AI can speed-build features, but not all approaches are equal. We’ll compare three styles you’ll see in modern dev teams: Vibe Coding, Context Engineering, and Spec-Driven Development. You’ll see three concrete demos: a vibe-coded UI whipped up from a single prompt to highlight speed and pitfalls; a context-engineered flow that plugs in project docs, APIs, and tool permissions to produce consistent results; and a spec-first pipeline where contracts generate types, tests, and CI gates, turning AI output into maintainable PRs. By the end, you’ll know when to reach for each approach—ideation, delivery with guardrails, or production-grade releases—and how to blend them without losing momentum.