## Summary
Implements M1 of the table sorting spec (#620): a shared `TableSort`
utility module and integration with the packets table.
### What's included
**1. `public/table-sort.js` — Shared sort utility (IIFE, no
dependencies)**
- `TableSort.init(tableEl, options)` — attaches click-to-sort on `<th
data-sort-key="...">` elements
- Built-in comparators: text (localeCompare), numeric, date (ISO), dBm
(strips suffix)
- NaN/null values sort last consistently
- Visual: ▲/▼ `<span class="sort-arrow">` appended to active column
header
- Accessibility: `aria-sort="ascending|descending|none"`, keyboard
support (Enter/Space)
- DOM reorder via `appendChild` loop (no innerHTML rebuild)
- `domReorder: false` option for virtual scroll tables (packets)
- `storageKey` option for localStorage persistence
- Custom comparator override per column
- `onSort(column, direction)` callback
- `destroy()` for clean teardown
**2. Packets table integration**
- All columns sortable: region, time, hash, size, HB, type, observer,
path, rpt
- Default sort: time descending (matches existing behavior)
- Uses `domReorder: false` + `onSort` callback to sort the data array,
then re-render via virtual scroll
- Works with both grouped and ungrouped views
- WebSocket updates respect active sort column
- Sort preference persisted in localStorage (`meshcore-packets-sort`)
**3. Tests — 22 unit tests (`test-table-sort.js`)**
- All 4 built-in comparators (text, numeric, date, dBm)
- NaN/null edge cases
- Direction toggle on click
- aria-sort attribute correctness
- Visual indicator (▲/▼) presence and updates
- onSort callback
- domReorder: false behavior
- destroy() cleanup
- Custom comparator override
### Performance
Packets table sorting works at the data array level (single `Array.sort`
call), not DOM level. Virtual scroll then renders only visible rows. No
new DOM nodes are created during sort — it's purely a data reorder +
re-render of the existing visible window. Expected sort time for 30K
packets: ~50-100ms (array sort) + existing virtual scroll render time.
Closes#620 (M1)
Co-authored-by: you <you@example.com>
