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FORA Protocol

Scenario Walkthrough

Definitive walkthrough of FORA v1.0 as of March 2026. Every field name, signature algorithm, and endpoint matches the current fora.proto.

Scenario

Section titled “Scenario”

Agent: Anthropic’s Claude (claude.ai), running the FORA Agent SDK Broker: Anthropic’s hosted Broker (broker.anthropic.com) Subscription: Anthropic has an annual deal with Hearst Media via SSP-Alpha exchange Request: Claude needs an article about AI regulation originally published by Hearst’s TechCrunch (techcrunch.com), syndicated to The Verge (theverge.com) via SSP-Beta exchange Extension Profiles: Both Exchanges declare supported_profiles: ["fora-news-v1"] in their manifests. The Broker forwards supported_profiles from the agent to enable profile-aware metadata in offers (e.g., news.iptc_guid, news.correction_status).

Phase 0: Provider Setup

Section titled “Phase 0: Provider Setup”

Before any agent request, providers configure their domains and Exchanges ingest content into catalogs.

0a. Hearst (TechCrunch) — RSL + fora.json

Section titled “0a. Hearst (TechCrunch) — RSL + fora.json”

rsl.txt — declares licensing terms and a maximum rate (price ceiling):

<!-- https://techcrunch.com/rsl.txt -->
<content url="/premium/*">
  <permits type="usage">ai-input ai-index search</permits>
  <prohibits type="usage">ai-train</prohibits>
  <payment type="crawl" currency="USD" amount="0.08"/>
  <!-- RSL amount is the MAXIMUM (price ceiling). Exchange may offer at or below. -->
</content>

fora.json — declares which Exchange is authorized to transact:

// GET https://techcrunch.com/.well-known/fora.json
{
  "ver": "1.0",
  "provider": "techcrunch.com",
  "contact": "licensing@hearst.com",
  "exchanges": [
    {
      "domain": "exchange.ssp-alpha.com",
      "endpoint": "https://exchange.ssp-alpha.com/fora/v1",
      "relationship": "PROVIDER_RELATIONSHIP_DIRECT"
    }
  ]
}

Edge function — deployed on Hearst’s CDN (Cloudflare/Fastly/Lambda@Edge). Blocks unauthorized AI bots with 403 + X-Content-Rules header pointing to the Exchange. Verifies Ed25519 signed URLs for authorized requests, using the Exchange’s published public key.

0b. Agent Key Announcement

Section titled “0b. Agent Key Announcement”

Anthropic publishes its agent’s Ed25519 public key in its WBA directory (the JWK Set at /.well-known/http-message-signatures-directory):

// GET https://claude.ai/.well-known/http-message-signatures-directory
// Content-Type: application/jwk-set+json
{
  "keys": [
    {
      "kty": "OKP",
      "crv": "Ed25519",
      "use": "sig",
      "alg": "EdDSA",
      "x": "7Hd8FjXz9K2qR4nPbY1sT0vWxU3gLmN5oA8pC6dE1fI",
      "not_before": "2026-01-01T00:00:00Z",
      "not_after": "2026-12-31T23:59:59Z"
    }
  ],
  "revocation_url": "https://claude.ai/.well-known/fora-invalidations.json"
}

The fora.json manifest still declares the role and contact, but the keys live in the WBA directory:

// GET https://claude.ai/.well-known/fora.json
{
  "ver": "1.0",
  "role": "ROLE_AGENT",
  "domain": "claude.ai",
  "contact": "legal@anthropic.com"
}

The Broker announces its key in its own WBA directory the same way:

// GET https://broker.anthropic.com/.well-known/http-message-signatures-directory
// Content-Type: application/jwk-set+json
{
  "keys": [
    {
      "kty": "OKP",
      "crv": "Ed25519",
      "use": "sig",
      "alg": "EdDSA",
      "x": "qW3rT8mNxVzP7sK1dL0yUoJ5bG2hF4iE6cA9nR3wS8g",
      "not_before": "2026-01-01T00:00:00Z",
      "not_after": "2026-12-31T23:59:59Z"
    }
  ],
  "revocation_url": "https://broker.anthropic.com/.well-known/fora-invalidations.json"
}

0c. SSP-Alpha Resource Ingestion

Section titled “0c. SSP-Alpha Resource Ingestion”

SSP-Alpha’s Resource Ingestion Pipeline runs in the background:

1. Crawl techcrunch.com/sitemap.xml -> discover all /premium/* URLs
2. Fetch rsl.txt -> extract permits/prohibits and RSL pricing ceiling ($0.08/crawl)
3. HTML crawl via readability -> extract text -> word count -> estimate tokens
4. Apply Hearst's private pricing (from SSP-Alpha config DB): $0.05/article
   (Below the RSL ceiling of $0.08 — compliant)
5. Third-party attestation (GumGum via CatalogService.PushResources):
   GumGum crawls the article, signs attestation claims with Ed25519:
   { verifier: "gumgum.com", claims: { estimated_quantity: 3300, word_count: 2500,
     language: "en", iab_categories: ["IAB19-6"] }, signature: "..." }
   Exchange validates: gumgum.com is in techcrunch.com's catalog_contributors,
   verifies signature against the key in gumgum.com's WBA directory
   (the JWK Set at gumgum.com/.well-known/http-message-signatures-directory),
   selected by the attestation's keyid (RFC 7638 thumbprint)
6. Build catalog entry:
   {
     domain: "techcrunch.com",
     path: "/premium/ai-regulation-2026.html",
     title: "AI Regulation: What Providers Need to Know",
     word_count: 2500,
     estimated_quantity: 3300,
     pricing: { model: PRICING_MODEL_PER_UNIT, rate: "0.05", currency: "USD", unit: "accesses", unit_cost: "0.00001515" },
     identity: {
       canonical_url: "https://techcrunch.com/premium/ai-regulation-2026.html",
       iptc_guid: "urn:newsml:techcrunch:20260315:ai-reg-001",
       content_hash: "a1b2c3d4e5f6...",
       hash_method: "simhash-v1",
       resource_mutability: RESOURCE_MUTABILITY_STATIC
     },
     attestations: [
       { verifier: "gumgum.com", keyid: "kPrK_qmxVWaYVA9wwBF6Iuo3vVzz7TxHCTwXBygrS4k",
         attested_at: "2026-03-14T09:00:00Z",
         uri: "https://techcrunch.com/premium/ai-regulation-2026.html",
         claims: { estimated_quantity: 3300, word_count: 2500, language: "en" },
         signature: "base64-ed25519-gumgum..." }
     ],
     terms: [
       { semantics: TERM_SEMANTICS_ENUMERATED,
         pricing: { model: PRICING_MODEL_PER_UNIT, rate: "0.05", currency: "USD", unit: "accesses" },
         restrictions: [
           { kind: RESTRICTION_KIND_FUNCTION,
             permitted: ["ai-input", "ai-index", "search"],
             prohibited: ["ai-train"] }
         ] }
     ]
   }
7. Compile into radix trie -> serialize to catalog.bin -> Exchange loads via atomic pointer swap

