Edit     delete word back / forward           ctrl+w alt+backspace ctrl+backspace ctrl+del",
+      "Edit     delete to start / to end             ctrl+u ctrl+k",
       "Edit     prompt history                       ↑ ↓",
   };
   for (size_t i = 0; i < sizeof(FIXED) / sizeof(FIXED[0]); i++) {
@@ -5656,7 +5739,8 @@ static int run_keys_panel(tui_t *t, int busy, int *quit) {
 
 #ifdef NCURSES_VERSION
 static int g_k_alt_up, g_k_alt_down, g_k_ctrl_home, g_k_ctrl_end,
-    g_k_ctrl_up, g_k_ctrl_down;
+    g_k_ctrl_up, g_k_ctrl_down, g_k_ctrl_left, g_k_ctrl_right, g_k_alt_left,
+    g_k_alt_right, g_k_ctrl_dc, g_k_alt_dc;
 
 static int ext_key(const char *cap) {
   char *s = tigetstr(cap);
@@ -5675,9 +5759,30 @@ static void keys_init(void) {
   g_k_ctrl_end = ext_key("kEND5");
   g_k_ctrl_up = ext_key("kUP5");
   g_k_ctrl_down = ext_key("kDN5");
+  g_k_ctrl_left = ext_key("kLFT5");
+  g_k_ctrl_right = ext_key("kRIT5");
+  g_k_alt_left = ext_key("kLFT3");
+  g_k_alt_right = ext_key("kRIT3");
+  g_k_ctrl_dc = ext_key("kDC5");
+  g_k_alt_dc = ext_key("kDC3");
 #endif
 }
 
+/* ctrl/alt+left/right move by word, ctrl/alt+delete deletes the next word. */
+static int word_key(int k, int *dir) {
+#ifdef NCURSES_VERSION
+  if (k && (k == g_k_ctrl_left || k == g_k_alt_left))
+    return *dir = -1, 1;
+  if (k && (k == g_k_ctrl_right || k == g_k_alt_right))
+    return *dir = 1, 1;
+  if (k && (k == g_k_ctrl_dc || k == g_k_alt_dc))
+    return *dir = 0, 1;
+#else
+  (void)k, (void)dir;
+#endif
+  return 0;
+}
+
 /* ncurses event → cst_keymap code (0 for events that are not keys). */
 static int tui_key_code(int rc, wint_t wch) {
   if (rc != KEY_CODE_YES)
@@ -5747,7 +5852,7 @@ static void run_perm_modal(tui_t *t) {
     draw_perm_modal(t);
     draw_status(t);
     wint_t wch = 0;
-    int rc = wget_wch(t->input, &wch);
+    int rc = tui_wget_wch(t->input, &wch);
     if (rc == ERR)
       continue;
     if (rc == KEY_CODE_YES) {
@@ -5810,7 +5915,7 @@ static void run_ask_modal(tui_t *t) {
   for (;;) {
     draw_ask_modal(t);
     wint_t wch = 0;
-    int rc = wget_wch(t->input, &wch);
+    int rc = tui_wget_wch(t->input, &wch);
     if (rc == ERR)
       continue;
     if (rc == KEY_CODE_YES) {
@@ -5940,6 +6045,7 @@ int cst_tui_run(cst_agent_t *agent) {
   define_key("\033[201~", KEY_PASTE_END);
   printf("\033[?2004h");
   fflush(stdout);
+  kitty_init();
 #endif
 
   tui_t t;
@@ -6083,7 +6189,7 @@ int cst_tui_run(cst_agent_t *agent) {
     }
 
     wint_t wch = 0;
-    int rc = wget_wch(t.input, &wch);
+    int rc = tui_wget_wch(t.input, &wch);
     if (rc == ERR)
       continue;
 
@@ -6097,7 +6203,7 @@ int cst_tui_run(cst_agent_t *agent) {
       if (code == 27 && !t.leader_pending) {
         /* Alt+key arrives as Esc followed by the key */
         wtimeout(t.input, 30);
-        nrc = wget_wch(t.input, &nx);
+        nrc = tui_wget_wch(t.input, &nx);
         wtimeout(t.input, 80);
         if (nrc != ERR) {
           int c2 = tui_key_code(nrc, nx);
@@ -6181,6 +6287,18 @@ int cst_tui_run(cst_agent_t *agent) {
         }
         continue;
       }
+      int wdir;
+      if (word_key((int)wch, &wdir)) {
+        if (wdir < 0)
+          t.cur = word_left(&t, t.cur), draw_input(&t);
+        else if (wdir > 0)
+          t.cur = word_right(&t, t.cur), draw_input(&t);
+        else {
+          input_erase(&t, t.cur, word_right(&t, t.cur));
+          after_edit(&t);
+        }
+        continue;
+      }
       switch (wch) {
       case KEY_HOME:
         if (t.in_len) {
@@ -6376,6 +6494,7 @@ out:
 
   tui_free(&t);
 #ifdef NCURSES_VERSION
+  kitty_restore();
   printf("\033[?2004l");
   fflush(stdout);
 #endif