Context Object Specification (COS)

Version: 0.2
Chapter: 220 — Document
Status: Informative — Supporting
Category: Core Model

1. Purpose

This chapter defines the abstract concept of a Document within the Context Object Specification (COS).

A Document represents the structural and logical container in which a Selection exists.

It provides the spatial, hierarchical, and semantic boundary for contextual interpretation.

2. Conceptual Role

A Document is the source environment of a Selection.

While Selection represents user intent, Document represents contextual space.

Without Document, a Selection has no meaningful interpretation.

3. Definition

A Document is a structured content container that provides:

structural hierarchy
logical segmentation
content continuity
reference boundaries for Selection

A Document is NOT a rendering artifact.

It is a logical representation of content space.

4. Document vs File vs Page

A Document MUST NOT be confused with physical or storage-level concepts.

Concept	Meaning
File	Storage unit (filesystem level)
Page	Rendering unit (visual layout)
Document	Logical content structure

A Document MAY be derived from files or pages, but is not equivalent to them.

5. Document Scope

In COS v0.2, a Document MAY originate from:

Web pages (HTML documents)
Markdown files
PDF documents
Rich text editors
Documentation systems

Future extensions MAY include:

database records
knowledge graphs
agent-generated content spaces

6. Relationship to Lean Core

In COS v0.2 lean core, Document is a supporting concept rather than a required top-level field.

Producer implementations MAY use an internal Document model to derive:

top-level source
context.segments
context.relations
stable segment identifiers

The emitted Context Object SHOULD NOT duplicate a full Document tree unless a Consumer explicitly needs it.

7. Document Structure (Conceptual Model)

When an implementation needs a Document model, it MAY use:

interface Document {
  id: string;
  type: DocumentType;
  title?: string;
  content: ContentNode;
  structure: DocumentStructure;
  metadata?: DocumentMetadata;
}

This definition is conceptual and independent of implementation.

8. Document Type

A Document MUST declare its type:

type DocumentType =
  | "webpage"
  | "pdf"
  | "markdown"
  | "editor"
  | "richtext";

Document type influences interpretation strategies in later Pipeline stages.

9. Content Model

A Document contains structured content represented as nodes.

interface ContentNode {
  type: string;
  text?: string;
  children?: ContentNode[];
}

This structure enables hierarchical traversal.

10. Document Structure

The Document structure represents logical organization.

It defines how content is organized into meaningful hierarchical units.

interface DocumentStructure {
  sections?: Section[];
  hierarchyDepth: number;
}

Structure is independent of visual layout.

10.1 Document Metadata

Definition

DocumentMetadata describes non-semantic information about a Document.

It does NOT describe content meaning.

It only describes origin, lifecycle, and system-level attributes.

Conceptual Model

interface DocumentMetadata {
  source: DocumentSource;
  createdAt?: number;
  updatedAt?: number;
  language?: string;
  version?: string;
}

Document Source

interface DocumentSource {
  type: "webpage" | "pdf" | "markdown" | "editor" | "unknown";
  uri?: string;
}

Constraints

DocumentMetadata MUST NOT contain:

semantic interpretation of content
structural hierarchy information
selection-related data
AI-generated reasoning

Motivation

Metadata exists to ensure:

traceability
reproducibility
system-level observability

It is strictly non-semantic.

11. Relationship to Selection

A Producer MAY maintain an internal Document model when the source has reusable logical structure. The emitted Selection is linked to its origin by the Context Object’s top-level source field and does not require a serialized Document.

Relationship:

Document
   │
   ├── contains
   ▼
Selection

A Selection without a Document is invalid within COS.

11.1 Selection Anchor References

A Document SHOULD expose stable logical content identifiers that can be referenced by Selection ranges and Hierarchy nodes.

These identifiers allow Consumers to locate the selected region from either direction:

from Selection to Document, through source.id and range node identifiers
from Document to Selection, through matching logical content node identifiers

The Document itself MUST NOT embed user Selection state.

Selection state belongs to the Context Object lifecycle, not to the source Document.

12. Document Immutability Principle

A Document SHOULD be treated as immutable during a Pipeline execution.

If modifications are required:

a new Document instance MUST be created
existing Selection references MUST remain valid

13. Document as Context Space

A Document defines the contextual boundary for interpretation.

It provides:

local meaning scope
hierarchical relationships
semantic grouping

Without Document, semantic inference becomes undefined.

14. Document vs Context Object

It is critical to distinguish:

Entity	Role
Document	Source space
Selection	Input signal
Context Object	Enriched result

Flow:

Document → Selection → Context Object

15. Implementation Independence

A Document is NOT tied to any specific format:

HTML DOM is NOT required
File system structure is NOT required
Rendering engine is NOT required

Any system capable of representing hierarchical content MAY implement a Document.

16. Example (Informative)

{
  "id": "doc-123",
  "type": "markdown",
  "title": "React Hooks Guide",
  "content": {
    "type": "root",
    "children": [
      {
        "type": "paragraph",
        "text": "useEffect is a React Hook..."
      }
    ]
  },
  "structure": {
    "hierarchyDepth": 3
  },
  "metadata": {
    "author": "example"
  }
}

17. Design Notes (Informative)

Document is intentionally defined in a minimal form.

The goal is not to replicate DOM or file systems.

Instead, it defines a portable semantic container that can be adapted across environments.

18. Summary

A Document is the logical content space in which a Selection exists.

It provides structural and semantic boundaries necessary for contextual interpretation.

Within the Context Object Specification, Document is the foundational spatial abstraction that enables meaningful enrichment in later pipeline stages.