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System Architecture Overview

System Architecture Overview

Seed & Source follows a layered, hexagonal architecture across all templates. This page explains the high-level structure.

Template layers

+-------------------------------------+
|  UI / Driving Adapters              |
|  (FastAPI routes, React, Rails)     |
+-------------------------------------+
|  Core / Domain                      |
|  use_cases/ -> entities/ -> ports/  |
+-------------------------------------+
|  Infrastructure / Driven Adapters   |
|  (PostgreSQL, Redis, Stripe, S3)    |
+-------------------------------------+

Service topology (local)

graph LR
    Browser --> ReactClient["React Client :3002"]
    Browser --> StaticLanding["Static Landing :4000"]
    ReactClient --> RailsAPI["Rails API :3001"]
    ReactClient --> PythonAPI["Python SaaS :8000"]
    RailsAPI --> Postgres[("PostgreSQL")]
    PythonAPI --> Postgres
    PythonAPI --> LicenseServer["License Server :8001"]
    LicenseServer --> Stripe[("Stripe")]

Key design rules

  1. Dependency inversion — core code never imports infrastructure code
  2. Feature injection — capabilities (payments, auth) are added via sscli inject without touching core logic
  3. Docker-first — all services run in containers locally; production mirrors the same image
  4. Single deploy artifact — each template builds to one Docker image with a render.yaml for Render

Template-specific architecture docs