Successfully converted filter dropdowns to checkbox-based multi-select UI. ## Changes Made ### Backend (server/routes/web.py): - Modified filter parameters to accept List[str] instead of Optional[str] (lines 217-221) - Updated filter logic to support multiple selections using 'in' operator and 'any()' for list fields (lines 242-260) - Changed context variables to pass empty lists instead of None (lines 304-308) ### Frontend CSS (server/templates/base.html): - Added .filter-dropdown classes for dropdown container (lines 78-156) - Added styling for dropdown buttons, menus, items, and count badges - Buttons highlight with blue background when filters are active ### Frontend JavaScript (server/templates/base.html): - Added toggleFilterDropdown() to manage dropdown open/close state (lines 1520-1539) - Added updateFilterButton() to update count badges (lines 1541-1570) - Added applyFilter() to build query params and trigger HTMX refresh (lines 1572-1604) - Added clearAllFilters() to reset all filters and reload table (lines 1620-1650) - Added applySearchWithFilters() for debounced search with filters (lines 1611-1618) - Implemented click-outside-to-close behavior (lines 1652-1659) ### UI Template (server/templates/issues.html): - Replaced all 5 filter dropdowns (status, project, priority, milestone, label) with checkbox-based filter dropdowns (lines 34-156) - Each filter shows count badge when selections are active - Updated Clear Filters button to use clearAllFilters() function - Updated active filters display to loop through multiple selected values for each filter type (lines 178-217) ## Testing - Ran server smoke tests: 9/9 passed - Ran filter-specific tests: 2/2 passed - Server starts successfully with new code ## How It Works 1. User clicks filter button to open dropdown 2. Checkboxes allow selecting multiple values 3. Count badge shows number of selections 4. onChange triggers immediate HTMX table refresh 5. Active filters display shows all selected filter values 6. Clear Filters button resets all checkboxes and reloads table All changes maintain backward compatibility with existing HTMX patterns and test infrastructure.