Hyperswitch

# MISSION: Scaffold "Hyperswitch" Production Architecture
You are an expert Senior Staff Software Architect and Full-Stack Engineer. Your mission is to scaffold and implement a production-grade, highly reliable, and modular codebase following the proven architecture of **Hyperswitch**.
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## 1. PROJECT SPECIFICATIONS & BENCHMARK
- **Reference Architecture**: Hyperswitch
- **What It Does**: Hyperswitch is an open-source, composable payments platform by Juspay, written in Rust, that connects many payment processors behind one API with routing, retries, vaulting, reconciliation and cost observability.
- **Domain & Category**: Open-Source Payments Orchestration
- **Production Scale**: 20+ people
- **Development Mode**: CLASSIC
- **Architectural Rationale**: Hyperswitch runs a panic-averse Rust router on Actix Web with Redis absorbing hot writes and a drainer persisting them to PostgreSQL, while a routing DSL that also compiles to WebAssembly keeps processor selection consistent between server and browser.
- **Live Website Reference**: https://hyperswitch.io
- **Source Repository**: https://github.com/juspay/hyperswitch
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## 2. PRODUCTION TECH STACK
- **Full Stack Array**: Rust, Actix-web, Diesel, PostgreSQL, Redis, sqlx, OpenSearch, WebAssembly, Docker, Grafana, Prometheus, OpenTelemetry, Cypress, Nix
- **Primary Language(s)**: Rust, JavaScript, MDX, Shell
- **License of the reference repo**: Apache-2.0
- **Backend & APIs**: Rust — Language for the router, drainer, scheduler and all crates/ members; the workspace forbids unsafe code.; Actix-web — HTTP framework used across the API crates, analytics and the drainer service.; Euclid — In-house DSL for static payment routing, with macros, a constraint graph and WebAssembly bindings for browsers.; utoipa — OpenAPI generation for request and response models; validate-openapi-spec.yml checks the published spec.; Smithy — smithy, smithy-core and smithy-generator crates derive Smithy models from shared enums and types.
- **Data & persistence**: PostgreSQL — Primary store for payments, attempts, mandates and merchants, with Diesel migrations since 2022.; Diesel — ORM with async-bb8-diesel pooling and 128-column tables, shared through the diesel_models crate.; Redis — KV store and streams; the drainer reads Redis streams and writes the queries to PostgreSQL.; OpenSearch — Search backend in the analytics crate, with AWS auth support; analytics also queries Postgres through sqlx.
- **Infrastructure & deploy**: Docker — Dockerfile builds router or other binaries per profile; docker-compose.yml runs Postgres, Redis and a migration runner.; Grafana — Observability configs for Grafana, Loki, Promtail, Tempo, Prometheus, Vector and an OpenTelemetry collector.; Cypress — End-to-end payment, payout and routing suites in cypress-tests and cypress-tests-v2, plus Postman collections via newman.; k6 — Load tests in loadtest/ with their own docker-compose and Grafana setup.; Nix — flake.nix provides a development shell, checked by nix.yaml.
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## 3. KEY ARCHITECTURAL DECISIONS (audited from https://github.com/juspay/hyperswitch @ d03f854)
1. **Strict panic-free lint policy across the workspace**: The root Cargo.toml forbids unsafe_code and warns on unwrap_used, expect_used, panic, indexing_slicing, as_conversions, print_stdout and more, and the Makefile runs clippy with -D warnings, so payment code paths are pushed towards explicit error handling with error-stack.
2. **Redis in front of Postgres, drained asynchronously**: diesel_models has a default kv_store feature, and crates/drainer is described as an "application that reads Redis streams and executes queries in database", so hot payment writes land in Redis first and a separate drainer persists them to PostgreSQL.
3. **A routing DSL compiled to native and WebAssembly**: crates/euclid is a "DSL for static routing" with euclid_macros and hyperswitch_constraint_graph, and crates/euclid_wasm exposes it as a WebAssembly JavaScript library via wasm-bindgen (make euclid-wasm), so routing rules can be checked in the browser with the same code the server runs.
4. **v1 and v2 APIs as compile-time feature sets**: Crates expose v1 and v2 features (for example in api_models, diesel_models and analytics), the Dockerfile selects VERSION_FEATURE_SET at build time, and separate diesel.toml / diesel_v2.toml files and api-migrations-compatibility.yml keep both schemas in check.
5. **Connectors as templated modules**: connector-template/ (mod.rs, transformers.rs, test.rs) and add_connector.md define how a new payment processor is added to crates/hyperswitch_connectors, so each integration follows the same request/response transformer structure.
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## 4. NON-NEGOTIABLE ARCHITECTURAL GUARDRAILS
1. **Monorepo & Modular Separation**:
   - Structure as a Turborepo monorepo with strict package boundaries:
     - `apps/web`: Application UI, routing, layouts, and server endpoints.
     - `packages/ui`: Shared design tokens, CSS variables, and Radix UI primitive components.
     - `packages/db`: Database schemas, client singleton, declarative migrations, and seed scripts.
     - `packages/config`: Shared TypeScript, ESLint, and build configurations.
2. **Strict Type Safety & Zero `any` Policy**:
   - Enable `strict: true`, `noImplicitAny: true`, and `strictNullChecks: true`.
   - Validate ALL external inputs, API request bodies, and query parameters with **Zod** schemas before execution.
3. **Frontend & Rendering Guidelines**:
   - Isolate interactive UI state to leaf components. Keep core pages lightweight and performant.
4. **Design System & Aesthetics**:
   - Keep every color, radius, shadow and font in a single token file (CSS variables) and consume tokens everywhere; never hardcode hex values in components.
   - Prefer crisp 1px borders and one subtle shadow scale over blurry default shadows. Pair one sans-serif for body/headings with one monospace for tags, badges, metrics, and code.
5. **Data Layer & Reliability**:
   - Write declarative schema definitions with foreign keys, composite indexes on queried filters, and automated timestamp triggers.
   - Use connection pooling and prepared statements for serverless database execution.
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## 5. STEP-BY-STEP SCAFFOLDING ROADMAP
- **Phase 1: Workspace & Root Config**: Initialize package manager, monorepo configuration (`turbo.json`, `tsconfig.base.json`, `package.json`).
- **Phase 2: Database Schema & Client**: Set up the data layer (PostgreSQL, Diesel, Redis, OpenSearch): client, connection pool, models, and migration scripts.
- **Phase 3: Design Tokens & UI Primitives**: Build accessible `Button`, `Input`, `Card`, `Badge`, and layout wrappers inside `packages/ui`.
- **Phase 4: Core Application Routes & Handlers**: Implement primary authentication, user session handling, and application routes.
- **Phase 5: Quality Assurance & Build Verification**: Run `tsc --noEmit`, ESLint, Prettier, and smoke test suites to ensure zero compilation or runtime errors.
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## 6. EXECUTION INSTRUCTIONS
1. Review all specifications, architectural guardrails, and stack choices above.
2. Present the full monorepo directory tree structure.
3. Systematically generate the complete, production-ready codebase according to the 5-phase roadmap above — starting with the root workspace setup, followed by the database schema, UI design system package, and full-stack application routes until the repository is fully scaffolded and ready to run.