> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/api-reference/account/set-cancel-on-disconnect.md).

# PUT /account/cancel-on-disconnect

Set cancel-on-disconnect

Set cancel-on-disconnect.

`operationId`: `setCancelOnDisconnect`

> **Declared server:** `https://api.testnet.nexus.xyz/v1`. See [Networks](/api-reference/guides/networks.md).

> **Not reachable through CCXT.** Cancel-on-disconnect is a Nexus session policy, not a CCXT method.

**Authentication:** `agentAuth`, `hmacAuth`.

## Set cancel-on-disconnect

> Enables or disables cancel-on-disconnect for the authenticated account. Opt-in is per account and off by default: someone who deliberately leaves a passive resting order while offline should not have a brief blip cancel it. Enable it when you want the guarantee that a dead client cannot keep orders resting — typical for market makers and algorithmic traders. Returns the resulting COD status (same shape as the GET).

````json
{"openapi":"3.1.0","info":{"title":"Nexus Exchange API","version":"0.9.101"},"tags":[{"name":"Account","description":"Balance and order management"}],"servers":[{"url":"https://api.testnet.nexus.xyz/v1","description":"Public testnet (play funds) — the default server and /v1 transport base for unversioned paths."},{"url":"https://api.nexus.xyz/v1","description":"Mainnet — **REAL FUNDS**. Collateral is USDX bridged from Ethereum Mainnet; orders placed here move real money, and there is no faucet. The durable per-network base. Listed after testnet on purpose, so nothing that reaches for \"the first https server\" lands on the real-funds target. Not resolvable yet: DNS/TLS is a separate infra change."},{"url":"http://localhost:9090","description":"Local development — the indexer served directly. Not a public network; whatever your local instance holds."}],"security":[{"hmacAuth":[]},{"agentAuth":[]}],"components":{"securitySchemes":{"hmacAuth":{"type":"apiKey","in":"header","name":"X-API-Key","description":"HMAC API key authentication. Send three headers:\n- `X-API-Key`: your key ID (e.g. `nx_a1b2c3...`)\n- `X-Timestamp`: current time in unix milliseconds\n- `X-Signature`: `hex(hmac_sha256(secret, timestamp + \"\\n\" + METHOD + \"\\n\" + path + \"\\n\" + query + \"\\n\" + sha256_hex(body)))`\n\nTimestamp must be within 30 seconds of server time.\n\n**The key is network-scoped; the signature is not.** The canonical string above has no network component, so the same signed request is byte-identical on every host. What stops a testnet key from authenticating against mainnet is that the key does not exist in that host's key store — sign only for the host that minted the key, and never replay a signed payload against another network. Presented to the wrong host, a key is refused with the same opaque `401` as an unknown key and must not be retried there. See “API keys are bound to one network” in the API description."},"agentAuth":{"type":"apiKey","in":"header","name":"x-agent","description":"Agent-key request signing. An agent is a secp256k1 keypair the wallet delegates trading to with `POST /agents/register`; the agent then signs each request itself, so the wallet key is never exposed. Send four headers:\n\n- `x-agent`: the agent's 20-byte address, hex, `0x` prefix optional — derived from its public key exactly like a wallet address (`keccak256(uncompressed_pubkey[1..])[12..]`). It must be registered on this host and not expired.\n- `x-timestamp`: the current time in unix milliseconds, as a base-10 integer.\n- `x-nonce`: an unsigned 64-bit integer, base 10. Required on every request; see “Nonces” for when it is enforced.\n- `x-signature`: `0x` followed by the hex of the 65-byte signature described under “Signature”.\n\n**Canonical string.** Six fields joined by LF (`\\n`), with no trailing newline:\n\n```\n{METHOD}\\n{path}\\n{query}\\n{sha256_hex(body)}\\n{x-timestamp}\\n{x-nonce}\n```\n\n- `METHOD` is upper-cased. The field order differs from `hmacAuth`: the method comes first and the timestamp comes after the body hash, so an HMAC canonical-string builder cannot be reused.