]> VERAX TEKNOLOJI LIMITED SIRKETI

Turkey e.dogru@cedulon.com

sec Cedulon agent receipt policy SCITT This document addresses auditable payments for AI agents and builds upon state-of-the-art HTTP 402, AP2 and credit card systems. We specify a cryptographically secured payment reconciliation protocol using a Trade Manifest (a signed offer before payment), a Policy Decision Point with default deny, a Spend Receipt (a COSE/CWT claim set issued after a gated payment), and rail-extract reconciliation.

Introduction Artificial Intelligence (AI) agents involved in travel, stock market transactions, etc. may need the capability of securely paying for their transactions. Previously defined protocols such as HTTP 402 and Google's Agent Payments Protocol (AP2) made it possible: HTTP 402 protocols attach stablecoin settlement to ordinary requests, and AP2 binds user intent to signed mandates. Card networks and processors issue agent-scoped tokens. What is missing is an interoperable audit layer: a machine-checkable answer to "was this spend allowed by policy, against which offer, and what bytes were delivered?" The answers have limits, and this document states them. "Allowed by policy" is the Receipt Issuer's signed assertion; the audit does not independently re-verify the policy decision (). What was delivered is machine-checkable only where an attributable payee countersignature binds a delivery hash (). Without such a layer, a prompt-injected or looping agent can drain a rail that has already accepted a valid signature, and a counterparty can ship the wrong artifact. The name Cedulon is from cedule, the older legal word for a written schedule or note. Cedulon does not clear funds, hold custody, or operate a payment facilitator. An optional escrow actor is defined only as a third-party role interface (). Implementations of this specification MUST NOT take custody of funds or operate escrow (MUST-T8-custody). Reconciling an internal ledger against an external statement is an old accounting control , and signing the artifacts on both sides is Grigg's triple-entry idea . This document profiles that control for parties that are software: a CBOR Object Signing and Encryption (COSE) receipt shape, an extract shape, and a verification algorithm precise enough that two implementations reach the same finding on the same evidence. The checkpoint chain that extends it over time is in . A Cedulon audit is intended to be read within the architecture for auditing AI agent delegation and interactions , which links user intent, delegation and authorization to an execution, registers the resulting records with a Supply Chain Integrity, Transparency, and Trust (SCITT) Transparency Service , and lists financial transactions by agents among its motivating cases. For a spend, this document adds a result that architecture does not define: completeness of signed receipts against an authenticated extract of the rail, over a declared account, rail and time window. This document does not define an integration profile for that architecture. Other related drafts are noted in .

Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here. This document uses Concise Binary Object Representation (CBOR) , CBOR Web Token (CWT) claim sets, and JavaScript Object Notation (JSON) documents. In the tables, CBOR types are written tstr (text string), bstr (byte string) and uint (unsigned integer). The following terms are used:

Trade Manifest:

A signed statement produced before payment. It binds a description of goods or service, price, currency, acceptance-criteria hash, cancel condition, expiry, and an optional AP2 mandate reference.

Policy Decision Point (PDP):

The function that evaluates a structured spend request against stored policy. The default is deny.

Rail:

The payment system that moves value and reports what it settled, such as the settlement path behind an HTTP 402 exchange . A Rail Extract names it by railId.

Payment Adapter:

The component that performs the payment on the rail. It calls the PDP first and is the only path from the agent to the rail (MUST-T5-1).

Spend Receipt:

A signed statement produced after a gated payment attempt. It binds payer, payee, amount, currency, policy hash, manifestHash or an explicit noManifest flag, rail payment reference, timestampMs, nonce, prevReceiptHash, and outcome.

Receipt Issuer:

The party that signs Spend Receipts.

Anchor:

An optional SCITT Transparency Service that registers a signed statement and returns a COSE receipt .

Dispute Evidence Bundle:

A package of the Trade Manifest, the Spend Receipt, and a delivery hash. It is evidence for a later human or legal process. It is not an arbitral award and not an escrow release.

Decision Token:

A portable, single-use PDP allow encoded as COSE_Sign1. The claim set binds requestHash, policyHash, expiryMs, nonce, and singleUseId. See .

Rail Extract:

An authenticated list of settlement records for one account, one rail, and one time window. See .

Verifier:

The party that runs the reconciliation of over the receipts, the Rail Extract, and the keys it holds.

Pinned key:

A public key the verifier obtained out of band, as opposed to a key an object carries beside its signature. See .

Working set:

The receipts and checkpoints the verification steps consume: those that verify under a usable pinned issuer key (the attested set), or, when no usable issuer key is pinned, every presented one. See .

Presented-unattested:

The state of a receipt or checkpoint the verifier holds no pinned issuer key for. Its signature is checked against the key the object itself carries (), which establishes internal consistency only, so the object is neither attested nor rejected: every presented object is weighed as one set and the completeness guarantee is reported as conditional. It is a state of the report, not a finding code. See .

Architecture The following diagram shows the payment path, the audit path, and the optional transparency service: PDP ^ | request / allow or deny Trade Manifest | (optional) -----> Payment Adapter --payment--> Rail | | v v Receipt Issuer Rail Extract | | v | Spend Receipt ---> Verifier <---+ | | v v Anchor / SCITT (optional) Report ]]> The payer agent never talks to the rail except through an adapter that calls the PDP first (MUST-T5-1).

Policy Decision Point The PDP evaluates structured fields only (MUST-T1-1): amount, currency, payee, tool identifier, nonce, optional manifest hash, and evaluation time. It applies limit, velocity, and scope checks (MUST-T2-1, MUST-T2-2). If the PDP is unreachable, uninitialized, or throws, the result is deny (MUST-T2-3). Denied attempts do not increment success counters (MUST-T2-4). An allow produces a Decision Token whose requestHash covers six fields: amount, currency, payee, tool, nonce, and manifestHash (MUST-T3-4, MUST-T6-1). The token is a COSE_Sign1 object (MUST-T6-4), is single-use (MUST-T6-2), and MAY be carried to the adapter that performs settlement.

Receipt Issuer After the adapter attempts settlement (success or a recorded deny that still needs an audit trail for an allowed-then-aborted path), the Receipt Issuer signs a Spend Receipt over the deterministic CBOR encoding of its claims (MUST-T4-1). Verifiers reject bad signatures and byte mismatch (MUST-T4-2).

Anchor / SCITT Parties MAY register the signed receipt (or a privacy-preserving hash encoding) as a SCITT Signed Statement and attach the COSE receipt (MAY-T4-6). This document does not operate a Transparency Service.

Lifecycle

1. Manifest. Optionally, the payee or a marketplace signs a Trade Manifest. A spend without one is marked noManifest and still passes limit, velocity and scope checks (MUST-T1-2); a deployment MAY refuse such spend (MAY-T1-4).
2. Policy check. The adapter submits a structured request to the PDP. Default is deny. An allow is a Decision Token (MUST-T6-4).
3. Payment. On allow, the adapter performs the x402 (or other rail) exchange using exactly the decision fields (MUST-T6-1). The Decision Token is consumed (MUST-T6-2). A reused nonce is denied (MUST-T3-1, MUST-T3-2). A tampered or expired token is denied (MUST-T6-5).
4. Receipt. The Receipt Issuer signs a Spend Receipt. Rail credentials MUST NOT appear in the receipt, logs, or tool results (MUST-T5-2, MUST-T7-1).
5. Dispute Evidence Bundle. If delivery bytes do not match the acceptance-criteria hash, an implementation MUST be able to emit a bundle of manifest + receipt + delivery hash (MUST-T8-3). The bundle MUST NOT be described as an arbitral award or escrow release (MUST-T8-4).

Afterwards, a verifier reconciles the receipts against the rail's own extract (). Appendix C follows one 10.00 TRY spend through these steps.

Trade Manifest A Trade Manifest is a signed offer issued before value moves. It MAY carry an AP2 mandate hash so that user intent and the offer stay linked (SHOULD-T8-5). A Trade Manifest MUST bind all of the following (MUST-T8-1):

• goods or service description
• price (integer minor units, encoded as a decimal string matching 0|[1-9][0-9]*)
• currency (ISO 4217 alphabetic or a documented token identifier)
• acceptance-criteria hash (SHA-256 of the exact delivery bytes, lowercase hexadecimal)
• cancel condition (opaque string agreed by the parties)
• expiry (POSIX milliseconds, expiresAtMs)

The hash is taken over the exact delivery bytes only. Hashing a schema instance instead would need a marker in the manifest saying so; this document defines no such marker, and until one is defined that use is out of scope rather than an alternative a verifier is expected to guess at. The acceptance-criteria hash therefore fits a delivery whose exact bytes are known when the offer is signed, such as a file; this document defines no such hash for a service, such as a travel booking, whose delivery is not a byte string. It MAY include ap2MandateHash. The corresponding CBOR label is always present; a missing mandate is encoded as CBOR null. It MAY name a payee. An offer that is specific to one counterparty carries that party's payee identifier; when present, every receipt that names this manifest has its payee compared against it as exact octets under MUST-T8-9, on that requirement's two-branch severity. An open offer legitimately omits the member, and no comparison is made. Unlike ap2MandateHash, the label is encoded only when the member is present, so the null convention above does not apply to it. The manifest is COSE_Sign1 over a deterministic CBOR claim map (). manifestHash is the SHA-256 of the signed COSE bytes (MUST-T8-7). A spend bound to a manifest MUST be denied if the requested amount or currency differs from the manifest (MUST-T8-2) or if the manifest is expired (MUST-T3-3). A spend that is not bound to a verified manifest MUST be marked noManifest on the receipt and MUST still pass limit, velocity, and scope checks (MUST-T1-2). An implementation MAY refuse all noManifest spend (MAY-T1-4).

Spend Receipt The Spend Receipt claim set is carried in COSE_Sign1 wrapping a CWT-compatible map . New receipts MUST use the COSE profile (). Claims (MUST-T4-3, MUST-T4-4, MUST-T4-7):

Claim	Description
payer	Payer agent identifier
payee	Payee identifier
amount	Minor units as a decimal string 0|[1-9][0-9]*
currency	Currency identifier
policyHash	SHA-256 of the canonical policy document (lowercase hex)
manifestHash	SHA-256 of the signed manifest COSE bytes, or null when noManifest is true
noManifest	Boolean; MUST be true if and only if manifestHash is null
x402PaymentRef	Rail payment reference, or null
timestampMs	POSIX milliseconds
nonce	Unique spend nonce; at least 128 bits of randomness; unique in the issuer scope
prevReceiptHash	Previous receipt hash, or null for the first receipt (SHOULD-T4-5)
outcome	settled or aborted

A receipt with outcome = settled MUST have a non-null x402PaymentRef (MUST-T4-7). An aborted receipt MUST NOT be added into checkpoint totals. All twelve labels in are always present. An empty optional value is encoded as CBOR null, never by omitting the label. receiptHash is the SHA-256 of the receipt's signed COSE bytes, encoded as lowercase hex. Verifiers MUST reject a receipt if the signature fails or if the decoded claim map does not match the presented claims (MUST-T4-2).

Optional payee countersignature A payee MAY attach a countersignature over the issuer's signed Spend Receipt (MAY-T8-10). The profile uses a detached COSE_Sign1 whose payload is a CBOR map with private-use labels:

Label	Claim	CBOR type
-70401	receiptCose	bstr (exact issuer COSE_Sign1 bytes)
-70402	deliveredHash	bstr (optional; SHA-256 of the exact delivered bytes)

The countersignature uses the header profile in and content type application/cedulon-countersign+cbor. This is a second Sign1 object, not RFC 9052 Countersignature0 (unprotected-header label 11). Countersignature0 would write into the issuer object and change receiptHash after issue, breaking the receipt chain. A detached Sign1 keeps the issuer bytes stable, reuses kid and content-type, and is absent by simply omitting the sibling object. Absence of a countersignature MUST NOT invalidate the issuer receipt (MAY-T8-10). A countersignature travels beside the issuer signature without being covered by it, so anyone holding an honest receipt can append one of their own. Attribution is therefore the gate: a countersignature that cannot be attributed to the pinned payee key - the signature fails, kid or content type does not match, label -70401 is not the issuer COSE bytes (MUST-T8-8), or the signature is valid under some other key - MUST be rejected as approval evidence. What is rejected is the countersignature, not the receipt: the verdict on the untouched issuer receipt MUST NOT change because an unattributable object was attached. An appendable object the issuer signature does not cover must not be able to manufacture a negative result. The identifiers countersign-bad (unverifiable) and countersign-key-mismatch (verifiable under another key) name the discarded object as warnings, and where the verifier pinned a payee key and no attributable countersignature remains, the countersign-missing warning still applies: a discarded forgery is the absence of the payee's word, not a substitute for it. The optional deliveredHash claim binds delivery to the receipt under the payee's key. A payee who countersigns MAY include the SHA-256 of the exact bytes it delivered in the same signed payload as the issuer receipt bytes. When an attributable countersignature carries deliveredHash and the verifier also holds the Trade Manifest, the two digests are compared as exact octets: deliveredHash against acceptanceCriteriaHash. A mismatch is delivery-mismatch, and it is a finding rather than a warning, because both ends of the comparison are signed. A deliveredHash carried by an unattributable countersignature is discarded with it. A countersigner MUST refuse to sign a deliveredHash that is not 32 octets; a verifier that meets one anyway treats the countersignature as carrying no deliveredHash, so the delivery question narrows as it does when the claim is absent, and the signature verdict does not move. A countersignature without the claim remains valid. A Dispute Evidence Bundle that includes a verified countersignature has stronger evidence that the payee accepted those bytes; the bundle is still not an award (MUST-T8-4).

