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ADR-010: Plugin Architecture ​

Status ​

Proposed | Accepted | Superseded by | Deprecates

Version History ​

  • v1: 2025-05-02 - Initial proposal

Context ​

As the ReX system evolves, there is an increasing need for extensibility through third-party plugins and custom enhancements without modifying the core system. Several use cases require this capability:

  1. Custom Storage Adapters: Organizations need to integrate with proprietary storage systems or cloud services.

  2. Specialized Content Processing: Domain-specific content transformation, validation, or enhancement.

  3. Integration Plugins: Connecting with external systems, analytics, or services.

  4. UI Extensions: Custom editing interfaces, visualization components, or content renderers.

  5. Workflow Customization: Integrating content operations with specific workflow or approval processes.

The current architecture provides some extension points through middleware and adapter patterns, but lacks a cohesive, standardized approach for plugin discovery, registration, configuration, and lifecycle management. This creates several challenges:

  • Inconsistent Extensibility: Different system components have varying degrees of extensibility.
  • Implementation Friction: Developers must understand internal details to extend the system.
  • Upgrade Challenges: Extensions may break during system upgrades without clear compatibility guidelines.
  • Limited Discovery: No standard mechanism for finding and evaluating plugins.
  • Security Concerns: No standardized approach to plugin isolation and security boundaries.

Decision ​

We will implement a comprehensive plugin architecture with the following key components:

1. Core Plugin Interface ​

typescript
interface ContentPlugin<TConfig = Record<string, unknown>> {
  // Plugin metadata
  id: string
  name: string
  version: string
  description: string

  // Capability declaration
  capabilities: PluginCapability[]

  // Lifecycle methods
  initialize(registry: ContentRegistry, config: TConfig): Promise<void>
  dispose(): Promise<void>

  // Extension points (each optional)
  adapters?: Record<string, AdapterFactory>
  middleware?: Record<string, MiddlewareFactory>
  components?: Record<string, React.ComponentType<any>>
  commands?: Record<string, CommandHandler>
}

type PluginCapability =
  | 'storage'
  | 'transformation'
  | 'validation'
  | 'ui'
  | 'workflow'
  | 'command'

2. Registry Integration ​

typescript
interface ContentRegistry {
  // Plugin management
  registerPlugin<TConfig>(
    plugin: ContentPlugin<TConfig>,
    config?: TConfig
  ): Promise<void>

  unregisterPlugin(pluginId: string): Promise<void>

  getPlugin(pluginId: string): ContentPlugin | undefined

  listPlugins(): ContentPlugin[]

  // Enhanced store/adapter access
  getAdapterFactory(id: string): AdapterFactory | undefined

  getMiddlewareFactory(id: string): MiddlewareFactory | undefined

  getComponent(id: string): React.ComponentType<any> | undefined

  executeCommand(commandId: string, ...args: any[]): Promise<any>
}

3. Plugin Discovery Mechanism ​

  • Package Naming Convention: Plugins use the naming pattern inherent-plugin-*
  • Manifest File: Plugins define inherent-plugin.json with metadata and capabilities
  • Runtime Discovery: Registry can discover plugins in Node.js or browser environments
  • Plugin Directory: Central directory of verified plugins with metadata

4. Security and Isolation ​

  • Capability Declaration: Plugins must explicitly declare required capabilities
  • Permission System: Registry can restrict plugin capabilities based on configuration
  • Sandboxing: UI components and transformations run in controlled environments
  • Verification: Optional cryptographic verification of plugin packages

5. Versioning and Compatibility ​

  • Semantic Versioning: Plugins follow semver for clear compatibility signaling
  • Compatibility Matrix: Plugins specify compatible ReX versions
  • Graceful Degradation: Plugins can specify fallback behaviors when facing incompatibilities
  • Upgrade Guidance: System provides clear guidance for plugin upgrades

Alternatives Considered ​

Option 1: Simple Extension Points Without Formal Plugin System ​

  • Pros: Lightweight approach, minimal API surface, easier to implement
  • Cons: Limited standardization, no discovery mechanism, manual integration
  • Outcome: Rejected as insufficient for long-term extensibility needs

Option 2: Hook-Based Plugin System ​

  • Pros: More familiar to developers from ecosystems like WordPress/frameworks
  • Cons: Less structured, harder to reason about capabilities, potential conflicts
  • Outcome: Partially adopted for specific extension points, but not as primary architecture

Option 3: Service-Based Architecture ​

  • Pros: Clear separation, strong isolation, potentially more secure
  • Cons: More complex, higher performance overhead, more challenging to implement
  • Outcome: Elements adopted for UI components, but full implementation deemed excessive

Option 4: Event-Based Plugin System ​

  • Pros: Loose coupling, easier backward compatibility, dynamic discovery
  • Cons: Harder to reason about, less explicit contracts, potential performance issues
  • Outcome: Rejected as primary approach, but adopted for notification patterns

Consequences ​

Benefits ​

  1. Standardized Extension: Consistent pattern for all types of system extensions
  2. Improved Developer Experience: Clear boundaries and interfaces for plugin developers
  3. Enhanced Discoverability: Standard mechanism for finding and evaluating plugins
  4. Stronger Security: Explicit capability declaration and permission handling
  5. Future Compatibility: Versioning and compatibility framework for sustainable ecosystem

Challenges ​

  1. Implementation Complexity: More sophisticated architecture to build and maintain
  2. API Stability Pressure: Plugin API requires strong commitment to backward compatibility
  3. Documentation Burden: Comprehensive documentation needed for plugin developers
  4. Security Vigilance: Need for ongoing security review of plugin mechanisms
  5. Performance Considerations: Plugin system adds some runtime overhead

Implementation ​

The implementation will proceed in the following phases:

Phase 1: Core Plugin Framework ​

  1. Implement core plugin interface in /src/lib/content/plugins/types.ts
  2. Enhance ContentRegistry with plugin management capabilities
  3. Create plugin discovery mechanism for Node.js environment
  4. Implement basic security checks and capability validation

Phase 2: Extension Point Integration ​

  1. Update adapter system to support plugin-provided adapters
  2. Enhance middleware to integrate with plugin-provided middleware
  3. Create component registry for plugin UI components
  4. Implement command system for plugin-defined operations

Phase 3: Developer Tools and Documentation ​

  1. Create plugin development starter kit
  2. Develop plugin debugging and testing utilities
  3. Implement plugin verification tools
  4. Create comprehensive plugin development documentation

Phase 4: Plugin Ecosystem ​

  1. Develop official plugins for common use cases
  2. Create plugin directory infrastructure
  3. Implement plugin update and compatibility checking
  4. Build community contribution guidelines and processes

Documentation Updates ​

The following documentation will need to be created or updated:

  1. New Documentation:

    • concepts/architecture/plugin-system.md: Conceptual explanation of plugin architecture
    • guides/advanced/plugin-development.md: Guide for developing plugins
    • reference/api/plugin-api.md: API reference for plugin developers
    • patterns/plugin-patterns.md: Common patterns for plugin implementation

  2. Updated Documentation:

    • Update architecture overview to include plugin architecture
    • Update adapter documentation with plugin integration information
    • Update middleware documentation with plugin extension patterns
    • Update React integration guides with plugin component usage

References ​

Released under the MIT License.

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