fix(cli): ignore terminal focus reports (salvage of #16780)

Ghostty/macOS window or tab navigation (Cmd+Shift+[ / ], Alt+Tab,
etc.) can deliver terminal focus reports (CSI I / CSI O) to the
running TUI. prompt_toolkit does not map those sequences by default,
so its parser falls back to literal key presses (ESC, [, I/O) and
inserts `[I` / `[O` into the prompt buffer after the ESC byte is
handled.

Fix: register the two sequences as Keys.Ignore in ANSI_SEQUENCES at
parser level, plus a no-op kb.add(Keys.Ignore) handler so the
default self-insert path never inserts focus-report bytes.

Salvage notes: original PR put the helper in cli.py. Salvaged into
hermes_cli/pt_input_extras.py alongside install_shift_enter_alias /
install_ctrl_enter_alias to match the established pattern for
ANSI_SEQUENCES augmentation. setdefault → in-check so any prior user
registration wins.

Closes #16780

cli.py

@@ -74,10 +74,15 @@ except (ImportError, AttributeError):
     _STEADY_CURSOR = None
 
 try:
-    from hermes_cli.pt_input_extras import install_shift_enter_alias, install_ctrl_enter_alias
+    from hermes_cli.pt_input_extras import (
+        install_ctrl_enter_alias,
+        install_ignored_terminal_sequences,
+        install_shift_enter_alias,
+    )
     install_shift_enter_alias()
     install_ctrl_enter_alias()
-    del install_shift_enter_alias, install_ctrl_enter_alias
+    install_ignored_terminal_sequences()
+    del install_shift_enter_alias, install_ctrl_enter_alias, install_ignored_terminal_sequences
 except Exception:
     pass
 import threading
@@ -12717,7 +12722,21 @@ class HermesCLI:
         
         # Key bindings for the input area
         kb = KeyBindings()
-        
+
+        from prompt_toolkit.keys import Keys as _IgnoreKeys
+
+        @kb.add(_IgnoreKeys.Ignore, eager=True)
+        def handle_ignored_terminal_sequence(event):
+            """Consume parser-level ignored terminal sequences before self-insert.
+
+            install_ignored_terminal_sequences() in hermes_cli.pt_input_extras
+            registers focus reports (CSI I / CSI O) as Keys.Ignore at the
+            VT100 parser level. Without this no-op binding the default
+            self-insert path would still fire and the bytes would land in
+            the buffer.
+            """
+            return None
+
         def handle_enter(event):
             """Handle Enter key - submit input.
             

hermes_cli/pt_input_extras.py

@@ -81,3 +81,40 @@ def install_ctrl_enter_alias() -> int:
             ANSI_SEQUENCES[seq] = alt_enter
             changed += 1
     return changed
+
+
+def install_ignored_terminal_sequences() -> int:
+    """Map terminal-emitted noise sequences to ``Keys.Ignore`` so they
+    are consumed by the VT100 parser before they reach key bindings or
+    the input buffer.
+
+    Currently covers focus reports:
+      - ``\\x1b[I`` — terminal regained focus (focus in)
+      - ``\\x1b[O`` — terminal lost focus (focus out)
+
+    Ghostty, iTerm2, and some xterm builds can emit these sequences when
+    the user switches tabs / windows or when a multiplexer toggles focus
+    tracking upstream. prompt_toolkit does not map these by default, so
+    its parser falls back to literal key presses (ESC, ``[``, ``I``/``O``)
+    and inserts ``[I``/``[O`` into the prompt buffer after the ESC byte
+    is handled.
+
+    Registering them as ``Keys.Ignore`` is parser-level — strictly
+    cleaner than post-hoc regex stripping in the input sanitizer because
+    the bytes never reach the buffer. ``setdefault`` is used so any user
+    or downstream registration wins.
+
+    Returns the number of sequences whose mapping was changed.
+    """
+    try:
+        from prompt_toolkit.input.ansi_escape_sequences import ANSI_SEQUENCES
+        from prompt_toolkit.keys import Keys
+    except Exception:
+        return 0
+
+    changed = 0
+    for seq in ("\x1b[I", "\x1b[O"):
+        if seq not in ANSI_SEQUENCES:
+            ANSI_SEQUENCES[seq] = Keys.Ignore
+            changed += 1
+    return changed

tests/cli/test_cli_terminal_shortcuts.py

@@ -0,0 +1,49 @@
+"""Regression tests for terminal navigation/focus escape sequences.
+
+Ghostty/macOS window and tab navigation can deliver terminal focus reports
+(CSI I / CSI O) to the running TUI. These must be consumed by the input parser,
+not inserted into the prompt buffer and cleaned up later.
+"""
+
+from prompt_toolkit.input.vt100_parser import Vt100Parser
+from prompt_toolkit.keys import Keys
+
+from hermes_cli.pt_input_extras import install_ignored_terminal_sequences
+
+
+def _parse_keys(data: str):
+    events = []
+    parser = Vt100Parser(events.append)
+    parser.feed_and_flush(data)
+    return [(event.key, event.data) for event in events]
+
+
+def test_focus_events_are_parser_level_ignored_before_prompt_buffer():
+    install_ignored_terminal_sequences()
+
+    assert _parse_keys("\x1b[O\x1b[Ihello") == [
+        (Keys.Ignore, "\x1b[O"),
+        (Keys.Ignore, "\x1b[I"),
+        ("h", "h"),
+        ("e", "e"),
+        ("l", "l"),
+        ("l", "l"),
+        ("o", "o"),
+    ]
+
+
+def test_regular_escape_shortcuts_still_parse_normally():
+    install_ignored_terminal_sequences()
+
+    assert _parse_keys("\x1bg") == [(Keys.Escape, "\x1b"), ("g", "g")]
+
+
+def test_install_is_idempotent_and_setdefault_safe():
+    """Second call should return 0 (no new mappings); existing user
+    registrations must not be overwritten."""
+    first = install_ignored_terminal_sequences()
+    second = install_ignored_terminal_sequences()
+    # At most first should be 2 (both CSI I + CSI O), second always 0
+    # since the entries are now present.
+    assert second == 0
+    assert first in (0, 1, 2)  # 0 if a prior test in same process already installed