SSP-Alpha also knows about Anthropic’s subscription, looked up by Anthropic’s account handle (minted at registration):

BillingAdapter.CheckSubscription("acct_7f3e21c9", "hearst-media")
  -> { subscription_id: "SUB-ANTHROPIC-HEARST-2026", active: true, quota_remaining: 850000 }

0d. The Verge Syndication via SSP-Beta

Section titled “0d. The Verge Syndication via SSP-Beta”
1. The Verge reprinted the TechCrunch article (syndication deal):
   theverge.com/premium/ai-regulation-republish.html


2. The Verge has fora.json pointing to SSP-Beta:
   {
     "ver": "1.0",
     "provider": "theverge.com",
     "exchanges": [{
       "domain": "exchange.ssp-beta.com",
       "endpoint": "https://exchange.ssp-beta.com/fora/v1",
       "relationship": "PROVIDER_RELATIONSHIP_DIRECT"
     }]
   }


3. SSP-Beta's ingestion pipeline:
   - Discovers the article, estimates 3100 tokens
   - The Verge's pricing: $0.07/article (higher than TechCrunch, below RSL ceiling)
   - Identity: same iptc_guid (syndicated from same TechCrunch wire)
     {
       canonical_url: "https://theverge.com/premium/ai-regulation-republish.html",
       iptc_guid: "urn:newsml:techcrunch:20260315:ai-reg-001",
       content_hash: "a1b2c3d4e5f7...",
       hash_method: "simhash-v1",
       resource_mutability: RESOURCE_MUTABILITY_STATIC
     }
   - Attestations: [{ verifier: "gumgum.com", claims: { estimated_quantity: 3100, word_count: 2350 } }]
   - Anthropic has NO subscription with SSP-Beta

Phase 1: Agent Request (SDK with Ed25519 Signing)

Section titled “Phase 1: Agent Request (SDK with Ed25519 Signing)”

Claude is answering a user question about AI regulation. The SDK triggers:

results, err := client.FetchBatch(ctx, []string{
    "https://techcrunch.com/premium/ai-regulation-2026.html",
})

Inside the SDK:

Step 1: Parse domain -> "techcrunch.com"


Step 2: ExchangeRegistry lookup
  - Cache miss for techcrunch.com
  - Background: fetch https://techcrunch.com/.well-known/fora.json
  - Discovers: exchange.ssp-alpha.com is authorized (PROVIDER_RELATIONSHIP_DIRECT)
  - Caches: techcrunch.com -> [ssp-alpha]


Step 3: Prepare RFC 9421 HTTP Message Signature (alg=ed25519)
  - requester.id = "claude-agent-001"
  - requester.domain = "claude.ai"
  - Sign the HTTP request per RFC 9421: the SDK adds Signature and
    Signature-Input headers covering the request method, path, and body digest
  - Authentication is asymmetric:
    the agent signs with its Ed25519 private key (never leaves the agent),
    the Exchange verifies with the public key fetched from the WBA
    directory at claude.ai/.well-known/http-message-signatures-directory

Key insight: The SDK discovers Exchanges from the provider’s fora.json. It only finds the authorized Exchange for THAT domain. Cross-provider discovery (same article on different domains) requires either a hosted Broker that has crawled multiple providers’ fora.json, or the agent explicitly requesting multiple URLs across providers.

Phase 2: Supply Discovery (Requester Identity, Subscription Detection, Content Attestations, Ed25519 Verification)

Section titled “Phase 2: Supply Discovery (Requester Identity, Subscription Detection, Content Attestations, Ed25519 Verification)”

The SDK sends DiscoverResources to SSP-Alpha — POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/DiscoverResources:

{
  "ver": "1.0",
  "exchange": "exchange.ssp-alpha.com",
  "requester": {
    "id": "claude-agent-001",
    "domain": "claude.ai",
    "type": "REQUESTER_TYPE_AGENT",
    "scopes": ["*"]
  },
  "uris": ["https://techcrunch.com/premium/ai-regulation-2026.html"],
  "acceptable_restrictions": [{ "axis": "RESTRICTION_KIND_FUNCTION", "values": ["ai-input"] }],
  "deadline": "0.5s"
}

Inside SSP-Alpha’s Exchange

Section titled “Inside SSP-Alpha’s Exchange”
1. Validate request (proto validation) -> pass
2. Verify the RFC 9421 HTTP Message Signature (alg=ed25519) on the request:
   a. Read the covered Signature-Agent header -> "claude.ai"
   b. Fetch the WBA directory at
      claude.ai/.well-known/http-message-signatures-directory,
      select the key whose RFC 7638 thumbprint matches the keyid
   c. Verify the signature against public key -> pass
3. Resolve tenant: techcrunch.com -> Hearst Media tenant
4. Find offers: lookup "/premium/ai-regulation-2026.html" in radix trie -> match
5. Check subscription with quota (the account handle is resolved from the
   requester's VERIFIED IDENTITY from step 2 — requester.id + domain, via the
   RFC 9421 signature — never from the request body):
   BillingAdapter.CheckSubscription("acct_7f3e21c9", "hearst-media")
     -> { subscription_id: "SUB-ANTHROPIC-HEARST-2026",
          active: true,
          quota_remaining: 850000 }
   850000 > 3300 estimated tokens -> quota sufficient
6. Build TWO offers:


