Bonus chapter — Engineering Intent Series Live demo : dungeon-demo-isl.netlify.app Source : example/dungeon/ in the ISL repository The first four articles of this series argued, from different angles, that LLM-driven development becomes predictable only when you replace prompts with a compilable specification. That is a strong claim, and a small toy app is not enough to defend it. So we built something that is not a toy: a Boardgame-style dungeon crawler — turn-based combat, fog of war, monster AI, spells with effect lifecycles, traps, secret passages, a campaign manager, a shop, an in-game editor. Single-page React app, fully generated from ISL. This article is a frank look at what worked, what hurt, and what we learned by pushing ISL well past the size where prompt-driven workflows fall apart. The Scope, in Numbers The example/dungeon/ stack is intentionally larger than a demo.…