refactor(cli): add protected TUI extension hooks for wrapper CLIs

Based on PR #1749 by @erosika (reimplemented on current main).

Extracts three protected methods from run() so wrapper CLIs can extend
the TUI without overriding the entire method:

- _get_extra_tui_widgets(): inject widgets between spacer and status bar
- _register_extra_tui_keybindings(kb, input_area): add keybindings
- _build_tui_layout_children(**widgets): full control over ordering

Default implementations reproduce existing layout exactly. The inline
HSplit in run() now delegates to _build_tui_layout_children().

5 tests covering defaults, widget insertion position, and keybinding
registration.

tests/test_cli_extension_hooks.py

@@ -0,0 +1,138 @@
+"""Tests for protected HermesCLI TUI extension hooks.
+
+Verifies that wrapper CLIs can extend the TUI via:
+  - _get_extra_tui_widgets()
+  - _register_extra_tui_keybindings()
+  - _build_tui_layout_children()
+without overriding run().
+"""
+
+from __future__ import annotations
+
+import importlib
+import sys
+from unittest.mock import MagicMock, patch
+
+from prompt_toolkit.key_binding import KeyBindings
+
+
+def _make_cli(**kwargs):
+    """Create a HermesCLI with prompt_toolkit stubs (same pattern as test_cli_init)."""
+    _clean_config = {
+        "model": {
+            "default": "anthropic/claude-opus-4.6",
+            "base_url": "https://openrouter.ai/api/v1",
+            "provider": "auto",
+        },
+        "display": {"compact": False, "tool_progress": "all"},
+        "agent": {},
+        "terminal": {"env_type": "local"},
+    }
+    clean_env = {"LLM_MODEL": "", "HERMES_MAX_ITERATIONS": ""}
+    prompt_toolkit_stubs = {
+        "prompt_toolkit": MagicMock(),
+        "prompt_toolkit.history": MagicMock(),
+        "prompt_toolkit.styles": MagicMock(),
+        "prompt_toolkit.patch_stdout": MagicMock(),
+        "prompt_toolkit.application": MagicMock(),
+        "prompt_toolkit.layout": MagicMock(),
+        "prompt_toolkit.layout.processors": MagicMock(),
+        "prompt_toolkit.filters": MagicMock(),
+        "prompt_toolkit.layout.dimension": MagicMock(),
+        "prompt_toolkit.layout.menus": MagicMock(),
+        "prompt_toolkit.widgets": MagicMock(),
+        "prompt_toolkit.key_binding": MagicMock(),
+        "prompt_toolkit.completion": MagicMock(),
+        "prompt_toolkit.formatted_text": MagicMock(),
+        "prompt_toolkit.auto_suggest": MagicMock(),
+    }
+    with patch.dict(sys.modules, prompt_toolkit_stubs), patch.dict(
+        "os.environ", clean_env, clear=False
+    ):
+        import cli as _cli_mod
+
+        _cli_mod = importlib.reload(_cli_mod)
+        with patch.object(_cli_mod, "get_tool_definitions", return_value=[]), patch.dict(
+            _cli_mod.__dict__, {"CLI_CONFIG": _clean_config}
+        ):
+            return _cli_mod.HermesCLI(**kwargs)
+
+
+class TestExtensionHookDefaults:
+    def test_extra_tui_widgets_default_empty(self):
+        cli = _make_cli()
+        assert cli._get_extra_tui_widgets() == []
+
+    def test_register_extra_tui_keybindings_default_noop(self):
+        cli = _make_cli()
+        kb = KeyBindings()
+        result = cli._register_extra_tui_keybindings(kb, input_area=None)
+        assert result is None
+        assert kb.bindings == []
+
+    def test_build_tui_layout_children_returns_all_widgets_in_order(self):
+        cli = _make_cli()
+        children = cli._build_tui_layout_children(
+            sudo_widget="sudo",
+            secret_widget="secret",
+            approval_widget="approval",
+            clarify_widget="clarify",
+            spinner_widget="spinner",
+            spacer="spacer",
+            status_bar="status",
+            input_rule_top="top-rule",
+            image_bar="image-bar",
+            input_area="input-area",
+            input_rule_bot="bottom-rule",
+            voice_status_bar="voice-status",
+            completions_menu="completions-menu",
+        )
+        # First element is Window(height=0), rest are the named widgets
+        assert children[1:] == [
+            "sudo", "secret", "approval", "clarify", "spinner",
+            "spacer", "status", "top-rule", "image-bar", "input-area",
+            "bottom-rule", "voice-status", "completions-menu",
+        ]
+
+
+class TestExtensionHookSubclass:
+    def test_extra_widgets_inserted_before_status_bar(self):
+        cli = _make_cli()
+        # Monkey-patch to simulate subclass override
+        cli._get_extra_tui_widgets = lambda: ["radio-menu", "mini-player"]
+
+        children = cli._build_tui_layout_children(
+            sudo_widget="sudo",
+            secret_widget="secret",
+            approval_widget="approval",
+            clarify_widget="clarify",
+            spinner_widget="spinner",
+            spacer="spacer",
+            status_bar="status",
+            input_rule_top="top-rule",
+            image_bar="image-bar",
+            input_area="input-area",
+            input_rule_bot="bottom-rule",
+            voice_status_bar="voice-status",
+            completions_menu="completions-menu",
+        )
+        # Extra widgets should appear between spacer and status bar
+        spacer_idx = children.index("spacer")
+        status_idx = children.index("status")
+        assert children[spacer_idx + 1] == "radio-menu"
+        assert children[spacer_idx + 2] == "mini-player"
+        assert children[spacer_idx + 3] == "status"
+        assert status_idx == spacer_idx + 3
+
+    def test_extra_keybindings_can_add_bindings(self):
+        cli = _make_cli()
+        kb = KeyBindings()
+
+        def _custom_hook(kb, *, input_area):
+            @kb.add("f2")
+            def _toggle(event):
+                return None
+
+        cli._register_extra_tui_keybindings = _custom_hook
+        cli._register_extra_tui_keybindings(kb, input_area=None)
+        assert len(kb.bindings) == 1