   Offer A (per-request):
     offer_id: "2325749d-50d3-431a-ac34-900d443ee88e"
     pricing: { model: PRICING_MODEL_PER_UNIT, rate: "0.05", currency: "USD",
                unit: "accesses", unit_cost: "0.00001515", estimated_quantity: 3300 }
     identity: { canonical_url: "https://techcrunch.com/premium/ai-regulation-2026.html",
                 iptc_guid: "urn:newsml:techcrunch:20260315:ai-reg-001",
                 content_hash: "a1b2c3d4e5f6...", hash_method: "simhash-v1" }
     attestations: [
       { verifier: "gumgum.com", keyid: "kPrK_qmxVWaYVA9wwBF6Iuo3vVzz7TxHCTwXBygrS4k",
         claims: { estimated_quantity: 3300, word_count: 2500, language: "en" },
         signature: "base64-ed25519-gumgum..." }
     ]
     terms: [
       { semantics: TERM_SEMANTICS_ENUMERATED,
         pricing: { model: PRICING_MODEL_PER_UNIT, rate: "0.05", currency: "USD", unit: "accesses" },
         restrictions: [
           { kind: RESTRICTION_KIND_FUNCTION,
             permitted: ["ai-input", "ai-index", "search"],
             prohibited: ["ai-train"] }
         ] }
     ]
     delivery_method: DELIVERY_METHOD_INSTRUCTIONS
     signature: "<hex-encoded detached Ed25519 signature over the entire canonical Offer — every field, incl. terms, pricing, expires_at>"
     signature_algorithm: "EdDSA"


   Offer B (subscription):
     offer_id: "4f155204-a53e-42aa-8471-154f87d7d3d5"
     pricing: { model: PRICING_MODEL_FREE, rate: "0", currency: "USD",
                unit_cost: "0", estimated_quantity: 3300 }
     subscription_id: "SUB-ANTHROPIC-HEARST-2026"
     identity: { same as Offer A }
     attestations: { same as Offer A }
     terms: [
       { semantics: TERM_SEMANTICS_ENUMERATED,
         pricing: { model: PRICING_MODEL_FREE, rate: "0", currency: "USD" },
         restrictions: [ same as Offer A ],
         scopes: ["subscription:SUB-ANTHROPIC-HEARST-2026"] }
     ]
     delivery_method: DELIVERY_METHOD_INSTRUCTIONS
     reporting: { required: true, window: "86400s",
                  required_fields: ["transaction_id", "function", "consumed_quantity"] }
     signature: "<hex-encoded detached Ed25519 signature over the entire canonical Offer — every field, incl. terms, pricing, expires_at>"
     signature_algorithm: "EdDSA"

Response

Section titled “Response”
{
  "ver": "1.0",
  "exchange": "exchange.ssp-alpha.com",
  "offers": [
    {
      "offer_id": "2325749d-50d3-431a-ac34-900d443ee88e",
      "exchange": "exchange.ssp-alpha.com",
      "title": "AI Regulation: What Providers Need to Know",
      "pricing": {
        "model": "PRICING_MODEL_PER_UNIT",
        "rate": "0.05",
        "currency": "USD",
        "unit": "accesses",
        "unit_cost": "0.00001515",
        "estimated_quantity": 3300
      },
      "delivery_method": "DELIVERY_METHOD_INSTRUCTIONS",
      "identity": {
        "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html",
        "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001",
        "content_hash": "a1b2c3d4e5f6...",
        "hash_method": "simhash-v1"
      },
      "attestations": [
        {
          "verifier": "gumgum.com",
          "keyid": "kPrK_qmxVWaYVA9wwBF6Iuo3vVzz7TxHCTwXBygrS4k",
          "attested_at": "2026-03-14T09:00:00Z",
          "uri": "https://techcrunch.com/premium/ai-regulation-2026.html",
          "claims": { "estimated_quantity": 3300, "word_count": 2500, "language": "en" },
          "signature": "base64-ed25519-gumgum..."
        }
      ],
      "terms": [
        {
          "semantics": "TERM_SEMANTICS_ENUMERATED",
          "restrictions": [
            {
              "kind": "RESTRICTION_KIND_FUNCTION",
              "permitted": ["ai-input", "ai-index", "search"],
              "prohibited": ["ai-train"]
            }
          ]
        }
      ],
      "signature": "base64-ed25519-sig-A...",
      "signature_algorithm": "EdDSA"
    },
    {
      "offer_id": "4f155204-a53e-42aa-8471-154f87d7d3d5",
      "exchange": "exchange.ssp-alpha.com",
      "title": "AI Regulation: What Providers Need to Know",
      "pricing": {
        "model": "PRICING_MODEL_FREE",
        "rate": "0",
        "currency": "USD",
        "unit_cost": "0",
        "estimated_quantity": 3300
      },
      "delivery_method": "DELIVERY_METHOD_INSTRUCTIONS",
      "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
      "reporting": {
        "required": true,
        "window": "86400s",
        "required_fields": ["transaction_id", "function", "consumed_quantity"]
      },
      "identity": {
        "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html",
        "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001",
        "content_hash": "a1b2c3d4e5f6...",
        "hash_method": "simhash-v1"
      },
      "attestations": [
        {
          "verifier": "gumgum.com",
          "keyid": "kPrK_qmxVWaYVA9wwBF6Iuo3vVzz7TxHCTwXBygrS4k",
          "attested_at": "2026-03-14T09:00:00Z",
          "uri": "https://techcrunch.com/premium/ai-regulation-2026.html",
          "claims": { "estimated_quantity": 3300, "word_count": 2500, "language": "en" },
          "signature": "base64-ed25519-gumgum..."
        }
      ],
      "terms": [
        {
          "semantics": "TERM_SEMANTICS_ENUMERATED",
          "restrictions": [
            {
              "kind": "RESTRICTION_KIND_FUNCTION",
              "permitted": ["ai-input", "ai-index", "search"],
              "prohibited": ["ai-train"]
            }
          ],
          "scopes": ["subscription:SUB-ANTHROPIC-HEARST-2026"]
        }
      ],
      "signature": "base64-ed25519-sig-B...",
      "signature_algorithm": "EdDSA"
    }
  ]
}

