POST /api/config/update

Write attributes into the key server configuration, and verify by re-reading.

Applies a batch of attribute writes and verifies each one against a FRESH read taken afterwards.

This route does NOT take the key server's own wire shape. The underlying operation takes a whole serialized XML ELEMENT per path; this surface builds that element itself, from {xpath, attr, value} triples, so that a caller cannot attach an attribute that changes which node a path resolves to, set the access flag, or rewrite attributes it did not name.

value must be a STRING. A JSON number or boolean would be stringified by some other layer and the stored form would not be the one you sent.

attr: "accessFlag" is refused at the door. It is the one genuine silent no-op left on this operation: the key server SKIPS that attribute inside its apply loop while the batch still returns success, so a caller sending it would be told the write landed when nothing happened.

An unresolvable xpath refuses the WHOLE batch before the wire, as a 400 naming every offender. The key server would refuse it too -- one bad entry rejects the entire batch -- but as a 500 naming only the first.

WARNING: the batch is ALL-OR-NOTHING at the key server, and a non-writable node rejects it before anything is applied. That refusal arrives as a 500 carrying the key server's own message, which names the node.

WARNING: observed is reported ONLY for an allow-listed (element, attribute) pair. For anything else applied is computed over the stored value but the value itself does not leave this process -- a route that echoed back what it just stored would be a credential oracle.

WARNING: an idempotent write cannot be distinguished from one that never happened. If the submitted value already equalled the stored one, the comparison matches either way.

Authentication

Send the session id as Authorization: Bearer <session id>, and an RFC 9449 DPoP proof in the DPoP header if your session is bound to a key. The two are required together, not as alternatives — see Authenticating and Proving you hold your key.

This surface sets no cookie

There is no session cookie on any response and none is read on any request. Do not set credentials: "include" on a browser fetch.

Request

Field	Type	Required	Description
writes	array of object	yes

writes[] object

Field	Type	Required	Description
xpath	string	yes	Must name an ELEMENT. The literal root is refused -- an attribute write needs an element.
attr	string	yes	accessFlag is refused.
value	string	yes	Must be a string.

Example

{
  "writes": [
    {
      "xpath": "...",
      "attr": "...",
      "value": "..."
    }
  ]
}

Responses

200

Every requested write is present in a fresh read taken after the update.

Field	Type	Required	Description
code	string	no	Absent on success; NOT_VERIFIED otherwise.
verified	boolean	no
batchSize	integer	no
outcomes	array of object	no
detail	string	no

outcomes[] object

Field	Type	Required	Description
xpath	string	no
attr	string	no
applied	boolean	no
observed	string	no	Present ONLY for an allow-listed (element, attribute) pair. For anything else applied is computed and the value itself does not leave the process.
reason	string	no	Present when applied is false.

Example

{
  "code": "...",
  "verified": true,
  "batchSize": 0,
  "outcomes": [
    {
      "xpath": "...",
      "attr": "...",
      "applied": true,
      "observed": "...",
      "reason": "..."
    }
  ],
  "detail": "..."
}

400

BAD_REQUEST -- writes absent, not an array or empty; an entry malformed; attr is accessFlag; value not a string; or one or more xpaths do not resolve, in which case the whole batch was refused BEFORE the wire and the detail names every offender.

401

No live session, a DPoP proof that did not verify, or a certificate session whose certificate the key server now refuses.

SESSION_NOT_FOUND -- the credential names no session this Gateway holds. SESSION_EXPIRED -- it aged out. Both carry reauth: true; obtain a new credential rather than retrying.

PROOF_* -- the sender constraint refused. See the DPoP section of this document for the full table; PROOF_MALFORMED is a 400 and PROOF_REPLAY_CACHE_FULL a 503, and the rest are here.

SCOPED_CREDENTIAL_EXPIRED -- a scoped browser credential passed its fixed lifetime. Use does not extend it: an idle timeout would be refreshed by exactly the traffic a stolen handle produces.

CERTIFICATE_REVOKED -- on a session established by certificate login, the key server re-checks the certificate that session was established with on its operations, and it is now named by revocation evidence (ADR 0115). detail is the key server's sentence. Every later operation of the session is refused the same way; log in with a different certificate.

403

Authenticated, and refused. The codes differ in what they say about where the refusal came from: ACCESS_DENIED, PRINCIPAL_DISABLED and DELEGATOR_REFUSED are the key server's -- the last one on a DELEGATED session whose delegator has since been disabled, lost its DELEGATION flag, been unenrolled or had its certificate revoked (ADR-0123); its detail is the key server's sentence naming the delegator, and no new login helps until an administrator restores it. REVOCATION_STATUS_UNAVAILABLE and REVOCATION_EVIDENCE_STALE are the key server's too, on a session established by certificate login: the same re-check found no current revocation evidence for that certificate's issuer under a policy that requires it (ADR 0115) -- the credential is not what was refused, and an operator importing a current CRL for the issuer is what helps -- while NOT_WRITABLE, BUILT_IN_PRINCIPAL, OWN_ACCOUNT and OBJECT_NOT_IN_CREDENTIAL_SCOPE are decided by the Gateway before anything is sent.