COSE Profile This profile uses deterministic CBOR Section 4.2.1 (definite lengths, shortest integer form, map keys sorted in bytewise lexicographic order of their encoded keys). Implementations MUST encode only the types used by Cedulon claim maps: null, bool, unsigned and negative integers, UTF-8 text, byte strings, arrays, and maps (MUST-T4-1). A decoder MUST refuse a CBOR map that carries a duplicate encoded key (MUST-T4-18). A decoder MUST also impose a bound on what it will attempt: on encoded size, on nesting depth, and on the number of elements it will decode from an audit input. It MUST refuse an input that exceeds a bound with a named refusal rather than by exhausting memory or the stack, and it SHOULD document the bounds it applies (MUST-T4-19). This document fixes no numbers, because the right bounds depend on the deployment; what it requires is that exceeding a bound is a named, reported refusal rather than a crash.

Claim labels Registered CWT claims are not required by this profile. Cedulon uses CWT private-use integer labels less than -65536. Every claim the tables below annotate as hash carries a SHA-256 digest rendered as exactly 64 lowercase hexadecimal characters ([0-9a-f]{64}). A signer MUST refuse to sign, and a validator MUST reject, a value that does not match that grammar, naming the claim in the refusal. A decoder that preserves unknown or foreign claims is a separate layer and keeps them unchanged; the grammar binds what a party signs and what a validator accepts, not what a decoder can carry. Receipt labels (MUST-T4-3, MUST-T4-4, MUST-T4-7):

Label	Claim	CBOR type
-70001	payer	tstr
-70002	payee	tstr
-70003	amount	tstr
-70004	currency	tstr
-70005	policyHash	tstr (hash)
-70006	manifestHash	tstr (hash) / null
-70007	noManifest	bool
-70008	x402PaymentRef	tstr / null
-70009	timestampMs	uint
-70010	nonce	tstr
-70011	prevReceiptHash	tstr (hash) / null
-70012	outcome	tstr (settled / aborted)

Checkpoint labels (MUST-T11-1):

Label	Claim	CBOR type
-70101	epoch	uint
-70102	startMs	uint
-70103	endMs	uint
-70104	receiptCount	uint
-70105	chainHeadHash	tstr (hash) / null
-70106	totals	map tstr -> tstr / null
-70107	prevCheckpointHash	tstr (hash) / null

Manifest labels (MUST-T8-1):

Label	Claim	CBOR type
-70201	description	tstr
-70202	amount	tstr
-70203	currency	tstr
-70204	acceptanceCriteriaHash	tstr (hash)
-70205	cancelCondition	tstr
-70206	expiresAtMs	uint
-70207	ap2MandateHash	tstr (hash) / null
-70208	payee	tstr (optional; encoded only when present)

Decision Token labels (MUST-T6-4):

Label	Claim	CBOR type
-70301	requestHash	tstr (hash)
-70302	policyHash	tstr (hash)
-70303	expiryMs	uint
-70304	nonce	tstr
-70305	singleUseId	tstr

COSE_Sign1 headers The protected header MUST be a deterministic CBOR map containing (MUST-T4-1, MUST-T4-8):

• 1 (alg) = -19 (Ed25519, ; the generic EdDSA value -8 from is deprecated for this profile)
• 3 (content type) = a tstr that distinguishes the payload: application/cedulon-receipt+cbor, application/cedulon-checkpoint+cbor, application/cedulon-manifest+cbor, application/cedulon-decision+cbor, application/cedulon-countersign+cbor, or application/cedulon-inclusion+cbor
• 4 (kid) = bstr, mandatory. The profile computes kid as the first eight bytes of SHA-256 over the issuer's SubjectPublicKeyInfo DER, in the Ed25519 SubjectPublicKeyInfo encoding of . A verifier MUST obtain the public key from an authenticated channel (preconfigured issuer set, directory, or transparency statement) and MUST reject a message whose kid does not match that key.

The unprotected header MUST be empty, and a decoder MUST refuse a message whose unprotected header is not an empty map, by the name cose-sign1-unprotected, rather than verify the signature and ignore the header (MUST-T4-21): every digest in is computed over octets that include the unprotected header, which the signature does not cover. The payload MUST be the CBOR encoding of the claim map. The signature is Ed25519 over the COSE Sig_structure ["Signature1", protected, h'', payload].

How a signed object is presented The signed octets above are what this profile defines and what every digest in is taken over. An object handed to a verifier travels with more than that, and this section names what. A presented Spend Receipt, epoch checkpoint, Trade Manifest, or Decision Token carries, beside the signed octets, its claim set or body in decoded form and the signer's public key as a SubjectPublicKeyInfo PEM; a countersigned receipt carries the payee's key the same way, and an object presented in the JSON encoding of repeats its signature there as base64. None of these is inside the signed octets, which is the whole point of naming them here: the signature covers the COSE message and nothing else, so every one of these members is a surface anyone holding the object can rewrite. This is the same shape the Rail Extract states in , and it is stated once here for the COSE objects rather than left to be inferred from an implementation. A carried key is not an identity source and MUST NOT be used as one (MUST-T4-11). Under a pin it has exactly one effect: an object that verifies under the pinned key while carrying a different key is reported as carried-key-mismatch, a warning, and stays attested (). With no pin held it is the only key present, so any signature check that runs against it says the object is internally consistent and says nothing about who signed it; two issuers cannot be told apart in that state. A Trade Manifest with no pinned key is not checked against its carried key at all (Appendix B, unauthenticated-manifest).

Canonical JSON encoding Not everything this document hashes or signs is CBOR. The policy document, the six request fields bound by a Decision Token, and the scoped body of a Rail Extract are JSON. Two implementations could agree on every other requirement in this document and still produce different bytes unless the encoding is named, which makes an independent verifier impossible to write from the text. This section names that encoding. Where this document says "the canonical encoding" of a JSON document, it means the encoding defined by , and the octets hashed or signed are the UTF-8 octets of that encoding. Three notes on the boundary of that reference:

• Section 3.1 takes I-JSON as its input, and an I-JSON object carries no duplicate member names. This document makes that precondition a rule at every place a verifier receives a JSON document as text - a rail extract body, a policy document, a stored receipt file: a text in which any object, at any depth, repeats a member name MUST be refused by the name json-duplicate-key, before the text is parsed (MUST-T4-20). A verifier handed an object rather than text, as a tool behind a JSON-RPC boundary is, cannot apply the rule and MUST NOT report that it did; whether the text was checked is then the transport's to state.
• Section 3.2.2.2 requires a serializer to terminate on a lone surrogate, and so does this document: a producer MUST refuse to encode a document containing one, by name, and MUST NOT sign what it could not encode. A verifier reading bytes it cannot canonicalize for this reason reports the input as failing verification with the refusal named beside the verdict; it does not crash. No field defined by this document may contain a lone surrogate, so a conforming document never reaches this rule.
• defines no encoding for an integer outside the IEEE 754 double range. No document defined here carries one: every amount and cumulative limit is already a decimal string before it is encoded, and every hash is lowercase hexadecimal. A document that would need such an integer is outside this specification.

Which octets are hashed Every hash-valued field in this document is SHA-256 of the input named below. All but two are rendered as lowercase hexadecimal, and a third differs in another respect. kid differs only in its rendering: the digest is computed over the same stated input and then truncated to its first 8 bytes, carried as a byte string rather than as hex ( states the same rule where the header is defined). ap2MandateHash differs in whose digest it is: AP2 defines the mandate and its octets, and this document carries the result opaquely rather than restating a rule it does not own. deliveredHash differs in its carrier: it is a claim in a CBOR map and is carried as the raw 32 digest bytes (bstr), not as hex; comparisons against acceptanceCriteriaHash are made over the digest value.

Field	Input to SHA-256
receiptHash	the signed COSE_Sign1 octets of the receipt
manifestHash	the signed COSE_Sign1 octets of the Trade Manifest
checkpointHash	the signed COSE_Sign1 octets of the checkpoint
statementHash	the signed COSE_Sign1 octets of the statement
acceptanceCriteriaHash	the exact delivery bytes, as defined in
deliveredHash	the exact bytes the payee delivered, under the same input rule as acceptanceCriteriaHash, computed by the payee when it countersigns
policyHash	the UTF-8 octets of the canonical policy document
requestHash	the UTF-8 octets of the canonical six-field request document
kid	the SubjectPublicKeyInfo DER; the digest is then truncated to its first 8 bytes
ap2MandateHash	the octets AP2 defines for its mandate; not profiled by this document

Wherever this table, or any other sentence in this document, says "the signed COSE_Sign1 octets", those are the octets of the untagged four-element COSE_Sign1 array of . This profile never wraps a message in CBOR tag 18, and the vectors in Appendix A carry the untagged form. A verifier that hashed a tagged copy would compute a different digest for every object in this profile, so the choice is stated here once rather than left to be inferred from the vectors. The six fields of the request document are the ones MUST-T6-1 names: amount, currency, payee, tool, nonce, and manifestHash. The request document is a JSON object carrying exactly those six members and no others, every member always present. amount is the decimal string of the request, in the amount syntax the receipt claims table states, never a JSON number: encodes the number 1 and the string "1" differently, and an implementation free to pick either would produce two digests for one request. currency, payee, and nonce are the request's text strings. tool is the request's text string, or JSON null where the deployment names none. manifestHash is the lowercase hexadecimal string, or JSON null for a spend bound to no manifest; an absent value is null, never an omitted member. A document with a seventh member, a missing member, or another type for one of these is not the request document this section defines. The policy document is different on purpose, and the difference is scope rather than an oversight. Its member set is the deployment's own: this document defines how the bytes of whatever policy document a PDP evaluates are encoded () and digested, not what its members are. policyHash binds a spend to the exact bytes its PDP evaluated; it is not a value two deployments are expected to compute from a shared schema, and nothing in the verification algorithm compares one deployment's policyHash to another's.

Decision Token A Decision Token is the portable encoding of a PDP allow. It is COSE_Sign1 with the header profile in and the labels in . All five labels are always present (MUST-T6-4). requestHash MUST be the SHA-256 of the canonical encoding of the six fields the PDP evaluated (MUST-T6-1), rendered as lowercase hexadecimal; defines that encoding and states the octets. policyHash MUST be the SHA-256 of the canonical policy document the PDP evaluated. expiryMs is a Unix time in milliseconds after which the token MUST be treated as expired (SHOULD-T6-3): expired when the evaluation time is strictly greater than expiryMs, not yet expired at exactly expiryMs, on the same boundary discipline MUST-T3-3 states for the manifest. nonce is the request nonce. singleUseId is the identifier consumed on the first settlement attempt (MUST-T6-2). A party that accepts a Decision Token MUST reject it if the signature fails, if kid does not match a configured PDP key, if the content type is not application/cedulon-decision+cbor, if the decoded claim map does not match the presented claims, or if expiryMs is in the past (MUST-T6-5).

Rail Extract Profile A verifier checks completeness against a rail extract, not against the issuer's own receipts alone (MUST-T10-7).

Record schema The extract body is a JSON document. Each settlement record MUST contain the following members, under these names:

Member	JSON type
ref	string (rail payment reference)
amount	string matching 0|[1-9][0-9]*
currency	string
timestampMs	number (POSIX milliseconds, an integer)

These member names are normative. A rail MAY add members of its own to a record; it MUST NOT rename the four above. The types above are stated in JSON terms. A record MAY carry a beneficiary member (string). A rail that can resolve a payment reference to the party credited declares it there; when present, it is compared against the payee of the receipt that names the same ref, and a difference is reported (beneficiary-mismatch). Resolving a reference to a beneficiary is a feature of the rail's own system: this profile does not assume it, and measures it only when the rail declares it.