Phase 2b: Cross-Provider via Broker (Header Signature Chain, OfferGroups, SimHash)

Section titled “Phase 2b: Cross-Provider via Broker (Header Signature Chain, OfferGroups, SimHash)”

If Anthropic uses its hosted Broker instead of the SDK directly, the Broker provides cross-provider intelligence. The agent sends a DiscoveryRequest to the Broker with multiple URIs (BrokerService.Resolve is discovery-only — it returns offers grouped by URI; execution happens later via a separate ExecuteTransaction call). Agent → Broker:

{
  "ver": "1.0",
  "requester": {
    "id": "claude-agent-001",
    "domain": "claude.ai",
    "type": "REQUESTER_TYPE_AGENT",
    "scopes": ["*"]
  },
  "uris": [
    "https://techcrunch.com/premium/ai-regulation-2026.html",
    "https://theverge.com/premium/ai-regulation-republish.html"
  ],
  "acceptable_restrictions": [{ "axis": "RESTRICTION_KIND_FUNCTION", "values": ["ai-input"] }],
  "constraints": {
    "preferred_exchanges": ["exchange.ssp-alpha.com"],
    "max_unit_cost": "0.00005",
    "reporting_capable": true,
    "budget_scope": "team:claude-rag",
    "period_budget": { "amount": "500.00", "currency": "USD" },
    "budget_period": "2592000s"
  }
}

Broker Fans Out with a Header Signature Chain

Section titled “Broker Fans Out with a Header Signature Chain”

The Broker queries both Exchanges. For each forwarded request, the Broker:

  1. Preserves the agent’s original requester message
  2. Preserves the agent’s RFC 9421 HTTP Message Signature (its labeled signature stays in the Signature/Signature-Input headers)
  3. Adds its own labeled RFC 9421 HTTP Message Signature, covering the request plus the agent’s prior signature (the ordered set of header signatures is the chain that proves the Broker forwarded it)

Broker → SSP-Alpha (multi-URI batch query) — POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/DiscoverResources:

{
  "ver": "1.0",
  "exchange": "exchange.ssp-alpha.com",
  "requester": {
    "id": "claude-agent-001",
    "domain": "claude.ai",
    "type": "REQUESTER_TYPE_AGENT",
    "scopes": ["*"]
  },
  "uris": [
    "https://techcrunch.com/premium/ai-regulation-2026.html",
    "https://theverge.com/premium/ai-regulation-republish.html"
  ],
  "acceptable_restrictions": [{ "axis": "RESTRICTION_KIND_FUNCTION", "values": ["ai-input"] }],
  "deadline": "0.4s"
}

The forwarding chain travels in the HTTP headers, not the request body: the agent’s labeled RFC 9421 signature and the Broker’s labeled RFC 9421 signature both sit in the Signature/Signature-Input headers. The agent’s signature covers @target-uri against the Exchange’s endpoint — the final recipient — not the Broker’s relay URL. SSP-Alpha’s Exchange verifies the full stack:

  1. The agent’s RFC 9421 HTTP Message Signature (alg=ed25519) — fetch public key from the WBA directory at claude.ai/.well-known/http-message-signatures-directory, Ed25519 verify
  2. Each forwarding hop’s labeled RFC 9421 HTTP Message Signature — for each one, look up the public key by its keyid thumbprint in the key set the Exchange is configured with (Signature-Agent stays the agent’s directory, so a hop’s key is not discovered through it), Ed25519 verify (each hop signs the request plus the prior hop’s signature)

SSP-Alpha returns offer_groups (batch mode — multiple URIs in query):

{
  "ver": "1.0",
  "exchange": "exchange.ssp-alpha.com",
  "offer_groups": [
    {
      "uri": "https://techcrunch.com/premium/ai-regulation-2026.html",
      "offers": [
        {
          "offer_id": "2325749d-50d3-431a-ac34-900d443ee88e",
          "exchange": "exchange.ssp-alpha.com",
          "pricing": { "model": "PRICING_MODEL_PER_UNIT", "rate": "0.05", "currency": "USD", "unit": "accesses", "unit_cost": "0.00001515", "estimated_quantity": 3300 },
          "identity": { "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html", "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001", "content_hash": "a1b2c3d4e5f6...", "hash_method": "simhash-v1" },
          "attestations": [{ "verifier": "gumgum.com", "claims": { "estimated_quantity": 3300, "word_count": 2500 }, "signature": "..." }],
          "signature": "base64-ed25519-sig-A...",
          "signature_algorithm": "EdDSA"
        },
        {
          "offer_id": "4f155204-a53e-42aa-8471-154f87d7d3d5",
          "exchange": "exchange.ssp-alpha.com",
          "pricing": { "model": "PRICING_MODEL_FREE", "rate": "0", "currency": "USD", "unit_cost": "0", "estimated_quantity": 3300 },
          "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
          "identity": { "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html", "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001", "content_hash": "a1b2c3d4e5f6...", "hash_method": "simhash-v1" },
          "attestations": [{ "verifier": "gumgum.com", "claims": { "estimated_quantity": 3300, "word_count": 2500 }, "signature": "..." }],
          "reporting": { "required": true, "window": "86400s", "required_fields": ["transaction_id", "function", "consumed_quantity"] },
          "signature": "base64-ed25519-sig-B...",
          "signature_algorithm": "EdDSA"
        }
      ]
    },
    {
      "uri": "https://theverge.com/premium/ai-regulation-republish.html",
      "offers": [],
      "absence_reason": "OFFER_ABSENCE_REASON_NOT_IN_CATALOG"
    }
  ]
}

