Context Object Specification (COS)

Version: 0.2
Chapter: 400 — Plugin Specification
Status: Normative — Plugin Profile
Category: Plugin Model

1. Purpose

This chapter defines the Plugin Specification of the Context Object Specification (COS).

The Plugin System provides an extensibility mechanism that allows domain-specific capabilities to integrate with COS without modifying the Core Model.

Plugins enable COS to support different domains, environments, and processing capabilities while preserving protocol stability.

2. Definition

A Plugin is an optional capability provider that extends COS functionality through controlled integration points.

A Plugin MAY provide:

• new data capabilities
• new enrichment capabilities
• new adapters
• domain-specific processing logic

A Plugin MUST NOT modify the COS Core Model.

3. Core Principle

The Plugin System follows:

Stable Core, Extensible Capability

The Core Model remains fixed.

Plugins provide additional capabilities around the Core Model.

4. Plugin Relationship Model

The relationship between COS and Plugins:

Context Object
  ↑
Extension Data
  ↑
Plugin
  ↑
External Capability

A Plugin produces or enables additional capabilities that may enrich a Context Object.

5. Plugin Model

A Plugin MUST provide a unique identity.

interface Plugin {
  id: string;
  version: string;
  capabilities: string[];
}

6. Plugin Identity

Each Plugin MUST define:

interface PluginIdentity {
  id: string;
  version: string;
}

Requirements:

id MUST be globally unique within an ecosystem version MUST follow semantic versioning

Example:

pdf-plugin@1.0.0

7. Plugin Capabilities

Capabilities describe what a Plugin provides.

interface PluginCapability {
  name: string;
  version?: string;
}

Examples:

pdf.page
pdf.annotation
code.ast
browser.dom

8. Capability Principle

Plugins SHOULD expose capabilities instead of implementation details.

Consumers SHOULD depend on:

Capability

rather than:

Plugin Implementation

Example:

Preferred:

requires:
pdf.annotation

Not:

requires:
PdfPluginV2

9. Plugin Lifecycle

A Plugin follows the lifecycle:

Register
    ↓
Initialize
    ↓
Available
    ↓
Execute
    ↓
Dispose

10. Registration

Registration makes a Plugin known to the COS runtime.

Example:

register(plugin);

During registration:

The runtime SHOULD verify:

• identity
• version
• capabilities

11. Initialization

Initialization prepares Plugin runtime resources.

A Plugin MAY:

• load configuration
• initialize services
• register stages
• register adapters

A Plugin MUST NOT modify existing Context Objects during initialization.

12. Available State

A Plugin enters Available state when:

• registration succeeds
• initialization succeeds
• required capabilities are satisfied

Available Plugins MAY participate in:

• Pipeline execution
• Adapter processing
• Context enrichment

13. Execution Model

A Plugin MAY contribute execution units.

Examples:

PDF Plugin

provides:

PDF Extraction Stage
PDF Annotation Adapter

Plugin execution MUST follow COS Pipeline rules.

13.1 Plugin and Stage Registration

A Plugin MAY register one or more Pipeline Stages.

Each registered Stage MUST:

• declare a unique Stage identifier
• declare the Plugin identifier that provides it
• declare provided and required capabilities
• follow Pipeline Stage isolation rules

If a Plugin registers multiple Stages, each Stage MUST be independently traceable.

A Plugin MUST NOT silently replace a built-in Stage or another Plugin’s Stage.

When multiple registered Stages provide the same capability, the Runtime MUST resolve the provider through explicit configuration, capability negotiation, or deterministic priority rules.

14. Plugin Output

Plugin-generated information MUST be represented through existing COS extension mechanisms.

Example:

Plugin
    ↓
Extension Data
    ↓
Context Object

Plugins MUST NOT introduce alternative Context Object structures.

15. Core Model Protection

Plugins MUST NOT modify:

• Selection
• Document
• Hierarchy
• Semantic
• Recommendation
• Metadata

Direct modification of Core Model fields is invalid.

16. Plugin Isolation

Each Plugin MUST operate independently.

A Plugin failure MUST NOT invalidate:

• COS Core
• Other Plugins
• Existing Context Objects

17. Plugin Categories

COS does not require a fixed Plugin taxonomy.

However, implementations MAY define categories:

17.1 Adapter Plugin

Connects external systems.

Examples:

Browser Adapter
PDF Adapter
Editor Adapter

17.2 Enrichment Plugin

Adds contextual information.

Examples:

Semantic Analyzer
Code Analyzer
Vision Processor

17.3 Capability Plugin

Provides reusable domain capabilities.

Examples:

Search Capability
Knowledge Capability
Storage Capability

18. Plugin Discovery

Plugin discovery is implementation-specific.

Possible mechanisms:

• static registration
• package discovery
• runtime loading
• service registry

COS does not mandate a discovery mechanism.

19. Plugin Security Boundary

Implementations SHOULD isolate Plugin execution.

Isolation MAY include:

• permission control
• sandboxing
• resource limits

20. Relationship to Other Specifications

Plugin Specification defines the plugin foundation.

Related specifications:

400 Plugin Specification
        ↓
410 Adapter
        ↓
420 Compatibility

21. Summary

The Plugin System provides a controlled extension mechanism for COS.

Plugins add capabilities without modifying the Core Model.

Through identity, capability declaration, lifecycle management, and isolation rules, COS enables ecosystem growth while maintaining protocol stability.