\n- `path` is the logical path the server authenticates, with no host and no query string — the same rule as `hmacAuth`; see “Base paths and the signed path” in the API description.\n- `query` is the raw query string exactly as sent, without the leading `?`. With no query it is the empty string, and its line stays in the string as an empty line; it is never dropped.\n- `sha256_hex(body)` is the lower-case hex SHA-256 of the exact body bytes sent. A request with no body hashes the empty byte string (`e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855`).\n- `x-timestamp` and `x-nonce` are the same decimal strings sent in those headers.\n\n**Digest.** `keccak256(utf8(canonical_string))`: raw Keccak-256 of the canonical string, **with no EIP-191 prefix and no EIP-712 structure**. A wallet library's `signMessage` / `personal_sign` adds the `\\x19Ethereum Signed Message:\\n` prefix, which produces a different digest and a signature that recovers to some other address. Sign the 32-byte hash directly (for example `eth_account`'s `unsafe_sign_hash`, or `@noble/curves` `secp256k1.sign(digest, key)`).\n\n**Signature.** Recoverable secp256k1 ECDSA over the digest, sent as 65 bytes `r (32) ‖ s (32) ‖ v (1)` with `v ∈ {27, 28}`. `s` must be low (at most half the curve order, per EIP-2). A high-S signature is refused even though it recovers the same signer, because accepting it would let one authorization be presented as two. The server recovers the signer from the digest and requires it to equal `x-agent`.\n\n**Freshness.** `x-timestamp` must be within ±30 seconds of the server's clock, on reads and writes alike. That window is the only bound on how long a captured read signature can be replayed.\n\n**Nonces.** The nonce is parsed on every request but enforced only on writes:\n\n- On a mutating method (anything but `GET`, `HEAD`, `OPTIONS` and `TRACE`), `x-nonce` must be strictly greater than the highest nonce this host has already accepted on a write from the same agent. The accepted value is persisted before the response is sent. Each agent address has its own nonce space, separate from the wallet-signed nonces of `POST /agents/register` and `POST /withdrawals`.\n- On a read, the nonce is neither checked nor consumed, so the same signed read verifies more than once inside its ±30 s window.\n\nA counter of `max(last + 1, now_ms)` is a simple nonce source: it is unique per signer and stays increasing across restarts.\n\n**Concurrent writes from one agent can be refused as replays.** The rule is about arrival order, not issue order. When two writes from the same agent are in flight together and the one with the higher nonce arrives first, the other is refused, and the refusal is the same opaque `401` as a bad signature. The fix is still being decided (ENG-17010). Until then, keep one write in flight per agent key, or register a separate agent key for each concurrent writer.\n\n**Failures are opaque.** Any failure returns the same `401` body with no reason (see the `Unauthorized` response): an unknown or expired agent, a stale timestamp, a malformed header, a wrong digest, a high-S signature or a replayed nonce all look alike. This contract does not say which check failed or in what order the checks run, and a client must not infer either. If a signer is rejected, check it against the test vector below before anything else.\n\n**What an agent key cannot do.** Agent keys are trade-only. **An agent key cannot withdraw**, and it cannot move funds off the account by any route:\n\n- `POST /api/v1/bridge/withdrawals` refuses an agent-signed request with `403` (code `AGENT_CANNOT_WITHDRAW`). The engine's withdrawal route is refused the same way.\n- `POST /withdrawals` requires the wallet's own EIP-712 signature in the body, which an agent key cannot produce.\n- The ordinary-transfer operations (`ownerSignature`) refuse any request that carries `x-agent`.\n\nAgent keys also cannot manage agent credentials: `GET /agents`, `PATCH /agents/{address}` and `DELETE /agents/{address}` refuse them with `403` (code `AGENT_KEY_FORBIDDEN`). A client that holds only an agent key manages them with the wallet's own signature instead (`walletSignature`). And they cannot mint the legacy `POST /ws-tokens` token, which is HMAC-only; use `POST /ws/token`. None of these operations lists `agentAuth`. Every operation that does list it accepts it.