POST

Governance

Start MPC signing

/api/v2/governance/proposals/{proposal_uuid}/mpc-ceremonies/{request_uuid}/signing-sessions
AUTHENTICATIONBearer token · governance:request_mpcService ownergovernance-serviceContract sourceOpenAPISTATUSProduction listed

Purpose and usage

What this endpoint does

Start commitment-bound threshold signing only after the pinned participant-readiness threshold is final.

When to use it

Call this when a workspace governor, policy administrator, custody participant, or governance agent needs to apply the documented mpc signing transition after re-reading the current authoritative state so it can make a proposal, authority, decision, or ceremony transition under the correct quorum and policy.

OUTCOME · Create or advance

What changes

Creates or advances only the mpc signing resource described by this contract after authorization, validation, policy, and idempotency gates pass.

WHY IT MATTERS

  • Gives people and agents a contract-backed way to advance mpc signing.
  • Keeps deliberation, approval evidence, authority assignment, and threshold-signing participation explicit and auditable.

ISOLATION + AUTHORITY

Tenant, workspace, proposal, voter, authority assignment, quorum, custody participant, and signing-session boundaries remain separate. A proposal, recorded decision, assigned role, or ceremony request does not by itself activate a contract, produce a threshold signature, move value, or grant publisher, matching, or trading authority.

BEFORE YOU CALL

  • Authenticate at the documented boundary: bearer+scope.
  • Supply the required proposal_uuid (path), request_uuid (path), requestCommitment (body), intentCommitment (body) exactly as defined by the live contract.
  • Use one Idempotency-Key only for retries of the same byte-equivalent logical mutation.
  • Resolve the current proposal or assignment version, eligible authority, quorum rule, and purpose-bound policy before relying on this result.

WHAT TO DO NEXT

  • Re-read mpc signing using the canonical identifier returned by this operation.
  • Reconcile an ambiguous response with the same idempotency key before attempting another mutation.
  • Re-read the proposal, assignment, quorum, or ceremony state and verify its version and commitments before advancing the governed action.

AGENT GUIDANCE

  • Use mpc signing only for the purpose and lifecycle stage described by this operation; do not treat it as authority for an adjacent action.
  • Supply the required proposal_uuid (path), request_uuid (path), requestCommitment (body), intentCommitment (body) exactly as defined by the live contract.
  • Keep proposal creation, review, decision recording, quorum satisfaction, authority assignment, ceremony request, participant signing, execution, and finality as separate lifecycle facts.
  • After a timeout or conflict, read authoritative state before deciding whether an equivalent retry is safe.
Contract reference

Use the deployed OpenAPI for exact parameters, schemas and security requirements. The tables below provide integration guidance.

Open this operation in OpenAPI

Request and response

Make the request

Examples illustrate integration intent; the referenced OpenAPI operation and component schemas define the executable shape.

PARAMETERS

Headers, path, query, and body

NAMELOCATIONPRESENCETYPE / RULES / PURPOSE
proposal_uuidpathRequired

identifierCanonical proposal uuid. It selects the exact proposal uuid addressed by this route.EXAMPLEproposal-uuid-01

request_uuidpathRequired

identifierStable request uuid selecting the exact resource addressed by this route.EXAMPLErequest-uuid-01

AuthorizationheaderRequired

Bearer tokenCredential containing governance:request_mpc authority.EXAMPLEBearer hc_live_…

Idempotency-KeyheaderRequired

ASCII string · 1–128Caller-generated stable key reused for retries of the same logical mutation.EXAMPLEpost-api-v2-governance-proposals-proposal-uuid-mpc-ceremonies-request-uuid-signing-sessions-request-001

X-Request-IDheaderOptional

stringOptional caller correlation identifier. The gateway emits the effective value on the response.

Content-DigestheaderRequired

stringRFC 9530 sha-256 digest of the exact transmitted request-body bytes.

Signature-InputheaderRequired

stringRFC 9421 sig1 input covering @method, @path, content-digest, content-type, and idempotency-key, with created, expires, nonce, keyid, and alg=ed25519.

