Covers server-side (suspendable rendering, streaming, error boundaries), client-side (linear async flows, wizard forms, cooperative scheduling, undo), and implementation path from the existing TCO trampoline. Updates TCO essay's continuations section to link to the new essay instead of dismissing the idea. Fixes "What sx is not" to acknowledge macros + TCO. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>