Scope An extract is scoped to one account identifier, one rail identifier, and one half-open time window [windowStartMs, windowEndMs). The signed body is one JSON document with exactly this shape:

Member	JSON type
accountId	string
railId	string
windowStartMs	number (POSIX milliseconds, an integer)
windowEndMs	number (POSIX milliseconds, an integer)
clockSkewMs	number (milliseconds, a non-negative integer; optional; see )
settlements	array of settlement records (schema above)

All six named members except clockSkewMs MUST be present; a body missing one, or a record renaming a core member, MUST be refused by name at both ends - by the signer before it signs and by the verifier before it checks a signature - so a malformed extract is the same refusal on both sides rather than a signature verdict. Additional members beyond these are the rail's to add, as with records. The integer-valued members - windowStartMs, windowEndMs, each record's timestampMs, and clockSkewMs - MUST be integers of magnitude at most 2^53 - 1, the range a JSON number carries exactly, and clockSkewMs MUST NOT be negative; a value outside those bounds, or a non-integer, is refused by name in the same way as a missing member. windowEndMs MUST be greater than windowStartMs: the window is half-open, so one that does not end after it starts declares no population, and a body carrying one is refused by name (malformed-extract-window) in the same way, at both ends. The body is read as text before it is read as an object. A text in which any object repeats a member name is refused as json-duplicate-key at both ends, before parsing and before any signature is checked (MUST-T4-20, ); a signer that parsed first would sign one of the two values and an honest verifier could check the other. clockSkewMs, when present, declares the boundary allowance the verifier applies at this window's edges during reconciliation (); when absent, the profile default of 300000 milliseconds (five minutes) applies.

Authentication The rail signs Ed25519 over the canonical encoding of the scoped body, which is a JSON document and therefore takes the encoding of : the signed octets are the UTF-8 octets of the encoding of the body above. The signature and the rail's public key travel beside the body, the signature as base64 and the key as a SubjectPublicKeyInfo PEM; neither is part of the signed octets. A verifier MUST obtain the extract from the rail or from a signature the rail published (MUST-T10-7). A deployment that cannot do so is running the reconciliation against evidence it did not obtain independently, and MUST report the guarantee as conditional. A signature on an extract proves internal consistency, not origin: a key generated by whoever produced the object verifies against itself. The verifier therefore MUST obtain the rail's public key out of band and MUST verify the extract signature against that key (MUST-T10-8). A key the extract carries is not that key: it is neither the rail's identity nor a fallback for one the verifier did not obtain. Where no such key is held, the carried key is the only key present, so the signature check that runs against it says the extract is internally consistent and says nothing about who produced it, and the verifier MUST treat the guarantee as conditional. Keys are compared as bytes. A verifier MUST compare the pinned key and the key that signed the extract by their SubjectPublicKeyInfo DER encoding, not by any text encoding of it, so that the same key presented in a different envelope still compares equal (MUST-T10-9). A pinned key the verifier cannot decode is a fault in the verifier's own configuration, not evidence about the extract, and MUST be reported as trust-key-unreadable rather than as a key mismatch. What a verifier emits for an extract it cannot authenticate depends on whether it stated an expectation. With no pinned key the verifier has asserted nothing, so the condition is unauthenticated-extract whatever the extract carries - a signature that verifies against the carried key establishes internal consistency and not origin, and one that fails or is refused is not a verdict about a key either. It is a warning: completeness findings may still be computed, but the guarantee is conditional on the extract being authentic. With a pinned key the verifier has asserted what it requires, and an extract that fails to meet it is a failure rather than a caveat; see the verification algorithm for which finding applies. See .

Scope agreement An extract declares a window and carries settlement records. The two MUST agree: a verifier MUST report every settlement record whose timestampMs falls outside [windowStartMs, windowEndMs) as extract-scope-mismatch, identified by that record's ref (MUST-T10-10). This check is about the extract's internal consistency and MUST be performed whether or not a rail key is pinned. A verifier that knows which account, rail, and window it is auditing MUST also check the extract against that expectation and MUST fail closed when the extract does not cover it (MUST-T10-11). An extract for another account or rail, or one whose window does not span the period under audit, cannot support a completeness claim about that period. A verifier that has not stated the period under audit MUST emit unstated-audit-window and MUST treat the guarantee as conditional (MUST-T10-15), whatever else verifies. Likewise, a verifier that has not stated the account or the rail under audit MUST emit unstated-audit-scope and MUST treat the guarantee as conditional (MUST-T10-18). Where no rail key is pinned at all, all three axes are equally unstated and unauthenticated-extract is the condition reported. A balanced audit under an unconditional guarantee is true of one account, on one rail, over one window, so a report that carries it MUST also carry that account, rail and window (MUST-T10-19). A completeness claim about an account needs one such report per rail that account can settle on; enumerating those rails is the deployment's statement.

Trust roots states the rule for one object: a signature proves internal consistency, not origin, so the verifier obtains the rail key out of band and checks the extract against it, and the key the extract carries is neither the rail's identity nor a fallback for one the verifier did not obtain (MUST-T10-8). The same discipline applies to the issuer: a verifier obtains the public key from an authenticated channel and rejects a kid that does not match that key (MUST-T4-8). This section states the verification algorithm, the separate root inputs, and the error semantics that name a missing or mismatched pin, for every signed object in the profile.

Object	Key the verifier pins	Section
Rail Extract	rail key
Spend Receipt, epoch checkpoint	issuer key
Payee countersignature	payee key
Decision Token	the deployment's own PDP signing key
Trade Manifest	publisher key

Without these roots, a verifier that checks a Spend Receipt against the key the receipt carries accepts a receipt signed by any key at all, and a forged receipt can make an unreceipted settlement look covered.

The issuer root A verifier MUST obtain the issuer's public key out of band and MUST verify Spend Receipt and epoch checkpoint signatures against that key. A key the object carries is not that key: it establishes no signer identity and is not a fallback for a pin the verifier does not hold (MUST-T4-9, MUST-T4-11). Where no issuer key is held, a signature checked against the key its own object carries establishes internal consistency and nothing more, which is the state and the last row of the table below describe. A verifier that holds no such key and is presented with any Spend Receipt or epoch checkpoint MUST treat the completeness guarantee as conditional and SHOULD report the condition; the identifier unauthenticated-issuer is used for it in this document. An audit given no receipts and no checkpoints rests on the extract alone and is not made conditional by this requirement. Reporting a mismatch is not sufficient on its own. A receipt that does not answer to the pinned issuer key MUST NOT count as coverage for the settlement it names, and the settlement MUST still be reported as uncovered (MUST-T4-10). Keys are compared as bytes, by their SubjectPublicKeyInfo DER encoding, on the same terms as MUST-T10-9. A pinned issuer key the verifier cannot decode is a fault in its own configuration and MUST be reported as trust-key-unreadable rather than as a mismatch against the objects; where no pinned key can be decoded at all, nothing is attested and the verifier MUST NOT fall back to accepting the keys the objects carry (MUST-T4-11). Membership in the attested set follows one rule: the signature verifies under a pinned issuer key. The kid header routes the check to a candidate key; the key an object carries beside its signature is not an identity source, because it travels outside the signed octets and anyone can rewrite it. Two consequences are stated so that implementations do not diverge on them. First, an honestly signed object whose carried key was swapped stays attested: the swap is reported (carried-key-mismatch, a warning) and MUST NOT move the object out of the attested set or change the verdict, on the same reasoning as - a surface the signature does not cover must not be able to manufacture a negative result. Second, an object that claims the pin, by its carried key or its kid, but does not verify under it is excluded from the attested set and MUST still be walked and named - for a receipt, receipt-chain-break with a signature-failed detail - never silently dropped; an object that neither verifies under the pin nor claims it is issuer-key-mismatch, excluded, and the settlement it names stays uncovered. The rule, read out per cell (steps 6 and 8 are the verification algorithm's):

Claims the pin (carried key or kid)	Verifies under the pin	Result
yes	yes	attested; a carried key other than the verifying one is carried-key-mismatch, a warning, and does not move the receipt
yes	no	excluded from the attested set; still walked and named in step 6 (receipt-chain-break, signature-failed detail); its settlement stays uncovered in step 8. A checkpoint has no chain walk to be named in, so it is reported as issuer-key-mismatch on this row as well as the next, and the window it would have covered is reported uncovered
no	no	issuer-key-mismatch; excluded; its settlement stays uncovered in step 8 (MUST-T4-9, MUST-T4-10)
no pin held	no pin to verify under	no comparison against a key the verifier holds happens, and the keys the objects carry are not a fallback for one (MUST-T4-11); each signature is still checked against the key its own object carries (), which establishes that the object is internally consistent and nothing about who signed it, so a broken signature is still named (receipt-chain-break, checkpoint-total-mismatch) while two different issuers cannot be told apart; receipts are presented-unattested, the verifier reports unauthenticated-issuer, and accusation-shaped findings take the two-branch severity of MUST-T8-9

A verifier MUST accept an issuer root that is a set of keys rather than a single key (MUST-T4-12), so that a key rotation mid-window does not force it off the pin. The same acceptance applies to a publisher pin, a witness pin, and a rail pin: a verifier MUST accept each of those roots as a set of keys, so a rotation inside the window does not force it off the pin.

The payee root The optional countersignature in travels beside the issuer signature without being covered by it. Anyone holding an honest receipt can append a countersignature of their own, so a verifier that checks it against the key carried next to it learns only that some key signed something. A countersignature MUST NOT be treated as evidence that the payee approved the payment unless it verifies against a payee key the verifier obtained out of band (MUST-T4-13). Without such a key the verifier SHOULD report the condition and MUST treat the guarantee as conditional. Where a verifier has pinned a key for a payee, a settled receipt naming that payee and carrying no attributable countersignature MUST be reported (MUST-T4-14): a countersignature that failed to verify, or verified under some other key, is discarded under and leaves the expectation open exactly as a missing one does. The discarded object itself is a warning, never a failure of the receipt it rode beside; states the invariant.

The decision root A Decision Token is issued by the policy decision point and consumed by the same deployment. A consumer MUST verify a Decision Token against its own issuing key and MUST NOT accept one it cannot check that way (MUST-T6-6).

The manifest root A verifier that is presented with a Trade Manifest MUST obtain the publisher's public key out of band and MUST verify the manifest signature against that key, not against a key the manifest carries (MUST-T4-15). A verifier without such a key that is presented with a Trade Manifest MUST report the completeness guarantee as conditional and SHOULD report the condition; the identifier unauthenticated-manifest is used for it in this document. An audit presented with no Trade Manifest is not made conditional by this requirement. A pinned manifest key the verifier cannot decode is a fault in its own configuration and MUST be reported as trust-key-unreadable rather than as a mismatch, on the same terms as MUST-T4-11. A manifest that does not verify against a readable pin MUST be reported as manifest-key-mismatch and MUST fail the audit. A verifier presented with a Trade Manifest MUST compare the manifest hash to the manifestHash of the receipts presented to the audit and MUST report a manifest that no presented receipt references (MUST-T4-17); the identifier manifest-covers-no-receipt is used for it in this document, and the completeness guarantee is conditional. The comparison runs against those presented receipts, including aborted ones, and is made before any extract window is applied and before any issuer key is applied; a hash on an aborted receipt, on a receipt outside the extract window, or on a receipt no pinned key attests still counts as a reference. This requirement asks whether any receipt names the terms, not whether a settlement in the window was made under them, and not whether the receipt that names them is attributable, so a forged receipt can silence this warning; the report it leaves behind is still conditional and still carries the finding that the receipt answers to no pinned key. This requirement does not reach the audit presented with no Trade Manifest, which remains a deployment choice under MUST-T1-2. Naming a manifest is not obeying one. A verifier presented with a Trade Manifest MUST compare the amount, the currency and the settlement time of every receipt that names it against the manifest's amount, currency and expiry, and MUST report a receipt that departs from them (MUST-T8-9); the identifier manifest-terms-mismatch is used for it in this document. Every receipt that names the manifest is measured, aborted ones included. The time compared is the receipt's timestampMs, against the boundary MUST-T3-3 states: strictly after expiresAtMs departs, exactly at it does not. Amount and currency are compared on the exact-octet terms of MUST-T8-2. Where a usable issuer key is pinned, the comparison is made over the receipts that verify under it and the audit fails. Where none is pinned, the departure is still reported and the audit does not fail on it alone. An issuer key is usable when the pinned issuer root holds at least one key the verifier can decode. A pinned root none of whose keys decode is already trust-key-unreadable and attests nothing, so the comparison takes the unpinned branch while that finding stands; the audit has failed on the configuration fault, and the departure is still reported without becoming a charge no readable key backs. Only receipts that name the manifest are measured against it. Under a usable issuer pin, a departure is a finding rather than a condition on the guarantee. A policy decision point presented with a Trade Manifest it cannot attribute MUST refuse the payment rather than settle and record the doubt (MUST-T4-16): a settled payment carrying the hash of terms nobody authorised cannot be withdrawn by reporting it afterwards.

What the roots do not cover A verifier that supplies none of these roots is not making an error, and this document does not require it to. It is making a weaker statement, and the guarantee it reports must say so. With no issuer key nothing distinguishes one submitted receipt from another, so conditions computed across the submitted set - two receipts claiming one settlement reference, for instance - cannot be attributed to anyone and are reported as conditions of the submission rather than as failures of a party; the finding stands, only its attribution changes.

