# InteriorScan Constitution

## Core Principles

### I. Self-Hosted First (NON-NEGOTIABLE)
All infrastructure must be self-hosted or FOSS. The ONLY external SaaS dependency is Stripe for billing. Database: PostgreSQL. Cache/sessions: Valkey. Processing: own GPU nodes. No vendor lock-in on reconstruction pipeline, viewer, or storage.

### II. Progressive Experience
Every feature must degrade gracefully. If WebGL fails, show 360° fallback. If processing fails, show uploaded photos. No feature should have a single point of failure that blocks the entire experience.

### III. FPS-Grade Immersion
The 3D viewer is not a "virtual tour" — it is a navigable space. Controls feel like a first-person game: WASD + mouse on desktop, tap-to-walk on mobile. Smooth movement, collision detection, gravity, head-bob optional. If it feels like a slideshow, it's wrong.

### IV. Photo-First Capture
Mobile phone is the only required hardware. iPhone LiDAR and 360° cameras are enhancements, not prerequisites. A real estate agent with an Android phone must be able to capture and publish a walkthrough in under 30 minutes.

### V. API-First Architecture
Every feature exposed via REST API before UI. InteriorScan is a reconstruction-as-a-service platform that happens to have a web UI, not a walled garden. White-label and embeddable viewers are first-class use cases.

### VI. TypeScript Strict
`strict: true` + `noUncheckedIndexedAccess: true`. No `any` without explicit justification. Zod for runtime validation. neverthrow for error handling in business logic.

### VII. Test-First (NON-NEGOTIABLE)
TDD mandatory: write failing test → user approves test → verify test fails → implement → verify test passes. No untested API endpoints, no untested business logic.

### VIII. Open Formats
All reconstruction outputs (mesh, point cloud, floor plan) must be exportable in open formats: OBJ, E57, LAS/LAZ, DXF, IFC (P4+). Proprietary lock-in is antithetical to this project's mission.

## Additional Constraints

- **Stack**: Next.js 16 App Router, Drizzle ORM, PostgreSQL, Valkey, three.js
- **Monorepo**: Turborepo + pnpm (tpl-next-saas template)
- **Billing**: Stripe only — no other payment/subscription SaaS
- **Lint/Format**: Biome 2.x ONLY — zero ESLint, zero Prettier
- **Testing**: Vitest v4 + Playwright
- **Design**: WCAG 2.2 AA minimum, d0a1 design palettes
- **Language**: Code/docs/commits in English. Team speaks Spanish.

## Governance

- Constitution supersedes all other practices
- Amendments require documentation, approval, and migration plan
- All PRs/reviews must verify compliance
- Retro-propagation: patterns validated in production must be PR'd back to `agentic-standards`

**Version**: 1.0.0 | **Ratified**: 2026-05-28 | **Last Amended**: 2026-05-28