diff --git a/cli.py b/cli.py
index 95bfcca615..1d09a4742a 100644
--- a/cli.py
+++ b/cli.py
@@ -3885,7 +3885,7 @@ _TERMINAL_INPUT_MODE_RESET_SEQ = (
     "\x1b[0m"      # reset text attributes
     "\x1b[?25h"    # ensure cursor visible
 )
-_EXTENDED_ENTER_KEYS_SEQ = "\x1b[>1u\x1b[>4;2m"
+_EXTENDED_ENTER_KEYS_SEQ = "\x1b[>4;2m"
 
 
 _BACKSLASH_LINE_CONTINUATION_RE = re.compile(r"\\[ \t]*$")
@@ -3920,10 +3920,14 @@ def _terminal_supports_extended_enter_keys(env: Optional[Mapping[str, str]] = No
 def _enable_extended_enter_keys(output=None, env: Optional[Mapping[str, str]] = None) -> bool:
     """Ask allowlisted terminals to report Shift+Enter distinctly.
 
-    Writes both the Kitty keyboard protocol push (CSI >1u) and xterm
-    modifyOtherKeys level 2 (CSI >4;2m), mirroring the Ink TUI. The exit reset
-    sequence already pops/resets both modes, so this is safe across normal
-    exits, Ctrl+C, and SIGTERM cleanup.
+    Writes xterm modifyOtherKeys level 2 (CSI >4;2m), mirroring the Ink TUI.
+    We do NOT push the Kitty keyboard protocol (CSI >1u) here because
+    prompt_toolkit 3.x cannot parse Kitty CSI-u sequences for control
+    characters — Ctrl+C arrives as ``\\x1b[99;5u`` instead of ``\\x03``,
+    which neither prompt_toolkit's key bindings nor the kernel's INTR
+    mechanism can match, leaving Ctrl+C completely dead (#56684).
+    The exit reset sequence already pops/resets both modes, so this is
+    safe across normal exits, Ctrl+C, and SIGTERM cleanup.
     """
     if not _terminal_supports_extended_enter_keys(env):
         return False