Reconciliation Completeness is the property that, given an authenticated rail extract, every settlement in the extract has a matching settled Spend Receipt, every settled receipt has a matching settlement, receipt and checkpoint hash chains verify, and checkpoint totals equal the sum of settled receipts in the checkpoint window. If a spend occurred without a receipt, the missing receipt is itself the evidence (MUST-T10-2). The property is stated over a population, and the extract is what declares it: one account, on one rail, over one window (). "Every settlement" means every settlement that extract carried. A settlement path no presented extract covers is not reconciled and not found missing - it is outside the population - so the report names the account, rail and window it was computed over (MUST-T10-19), and a verifier that stated none of them says so instead (MUST-T10-18). A checkpoint published with its totals withheld (, Checkpoint claims) cannot contribute the last of those to the property. It is not a violation of completeness and it is not a demonstration of it either: the comparison was not made, and a result that rests on a comparison nobody made is conditional (MUST-T11-12).

Verification algorithm A verifier MUST perform all of these steps and MUST report every finding they produce (MUST-T10-1). They are numbered for reference, not to require an evaluation order: no step short-circuits another, and an implementation may evaluate them in any order that produces the same set of findings. Two data dependencies limit that freedom, because "any order" read naively would break them. An order that runs a step before the step it consumes does not produce the same set of findings and is not permitted. The first is the index of refs: step 7 builds it, and steps 8 and 9 reconcile it. The second is the issuer pin. The step that resolves it decides the working set: the attested set - the receipts and checkpoints that verify under a usable pinned issuer key - or, when no usable key is pinned, the whole presented set, whose members are presented-unattested. Every later step that walks receipts consumes the working set: the indexing and reconciliation in steps 7 through 9 and the MUST-T8-9 comparison. The chain walk in step 6 consumes the working set plus one addition named in : a receipt that claims the pin and fails to verify under it is walked so the break can be named, and is attested nowhere. A receipt that neither claims the pin nor verifies under it is reported once (issuer-key-mismatch) and then excluded, which is what keeps the settlement it names visible as uncovered (MUST-T4-10); an implementation that let it back into any of those steps would let a forged receipt cover a settlement, satisfy a checkpoint count, or invent a terms charge. Two checks deliberately stay on the presented set whatever any key says, and MUST NOT acquire the dependency: MUST-T4-17, which asks whether a manifest was named at all, and the per-receipt defect checks that ask what a receipt says about itself. Checkpoint and witness verification consumes that working set and is specified in (Verification algorithm), which an implementation of this audit also implements: a receipt that falls in no presented checkpoint window, including every receipt when no checkpoint is presented, fails that document's window-coverage check. When a step names an identifier in backticks, that identifier SHOULD be used for the condition in diagnostic output. The normative requirement is the behaviour: report the condition, identified by the ref or other handle given in the step. The identifiers are not an interoperability surface.

1. Establish the subject of the audit. When an extract is supplied, the settlement records it carries are the ones reconciled; a settlement list from any other source MUST NOT be substituted for them (MUST-T10-12). If the caller supplies both and they differ, the verifier MUST report that the caller-supplied list disagrees with the extract, and MUST still reconcile the extract. The identifier extract-settlement-mismatch SHOULD be used for this condition in diagnostic output.
2. Verify the extract signature against the out-of-band rail key (MUST-T10-8, MUST-T10-9). If no key is pinned, the check that runs is against the key the extract carries, which establishes internal consistency and not origin; the verifier MUST still compute it, MUST NOT read it as a statement about who produced the extract, and MUST treat the completeness guarantee as conditional (MUST-T10-7). The identifier unauthenticated-extract SHOULD be used for this condition in diagnostic output, whatever the extract carries. If a key is pinned and cannot be decoded, the verifier MUST report that the pinned key is unreadable. The identifier trust-key-unreadable SHOULD be used for this condition. If a key is pinned and the signature does not verify against it, or verifies against a different key, the verifier MUST report that the extract is not signed by the pinned key. The identifier extract-key-mismatch SHOULD be used for this condition. The rows of an extract the pin refused are not reconciled against the receipts, and no settlement finding is read out of that document (MUST-T10-20); the identifier settlement-comparison-skipped SHOULD be used to say that the comparison did not run. A finding that puts the extract itself in doubt MUST prevent an unconditional guarantee.
3. Check scope. The verifier MUST report each settlement record whose timestampMs falls outside the declared window, identified by that record's ref (MUST-T10-10). When the verifier states an expected account, rail, or window, it MUST report an extract that does not cover it (MUST-T10-11). The identifier extract-scope-mismatch SHOULD be used for both conditions. If the verifier stated no period, it MUST treat the guarantee as conditional (MUST-T10-15). The identifier unstated-audit-window SHOULD be used for this condition. If it stated no account or no rail, it MUST treat the guarantee as conditional for the same reason (MUST-T10-18); the identifier unstated-audit-scope SHOULD be used. Whatever the verdict, the report MUST name the account, rail and window the extract declared, in every structure it returns for the audit (MUST-T10-19).
4. Resolve each Spend Receipt against the issuer root () in one pass. Decode the COSE_Sign1; a content type that is not the receipt type, a decoder bound, or a decoded claim map that does not match the presented claims is a named refusal, not a signature verdict (MUST-T4-2, MUST-T4-8). Then ask one question: does the signature verify under a pinned issuer key. kid routes the check to a candidate key and carries no authority of its own; the carried key is not consulted for membership at all. The resolution table in reads the answer out per cell. Every cell there is a named condition plus a membership decision; no cell is a silent removal. Where a countersignature is present, governs what it establishes (MUST-T4-13, MUST-T4-14). Where a Trade Manifest is presented, governs it (MUST-T4-15): with no publisher key pinned the verifier reports unauthenticated-manifest and the guarantee is conditional; with a pin that cannot be read, trust-key-unreadable; with a pin the manifest does not answer to, manifest-key-mismatch; and with a manifest that no presented receipt references, manifest-covers-no-receipt (MUST-T4-17). A receipt that names the manifest but departs from its amount, currency, expiry or, where the manifest names one, payee is reported as manifest-terms-mismatch; with a usable issuer key pinned the comparison runs over the attested receipts and the departure fails the audit, and with no usable issuer key it is a warning over the presented receipts and does not by itself fail the audit (MUST-T8-9). An audit presented with no Trade Manifest is not made conditional by this step.
5. Scope the receipts. Membership follows the ref binding first: a receipt whose ref appears on the extract is reconciled against this extract even when its own timestampMs falls outside the declared window - the rail has signed that the settlement belongs to the window, and the receipt follows its settlement. The timestampMs sieve applies only to receipts the extract does not name: such a receipt outside the window is not a completeness failure against this extract (MUST-T10-16); auditing a longer period requires extracts that cover it. At the window's edges the declared allowance applies (): an unmatched settled receipt within clockSkewMs of windowEndMs, and an unmatched settlement record within clockSkewMs of windowStartMs, are reported as boundary-deferred, a warning, rather than as step 8's completeness findings - two honest clocks can disagree by less than the allowance, and both verifiers of an honest edge payment would otherwise reach the same false accusation (MUST-T10-17). Where the following window's extract is presented and verifies, a deferred receipt whose ref appears on it is resolved and not reported, and one whose ref does not appear hardens into the step 8 finding; a deferred settlement record near the opening edge resolves through this step's ref binding, since the prior window's receipt that names its ref is reconciled here regardless of timestamp. The following window's extract closes or hardens closing-edge deferrals only; an opening-edge record stays deferred until a receipt in the presented bag names its ref, whether or not a following extract is presented. In a single-window audit a deferred record keeps the guarantee conditional. Receipts remain subject to every other check regardless of window.
6. Walk the receipts of the working set, together with any receipt that claims the pin and failed to verify under it (), in issuer order. Issuer order is the order induced by the prevReceiptHash chain: the verifier rebuilds the chain from the links, and the order in which receipts were presented carries no weight. timestampMs is issuer-asserted and is not an ordering source. The first prevReceiptHash MUST be null. Each later prevReceiptHash MUST equal receiptHash of the previous receipt. A miss, and a receipt the links cannot place, MUST be reported as a break in the receipt chain. The identifier receipt-chain-break SHOULD be used for this condition. An issuer stream that does not chain its receipts (SHOULD-T4-5) is therefore reported as a break from its second receipt on: the SHOULD states what an issuer owes, and this step states what a verifier does with a stream that did not.
7. Index the settled receipts of the working set and the extract records by ref. A ref that appears more than once on either side MUST be reported as a repeated reference (MUST-T10-6). The identifier duplicate-ref SHOULD be used for this condition.
8. For each ref that appears exactly once on each side, require a one-to-one match on ref AND amount AND currency (MUST-T10-1), compared as exact octets on the terms of MUST-T8-2; step 9's aggregation is the only place this algorithm reads an amount as a number. Amount or currency mismatch MUST be reported as a settlement that does not match its receipt, identified by that ref. The identifier settlement-mismatch SHOULD be used for this condition. A settlement with no receipt MUST be reported as lacking a receipt, identified by its ref (MUST-T10-2). The identifier settlement-without-receipt SHOULD be used for this condition. A settled receipt with no extract row MUST be reported as a completeness failure (MUST-T10-3). The identifier receipt-without-settlement SHOULD be used for this condition. A settled receipt with a null rail ref MUST be reported as settled without a rail reference; this check asks what a receipt says about itself and runs over the presented receipts, attested or not. The identifier settled-without-ref SHOULD be used for this condition. Where a settlement record declares a beneficiary (), it MUST be compared against the matched receipt's payee as exact octets; a difference is beneficiary-mismatch and fails the audit. Where neither the manifest names a payee nor any settlement record declares a beneficiary, the report MUST carry counterparty-unbound, a scope record: ref, amount and currency closed against the payer's account extract, and the counterparty's identity was not bound. It is a statement of what the evidence did not cover, not a doubt about what it did, so it does not move the verdict and does not by itself make the guarantee conditional.
9. A ref already reported as repeating MUST still be reconciled by amount rather than dropped from the comparison (MUST-T10-13). For each currency under that ref, compare the total settled against the total receipted. A settled total that exceeds the receipted total MUST be reported as a settlement lacking a receipt, and the finding MUST state the unaccounted amount. The identifier settlement-without-receipt SHOULD be used for this condition. A settled total that is less than the receipted total MUST be reported as a settlement that does not match its receipt, identified by that ref. The identifier settlement-mismatch SHOULD be used for this condition. An amount on that repeating ref that cannot be parsed as an integer MUST be reported without abandoning the audit; the identifier malformed-amount SHOULD be used for this condition. A verifier MUST still report findings for the remaining records.
10. Aborted receipts are not matched to extract rows and are not added to totals.
11. If any finding remains that is not a warning (a warning is a condition that only makes the completeness guarantee conditional), the audit MUST fail (MUST-T10-4).

Finding codes The identifiers are listed in Appendix B. They are for diagnostic output. They are not an interoperability surface. A finding object that can be carried on the wire is outside the scope of this document and may be defined later. Two implementations interoperate when they accept the same inputs and fail or warn on the same conditions, not when they print the same strings. A condition that makes the audit fail is a finding. A condition that only makes the completeness guarantee conditional is a warning. Warnings MUST still appear in operator-facing output (MUST-T10-14). A finding that puts the extract itself in doubt (extract-key-mismatch, trust-key-unreadable, extract-scope-mismatch, or extract-settlement-mismatch) MUST also prevent an unconditional guarantee, not merely fail the audit. A finding that puts a presented Trade Manifest in doubt (manifest-key-mismatch, or trust-key-unreadable on the manifest pin) does the same. An unconditional guarantee therefore requires all of: an extract, a pinned rail key the extract's signature verifies against, a stated period the extract covers, an issuer root for whatever receipts and checkpoints are presented, a manifest root for whatever Trade Manifest is presented, no finding that puts the extract in doubt, and no warning that withholds part of the comparison. A checkpoint whose totals were signed as withheld (checkpoint-totals-redacted) removes a comparison the guarantee rests on, and a presented checkpoint a supplied witness does not hold (checkpoint-not-anchored) leaves part of the chain unwitnessed. Either one makes the result conditional. Anything less than the whole list is conditional, and the report MUST say so. An implementation MUST make the guarantee and any warnings visible in whatever human-readable audit report it produces under this document, not only in a returned structure (MUST-T10-14). A report that says the books balance while withholding that the balance is conditional invites the reader to take a conditional result for an unconditional one. Checkpoints SHOULD be registered with a Transparency Service (SHOULD-T11-5). A test deployment MAY use an in-process append-only log as the witness (MAY-T11-6). Cedulon still MUST NOT take custody. The guarantee named above is about completeness against the extract, which is the subject of T10. It is not a claim that no checkpoint was suppressed. Suppression is the subject of T11, and a report MUST NOT be read as settling it when no witness was consulted: with no witness receipts, the presented chain is self-consistent by construction and says nothing about what it left out (MUST-T11-9). A verifier that consulted a witness and found every presented checkpoint recorded, with nothing recorded that was not presented, has discharged T11 for the period those receipts cover, and for no longer.

Policy Semantics Policy is default deny. The engine understands three families of rule:

• Limit: maximum amount per payment; maximum cumulative amount per window (MUST-T2-2).
• Velocity: maximum number of allowed payments per window (MUST-T2-1).
• Scope: optional allow-lists for payee, currency, and tool name.

