fix(ui): scroll selected item into view on slash command dropdown keyboard navigation (closes #838)

* fix(ui): scroll selected item into view on slash command dropdown keyboard nav

navigateCmdDropdown() in commands.js now calls scrollIntoView({block:'nearest'})
after updating the .selected class, so the highlighted item stays visible
when the dropdown overflows and the user navigates with ↓/↑. Closes #838.

* test: lock in scrollIntoView for slash command dropdown navigation (#838)

4 regression tests in test_cmd_dropdown_scroll_838.py:
- navigateCmdDropdown calls scrollIntoView on the selected item
- Uses {block:"nearest"} (minimum-distance scroll, not jumpy)
- Scroll call comes AFTER the .selected classList.add (correct target)
- .cmd-dropdown has overflow-y:auto so the dropdown itself is the scroll
  container (scrollIntoView does not bubble up to the viewport)

Full suite: 1749 passed, 0 failures.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: nesquena-hermes <nesquena-hermes@users.noreply.github.com>
Co-authored-by: Nathan Esquenazi <nesquena@gmail.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_cmd_dropdown_scroll_838.py

@@ -0,0 +1,69 @@
+"""Tests for #838 — slash command dropdown keyboard navigation keeps the
+selected item in view."""
+import os
+import re
+
+
+_SRC = os.path.join(os.path.dirname(__file__), "..")
+
+
+def _read(name):
+    return open(os.path.join(_SRC, name), encoding="utf-8").read()
+
+
+class TestNavigateCmdDropdownScroll:
+    """navigateCmdDropdown must scroll the newly selected item into view so
+    keyboard navigation on a long list doesn't leave the highlight below the
+    visible area of the dropdown."""
+
+    def test_navigate_calls_scroll_into_view(self):
+        js = _read("static/commands.js")
+        m = re.search(r'function navigateCmdDropdown\(.*?\n\}', js, re.DOTALL)
+        assert m, "navigateCmdDropdown not found"
+        fn = m.group(0)
+        assert 'scrollIntoView' in fn, (
+            "navigateCmdDropdown must call scrollIntoView on the newly "
+            "selected item so ↓/↑ keeps the highlight visible (#838)"
+        )
+
+    def test_scroll_uses_nearest_block_alignment(self):
+        """`{block:'nearest'}` is the correct option: scrolls only when
+        needed, minimum distance — won't jump the list around on every
+        arrow-key press when the item is already in view."""
+        js = _read("static/commands.js")
+        m = re.search(r'function navigateCmdDropdown\(.*?\n\}', js, re.DOTALL)
+        assert m
+        fn = m.group(0)
+        assert "block:'nearest'" in fn or 'block: "nearest"' in fn, (
+            "scrollIntoView should use {block:'nearest'} to scroll the "
+            "minimum amount needed"
+        )
+
+    def test_scroll_after_selected_class_update(self):
+        """The scroll call must come AFTER adding the .selected class so
+        the correct item is targeted."""
+        js = _read("static/commands.js")
+        m = re.search(r'function navigateCmdDropdown\(.*?\n\}', js, re.DOTALL)
+        assert m
+        fn = m.group(0)
+        selected_pos = fn.find("classList.add('selected')")
+        scroll_pos = fn.find("scrollIntoView")
+        assert selected_pos != -1 and scroll_pos != -1
+        assert selected_pos < scroll_pos, (
+            "scrollIntoView must run after classList.add('selected') so it "
+            "scrolls the newly-highlighted item into view"
+        )
+
+    def test_cmd_dropdown_is_scroll_container(self):
+        """Regression guard: the .cmd-dropdown must have overflow-y:auto
+        (or similar) so scrollIntoView finds it as the scroll ancestor
+        rather than bubbling up to the viewport."""
+        css = _read("static/style.css")
+        m = re.search(r'\.cmd-dropdown\s*\{[^}]+\}', css)
+        assert m, ".cmd-dropdown rule not found"
+        block = m.group(0)
+        assert 'overflow-y:auto' in block or 'overflow-y: auto' in block or \
+               'overflow:auto' in block or 'overflow: auto' in block, (
+            ".cmd-dropdown must have overflow-y:auto so scrollIntoView "
+            "scrolls within the dropdown, not the whole page"
+        )