Note: SSP-Alpha returns an empty offers array for the theverge.com URI with absence_reason: NOT_IN_CATALOG because The Verge is not an SSP-Alpha tenant. This v1.0 diagnostic lets the Broker distinguish “not in catalog” from “resource blocked for your use case.” The Broker also queries SSP-Beta:

// SSP-Beta returns (single-URI, flat offers):
{
  "ver": "1.0",
  "exchange": "exchange.ssp-beta.com",
  "offers": [
    {
      "offer_id": "ecb6fef4-1d83-4751-ab92-b3bc7c2fee39",
      "exchange": "exchange.ssp-beta.com",
      "pricing": { "model": "PRICING_MODEL_PER_UNIT", "rate": "0.07", "currency": "USD", "unit": "accesses", "unit_cost": "0.00002258", "estimated_quantity": 3100 },
      "identity": {
        "canonical_url": "https://theverge.com/premium/ai-regulation-republish.html",
        "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001",
        "content_hash": "a1b2c3d4e5f7...",
        "hash_method": "simhash-v1"
      },
      "attestations": [{ "verifier": "gumgum.com", "claims": { "estimated_quantity": 3100, "word_count": 2350 }, "signature": "..." }],
      "signature": "base64-ed25519-sig-C...",
      "signature_algorithm": "EdDSA"
    }
  ]
}

Content Deduplication: IPTC GUID + SimHash Fallback

Section titled “Content Deduplication: IPTC GUID + SimHash Fallback”

The Broker groups offers by content identity:

Step 1: Group by iptc_guid
  - iptc_guid "urn:newsml:techcrunch:20260315:ai-reg-001" matches across all 3 offers
  - These are ALL the same underlying article (TechCrunch original, syndicated to The Verge)


Step 2: SimHash cross-check (for non-news content without IPTC guids)
  - SSP-Alpha hash: "a1b2c3d4e5f6..." (simhash-v1)
  - SSP-Beta hash:  "a1b2c3d4e5f7..." (simhash-v1)
  - Hamming distance = 1 bit -> substantially similar (threshold < 3 bits)
  - For 99% of web content that lacks IPTC guids, SimHash is the primary dedup signal.
    The Exchange computes SimHash during ingestion from extracted article text.
    The Broker groups by SimHash similarity (Hamming distance).
    This is approximate but catches obvious syndication and republication.

Broker Selection Engine

Section titled “Broker Selection Engine”
Step 3: Rank within content group
  Priority order:
  a) Subscription from preferred exchange
     -> 4f155204-a53e-42aa-8471-154f87d7d3d5 ($0, SSP-Alpha, attested by gumgum.com) <- WINNER
  b) Subscription from any exchange
     -> none
  c) Per-request from preferred exchange (rank by attestation trust, then unit_cost)
     -> 2325749d-50d3-431a-ac34-900d443ee88e ($0.05, SSP-Alpha, attested by gumgum.com)
  d) Per-request by unit_cost (all exchanges)
     -> ecb6fef4-1d83-4751-ab92-b3bc7c2fee39 ($0.07, SSP-Beta, attested by gumgum.com)


  Note: attestation claims enable selection beyond cheapest price.
  Offers with third-party attestations (Level 2) are preferred over
  self-attested (Level 1) or unattested (Level 0) content.


  Selected: 4f155204-a53e-42aa-8471-154f87d7d3d5 (subscription, zero marginal cost, third-party attested)


Step 4: Budget check
  - Subscription offer: cost = $0 -> always within budget
  - Cumulative spend for scope "team:claude-rag": $142.50 of $500.00 period budget
  - Proceed

Phase 3: Transaction (Requester + Header Signature Chain, Subscription Skip, Quota Check)

Section titled “Phase 3: Transaction (Requester + Header Signature Chain, Subscription Skip, Quota Check)”

SDK or Broker commits to the subscription offer.

Direct (SDK) request — single signature in the headers:

Section titled “Direct (SDK) request — single signature in the headers:”

POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/ExecuteTransaction

{
  "ver": "1.0",
  "idempotency_key": "tx-claude-001",
  "requester": {
    "id": "claude-agent-001",
    "domain": "claude.ai",
    "type": "REQUESTER_TYPE_AGENT",
    "scopes": ["*"]
  },
  "items": [
    {
      "offer": {
        "offer_id": "4f155204-a53e-42aa-8471-154f87d7d3d5",
        "exchange": "exchange.ssp-alpha.com",
        "title": "AI Regulation: What Providers Need to Know",
        "pricing": {
          "model": "PRICING_MODEL_FREE",
          "rate": "0",
          "currency": "USD",
          "unit_cost": "0",
          "estimated_quantity": 3300
        },
        "delivery_method": "DELIVERY_METHOD_INSTRUCTIONS",
        "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
        "expires_at": "2026-03-15T14:00:00Z",
        "identity": {
          "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html",
          "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001",
          "content_hash": "a1b2c3d4e5f6...",
          "hash_method": "simhash-v1",
          "resource_mutability": "RESOURCE_MUTABILITY_STATIC"
        },
        "signature": "base64-ed25519-sig-B...",
        "signature_algorithm": "EdDSA"
      },
      "agent_acceptance": {
        "signature": "base64-ed25519-acceptance-sig...",
        "signature_algorithm": "EdDSA"
      }
    }
  ]
}

Orchestrated request — forwarding chain in the headers:

Section titled “Orchestrated request — forwarding chain in the headers:”

POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/ExecuteTransaction

{
  "ver": "1.0",
  "idempotency_key": "tx-claude-001",
  "requester": {
    "id": "claude-agent-001",
    "domain": "claude.ai",
    "type": "REQUESTER_TYPE_AGENT",
    "scopes": ["*"]
  },
  "items": [
    {
      "offer": {
        "offer_id": "4f155204-a53e-42aa-8471-154f87d7d3d5",
        "exchange": "exchange.ssp-alpha.com",
        "title": "AI Regulation: What Providers Need to Know",
        "pricing": {
          "model": "PRICING_MODEL_FREE",
          "rate": "0",
          "currency": "USD",
          "unit_cost": "0",
          "estimated_quantity": 3300
        },
        "delivery_method": "DELIVERY_METHOD_INSTRUCTIONS",
        "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
        "expires_at": "2026-03-15T14:00:00Z",
        "identity": {
          "canonical_url": "https://techcrunch.com/premium/ai-regulation-2026.html",
          "iptc_guid": "urn:newsml:techcrunch:20260315:ai-reg-001",
          "content_hash": "a1b2c3d4e5f6...",
          "hash_method": "simhash-v1",
          "resource_mutability": "RESOURCE_MUTABILITY_STATIC"
        },
        "signature": "base64-ed25519-sig-B...",
        "signature_algorithm": "EdDSA"
      },
      "agent_acceptance": {
        "signature": "base64-ed25519-acceptance-sig...",
        "signature_algorithm": "EdDSA"
      }
    }
  ]
}

The request body is identical to the direct case; the forwarding chain lives in the HTTP headers. The Broker preserves the agent’s labeled RFC 9421 signature and adds its own labeled RFC 9421 signature (covering the request plus the agent’s signature) to the Signature/Signature-Input headers. The Exchange verifies both: the agent’s identity (via the agent’s RFC 9421 HTTP Message Signature, alg=ed25519, + public key fetched from the agent’s WBA directory at claude.ai/.well-known/http-message-signatures-directory) and each forwarding hop (via that hop’s labeled RFC 9421 signature + the hop’s public key, selected by its keyid thumbprint from the key set the Exchange is configured with).

Inside SSP-Alpha’s Exchange

Section titled “Inside SSP-Alpha’s Exchange”
1. Validate request (proto validation) -> pass
2. Verify the RFC 9421 HTTP Message Signature (alg=ed25519) on the request:
   - Fetch public key from the WBA directory at
     claude.ai/.well-known/http-message-signatures-directory
     (domain from the covered Signature-Agent header, key by keyid thumbprint)
   - Ed25519 verify -> pass
2b. Verify forwarding signature chain (if any forwarding hops added labeled signatures):
   - For each hop's labeled RFC 9421 signature: look up the public key by its
     keyid thumbprint in the Exchange's configured key set (Signature-Agent
     stays the agent's directory)
   - Ed25519 verify each hop's signature -> pass
2c. Verify `agent_request_acceptance` when the request carries it (this example
   omits the optional field): Ed25519 verify the signed request set against the
   requester's published agent key, then require this request's items to be the
   complete in-order projection addressed to this Exchange. This runs before
   the idempotency check — see
   [Projected execute requests](/protocol/authentication/#projected-execute-requests)
3. Check idempotency: tx-claude-001 not seen before -> proceed
4. Verify offer signature:
   - Ed25519 verify exchange_signature on offer -> pass
   - Reconstruct offer data from signed token (stateless, no offer storage)
5. subscription_id present on offer -> SKIP billing.Authorize (already paid under subscription)
6. Quota check:
   - BillingAdapter.CheckSubscription("acct_7f3e21c9", "hearst-media")
     -> quota_remaining: 850000 tokens
   - Estimated consumption: 3300 tokens
   - 850000 > 3300 -> sufficient quota, proceed
   - Deduct 3300 from quota -> new remaining: 846700
7. Compute agent identity hash:
   agentHash = RFC 7638 JWK thumbprint of the agent's request-signing public key
             = the keyid this request's RFC 9421 signature was just verified with
             = "NzbLsXh8..."
   (A hash of the agent's id and domain would bind nothing: the edge checks the
   hash against a key the fetcher must prove it holds, and anyone can recompute
   a hash of two public identifiers.)
8. Write transaction log (WAL) — MUST succeed before signing URL:
   {
     transaction_id: "txn-alpha-001",
     billing_id: "bill-sub-alpha-001",
     offer_id: "4f155204-a53e-42aa-8471-154f87d7d3d5",
     subscription_id: "SUB-ANTHROPIC-HEARST-2026",
     amount: "0",
     agent_identity_hash: "NzbLsXh8...",
     offer_snapshot_json: "<full offer at transaction time, including exchange_signature>",
     reporting_required: true,
     reporting_deadline: "2026-03-16T15:00:00Z"
   }
9. Sign the delivery URL (Ed25519, tenant signing key — a different key from the
   Ed25519 offer signing key, verified by a different party):
   canonical = "GET\n" + <the URL below without its sig parameter, query sorted>
   sig = base64url(Ed25519-sign(canonical, tenant private key))


   Signed URL:
   https://cdn.techcrunch.com/server/premium/ai-regulation-2026.html
     ?agent_id=NzbLsXh8...
     &exp=1710517800
     &kid=vJ3xR1mQ...
     &sig=k7Qm2xR9vT4nB8aL...


10. Create reporting obligation: due by 2026-03-16T15:00:00Z

Response

Section titled “Response”
{
  "ver": "1.0",
  "agent_identity_hash": "NzbLsXh8...",
  "items": [
    {
      "transaction_id": "txn-alpha-001",
      "billing_id": "bill-sub-alpha-001",
      "resource_title": "AI Regulation: What Providers Need to Know",
      "retrieval_endpoint": "https://cdn.techcrunch.com/server/premium/ai-regulation-2026.html?agent_id=NzbLsXh8...&exp=1710517800&kid=vJ3xR1mQ...&sig=k7Qm2xR9vT4nB8aL...",
      "cost": { "amount": "0", "currency": "USD", "unit_cost": "0" },
      "delivery_method": "DELIVERY_METHOD_INSTRUCTIONS",
      "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
      "subscription_unit_value": { "amount": "0.05", "currency": "USD", "unit_cost": "0.00001515" },
      "reporting_obligation": {
        "required": true,
        "window": "86400s",
        "required_fields": ["transaction_id", "function", "consumed_quantity"]
      },
      "expires_at": "2026-03-15T15:30:00Z"
    }
  ]
}

The subscription_unit_value field carries the per-unit cost ($0.05) even though cost.amount is 0. This enables financial attribution under ASC 606 prepaid drawdown accounting: Anthropic can track the value of content consumed against the subscription’s total prepaid amount.

