seij-commons-js

Seij's shared JavaScript/TypeScript commons: a single monorepo where we publish tools used across our projects so we stop reinventing the wheel. It supports both our open source work and private software, and serves as Seij's open source layer for JavaScript. Everything is written in TypeScript.

At its core, this repo provides a runtime, extension-driven architecture for business UIs: an extension platform plus a domain stack that turns backend model descriptions into dynamic screens. The flow is: model definitions (entity-graph) → data access (entity-storage) → UI shell (gen-ui, upcoming), with extension points to enrich and specialize screens.

It is not built as a framework but as a toolkit: depending on the product, Seij uses all or only parts of the stack.

flowchart LR
  ExtensionPlatform[extension-platform]
  ExtensionTooling[extension-tooling]
  CommonTypes[common-types]
  CommonValidation[common-validation]
  CommonServices[common-services]
  CommonUI[common-ui]
  CommonUIAuth[common-ui-auth]
  CommonUIIcons[common-ui-icons]
  CommonMarkdown[common-ui-markdown]
  CommonCsv[common-ui-csv-export]
  EntityGraph[entity-graph]
  EntityStorage[entity-storage]
  EntityValidation[entity-validation]
  GenUI["gen-ui (upcoming)"]

  ExtensionPlatform --> ExtensionTooling
  CommonValidation --> CommonTypes
  CommonServices --> CommonTypes

  EntityGraph --> ExtensionPlatform
  EntityGraph --> CommonTypes
  EntityGraph --> CommonValidation

  EntityStorage --> ExtensionPlatform
  EntityStorage --> CommonTypes
  EntityStorage --> EntityGraph

  EntityValidation --> EntityGraph
  EntityValidation --> CommonValidation

  CommonUI --> CommonTypes
  CommonUI --> CommonValidation
  CommonUI --> CommonUIIcons

  CommonMarkdown --> CommonUI

  CommonUIAuth --> CommonUI


  GenUI --> EntityStorage
  GenUI --> EntityGraph
  GenUI --> CommonUI
  GenUI --> EntityValidation
  GenUI --> CommonMarkdown
  GenUI --> CommonCsv

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Audience

• Internal teams at Seij
• Customers who depend on Seij libraries
• Medatarun project maintainers

What it provides

• Core language utilities and common types
• UI building blocks for business-oriented software
• A lightweight runtime extension system for JS/TS (think Eclipse, VSCode, or IntelliJ-style plugins)
• Tools for managing business entities in business-oriented software

Tech and dependencies

• TypeScript-first libraries consumed as packages
• UI overlays on Fluent UI with React (common-ui-* modules), with a goal of framework agnosticism
• common-ui-icons provides icon tooling to have backend defined icons and multi-provider icons
• OpenID Connect integration via react-oidc-context and oidc-client-ts (common-ui-auth module)
• Markdown tooling based on remark/rehype

Maturity and scope

These libraries are used in production and are considered mature for Seij's ecosystem.

They also serve as base tooling for Medatarun UI.

They are not designed to be used as building blocks by a generic audience.