Fail-closed: missing engine, crash, or exception yields deny (MUST-T2-3). Implementations SHOULD emit stable reason codes (SHOULD-T2-5). Decision tokens SHOULD expire after a short time-to-live (TTL) (SHOULD-T6-3). The agent-facing spend interface MUST invoke the PDP and MUST NOT expose a parallel ungated rail call to the model (MUST-T5-1). One boundary is stated here rather than left to be inferred. In the retrospective audit, "allowed by policy" is the Receipt Issuer's signed assertion: the spend passed the issuer's gate under the policyHash the receipt names. The Decision Token is consumed at the gate, and the verification algorithm never sees it; the audit does not independently re-verify the PDP's allow. The completeness side of the audit has an independent leg - the rail extract - and the policy side deliberately does not: that is a trust boundary of this profile, not an oversight. A deployment that wants the policy answer to be independently verifiable needs a receipt-to-token binding, which this document does not define; adding it would change what a receipt carries.

Privacy Considerations A public transparency encoding MUST support omitting or hashing payer and payee identifiers and MUST support amount redaction or bucket encoding (MUST-T9-1). Implementations MUST NOT write government-ID numbers, the Primary Account Number (PAN) of a payment instrument, or street address into a public statement (MUST-T9-2). Default public anchors SHOULD publish policyHash, manifestHash, receiptHash, and timestampMs rather than full claims (SHOULD-T9-3). A private auditor MAY receive an unredacted receipt out of band (MAY-T9-4). The paragraph above counts receipt fields. A checkpoint publishes something a receipt does not: a per-currency total for a whole window, which discloses trading volume even when every individual receipt is redacted (MUST-T9-5). The rule is the one defines and applies: totals MAY be withheld by signing it as null (MUST-T11-12), and only that form counts as a redaction (MUST-T11-13). The structural claims are not redactable, because a verifier that cannot read the window or the chain head cannot check anything at all, and a checkpoint that hid them would be indistinguishable from a broken one. When totals are withheld, a verifier that cannot recompute them says so, and the completeness guarantee for that window is conditional. A deployment that wants an unconditional result publishes the totals; a deployment that wants the volume private accepts a conditional one. What a deployment MUST NOT do is obtain the unconditional result while withholding the evidence for it.

Security Considerations This section is authoritative for the protocol requirements in this document. The threat narratives in are informative and do not override it. Requirement identifiers take the form KEYWORD-Tn-k, where KEYWORD is MUST, SHOULD, or MAY, n is the threat number in this section, and k is a sequence number within that threat. MUST-T8-custody is the custody prohibition under T8. The tables below define the requirement text those citations refer to.

T1: Prompt injection leads to unauthorized spend An attacker plants instructions in tool output, a web page, or a retrieved document. The agent then calls a spend tool outside the principal's intent. Narrative: .

ID	Requirement
MUST-T1-1	The PDP MUST decide from structured request fields and stored policy, not from model-generated prose.
MUST-T1-2	A spend that is not bound to a verified Trade Manifest MUST be marked noManifest on the Spend Receipt and MUST still be subject to limit, velocity, and scope policy.
SHOULD-T1-3	Hosts SHOULD require a human confirmation channel for first-use payees.
MAY-T1-4	An implementation MAY refuse all noManifest spend.

T2: Runaway agent (loop spend) A stuck tool loop or recursive planner issues many payments. Velocity and cumulative-limit counters live in the PDP, fail-closed. Narrative: .

ID	Requirement
MUST-T2-1	Policy MUST express a maximum payment count per configured time window (velocity).
MUST-T2-2	Policy MUST express a maximum amount per payment and a maximum cumulative amount per window.
MUST-T2-3	If the PDP is unreachable, uninitialized, or throws during evaluation, the spend MUST be denied (fail-closed, default deny).
MUST-T2-4	A denied attempt MUST NOT increment the allowed-spend counters as if it had succeeded.
SHOULD-T2-5	Implementations SHOULD emit a stable reason code for velocity and limit denials.

T3: Replay of payment authority An observer replays a signed payment payload, mandate, or Cedulon decision token. Every gated spend carries a unique nonce; manifests expire; tokens are single-use. Narrative: .

ID	Requirement
MUST-T3-1	Every spend attempt that the PDP allows MUST include a nonce that the implementation has not accepted before.
MUST-T3-2	A second attempt that reuses a nonce MUST be denied.
MUST-T3-3	A Trade Manifest MUST carry an expiry; a spend against an expired manifest MUST be denied. The manifest is expired when the settlement time is strictly greater than expiresAtMs; a settlement at exactly expiresAtMs is within the manifest.
MUST-T3-4	A PDP allow decision MUST be bound to the SHA-256 of the canonical encoding of the request fields it evaluated, as stated in , and MUST be single-use.
SHOULD-T3-5	Nonce stores SHOULD persist across process restart when the deployment is not a test fixture.

T4: Receipt forgery or repudiation A party alters a receipt, invents a receipt, or denies a real spend. Receipts are signed; verification covers the signed bytes; a hash chain links them. Narrative: .

ID	Requirement
MUST-T4-1	A Spend Receipt MUST be signed by the Receipt Issuer over the deterministic CBOR encoding of its claims, as profiled in . The phrase "canonical encoding" is reserved for JSON documents ().
MUST-T4-2	Verifiers MUST reject a receipt whose signature does not validate or whose canonical bytes do not match the signed payload.
MUST-T4-3	A Spend Receipt MUST include payer, payee, amount, currency, policyHash, timestampMs, and nonce.
MUST-T4-4	A Spend Receipt MUST include manifestHash or an explicit noManifest flag, never an ambiguous empty hash. Empty optional values are CBOR null; labels are never absent.
SHOULD-T4-5	Receipts SHOULD form a hash chain (prevReceiptHash) so omission is detectable within one issuer stream.
MAY-T4-6	Parties MAY register the signed receipt as a SCITT statement to obtain a COSE receipt.
MUST-T4-7	A Spend Receipt MUST include outcome (settled or aborted). A settled receipt MUST have a non-null rail ref. Aborted receipts MUST NOT enter checkpoint totals.
MUST-T4-8	COSE_Sign1 protected headers MUST use alg -19 (Ed25519), a mandatory kid, and a payload-specific content type. Verifiers MUST reject a kid that does not match the configured issuer key.
MUST-T4-9	A verifier MUST obtain the issuer public key out of band and MUST verify Spend Receipt and epoch checkpoint signatures against that key. A key carried by the object MUST NOT be treated as the signer's identity and MUST NOT be used as a fallback where no key was obtained (MUST-T4-11). A verifier without such a key that is presented with any Spend Receipt or epoch checkpoint MUST report the completeness guarantee as conditional. An audit presented with neither rests on the extract alone and is not made conditional by this requirement.
MUST-T4-10	A receipt that does not verify against the pinned issuer key MUST NOT count as coverage for the settlement it names, and that settlement MUST still be reported as uncovered. Reporting the mismatch is not sufficient on its own.
MUST-T4-11	Pinned issuer keys MUST be compared by SubjectPublicKeyInfo DER encoding. A pinned key that cannot be decoded MUST be reported as a verifier configuration fault rather than as a mismatch, and where no pinned key decodes, the verifier MUST NOT fall back to the keys the objects carry.
MUST-T4-12	A verifier MUST accept an issuer, publisher, witness, or rail root comprising more than one key, so that a key rotation inside the audited window does not require it to abandon pinning.
MUST-T4-13	A payee countersignature MUST NOT be treated as evidence of payee approval unless it verifies against a payee key the verifier obtained out of band.
MUST-T4-14	Where a verifier has pinned a key for a payee, a settled receipt naming that payee and carrying no attributable countersignature MUST be reported.
MUST-T4-15	A verifier that is presented with a Trade Manifest MUST obtain the publisher public key out of band and MUST verify the manifest signature against that key, not against a key the manifest carries. A pin that cannot be read MUST be reported as trust-key-unreadable; a readable pin the manifest does not answer to MUST be reported as manifest-key-mismatch and MUST fail the audit. A verifier without such a key that is presented with a Trade Manifest MUST report the completeness guarantee as conditional. An audit presented with no Trade Manifest is not made conditional by this requirement.
MUST-T4-16	A policy decision point presented with a Trade Manifest it cannot verify against a key supplied out of band MUST refuse the payment.
MUST-T4-17	A verifier presented with a Trade Manifest MUST compare the manifest hash against the manifestHash of the receipts presented to the audit, including aborted ones, before any extract window is applied and before any issuer key is applied, and MUST report a presented manifest that no presented receipt references. An audit presented with no Trade Manifest is not made conditional by this requirement.
MUST-T4-18	A decoder MUST refuse a CBOR map that carries a duplicate encoded key.
MUST-T4-19	A decoder MUST impose a bound on encoded size, nesting depth, and the number of elements it will decode from an audit input, and MUST refuse an input that exceeds a bound with a named refusal rather than by exhausting memory or the stack. It SHOULD document the bounds it applies. This document fixes no numbers.
MUST-T4-20	A verifier that receives a JSON document as text MUST refuse a text in which any object repeats a member name, by name (json-duplicate-key), before parsing it. A verifier handed an object rather than text cannot apply this rule and MUST NOT report that it did.
MUST-T4-21	A decoder MUST refuse a COSE_Sign1 message whose unprotected header is not an empty map, by name (cose-sign1-unprotected), rather than verifying the signature and ignoring the header.

T5: Policy bypass via direct rail access The agent or an attacker calls the rail without the PDP. The only payment function is the adapter that calls the PDP first. Narrative: .

ID	Requirement
MUST-T5-1	The agent-facing spend interface MUST invoke the PDP and MUST NOT expose a parallel ungated rail call to the model.
MUST-T5-2	Rail credentials, wallet handles, and facilitator tokens MUST NOT be placed in tool results or prompts.
SHOULD-T5-3	Hosts SHOULD run the PDP and signing keys in a process the model runtime cannot write.
MAY-T5-4	A deployment MAY use OS or hardware isolation between the model and the PDP.

T6: Time-of-check to time-of-use (TOCTOU) between policy check and payment An allow is computed; the request is then swapped before the rail sees it. Settlement pays only the exact fields hashed into the single-use decision. Narrative: .

ID	Requirement
MUST-T6-1	Payment settlement MUST use the same six requestHash fields the PDP evaluated: amount, currency, payee, tool, nonce, and manifestHash.
MUST-T6-2	An allow decision MUST be consumed on the first settlement attempt, success or fail-closed abort, and MUST NOT authorize a later different request.
SHOULD-T6-3	Implementations SHOULD treat a decision older than a short TTL as expired.
MUST-T6-4	An allow Decision Token MUST be COSE_Sign1 with CWT private-use labels -70301..-70305 (requestHash, policyHash, expiryMs, nonce, singleUseId) and content type application/cedulon-decision+cbor.
MUST-T6-5	A party that accepts a Decision Token MUST reject a failed signature, a kid or content-type mismatch, a claim-map mismatch, or an expired expiryMs. The token is expired when the evaluation time is strictly greater than expiryMs; at exactly expiryMs it is not.
MUST-T6-6	A consumer of a Decision Token MUST verify it against its own issuing key and MUST NOT accept a token it cannot check that way.
MUST-T6-7	A party that records a settlement under a Decision Token MUST refuse it when that settlement's timestampMs is strictly greater than the token's expiryMs. At exactly expiryMs the settlement remains inside the token's authority; the boundary is the one MUST-T6-5 states.

A later verifier cannot make this comparison. Decision Tokens are not among the inputs enumerates: the extract, the receipts, the manifests, the checkpoints, and the witness receipts. The rule is written on the party that can apply it. Verification does not repeat it. MUST-T6-7 does not let a later verifier detect a settlement that predates its decision. That would require carrying the decision's issuance time on the token and binding the receipt to it, which this document does not define. MUST-T6-4 names the same five labels.

T7: Signing-key leakage Keys leak from disk, logs, or a prompt. Forged manifests or receipts follow. Narrative: .

ID	Requirement
MUST-T7-1	Secret key material MUST NOT appear in receipts, checkpoints, manifests, decision tokens, logs, or example output.
MUST-T7-2	Example and test keys MUST be generated at runtime or stored as clearly fake fixtures, never as production secrets.
SHOULD-T7-3	Production deployments SHOULD use a hardware security module (HSM) or operating-system key store and SHOULD rotate keys.
MAY-T7-4	Implementations MAY encrypt keys at rest.
MUST-T7-5	An implementation that stores a signing key in the clear MUST report the protection it actually obtained, measured from the stored object rather than derived from the platform.
MUST-T7-6	A writable directory anywhere on the path to a stored signing key makes the file permission moot, and a symbolic link on that path hands the destination to whoever placed it. An implementation MUST refuse both rather than report the key as protected.

T8: Counterparty price gouging or defective delivery The payee ships a different artifact, or the price exceeds the signed offer. The Trade Manifest binds price and an acceptance-criteria hash before payment. Narrative: .