Phase 4: Content Fetch (Ed25519 Signed URL, Agent Identity Binding)

Section titled “Phase 4: Content Fetch (Ed25519 Signed URL, Agent Identity Binding)”
Agent -> CDN: GET https://cdn.techcrunch.com/server/premium/ai-regulation-2026.html
              ?agent_id=NzbLsXh8...
              &exp=1710517800
              &kid=vJ3xR1mQ...
              &sig=k7Qm2xR9vT4nB8aL...
              Header: X-FORA-Agent-Key: <agent public key, base64url>
              Header: Signature-Input: sig1=("@method" "@target-uri");keyid=...;alg="ed25519";created=...;expires=...
              Header: Signature: sig1=:<standard base64>:


Edge Function:
  1. Has a sig param? YES
  2. Resolve kid to a public key from the Exchange key directory (cached)
  3. Verify the Ed25519 signature over "GET\n<URL without sig, query sorted>" -> PASS
  4. Check expiry: exp > now? -> PASS (URL valid for 5 minutes)
  5. Check agent identity binding:
     thumbprint(presented public key) == agent_id? -> PASS
     Verify the RFC 9421 signature with that key (proof of possession) -> PASS
     (The agent must hold the private half; presenting the public key is not enough)
  6. Strip agent_id, exp, kid, sig -> CDN serves content from S3/origin


CDN access log records:
  - URL with all params (agent_id, exp, kid, sig)
  - Client IP, timestamp, bytes transferred, HTTP 200
  - This log is controlled by the provider (Hearst) and used for reconciliation

Canonical message: the literal GET, one newline, then the whole URL with the sig parameter removed and the remaining query sorted by key — so scheme, host, path and every other parameter are covered. The delivery-URL signature and the offer signature are both Ed25519; they use different keys and are verified by different parties. See Signed URL Verification.

Phase 5: Usage Reporting (Mandatory, with Token Count)

Section titled “Phase 5: Usage Reporting (Mandatory, with Token Count)”

The SDK auto-submits a usage report (background, non-blocking). Usage reporting is mandatory for subscription transactions — failure to report within the window triggers DENIAL_REASON_REPORTING_OVERDUE on subsequent transactions.

POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/ReportUsage

{
  "ver": "1.0",
  "exchange": "exchange.ssp-alpha.com",
  "idempotency_key": "ur-claude-001",
  "transaction_id": "txn-alpha-001",
  "billing_id": "bill-sub-alpha-001",
  "usage": {
    "function": ["ai-input"],
    "subfn": ["rag"],
    "consumed_quantity": 3150,
    "displayed_to_user": true,
    "citation_included": true
  },
  "timestamp": "2026-03-15T15:30:00Z",
  "assets": [
    {
      "uri": "https://techcrunch.com/premium/ai-regulation-2026.html",
      "title": "AI Regulation: What Providers Need to Know"
    }
  ]
}

Inside the Exchange

Section titled “Inside the Exchange”
1. Validate request fields -> pass
2. Lookup transaction: txn-alpha-001 -> found, billing_id matches -> pass
3. Submit to Reporting Tracker:
   a. Validate required_fields present: transaction_id, function, consumed_quantity -> all present
   b. Check reporting window: deadline 2026-03-16T15:00:00Z, current time 2026-03-15T15:30:00Z -> within window
   c. Validate consumed_quantity: 3150 actual vs 3300 estimated -> within +/-20% tolerance
   d. Transition obligation: Pending -> Fulfilled
4. Write usage report to transaction log (durable)

Response

Section titled “Response”
{
  "ver": "1.0",
  "report_id": "rpt-001"
}

A successful UsageReportResponse carries only the Exchange-assigned report_id (the durable identity the agent references when filing a dispute). A rejected report is not a success body — it travels as a non-OK transport error carrying ErrorDetail.usageReportRejection (e.g. { "usage_report_rejection": { "reason": "USAGE_REPORT_REJECTION_REASON_WINDOW_EXPIRED" } }).

Phase 6: Reconciliation + Provider Audit

Section titled “Phase 6: Reconciliation + Provider Audit”

Three-Sided Reconciliation

Section titled “Three-Sided Reconciliation”

Three independent records that must agree:

1. Edge delivery log (Hearst controls):
   - url_hash=9f2c7a4e... fetched at 15:25:00, 200 OK, 45KB
   - agent_id=NzbLsXh8..., signature and agent binding verified by the edge


2. Exchange transaction log (SSP-Alpha controls):
   - txn-alpha-001: signed_url_hash=9f2c7a4e... (the join key to the log above)
   - subscription SUB-ANTHROPIC-HEARST-2026, amount=$0
   - subscription_unit_value: $0.05 (value of the access for accounting)
   - offer_snapshot: article "AI Regulation...", 3300 est tokens
   - offer_snapshot includes exchange_signature (Ed25519, non-repudiable)
   - reporting_deadline: 2026-03-16T15:00:00Z


3. Usage report (Anthropic filed):
   - txn-alpha-001: 3150 actual tokens, function=ai-input, citation=yes
   - Filed at 15:30:00, within reporting window

Reconciliation Checks

Section titled “Reconciliation Checks”
PASS: CDN log has txn-alpha-001 -> content was actually served
PASS: Exchange has txn-alpha-001 -> transaction was authorized
PASS: Usage report received before deadline -> reporting obligation fulfilled
PASS: Token count 3150 vs estimate 3300 -> within +/-20% tolerance
PASS: Function ai-input matches the term's RESTRICTION_KIND_FUNCTION permitted list
PASS: Citation included as required by the Offer's attribution terms

Provider Audit Access

Section titled “Provider Audit Access”

Hearst queries the Exchange’s provider audit API to independently verify all transactions for their content:

