CODEAI-696 — generated sites share one layout

Every site wix-headless generated used the same fixed layout (same hero, same nav), so two sites from different prompts looked like the same template re-skinned — only colors/fonts varied. This makes the homepage structure vary per build while keeping the deterministic, no-LLM-layout pipeline (≤600s, reliable).

Approach — combinatorial section composition

compose.mjs now assembles the homepage from one randomly chosen fragment per slot instead of filling a single fixed skeleton:

• index.astro is a thin shell — {{hero}} {{home-markers}} {{about}}.
• fragments/hero/ (4) × fragments/about/ (3) × fragments/nav/ (3) = 36 homepage combinations. New fragments are auto-discovered (drop a file in, no code change).
• Random per run (Math.random); pass an integer layoutSeed for a reproducible pick (tests). The chosen combo + seed are recorded in the manifest (data.layout) since the run is otherwise non-reproducible.
• Every fragment preserves the exact slots/markers the pipeline depends on (heroHeadline/heroSub, data-decorative-slot="hero"|"about", <!-- home:* --> / <!-- nav:links -->, nav-actions, site-nav, transition:persist) → downstream build agents stay variant-agnostic. global.css / Layout.astro / Footer.astro are shared (View-Transitions wiring untouched).

BUILD-astro.md documents that layout is auto-randomized by compose (no input required). DISCOVERY-create.md no longer promises a specific layout in the plan (structure is chosen post-approval at compose time).

Supersedes the earlier "3 whole-page variants" approach — those whole-page templates were decomposed into the per-slot fragment library (this branch was squashed to a single clean commit).

Verification

• compose unit runs: across 16 seeds, every combo renders all slots/markers with no leftover {{…}}; same layoutSeed reproducible; random runs produce distinct combos; global.css/Layout/Footer stable across layouts.
• End-to-end: 3 minimal yoga sites built + published, each with a visibly different hero/nav layout (centered-banner / stacked-top / split-left), confirmed via Playwright screenshots.

Scope & follow-ups

• v1 scope: homepage hero + navigation.
• Follow-ups: per-vertical page fragments (products/services/blog); section-order shuffle + vibe-weighted selection for more variety; persist chosen combo to .wix/layout.json/AGENTS.md for after-the-fact reproducibility; fragment-authoring contract doc + build-all-combos smoke test.
• Independent of PR fix(wix-headless): carry the user's vibe choice through to the generated theme #405 (CODEAI-667 theme vibe-binding), which stays in draft.

🤖 Generated with Claude Code