\n\n**Test vector.** The key below is a public test key: never fund it or register it. The `x-nexus-test-vectors` extension on this scheme carries this vector and two more (an empty-body `GET`, and a `DELETE` with a query). Together they cover both values of `v`.\n\n- private key: `0x4c0883a69102937d6231471b5dbb6204fe5129617082792ae468d01a3f362318` → `x-agent: 0x2c7536e3605d9c16a7a3d7b1898e529396a65c23`\n- request: `post /orders` (the method is lower-case on purpose; the canonical string upper-cases it), no query, body `{\"market_id\":\"BTC-USDX-PERP\",\"side\":\"Buy\",\"order_type\":\"Limit\",\"quantity\":\"0.1\",\"price\":\"50000\"}`, `x-timestamp: 1776033900123`, `x-nonce: 42`\n- canonical string (LF shown as `⏎`): `POST⏎/orders⏎⏎59ddf9017ca0eb5f8802afd1a2d1584b2d93b0260a0fcd62a1b94b3ff92b332c⏎1776033900123⏎42`\n- digest: `0xe27ade6101c417d2c393abfce8f35b6e1551cf0ce5c50dfbe12f8d6f399ffc35`\n- `x-signature: 0xeef09105834062da10d208be38311995d04cbc5e05043b89e7cbe6d4497d11b51f61729639551a8cfb6ea3e4fe0765afeba7bf3b5f5e09f63bc095c89005b61d1c`\n\n**Network scope.** Like every credential here, an agent registration belongs to the host it was registered on. The canonical string has no network component, so the refusal elsewhere comes from the agent being unknown to that host."}},"schemas":{"SetCancelOnDisconnectRequest":{"type":"object","description":"Cancel-on-disconnect opt-in change for the authenticated account.","properties":{"enabled":{"type":"boolean","description":"True to enable COD for the account, false to disable."}},"required":["enabled"]},"CancelOnDisconnectStatus":{"type":"object","description":"Cancel-on-disconnect status for the authenticated account.","properties":{"enabled":{"type":"boolean","description":"The account's own COD opt-in setting."},"active":{"type":"boolean","description":"Whether COD will actually fire for this account: the account opt-in AND the exchange-side feature switch. When `enabled` is true but `active` is false, the exchange has the feature switched off and no cancel fires on disconnect."},"grace_secs":{"type":["integer","null"],"description":"Seconds the exchange waits after the last `/ws` disconnect before cancelling; a reconnect within the window disarms the cancel. Null when the feature is unavailable on this deployment."}},"required":["enabled","active"]}},"responses":{"Unauthorized":{"description":"Authentication failed. All 401 responses return the same opaque body to prevent information leakage. A credential minted on a different network is one of the causes it hides — by design, so that a key id cannot be probed for existence on another network. Do not retry it against another host.","content":{"application/json":{}}}}},"paths":{"/account/cancel-on-disconnect":{"put":{"tags":["Account"],"summary":"Set cancel-on-disconnect","description":"Enables or disables cancel-on-disconnect for the authenticated account. Opt-in is per account and off by default: someone who deliberately leaves a passive resting order while offline should not have a brief blip cancel it. Enable it when you want the guarantee that a dead client cannot keep orders resting — typical for market makers and algorithmic traders. Returns the resulting COD status (same shape as the GET).","operationId":"setCancelOnDisconnect","requestBody":{"required":true,"content":{"application/json":{"schema":{"$ref":"#/components/schemas/SetCancelOnDisconnectRequest"}}}},"responses":{"200":{"description":"The resulting cancel-on-disconnect status for the account.","content":{"application/json":{"schema":{"$ref":"#/components/schemas/CancelOnDisconnectStatus"}}}},"400":{"description":"Malformed request body."},"401":{"$ref":"#/components/responses/Unauthorized"}}}}}}
````

**Test it** cannot sign this request. `X-Signature` is an HMAC computed per call: see [Authentication](/api-reference/guides/authentication.md), or use an SDK.

***

<sub>API version</sub> <sub></sub><sub>`0.9.131`</sub>


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