A generic multi-select component that supports include/exclude toggles and 'any/all' mode for each filter dimension. It is fully decoupled from business logic, accepting options, selected values, and callbacks as props. The component handles keyboard navigation, accessibility, and renders a dropdown with checkboxes. It can be extracted and reused in any React project requiring faceted filtering with exclusion support.

Central module containing custom hooks for event filtering and aggregation: useYearEvents, useMonthEvents, useDayEvents, useCfpEvents, useCfpCompanionEvents, and applyCommonFilters. These hooks parse URL search parameters to build filter state (topics, regions, countries, online/in-person, favorites) and apply them to the event list. The pattern of deriving filter state from URL params and exposing filtered data via hooks is clean, testable, and reusable for any list-based application with complex filtering.

A Node.js script that parses the community-maintained markdown files (README.md and archives) into structured JSON. It extracts event name, date, URL, location, and badges (CFP, CC, sponsoring) using regex patterns. It also merges supplementary data from CSV files (tags, metadata, CFP durations). The parser is idempotent and produces a consistent schema. This pattern of parsing semi-structured markdown into JSON is reusable for any project that uses markdown as a data source, and the script demonstrates careful handling of edge cases (multiple badges, date formats, location variations).