ID	Requirement
MUST-T8-1	A Trade Manifest MUST bind goods or service description, price, currency, acceptance-criteria hash, cancel condition, and expiry.
MUST-T8-2	A spend bound to a manifest MUST be denied if the requested amount or currency differs from the manifest. Amount and currency are compared as the exact octets of their text strings: no case folding, no Unicode normalisation, no numeric reinterpretation.
MUST-T8-3	If delivery bytes do not hash to the acceptance-criteria hash, the implementation MUST be able to produce a Dispute Evidence Bundle containing the manifest, the spend receipt, and the delivery hash.
MUST-T8-4	The Dispute Evidence Bundle MUST NOT be described as an arbitral award or escrow release.
MUST-T8-7	manifestHash MUST be the SHA-256 of the signed Trade Manifest COSE bytes and MUST NOT include the issuer public key encoding.
SHOULD-T8-5	Manifests SHOULD reference an AP2 mandate hash when one exists.
MAY-T8-6	Parties MAY add an optional escrow actor as a third-party role interface; an implementation of this specification MUST NOT take custody (MUST-T8-custody).
MUST-T8-custody	Implementations of this specification MUST NOT take custody of funds or operate escrow.
MUST-T8-8	If a payee countersignature is present, a verifier MUST reject it when the signature fails, when kid or content type does not match the configured payee key, or when the receiptCose value (label -70401) is not the issuer COSE_Sign1 bytes.
MUST-T8-9	A verifier presented with a Trade Manifest MUST compare the amount, currency and settlement time of every receipt that names it, aborted ones included, against the manifest amount, currency and expiry - amount and currency on the exact-octet terms of MUST-T8-2, time on the boundary of MUST-T3-3, and, where the manifest names a payee, the receipt payee on the same exact-octet terms - and MUST report a receipt that departs from them. Where a usable issuer key is pinned (a pinned issuer root at least one of whose keys the verifier can decode), the comparison is made over the receipts that verify under it and a departure MUST fail the audit. Where no usable issuer key is pinned, the departure MUST still be reported and MUST NOT by itself fail the audit. Receipts that do not name the manifest are not measured against it. A Trade Manifest that a stated publisher pin refuses is not terms for this purpose: where the verifier reports manifest-key-mismatch, it MUST NOT read a charge out of that document's body, neither this comparison nor the acceptance-hash comparison of .
MAY-T8-10	A payee MAY attach a detached COSE_Sign1 countersignature over the issuer receipt bytes. Absence MUST NOT invalidate the issuer receipt.
MAY-T8-11	An attributable countersignature MAY carry deliveredHash. When present and the verifier holds the Trade Manifest, the verifier MUST compare it against acceptanceCriteriaHash as exact octets and MUST report a mismatch as a failing finding (delivery-mismatch). A deliveredHash on an unattributable countersignature MUST be discarded with it.

Optional escrow role Parties MAY name an escrow actor in a Trade Manifest as a third-party role that holds funds under rules outside this protocol (MAY-T8-6). Implementations of this specification MUST NOT take custody or operate escrow (MUST-T8-custody).

T9: Personally identifiable information (PII) leakage into the transparency log A public receipt or transparency statement carries names, addresses, or full amounts that should stay private. Log-facing encodings offer redaction. See also . Narrative: .

ID	Requirement
MUST-T9-1	A transparency encoding MUST support omitting or hashing payer/payee identifiers and MUST support amount redaction or range/bucket encoding.
MUST-T9-2	Implementations MUST NOT write raw government-ID, payment-instrument PAN, or street address fields into a public transparency statement.
SHOULD-T9-3	Default public anchors SHOULD publish policyHash, manifestHash, receiptHash, and timestamp rather than full claim sets.
MAY-T9-4	A private auditor MAY receive an unredacted receipt out of band.
MUST-T9-5	A checkpoint discloses a per-currency window total, which the receipt-field rules above do not cover. Withholding it is governed by MUST-T11-12 and MUST-T11-13: null in the signed payload, and no other form of redaction honoured.

T10: Secret spend via rail bypass An operator, leaked credential, or a second binary can settle on the rail and omit the Receipt Issuer. Completeness reconciles the extract to the receipts. See . Narrative: .

ID	Requirement
MUST-T10-1	A verifier MUST match each extract settlement to a settled receipt on ref AND amount AND currency. An audit presented with no extract, no receipts and no checkpoints reports no completeness finding. It is not thereby unconditional, and the warnings for the roots it was not given still apply.
MUST-T10-2	A settlement with no matching receipt MUST be reported as a completeness failure identified by that settlement ref.
MUST-T10-3	A settled Spend Receipt whose x402PaymentRef is not on the extract MUST be reported as a completeness failure.
MUST-T10-4	An audit that has any fail-severity completeness finding MUST fail.
SHOULD-T10-5	Hosts SHOULD still apply T5 (no ungated rail in the model process). Completeness does not replace prevention.
MUST-T10-6	A ref that appears more than once among settled receipts or among extract rows MUST be reported as duplicate-ref.
MUST-T10-7	A verifier MUST obtain the extract from the rail or from a rail signature. With no pinned rail key the extract MUST be reported as unauthenticated-extract, whatever it carries, and the completeness guarantee is conditional. With a pinned key, see MUST-T10-8: the extract MUST fail closed rather than warn.
MUST-T10-8	A verifier MUST obtain the rail public key out of band and MUST verify the extract signature against that key. A key the extract carries MUST NOT be treated as the rail's identity and MUST NOT stand in for a key the verifier did not obtain. Without such a key the guarantee is conditional and the condition is reported as unauthenticated-extract.
MUST-T10-9	Keys MUST be compared by SubjectPublicKeyInfo DER encoding rather than by any text encoding. A pinned key that cannot be decoded MUST be reported as trust-key-unreadable, not as a key mismatch.
MUST-T10-10	Every settlement record whose timestampMs falls outside the extract's declared window MUST be reported as extract-scope-mismatch, identified by that record's ref. This check MUST run whether or not a key is pinned.
MUST-T10-11	When the verifier states an expected account, rail, or window, an extract that does not cover it MUST fail closed as extract-scope-mismatch.
MUST-T10-12	When an extract is supplied, the records it carries are the subject of reconciliation. A settlement list from another source MUST NOT be substituted; a disagreeing list MUST be reported as extract-settlement-mismatch.
MUST-T10-13	A ref reported as duplicate-ref MUST still be reconciled by aggregate amount per currency, and a shortfall MUST state the unaccounted amount. An unparseable amount MUST be reported as malformed-amount without aborting the audit.
MUST-T10-14	An implementation MUST surface the guarantee and any warnings in any human-readable audit report it produces, not only in a returned structure.
MUST-T10-15	A verifier that supplies a rail pin but has not stated the period under audit MUST emit unstated-audit-window and MUST treat the guarantee as conditional; with no rail pin at all the condition reported is unauthenticated-extract.
MUST-T10-16	When an extract is supplied, a receipt whose ref appears on it is reconciled against it regardless of its own timestampMs; the window sieve applies only to receipts the extract does not name, and such a receipt outside the window MUST NOT be reported as a completeness failure against that extract.
MUST-T10-17	An unmatched settled receipt within the declared clockSkewMs of windowEndMs, and an unmatched settlement record within it of windowStartMs, MUST be reported as boundary-deferred, a warning, rather than as a completeness failure. A closing-edge deferral resolves against the following window's extract and hardens into the completeness finding when that extract is presented and does not name the ref; an opening-edge deferral resolves only against a receipt in the presented bag that names its ref, and a following extract does not harden it. Absent a declared clockSkewMs, the profile default of 300000 milliseconds applies.
MUST-T10-18	A verifier that supplies a rail pin but has not stated the account or the rail under audit MUST emit unstated-audit-scope and MUST treat the guarantee as conditional; with no rail pin at all the condition reported is unauthenticated-extract.
MUST-T10-19	A report MUST name the account, rail and window the extract declared, in the printed report, in the finding object it returns, and in every other structure the implementation returns for that audit, a tool result or an export included. Where no extract was presented there is no declared population, and the structure names none.
MUST-T10-20	Where a stated rail pin refuses the presented extract and the verifier reports extract-key-mismatch, the verifier MUST NOT read a settlement finding out of that document's body: not a mismatch against a receipt, not money reported as unaccounted for, and not a receipt left unmatched by rows the refused document omits. The verifier MUST report settlement-comparison-skipped in the same result. A pinned key the verifier cannot decode is trust-key-unreadable and is not a refusal of the document, so it does not reach this requirement.

In MUST-T10-4, a completeness finding that makes the audit fail is distinct from a warning that only makes the guarantee conditional. The verification algorithm states that distinction by behaviour ().

T11: Checkpoint suppression or rollback Checkpoint suppression and rollback, and the witness that detects them, are addressed in . The two requirements below are defined here because the core label set and the reconciliation depend on them.

ID	Requirement
MUST-T11-1	An epoch checkpoint MUST be COSE-signed and MUST bind epoch number, time window, receipt count, chain-head hash, per-currency totals, and the previous checkpoint hash.
MUST-T11-12	Withheld checkpoint totals MUST be encoded as null in the signed payload. A verifier MUST report that the totals comparison was skipped and MUST treat the guarantee as conditional; receiptCount and chainHeadHash MUST still be checked.

T12: Settlement without a recorded receipt The threats above are about a counterparty, a rail or an attacker. This one is about the issuer's own implementation, and it produces exactly the condition the rest of this document exists to make detectable. Ordering, recovery and observability: .

ID	Requirement
MUST-T12-1	An issuer MUST NOT complete a settlement whose receipt it cannot record durably. The ability to record MUST be established before value moves, not after.
MUST-T12-2	Where a settlement has been made and its record cannot be completed, the issuer MUST undo the settlement in every place it still controls: in memory, on the rail ledger it controls, and in any later write it has not yet issued. A refused payment MUST NOT consume the nonce or the payment allowance it never used.
MUST-T12-3	Two issuers MUST NOT share one durable state. An implementation that permits it MUST fail loudly rather than let one writer overwrite the other's receipt, and the failure MUST name what an operator can act on.
MUST-T12-4	Where a settlement has entered a rail the issuer does not control, and the local record cannot be completed, the outcome is indeterminate. The issuer MUST NOT treat the payment as reversed, and MUST NOT return the authority to spend, unless it holds authenticated evidence that the rail did not complete the settlement or that a reversing entry completed.

IANA Considerations This document requests the registration of four media types in the "Media Types" registry , in the standards tree, each carrying the +cbor structured syntax suffix that registers. Each names one of the COSE_Sign1 objects this document defines and is carried as the COSE content type header parameter (label 3) of that object (). The value is a normative check inside a protected header (MUST-T4-8, MUST-T6-5), which is why the names cannot stay unregistered while that check stands. Registration in the standards tree requires IETF approval; until then, an implementation outside a closed deployment should treat these names as placeholders that a registration may change. The provisional registration procedure of Section 5.2.1 is available to an Internet-Draft, and a provisional entry, if one is made, is superseded by the registration this section requests. The claim labels this document assigns inside the CBOR claim sets, -70001 through -70402 (, ), lie in the Private Use range of the "CBOR Web Token (CWT) Claims" registry , integer values less than -65536, and this document requests no assignment for them. A later Standards Track revision that moves them into the assigned range will request new labels then, without reinterpreting these. No other IANA action is requested. The four templates follow. The checkpoint and inclusion types are in . Fields that are the same for every one are stated once, in the first, and the others say so.

application/cedulon-receipt+cbor

Type name:

application

Subtype name:

cedulon-receipt+cbor

Required parameters:

N/A

Optional parameters:

N/A

Encoding considerations:

binary. A COSE_Sign1 structure in deterministic CBOR , untagged, as profiled in and .

Security considerations:

See of this document. The object is signed; its evidentiary weight depends on the verifier holding the issuer key out of band (), never on a key the object carries.

Interoperability considerations:

The claim set is a CBOR map with the labels and types stated in , encoded per Section 4.2.1. A decoder refuses a duplicate key (MUST-T4-18), an input beyond its stated bounds (MUST-T4-19), and a non-empty unprotected header (MUST-T4-21) by name rather than accepting it.

Published specification:

This document, .

Applications that use this media type:

Agent payment adapters, policy decision points, auditors, and dispute-evidence tooling that produce or verify Cedulon Spend Receipts.

Fragment identifier considerations:

N/A

Additional information:

Deprecated alias names for this type: N/A. Magic number(s): N/A. File extension(s): N/A. Macintosh file type code(s): N/A.

Person and email address to contact for further information:

Emek Can Dogru, e.dogru@cedulon.com

Intended usage:

COMMON

Restrictions on usage:

N/A

Author:

Emek Can Dogru

Change controller:

IETF

application/cedulon-manifest+cbor

Type name:

application

Subtype name:

cedulon-manifest+cbor

Encoding considerations:

binary. A COSE_Sign1 structure in deterministic CBOR, untagged, as profiled in and .

Security considerations:

See of this document. A manifest is an offer signed before payment; it binds terms, not delivery, and is verified only against a publisher key held out of band ().

Interoperability considerations:

As for application/cedulon-receipt+cbor; the labels are those of the manifest table in , and the payee label is encoded only when present.

Published specification:

This document, .