GET https://exchange.ssp-alpha.com/provider/techcrunch.com/transactions
    ?from=2026-03-15T00:00:00Z
    &to=2026-03-16T00:00:00Z

Response includes signed Offer snapshots for every transaction:

{
  "transactions": [
    {
      "transaction_id": "txn-alpha-001",
      "billing_id": "bill-sub-alpha-001",
      "offer_snapshot": {
        "offer_id": "4f155204-a53e-42aa-8471-154f87d7d3d5",
        "exchange": "exchange.ssp-alpha.com",
        "pricing": { "model": "PRICING_MODEL_FREE", "rate": "0", "currency": "USD" },
        "subscription_id": "SUB-ANTHROPIC-HEARST-2026",
        "signature": "base64-ed25519-sig-B...",
        "signature_algorithm": "EdDSA"
      },
      "cost": { "amount": "0", "currency": "USD" },
      "subscription_unit_value": { "amount": "0.05", "currency": "USD" },
      "agent_id": "NzbLsXh8...",
      "timestamp": "2026-03-15T15:25:00Z"
    }
  ]
}

What Hearst can verify:

  1. Offer authenticity: Hearst verifies the exchange_signature on each offer_snapshot using SSP-Alpha’s published Ed25519 public key (fetch SSP-Alpha’s WBA directory at exchange.ssp-alpha.com/.well-known/http-message-signatures-directory and read its keys). This proves the Exchange actually issued this Offer — it cannot deny having offered these terms.

  2. RSL price ceiling compliance: Hearst’s RSL declares a maximum rate of $0.08/crawl. The subscription’s subscription_unit_value of $0.05 is below this ceiling. If any per-request Offer exceeded $0.08, Hearst would detect it by comparing offer_snapshot.pricing.rate against their RSL terms.

  3. Private floor compliance: Hearst’s contract with SSP-Alpha specifies a private minimum rate of $0.04/article. The subscription_unit_value of $0.05 is above this floor. Private floor pricing is contractual (not protocol-enforced), but the audit data makes violations detectable.

What Hearst Sees (Subscription Summary)

Section titled “What Hearst Sees (Subscription Summary)”
Under subscription SUB-ANTHROPIC-HEARST-2026, Anthropic consumed
3,150 tokens from "AI Regulation: What Providers Need to Know"
for RAG/grounding. Citation was included. Value: $0.05 per article.

This data feeds into Hearst’s subscription renewal negotiation:

"Anthropic consumed 2.3M tokens from TechCrunch last quarter under
the current deal at $0.05/article. Given our RSL ceiling of $0.08
and the volume, we want to renegotiate to $0.06 for next year."

Phase 7: Dispute Resolution (v1.0 — When Things Go Wrong)

Section titled “Phase 7: Dispute Resolution (v1.0 — When Things Go Wrong)”

If the content delivered by the CDN does not match what was promised in the Offer, the agent can file a dispute. The dispute chain enforces a strict order: the agent MUST have filed a UsageReport (Phase 5) before disputing.

Example: Content Hash Mismatch

Section titled “Example: Content Hash Mismatch”
Agent verifies delivered content:
  1. Compute SimHash of received HTML -> "a1b2c3d4e5f9..."
  2. Compare with Offer's identity.content_hash -> "a1b2c3d4e5f6..."
  3. Hamming distance = 2 bits -> within SimHash tolerance (threshold 3)
  4. No dispute needed (content is substantially similar)


But if Hamming distance > threshold, or content is entirely different:
  Agent files DisputeTransaction

Dispute Request

Section titled “Dispute Request”
POST https://exchange.ssp-alpha.com/fora/v1/fora.v1.ExchangeService/DisputeTransaction


{
  "ver": "1.0",
  "transaction_id": "txn-alpha-001",
  "billing_id": "bill-sub-alpha-001",
  "report_id": "rpt-001",
  "reason": "DISPUTE_REASON_CONTENT_MISMATCH",
  "description": "Content hash differs from offer: expected a1b2c3d4e5f6, received a1b2c3d4ffff",
  "received_content_hash": "a1b2c3d4ffff...",
  "received_hash_method": "simhash-v1"
}

Dispute Response

Section titled “Dispute Response”
{
  "dispute_id": "disp-alpha-001",
  "status": "DISPUTE_STATUS_AUTO_RESOLVED",
  "resolution": "RESOLUTION_TYPE_CREDIT",
  "estimated_resolution": "2026-03-15T16:00:00Z"
}

Three-tier resolution: Tier 1 automated (<1s, auto-disputable claims like CDN failure or hash mismatch), Tier 2 rule-based (<24h), Tier 3 pattern investigation (async). The dispute lifecycle progresses through: FILED -> AUTO_RESOLVED / EVIDENCE_NEEDED -> UNDER_REVIEW -> RESOLVED -> FINAL. Appeals re-enter UNDER_REVIEW.

What the Broker Adds (Cross-Provider Intelligence)

Section titled “What the Broker Adds (Cross-Provider Intelligence)”

Without Broker (SDK only): the agent found the article via SSP-Alpha (from fora.json) and got the subscription deal. It never knew The Verge also had the article at $0.07 via SSP-Beta.

With Broker: it queried both Exchanges, discovered the same article via iptc_guid match (confirmed by SimHash similarity), received attestation data from both sources, and still chose the subscription offer — but now Anthropic has intelligence:

"This article is available from two sources:
  - SSP-Alpha (TechCrunch, subscription, $0/request, third-party attested by gumgum.com)
  - SSP-Beta (The Verge, per-request, $0.07/request, third-party attested by gumgum.com)


Our subscription saves us $0.07 per request from the alternative source.
At 10K requests/month for this provider's content, that's $700/month
in avoided per-request costs — data for the subscription renewal.


Both sources carry Level 2 (third-party) attestations from gumgum.com.
TechCrunch original has higher word_count (2500 vs 2350) — more complete."

This is the Broker’s value: not just cheapest price, but market intelligence for subscription negotiations and attestation-aware content selection.