Code review and cleanup.

docs/testing/xterm-handoff.md

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+# XTerm handoff verification
+
+While input is delegated to a terminal reader in XTerm, Cthulhu suppresses
+ordinary key echo, input-driven speech interruption and lock-state feedback.
+It releases its command grabs. On return, Caps Lock tracking adopts the current
+XKB lock state before treating Caps Lock as the reader modifier again.
+
+Focused checks:
+
+```sh
+go test ./internal/app -run 'Test(XTerm|DelegatedInput)' -count=1
+python3 tests/native_x11.py
+```
+
+The native harness uses a private X display and checks grab suspension,
+restoration and lock state with synthetic input. Audible output from another
+reader and physical keyboard handling require live verification.
+
+1. Quit Cthulhu with Cthulhu+Q. Press Ctrl+Escape, then Shift+G to rebuild and
+   launch it. These are separate key presses.
+2. Focus XTerm with your console reader active. Press its reader modifier and
+   navigation keys. Expect the console reader to receive them, without
+   Cthulhu modifier echo or Cthulhu interrupting its speech.
+3. Change Caps Lock in XTerm, then switch to an ordinary desktop application.
+   Expect Cthulhu to resume focused-control speech and Braille and accept its
+   configured modifier commands with the current lock state.
+4. Switch back and repeat with keypad commands where configured. Confirm
+   focus stays on the intended application and no key remains grabbed after
+   handoff. Restore the original lock state.
+5. Record the exact keys, focused application, speech and Braille for failures.