v1.1.0 • Production Ready • FCS-2.0 Enhanced

Contextual Ads Protocol v1.1

Machine-readable specification for agent-aware, intention-aligned advertising with FCS-2.0 trust metadata

Download Specification

Get the complete JSON Schema specification for implementation and validation:

Download JSON Schema View Raw Schema Back to Homepage

Overview

The Contextual Ads Protocol v1.1 is a comprehensive specification for privacy-preserving, agent-native advertising. It defines how advertisements can emerge organically from user-initiated contexts while maintaining verifiable trust through FCS-2.0 (Forward Commerce Signals) metadata.

Key Principle: Advertisements that emerge organically from user-initiated contexts, aligning with latent intent rather than imposing external prompts.

Core Features

FCS-2.0 Integration

Complete ad lineage tracking with cryptographic signatures (ed25519, ecdsa-p256, rsa-2048) and verifiable provenance chains.

Contextual Seeds

Three-tier semantic compression: Termline (24 tokens), Backbone (100 tokens), Field (374 tokens) for adaptive expansion.

Compliance Metadata

Built-in support for GDPR, EU AI Act, DMA, SOC-2, and PCAOB regulatory requirements.

Trust Verification

Claims verification, regional compliance tracking, and audit provider attribution for transparency.

Schema Structure

Property	Type	Description
@context	string	Protocol namespace identifier
@type	string	Type identifier (ContextualAdFeed)
publisher	object	Publisher/sponsor metadata with trust lineage
offers	array	Array of contextual ad offers
metadata	object	Feed-level metadata (update frequency, semantic density)

Offer Object Schema

Required Properties

id - Unique offer identifier
product - Product information (name, category, URL)
contextualSeeds - Termline, backbone, and field seeds
verification - Claims verification and compliance metadata

Optional Enhancements

fcsAdLineage - FCS-2.0 trust verification metadata
complianceMetadata - Regulatory compliance flags
bidMetadata - Programmatic auction information
analytics - Privacy-preserving tracking endpoints

FCS-2.0 Ad Lineage

The FCS-2.0 ad lineage system provides complete chain-of-custody tracking for advertisements:

{
  "fcsAdLineage": {
    "seedId": "OFFER-ID-001",
    "campaignId": "campaign-q4-2025",
    "creativeHash": "sha256:9ac4a1e6f3b2c7d8...",
    "signedBy": "contextual-ads.ai",
    "signature": "ed25519:a1b2c3d4e5f6...",
    "verifyUrl": "https://contextual-ads.ai/fcs/verify/OFFER-ID-001",
    "timestamp": "2025-12-24T00:00:00Z",
    "lineageChain": [
      {
        "actor": "contextual-ads.ai",
        "action": "seed-generation",
        "timestamp": "2025-12-24T00:00:00Z",
        "signature": "ed25519:abc123..."
      }
    ]
  }
}

Compliance & Regulatory

Supported Compliance Frameworks

GDPR Article 22: Transparency for automated decision-making
EU AI Act Article 52: Transparency requirement for AI-generated content
DMA Articles 5-6: Gatekeeper transparency and data portability
SOC-2: Audit trail compliance for enterprise trust
PCAOB: Compliance for financial services advertising

Disclosure Modes

Four standard disclosure modes for sponsorship transparency:

inline - Disclosure embedded in ad content
adjacent - Disclosure next to ad placement
embedded - Disclosure within metadata
overlay - Disclosure shown on interaction

Implementation Resources

JSON Schema Validation

The specification uses JSON Schema Draft-07 for validation. Validate your ad feeds using:

Schema URL: https://contextual-ads.ai/spec/v1.1/schema.json
Schema ID: https://contextual-ads.ai/spec/v1.1/schema.json

Example Implementation

A complete example is included in the JSON Schema. Download the schema to see a full working example of a contextual ad feed.

Quick Start

1. Download the Schema

curl -O https://contextual-ads.ai/spec/v1.1/schema.json

2. Validate Your Feed

Use any JSON Schema validator to check your ad feed against the specification.

3. Implement FCS-2.0 Headers

Add trust verification headers to your HTTP responses:

X-FCS-Version: 2.0
X-Trust-Lineage: contextual-ads.ai:semantic-match:2025-12-24T00:00:00Z
X-FCS-Ad-Lineage: seedId=OFFER-001;signature=ed25519:...