Applications that use this media type:

Payees and marketplaces that publish signed offers to paying agents, and verifiers reconciling receipts against those offers.

Required parameters, optional parameters, fragment identifier considerations, additional information, contact, intended usage, restrictions on usage, author, change controller:

As for application/cedulon-receipt+cbor.

application/cedulon-decision+cbor

Type name:

application

Subtype name:

cedulon-decision+cbor

Encoding considerations:

binary. A COSE_Sign1 structure in deterministic CBOR, untagged, as profiled in and .

Security considerations:

See of this document. A Decision Token is consumed at the gate by the party that issued it (); it is not an input to the retrospective audit (), and a verifier that treated it as one would be claiming a check the audit does not make.

Interoperability considerations:

As for application/cedulon-receipt+cbor; the labels are those of the Decision Token table in , all five always present.

Published specification:

This document, .

Applications that use this media type:

Policy decision points and the payment adapters that consume their allow decisions.

Required parameters, optional parameters, fragment identifier considerations, additional information, contact, intended usage, restrictions on usage, author, change controller:

As for application/cedulon-receipt+cbor.

application/cedulon-countersign+cbor

Type name:

application

Subtype name:

cedulon-countersign+cbor

Encoding considerations:

binary. A detached COSE_Sign1 structure in deterministic CBOR, untagged, as profiled in , whose payload carries the exact issuer receipt octets it countersigns.

Security considerations:

See of this document. A countersignature that does not verify under a payee key held out of band carries no evidentiary weight and cannot move the verdict on the receipt it travels beside (, ).

Interoperability considerations:

As for application/cedulon-receipt+cbor; the optional deliveredHash claim is a 32-octet byte string and is read as absent when it is not.

Published specification:

This document, .

Applications that use this media type:

Payees that acknowledge a receipt and, optionally, bind the bytes they delivered.

Required parameters, optional parameters, fragment identifier considerations, additional information, contact, intended usage, restrictions on usage, author, change controller:

As for application/cedulon-receipt+cbor.

Implementation Status This section is to be removed before publishing as an RFC. RFC 7942 note. Detailed status is kept in the companion repository, where it can be corrected without a revision of this document.

Implementation:

A companion implementation with a runnable verification suite at https://github.com/dogrucanemek-alt/cedulon. The code is a profile of this document, not a second specification. This -04 is not an IETF working-group item.

Maturity:

Research code by a single implementer. Three readers have run the code on their own machines against a pinned commit and reported figures matching the author's: two from a clean clone of the whole suite, one re-running the published reproduction. That is byte-stability across environments and not an independent implementation; the same code agreeing with itself on three machines rules out a local accident and nothing more. One reader reports an independent implementation of the Signed Statement identity, kept deliberately separate from this codebase; no independent implementation of the reconciliation algorithm is known to the author. One reader rebuilt the regenerated receipt vector of Appendix A from this text alone, in an independent toolchain, and obtained the published 307 octets byte for byte, SHA-256 0f1fe8859faf25de906b08142674f1270656d8ea7bfc00853c2fc6e9d3f5a10b; that reader had read parts of the public repository and says so, so it is not a clean-room result.

Coverage:

The receipt, checkpoint, extract, reconciliation and verification algorithm are implemented, including the transparency witness input, the withheld and not-anchored conditions, and signed totals redaction. Every requirement added in the posted series is covered by a red-then-green case written before the text, with one exception: the reversal branch of MUST-T12-4 is specified and not executed, because this tree carries no authenticated external-rail path. MUST-T6-7, the one requirement this document adds beyond that series, is likewise specified and not executed: no case in the suite compares a settlement's timestampMs to a Decision Token's expiryMs. The escrow role, reversal, refund and partial settlement are not implemented. The witness used in the suite is the in-process log that MAY-T11-6 permits, a Merkle tree that issues inclusion proofs; tier 2 of (The transparency witness) is exercised against it red-then-green, and the implementation has not been run against a deployed Transparency Service.

Continuous integration runs the pre-release suite - the post-release registry checks are a separate job, deliberately excluded, so "the suite" names exactly what was measured - on three hosted runners, each as a non-root user: Linux, macOS and Windows. At the commit this revision describes, all three assert every case, 596 of 596, with none skipped. A local Windows run without symbolic-link privilege skips four POSIX-mode cases with a stated reason rather than passing silently.

Licensing:

Apache-2.0.

Contact:

The author of this document.

Experience:

The posted series was driven by what readers found rather than by a plan. T12 came from none of them: it was found while writing an adversarial task, in the ordering the implementation itself used.

The manifest root (MUST-T4-15) and the gate's refusal to settle against a manifest it cannot attribute (MUST-T4-16) were published as 0.4.0 rather than as a patch: the gate had been answering 200 to an unattributable manifest and writing that manifest's hash into the receipt, and refusing it is a change in behaviour that a version number ought to announce. Note on distribution: everything the posted series added is in the published packages at version 0.9.0, and the workspace publishes 0.13.1 as this revision is written. A reader can check a claim against an installed package rather than against a working tree. A second implementation is named here. Same author as this document; not an independent implementation.

Organization:

VERAX TEKNOLOJI LIMITED SIRKETI.

Implementation:

Verax. An MCP body that consumes the published @cedulon/* libraries to write signed decision records, effect extracts and checkpoints. The code is a profile of this document, not a second specification.

Description:

The body admits six tools through its own gate: memory.get, memory.put, message.read, message.send, spend and audit.explain. An admitted call leaves a signed decision record; a retry under the same reference is answered from that record rather than writing a second one, and a denial the body cannot append is refused to the caller instead of being recorded. An allowed call is expected to leave an effect row, and the audit path reconciles the rows against the records; an allow whose effect cannot be found is reported as such rather than assumed to have run. A halted body answers every further call with a signed denial record. Each halt and resume is also written to the ledger as a control record signed by the body's record key, naming whoever the halt history names. When an operator is registered, an approval over HTTP carries a passkey (WebAuthn) assertion bound to the held request, and the offline verifier checks it again against the operator's public key; a command-line approval stays unsigned. Once an operator is registered, a resume over HTTP is refused without such an assertion; a halt may carry one and is never refused for lacking it; a halt or resume from the command line stays unsigned. Each token revocation is also written as a signed denial record. The offline verifier holds each record to the inputs row its signed inputs hash names, and each checkpoint's counts to the records it covers.

Level of maturity:

Research and pilot. Witnesses are self or same-org. There is no third-party witness of the body's own effects and no outside audit. A checkpoint hash can be registered with a Transparency Service that someone else runs, and the receipt is checked offline; that receipt shows the checkpoint existed, not what the tools did. One live spend row has been reconciled against a card statement: 10.00 TRY on 6 September 2026, a charge made by hand after the rail deferred it and an operator approved it. That statement carried dates without times and the rule named no descriptor, so the row was matched on the wide date window by amount, currency and class; a settled rather than a pending row is unproven, as is a statement holding several rows of one amount. A tenant boundary has not been exercised with two live customers.

Coverage:

@cedulon/cose and @cedulon/core implement the signed decision record (COSE Sign1 and the Decision Record). @cedulon/effect-extract implements the effect extract. @cedulon/checkpoint implements the checkpoint. @cedulon/audit is called when a window is explained. @cedulon/x402-adapter is present as a library; there is no live x402 rail, and the body does not move money.

Version compatibility:

Verax 0.4.6 depends on @cedulon/* 0.13.1. Those published packages implement the posted draft-dogru-cedulon-09 profile and, from 0.13.0, the posted draft-dogru-cedulon-decision-profile-03. 0.13.1 changes no behaviour from 0.13.0. This document is the split form of that numbered series.

Licensing:

Apache-2.0.

Implementation experience:

Used by its author to record tool calls and to reconcile one live card charge. Gaps that remain - a third-party witness, two live customers on one body, a live payment rail - are named in STATUS.md in the Verax repository, not claimed here.

Contact:

The author of this document.

URL:

https://github.com/verax-ai/verax. The packages @verax-ai/body, @verax-ai/proxy and @verax-ai/inventory are on npm at 0.4.6 (https://www.npmjs.com/package/@verax-ai/body, https://www.npmjs.com/package/@verax-ai/proxy, https://www.npmjs.com/package/@verax-ai/inventory). The MCP Registry name is io.github.verax-ai/verax. The archived release is https://doi.org/10.5281/zenodo.22811593.

Evolution and Future Work (Informative) This document is an individual Internet-Draft. If the work is taken up, the intended track is a Standards Track profile of COSE and CWT for agent-spend receipts. Two extensions are sketched and not specified here: re-attestation of receipts when a signature algorithm is retired , and reconciliation evaluated as settlements arrive rather than per epoch . The same completeness check could apply to other consumed resources, such as compute or data; this document does not specify those profiles.

Informative Notes on Adjacent Protocols x402 uses HTTP 402 to negotiate stablecoin payment. AP2 uses signed mandates as verifiable credentials. Cedulon does not replace either protocol. Profiles built on HTTP Message Signatures authenticate bots; they are not a spend receipt. The drafts below are complementary, and none of them defines rail-extract completeness. draft-bates-atp covers tamper-evident causal lineage as a signed directed acyclic graph. draft-vauban-x402-stark-receipts specifies x402 receipt-format variants that a Cedulon Spend Receipt MAY carry as a rail proof. draft-schrock-ep-outcome-binding compares authorized action bytes to independently observed effects. draft-marques-asqav-compliance-receipts profiles access-control action receipts (the broader Acta family includes ). draft-hopley-x402-compliance-receipt records an admission-time compliance decision. draft-abak-agent-control-delivery-evidence states evidence requirements for a governance control - stop, suspend, revoke - travelling toward the component expected to constrain a runtime, and keeps emission, receiver-side observation, enforcement outcome and observed control effect as separate results. Its object moves the other way from this one: Cedulon reconciles a spend that already happened against what the rail reported, and evidences neither the delivery of a control instruction nor its enforcement. A denied spend leaves no portable artifact here at all - a Decision Token encodes an allow () - so what a Cedulon audit says about a refusal it says through the settlement that did not appear on the extract, which is an effect observation over a declared population and not an acknowledgement from an enforcement point. Its bounded-population rule and this document's MUST-T10-18 and MUST-T10-19 are the same kind of bound on two different objects. draft-kuehlewind-audit-architecture , the architecture a Cedulon audit is intended to be read within, is described in ; it also covers propagation of audit context across domains and optional attestation under the Remote ATtestation procedureS (RATS) architecture. draft-birkholz-verifiable-agent-conversations defines a COSE-signed record of an agent's conversation - session metadata, messages, tool invocations, reasoning traces - for the same Transparency Services. A Spend Receipt is the kind of artifact such a record would name for a payment step; neither document profiles the other, and the conversation record does not define rail-extract completeness.

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. Federal Information Processing Standard, FIPS This document defines procedures for the specification and registration of media types for use in HTTP, MIME, and other Internet protocols. This memo documents an Internet Best Current Practice. I-JSON (short for "Internet JSON") is a restricted profile of JSON designed to maximize interoperability and increase confidence that software can process it successfully with predictable results. This document describes elliptic curve signature scheme Edwards-curve Digital Signature Algorithm (EdDSA). The algorithm is instantiated with recommended parameters for the edwards25519 and edwards448 curves. An example implementation and test vectors are provided. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR), and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON. This document specifies algorithm identifiers and ASN.1 encoding formats for elliptic curve constructs using the curve25519 and curve448 curves. The signature algorithms covered are Ed25519 and Ed448. The key agreement algorithms covered are X25519 and X448. The encoding for public key, private key, and Edwards-curve Digital Signature Algorithm (EdDSA) structures is provided. Cryptographic operations like hashing and signing need the data to be expressed in an invariant format so that the operations are reliably repeatable. One way to address this is to create a canonical representation of the data. Canonicalization also permits data to be exchanged in its original form on the "wire" while cryptographic operations performed on the canonicalized counterpart of the data in the producer and consumer endpoints generate consistent results. This document describes the JSON Canonicalization Scheme (JCS). This specification defines how to create a canonical representation of JSON data by building on the strict serialization methods for JSON primitives defined by ECMAScript, constraining JSON data to the Internet JSON (I-JSON) subset, and by using deterministic property sorting. The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack. This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR. This document, along with RFC 9053, obsoletes RFC 8152. Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need to be able to define basic security services for this data format. This document defines a set of algorithms that can be used with the CBOR Object Signing and Encryption (COSE) protocol (RFC 9052). This document, along with RFC 9052, obsoletes RFC 8152. This specification refers to cryptographic algorithm identifiers that fully specify the cryptographic operations to be performed, including any curve, key derivation function (KDF), and hash functions, as being "fully specified". It refers to cryptographic algorithm identifiers that require additional information beyond the algorithm identifier to determine the cryptographic operations to be performed as being "polymorphic". This specification creates fully-specified algorithm identifiers for registered JSON Object Signing and Encryption (JOSE) and CBOR Object Signing and Encryption (COSE) polymorphic algorithm identifiers, enabling applications to use only fully-specified algorithm identifiers. It deprecates those polymorphic algorithm identifiers. This specification updates RFCs 7518, 8037, and 9053. It deprecates polymorphic algorithms defined by RFCs 8037 and 9053 and provides fully-specified replacements for them. It adds to the instructions to designated experts in RFCs 7518 and 9053. CBOR Object Signing and Encryption (COSE) Receipts prove properties of a Verifiable Data Structure (VDS) to a verifier. VDSs and associated Proof Types enable security properties, such as minimal disclosure, transparency, and non-equivocation. Transparency helps maintain trust over time and has been applied to certificates, end-to-end encrypted messaging systems, and supply chain security. This specification enables concise transparency-oriented systems by building on Concise Binary Object Representation (CBOR) and COSE. The extensibility of the approach is demonstrated by providing CBOR encodings for Merkle inclusion and consistency proofs. Traceability in supply chains is a growing security concern. While Verifiable Data Structures (VDSs) have addressed specific issues, such as equivocation over digital certificates, they lack a universal architecture for all supply chains. This document defines such an architecture for single-issuer signed statement transparency. It ensures extensibility and interoperability between different transparency services as well as compliance with various auditing procedures and regulatory requirements. Informative References This document describes a simple process that allows authors of Internet-Drafts to record the status of known implementations by including an Implementation Status section. This will allow reviewers and working groups to assign due consideration to documents that have the benefit of running code, which may serve as evidence of valuable experimentation and feedback that have made the implemented protocols more mature. This process is not mandatory. Authors of Internet-Drafts are encouraged to consider using the process for their documents, and working groups are invited to think about applying the process to all of their protocol specifications. This document obsoletes RFC 6982, advancing it to a Best Current Practice. The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes. This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230. This document describes a mechanism for creating, encoding, and verifying digital signatures or message authentication codes over components of an HTTP message. This mechanism supports use cases where the full HTTP message may not be known to the signer and where the message may be transformed (e.g., by intermediaries) before reaching the verifier. This document also describes a means for requesting that a signature be applied to a subsequent HTTP message in an ongoing HTTP exchange. x402 Foundation Google Agentic Commerce Vauban Research

