Reactive tracking (deref/computed/effect dep discovery) and island lifecycle now use the general scoped effects system instead of parallel infrastructure. Two scope names: "sx-reactive" for tracking context, "sx-island-scope" for island disposable collection. Eliminates ~98 net lines: _TrackingContext class, 7 tracking context platform functions (Python + JS), *island-scope* global, and corresponding RENAME_MAP entries. All 20 signal tests pass (17 original + 3 new scope integration tests), plus CEK/continuation/type tests clean. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>