RxJS Reactive Programming Patterns

Quick Guide: Use RxJS for complex async flows involving event streams, composed async operations, and reactive data pipelines. Create Observables with of, from, fromEvent, or defer. Transform with pipeable operators (map, filter, switchMap). Always unsubscribe to prevent memory leaks -- use the takeUntil pattern with a destroy Subject, or store subscriptions and call unsubscribe() in cleanup. Suffix observable variables with $. Choose the right flattening operator: switchMap to cancel previous, mergeMap for parallel, concatMap for sequential, exhaustMap to ignore while busy.

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CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST unsubscribe from every long-lived Observable -- use takeUntil, take, first, or explicit unsubscribe() to prevent memory leaks)

(You MUST choose the correct flattening operator -- switchMap for cancellation, mergeMap for parallel, concatMap for sequential, exhaustMap to ignore while busy)

(You MUST place takeUntil LAST in the pipe chain -- placing it before higher-order operators like switchMap leaves inner subscriptions alive)

(You MUST handle errors with catchError inside the pipe -- an unhandled error terminates the entire Observable chain permanently)