SignatureheaderRequired

stringRFC 9421 sig1 Ed25519 signature made by an active key registered to the bearer client.

intentCommitmentbodyRequired

lowercase SHA-256 digestExact retained governance-intent commitment. It is validated as part of the request body before any operation is attempted.EXAMPLEintentCommitment-01

requestCommitmentbodyRequired

lowercase SHA-256 digestExact participant-ready MPC ceremony commitment.EXAMPLErequestCommitment-01

REQUEST

JSON body example

{
  "intentCommitment": "example-intentcommitment",
  "requestCommitment": "example-requestcommitment"
}

RESPONSES

Status and payload examples

201Mutation accepted and canonical state returned.Mutation completed · JSON RESPONSE+
{
  "proposal": "example-proposal"
}
INTEGRATION DECISION
CALLER ACTION
Accept the returned representation or receipt, then re-read mpc signing using the canonical identifier returned by this operation.
RETRY SAFETY
Do not repeat a successful mutation merely to confirm it. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions.
STATE RECONCILIATION
Persist returned identifiers, versions, commitments, and receipts. Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
400The request syntax, required metadata, or JSON body is malformed.Request must change · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Rebuild the request from the live OpenAPI operation and correct the rejected method, media type, header, parameter, or body field.
RETRY SAFETY
Do not retry the same invalid request. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions.
STATE RECONCILIATION
Compare the submitted values with the documented constraints before another call. Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
401Bearer credential is missing, expired, or invalid.Authentication required · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Discard the rejected credential, complete the documented authentication or reassertion flow, and rebuild any request signature with fresh timestamps and nonces.
RETRY SAFETY
Retry only with a newly valid credential and fresh replay-protection values. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions.
STATE RECONCILIATION
Assume the outcome is unknown only when the connection failed after transmission; otherwise authentication failed before domain work. Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
403The principal lacks the required scope, role, tenant, or step-up authority.Authority or policy denied · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Verify the exact scope, tenant or workspace membership, owner boundary, step-up purpose, feature policy, and resource eligibility. Never broaden authority automatically.
RETRY SAFETY
Do not retry until the missing authority or policy condition has been deliberately resolved with least privilege.
STATE RECONCILIATION
Confirm the caller and resource resolve to the same authority boundary for owner-scoped wallet inventory, custody policy, balances, intents, reservations, transactions, and receipts.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
404The requested resource does not exist within the authenticated authority boundary.Resource not visible · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Verify the canonical identifier and authenticated owner boundary. A 404 may intentionally conceal a resource outside the caller's authority.
RETRY SAFETY
Do not retry the unchanged identifier repeatedly. Refresh the relevant collection or lookup before choosing another identifier.
STATE RECONCILIATION
Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
409The request conflicts with current state or an idempotency key was reused inconsistently.State reconciliation required · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Stop the mutation sequence and fetch the latest authoritative resource, lifecycle state, version, ETag, reservation, or existing idempotency result.
RETRY SAFETY
Retry only after reconciling the conflict. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions.
STATE RECONCILIATION
Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
422Path, query, or body validation failed.Request must change · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Rebuild the request from the live OpenAPI operation and correct the rejected method, media type, header, parameter, or body field.
RETRY SAFETY
Do not retry the same invalid request. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions.
STATE RECONCILIATION
Compare the submitted values with the documented constraints before another call. Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.
503The authoritative service or read model is unavailable.Dependency unavailable or outcome uncertain · JSON RESPONSE+
{
  "code": "invalid_credentials",
  "message": "the supplied Hybrid credential is invalid"
}
INTEGRATION DECISIONinvalid_credentials
CALLER ACTION
Preserve the exact request and treat the outcome as uncertain until authoritative state proves whether it committed.
RETRY SAFETY
Reconcile before retrying. For one logical mutation, retain the same Idempotency-Key and byte-equivalent request. Never reuse that key for changed instructions. Use bounded backoff with jitter.
STATE RECONCILIATION
Re-read the wallet, intent, reservation, and transaction status on the same network; compare policy version, nonce, digest, and terminal receipt before another command.
ESCALATE WHEN
Escalate when funds, reservations, transaction digests, or MPC state remain ambiguous after authoritative wallet and network reconciliation.

OPERATIONAL NOTES

Security and lifecycle guarantees

  • Start commitment-bound threshold signing only after the pinned participant-readiness threshold is final. Authoritative owner: governance-service.
  • The Rust gateway validates the public contract and routes only to the authoritative owner; clients never address internal services directly.
  • Mutations are retry-safe only when the same Idempotency-Key and canonical request body are reused.
  • The tables and examples are derived from the current gateway source OpenAPI. Re-fetch the deployed OpenAPI before execution; deployment status is shown separately on this page.
  • Only parameters present in the OpenAPI operation are accepted; undocumented query keys fail closed with HTTP 422.
Reference version and availability details

This route is implemented in canonical gateway source and appears in the production OpenAPI snapshot observed 2026-10-02T23:27:55.510Z. Authentication, tenant, feature, venue, and market policy still apply.

Verify the exact production OpenAPI operation Return to the V2 directory