---
title: "Module Invariants"
slug: "module-invariants"
updated: 2026-08-26T07:24:20Z
published: 2026-08-26T07:24:20Z
canonical: "docs.viewlift.com/module-invariants"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.viewlift.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Module Invariants

## Module Invariants

1. **Feature Ownership**
  - Each module represents a single feature or domain.
  - A module owns the UI composition, interaction logic, and data wiring for its feature.
2. **UI Composition Layer**
  - Modules are allowed to return JSX.
  - Modules compose:
    - components from `components/`
    - data from `services/`
    - feature-specific state and logic
3. **No Primitive UI Definitions**
  - Modules must not define low-level or reusable UI primitives.
  - All shared or generic UI must live in `components/`.
4. **Service-Driven Data Access**
  - Modules must not perform direct API or GraphQL calls.
  - All data access must go through `services/`.
5. **Controlled Side Effects**
  - Side effects are allowed only via `services/`.
  - Modules must not perform direct network, storage, or global state mutations.
6. **Error Handling Boundary**
  - Modules may catch `AppError` only to:
    - map errors to UI states
    - trigger navigation or recovery flows
  - Modules must not suppress or silently ignore errors.
7. **Explicit Public Surface**
  - Internal files must not be imported across modules.