# Two-Weeks-Team - **Event:** [Built with Opus 4.7: a Claude Code hackathon](https://cerebralvalley.ai/e/built-with-4-7-hackathon) - **When:** Apr 21 at 12:00 PM – Apr 27 at 2:00 AM (EDT) - **Where:** Online - **Team:** [michael chang](https://cerebralvalley.ai/u/sgwannabe) - **GitHub:** https://github.com/Two-Weeks-Team/PreviewForgeForClaudeCode - **Demo video:** https://youtu.be/_xHL8SZqfyI - **Gallery:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery - **Page:** https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery/96 Nobody knows what will get built when a project starts. Specs go stale. Wireframes lie. By demo day half the assumptions were wrong. So we put the picture first. Preview-Driven Development (PDD). Before any spec, before any code, the harness renders the project as nine different mockups in parallel — each a different Opus 4.7 persona pulling your idea in a different direction. You see what could be built. You select one. Preview is all you need. The selection IS the spec. Three cycles run back-to-back: Preview-Driven Development (the gallery is the spec) → Spec-Driven Development (OpenAPI hashed and locked) → Test-Driven Development (5-judge double-gate). Test-Driven Development (TDD) drove code with tests. Spec-Driven Development (SpecDD) drove code with specs. PDD drives them both by deciding what the picture is. The whole run is one autonomous session. Two anchored asks the user knows are coming (H1 selection, H2 freeze). Two adaptive asks the harness fires on its own (Socratic when intent can't be inferred, budget guard at 12× the standard token ceiling). Everything else: auto-decide. Fifty minutes from one line to a working app. Four asks total. Ten of fourteen scenes silent. A conversation with shape. LunchPull, the demo: 44 files, ~3,600 lines, spec conformance 98. Apache-2.0. Single Claude Code plugin. Zero third-party deps. 143 Opus 4.7 personas. Two human clicks. Preview is all you need. --- Markdown version of https://cerebralvalley.ai/e/built-with-4-7-hackathon/hackathon/gallery/96. Site index for agents: https://cerebralvalley.ai/llms.txt · full text: https://cerebralvalley.ai/llms-full.txt