409

NOT_VERIFIED -- the key server did not refuse the batch, and the read-back does not show every requested value stored.

500

A fault rather than a refusal.

OP_FAILED is the catch-all: the key server refused in words that match no classified pattern, so the Gateway cannot say more than that the operation did not happen. Some key server refusals that are conceptually a caller error arrive here rather than as a 4xx, because the wire carries no distinguishing code -- where a route can recognise one from its message it maps it, and each such mapping is documented on the operation.

503

A capacity ceiling or a missing deployment prerequisite. retryable says which.

A scope of session or process names the ceiling that was hit, and the response carries Retry-After.

BUILD_NOT_ADMITTED (scope: process, retryable: true, Retry-After): the key server does not admit this Gateway's client build. Every key-server connection the Gateway opens attests the signed release it runs (TE_RELEASE_MANIFEST) right after it authenticates; while that attestation is refused -- the release is not registered at the key server's code-signing level, the level was raised under it, or the installed files no longer match the signed manifest -- every route but GET /api/health and GET /api/ready answers this, and detail names the cause. It is never a 401 or a 403: no credential or role of the caller's is at fault. The Gateway re-attempts on a timer and recovers without a restart once the key server admits it; GET /api/ready says when.

Error handling

Every failure answers JSON carrying at least code and detail. Match on code — detail is written for a human debugging the call and its wording is not part of the contract. See the error model.

Status	Meaning
400	BAD_REQUEST -- writes absent, not an array or empty; an entry malformed; attr is accessFlag; value not a string; or one or more xpaths do not resolve, in which case the whole batch was refused BEFORE the wire and the detail names every offender.
401	No live session, a DPoP proof that did not verify, or a certificate session whose certificate the key server now refuses. SESSION_NOT_FOUND -- the credential names no session this Gateway holds. SESSION_EXPIRED -- it aged out. Both carry reauth: true; obtain a new credential rather than retrying. PROOF_* -- the sender constraint refused. See the DPoP section of this document for the full table; PROOF_MALFORMED is a 400 and PROOF_REPLAY_CACHE_FULL a 503, and the rest are here. SCOPED_CREDENTIAL_EXPIRED -- a scoped browser credential passed its fixed lifetime. Use does not extend it: an idle timeout would be refreshed by exactly the traffic a stolen handle produces. CERTIFICATE_REVOKED -- on a session established by certificate login, the key server re-checks the certificate that session was established with on its operations, and it is now named by revocation evidence (ADR 0115). detail is the key server's sentence. Every later operation of the session is refused the same way; log in with a different certificate.
403	Authenticated, and refused. The codes differ in what they say about where the refusal came from: ACCESS_DENIED, PRINCIPAL_DISABLED and DELEGATOR_REFUSED are the key server's -- the last one on a DELEGATED session whose delegator has since been disabled, lost its DELEGATION flag, been unenrolled or had its certificate revoked (ADR-0123); its detail is the key server's sentence naming the delegator, and no new login helps until an administrator restores it. REVOCATION_STATUS_UNAVAILABLE and REVOCATION_EVIDENCE_STALE are the key server's too, on a session established by certificate login: the same re-check found no current revocation evidence for that certificate's issuer under a policy that requires it (ADR 0115) -- the credential is not what was refused, and an operator importing a current CRL for the issuer is what helps -- while NOT_WRITABLE, BUILT_IN_PRINCIPAL, OWN_ACCOUNT and OBJECT_NOT_IN_CREDENTIAL_SCOPE are decided by the Gateway before anything is sent.
409	NOT_VERIFIED -- the key server did not refuse the batch, and the read-back does not show every requested value stored.
500	A fault rather than a refusal. OP_FAILED is the catch-all: the key server refused in words that match no classified pattern, so the Gateway cannot say more than that the operation did not happen. Some key server refusals that are conceptually a caller error arrive here rather than as a 4xx, because the wire carries no distinguishing code -- where a route can recognise one from its message it maps it, and each such mapping is documented on the operation.
503	A capacity ceiling or a missing deployment prerequisite. retryable says which. A scope of session or process names the ceiling that was hit, and the response carries Retry-After. BUILD_NOT_ADMITTED (scope: process, retryable: true, Retry-After): the key server does not admit this Gateway's client build. Every key-server connection the Gateway opens attests the signed release it runs (TE_RELEASE_MANIFEST) right after it authenticates; while that attestation is refused -- the release is not registered at the key server's code-signing level, the level was raised under it, or the installed files no longer match the signed manifest -- every route but GET /api/health and GET /api/ready answers this, and detail names the cause. It is never a 401 or a 403: no credential or role of the caller's is at fault. The Gateway re-attempts on a timer and recovers without a restart once the key server admits it; GET /api/ready says when.