Acknowledgments Vernon Wharff showed that the object carrying the checkpoint guarantee was neither profiled for registration nor read during verification, and asked whether a recorded checkpoint absent from the chain deserves its own identifier. Iman Schrock confirmed that finding independently and drew its boundary. Iman Schrock and Pablo Etcheverry ran the implementation against a pinned commit and reported defects that shaped this document. Iman Schrock found the extract-binding defects and proposed their repair, asked whether the profile should accept a pinned witness key, and corrected this document's description of what its continuous integration measures. He is also the author of , cited here as adjacent work, and the reader whose independent implementation of the Signed Statement identity is noted in ; he asked for it to be kept separate from any cross-implementation claim about Cedulon, and that separation is his and is recorded here as he stated it. Pablo Etcheverry found that a repeated reference hid the unaccounted amount, ran the suite on a platform its author had not, and found that nothing compared a settlement's clock to the clock of the decision that authorized it. Nicholas Templeman ran the suite from a clean clone, corrected two claims written about that run, and classified his own run as a repetition of the author's checks rather than an independent implementation. Walter Hawkins did not run it; he pressed for the run to be stated precisely enough to be repeatable. Tiago Pinto ran the Appendix A vectors in an independent toolchain before reading the text, confirmed the signatures, the SPKI-derived kid, and deterministic re-encoding byte for byte, and listed the places where an independent implementation could not be built from the text. The witness tiers, the key-resolution rule, the extract shape, issuer order, the boundary allowance, and the countersignature and delivery bindings follow that list, and answers a later point of his. He consented to that run being recorded as the first run of these vectors outside the companion codebase and not as an independent implementation. Steven Mih and Anton Sokolov published the canonicalization vectors of ; running them through this profile's encoder put the I-JSON precondition on the page as a rule. None of them reviewed this text, and any error in it is the author's. Field survey notes and the informative threat-model narrative in the companion repository helped shape the requirement identifiers used here. Those identifiers are defined in and, for T11, in .

Appendix A. Test Vectors These vectors use RFC 8032 Ed25519 secret scalar #1 (fixture only; never a production key). Hex is lowercase. The vectors below MUST stand as the locked tests of this document: an implementation matches them or it does not, and where an implementation and a vector disagree, one of the two is wrong and this document does not say in advance which. Receipt COSE_Sign1: Claims: payer=payer-1, payee=payee-1, amount=1, currency=USD, policyHash= fca4142da8ad241d24928227893894f4b5365efb746a4529fe9df0119d10da2c (the SHA-256 of the UTF-8 octets of the ASCII string cedulon/appendix-policy, standing in for a canonical policy document; the field's input rule is in ), manifestHash=null, noManifest=true, x402PaymentRef=null, timestampMs=1700000000000, nonce=n100000000000000, prevReceiptHash=null, outcome=aborted. COSE_Sign1 hex (whitespace ignored): Manifest COSE_Sign1: Body: description=fixture-goods, amount=1, currency=USD, acceptanceCriteriaHash= e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 (the SHA-256 of an empty delivery; the field is a digest of the exact delivery bytes, so the vector carries a well-formed one), cancelCondition=none, expiresAtMs=1700000000000, ap2MandateHash=null. COSE_Sign1 hex (whitespace ignored):

Appendix B. Finding Codes

Code	Effect	Meaning
settlement-without-receipt	audit fails	Extract row has no matching settled receipt, or a repeating ref settled more than it receipted
receipt-without-settlement	audit fails	Settled receipt ref is not on the extract
settlement-mismatch	audit fails	Same ref, different amount or currency, including a repeating ref that settled less than it receipted
duplicate-ref	audit fails	Ref appears more than once on one side
settled-without-ref	audit fails	outcome is settled and x402PaymentRef is null
receipt-chain-break	audit fails	Signature or prevReceiptHash failed, or the links cannot place a receipt (issuer order, step 6)
unauthenticated-extract	guarantee conditional	No verifier-supplied rail key, whatever the extract carries: a signature that verifies establishes internal consistency and not that the named rail produced the extract, and one that fails or is refused is not a key verdict either. The same code is reported when a rail key is pinned and no extract was presented at all, because there is nothing to check the pin against. A presented extract that does not verify under a pinned key is extract-key-mismatch instead
extract-key-mismatch	audit fails	Extract is signed by a key other than the pinned rail key, or does not verify against it
settlement-comparison-skipped	guarantee conditional	The pinned rail key refused the presented extract, so its rows were not reconciled against the receipts (MUST-T10-20). The code says what did not run; the refusal itself is reported as extract-key-mismatch
trust-key-unreadable	audit fails	A pinned key - rail, issuer, or manifest publisher - could not be decoded; the verifier's configuration is at fault, and nothing falls back to the keys the objects carry
issuer-key-mismatch	audit fails	An object is signed by a key other than the pinned issuer key, or does not verify under it at all, so it is not coverage for anything it names. A checkpoint reaches this code by either route: unlike a receipt, which is named in the chain walk as receipt-chain-break when it claims the pin and fails, a checkpoint that claims the pin and fails is reported here and leaves its window uncovered
countersign-key-mismatch	conditional	A countersignature verifies under a key other than the one pinned for that payee; unattributable, discarded as approval evidence, and the receipt it rode beside is unaffected ()
countersign-missing	conditional	A payee key is pinned and a settled receipt for that payee carries no attributable countersignature; a discarded garbage or foreign-key object leaves this open
unauthenticated-issuer	conditional	No verifier-supplied issuer key and at least one receipt or checkpoint presented; their signatures are checked against the keys the objects carry (), which establishes that each object is internally consistent and not that the named issuer produced it
unauthenticated-countersigner	conditional	No verifier-supplied payee key; a countersignature is present but proves no approval
unauthenticated-manifest	conditional	No verifier-supplied manifest key and a Trade Manifest was presented; its signature is not checked at all, because the check that exists under a pin (manifest-key-mismatch) has no key to run against and the key the manifest carries is not a fallback for one. An audit presented with no Trade Manifest is not this condition
manifest-key-mismatch	audit fails	A presented Trade Manifest is signed by a key other than the pinned publisher key, or does not verify against it
manifest-covers-no-receipt	conditional	A presented Trade Manifest is referenced by no presented receipt, including aborted ones and those outside the extract window; the manifest states terms no presented receipt names. It is reported on what was presented, not on whether the manifest was attributed, so it appears beside manifest-key-mismatch as well
manifest-terms-mismatch	audit fails under a usable issuer pin; warning without one	A receipt names this Trade Manifest but departs from it in amount, currency, settlement time, or, where the manifest states one, payee. A manifest refused by a stated publisher pin is not compared at all; a gate applying MUST-T8-2 and MUST-T3-3 would have refused the payment. The two severities are the two branches of MUST-T8-9
extract-scope-mismatch	audit fails	A record falls outside the declared window, or the extract does not cover the expected account, rail, or window
extract-settlement-mismatch	audit fails	A caller-supplied settlement list disagrees with the extract on ref, amount, currency or timestamp, which are the fields compared; the extract is authoritative. A beneficiary that differs is not part of this comparison and is reached by beneficiary-mismatch, against the receipt payee
malformed-amount	audit fails	An amount on a ref already reported as repeating that could not be parsed as an integer
unstated-audit-window	guarantee conditional	A supplied rail pin states no period, so the extract defined its own. Where no rail key is pinned at all the period is equally unstated, and unauthenticated-extract is the condition reported
unstated-audit-scope	guarantee conditional	A supplied rail pin states no account or no rail, so the extract defined the settlement path it reported on. The same "no pin at all" case is unauthenticated-extract
countersign-bad	conditional	Present payee countersignature failed verify (signature, content type, or payload binding); unattributable, discarded as approval evidence. One verifiable under another key is countersign-key-mismatch
carried-key-mismatch	conditional	An object verifies under a pinned issuer key but the key carried beside its signature is a different one; the unsigned surface was rewritten, the object stays attested ()
boundary-deferred	conditional	An unmatched item sits within the declared clockSkewMs of the window edge; deferred to the adjacent window rather than reported as a completeness failure (step 5)
beneficiary-mismatch	audit fails	A settlement record declares a beneficiary and the matched receipt's payee differs
counterparty-unbound	scope record; verdict and guarantee unchanged	Neither the manifest names a payee nor any settlement record declares a beneficiary: ref, amount and currency closed against the payer's account extract, and the counterparty's identity was not bound
delivery-mismatch	audit fails	An attributable countersignature carries deliveredHash and it differs from the acceptance-criteria hash of a Trade Manifest the audit did not refuse; both ends are signed (MAY-T8-11). Where a stated publisher pin refuses the manifest, its acceptance hash founds nothing and this comparison is not made (MUST-T8-9)
malformed-policy-hash (and its family: malformed-request-hash, malformed-acceptance-criteria-hash, malformed-manifest-hash, malformed-receipt-hash, malformed-prev-receipt-hash, malformed-chain-head-hash, malformed-prev-checkpoint-hash, malformed-ap-two-mandate-hash)	audit fails	A hash-shaped claim does not match the 64-lowercase-hex grammar of ; the claim is named in the code

Appendix C. Worked Example: A 10.00 TRY Spend This appendix is informative. An agent pays 10.00 Turkish lira (TRY) for a file. Amounts are integer minor units, so the amount is 1000. The run used the companion implementation with keys generated for the run; the keys are not published, so signatures and hashes are not shown. No real rail was involved.

1. The PDP allows the request (amount 1000, currency TRY, payee shop-1) and the adapter settles it under rail reference x402-n-10try-example-0001.
2. The Receipt Issuer signs a Spend Receipt with these claims (policyHash omitted):

3. The rail signs an extract for account acct-1, rail rail-1 and the one-hour window [1789400000000, 1789403600000), with one row: ref x402-n-10try-example-0001, amount 1000, currency TRY. The issuer signs one checkpoint for the same hour.
4. A verifier that holds the issuer key and the rail key, and states that account, rail and window, reconciles them. The result is balanced under an unconditional guarantee. It carries the scope record counterparty-unbound, because no manifest names a payee.

The same audit was then run against an extract the rail signed with a second 10.00 TRY row, ref rail-ref-unreceipted, twenty minutes into the window, that no receipt names. The verifier reported settlement-without-receipt for that ref and the audit failed. That row is the case this document exists to detect: money that left through the rail without a receipt. The same control has also been run once with real money, by a related implementation from the same author that records a spend as a signed decision and effect record rather than as the Spend Receipt of this document. On 6 September 2026 an agent asked to spend 10.00 TRY on advertising, the policy deferred the request, it was approved under the operator's account, and the amount was paid by card to the advertising platform. The next day the payer's bank statement arrived, and its line for that payment was reconciled against the approved spend: one matched, none unaccounted for. Two limits apply. The statement was received as an image rather than as a signed file from the bank, and the line was transcribed from it, so under this document the result would be conditional (unauthenticated-extract). The line also did not carry the spend reference, because the platform billed under its own descriptor, so the match rested on amount, currency and date alone.