> ## Documentation Index > Fetch the complete documentation index at: https://docs.arcus.xyz/llms.txt > Use this file to discover all available pages before exploring further. # List the caller's invite codes > Returns the caller's earned invite codes with redemption status. **The response body shown here is a static example, not live data.** After you click **Send**, your live result appears in a separate panel headed **200 OK**. The panel under the status-code tabs is a fixed sample from the spec — its field values (fees, prices, sizes, IDs, timestamps) are placeholders. Use **Send**, or call the endpoint, for current values. Returns the caller's earned invite codes with redemption status. One invite code is earned per `$1M` of lifetime perps trading volume (`INVITE_VOLUME_PER_CODE_QUANTUMS`); codes are generated automatically and appear here as volume milestones are crossed. **Signed, unlike the other affiliate reads.** An invite code is a bearer secret that grants perps trading access, and `X-API-Key` alone proves nothing (API keys are Ed25519 public keys, listable by anyone via `GET /v1/apiKeys`). The Ed25519 request signature proves possession of the private key, and the key must be registered to `address`. With no request body the signing message is `timestamp + action` (action `inviteCodes` — the path segment verbatim, casing included). The response is returned with `Cache-Control: no-store`. ## OpenAPI ````yaml /api-reference/openapi.yml get /v1/affiliate/inviteCodes openapi: 3.1.0 info: title: Arcus API version: 1.0.0 description: > REST API for the Arcus exchange. Provides endpoints for order management, market data, and account onboarding. ## Coming soon (not implemented yet) The following features are declared in this spec (or implied by it) but are **not yet live** on the gateway or matching engine. Schemas and endpoints may be present so clients can wire against the final shape, but today the gateway returns `501 Not Implemented` or the feature is simply absent. Do not depend on these in production until they are announced as live. - **Next predicted funding rate** — the predicted funding rate for the upcoming interval is not yet exposed on `GET /markets` or the markets WebSocket channel. Only the current realized rate is available today. - **Funding rate calculations** — the authoritative calculation methodology (premium sampling window, interest-rate component, clamping, payment schedule) is still being finalized and is not documented here yet. - **Advanced order types** — trailing stop, stop-limit, OCO, and other conditional / bracket order variants beyond plain `LIMIT` and `MARKET` are not yet supported. ## Authentication Order management and credential-creating endpoints require **three** request headers: - `X-API-Key` — hex-encoded Ed25519 public key (64 chars). The public key *is* the API key. Obtain/register one via `POST /createApiKey`. - `X-Timestamp` — Unix time in **nanoseconds** as a decimal string (e.g. `"1713825891591000000"`). Millisecond or second epochs are rejected with `401 Unauthorized`. Must be within ±30,000 ms (`MaxTimestampDriftMs`, the drift window stays configured in milliseconds) of server wall-clock; otherwise the request is rejected with `401 Unauthorized`. - `X-Signature` — lowercase hex-encoded Ed25519 signature (128 chars). **Single-order endpoints** (`placeOrder`, `cancelOrder`, `modifyOrder`) use the **ordersign typed canonical payload** as the signing message — a compact, key-sorted JSON object with engine-native integer values. The payload is NOT the raw HTTP body; it is built from the parsed request fields: ``` placeOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,"g":N,"m":N,"op":1,"p":N,"q":N,"r":0|1,"s":N,"t":N,"v":1} cancelOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,[,"id":"…"],"m":N,"op":2,"v":1} modifyOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,"g":N,"id":"…","m":N,"op":3,"p":N,"q":N,"r":0|1,"s":N,"t":N,"v":1} ``` `ct` in the payload must equal `X-Timestamp`. Integer values `p`, `q` etc. are engine-native ticks/quantums, not human-readable decimals. Keys in brackets are conditional (omitted when empty). `op` is the operation enum: `1`=place, `2`=cancel, `3`=modify, `4`=placeUntriggered (TPSL). See the `ordersign` package for full field definitions and reference signing code. **Batch endpoints still require this header to be present** (its value is not verified) — see below. - **Batch endpoints are signed per order, but the `X-Signature` header must still be present.** `POST /batchPlaceOrders` and `POST /batchCancelOrders` require `X-API-Key` + `X-Timestamp` + `X-Signature`; the gateway does **not** verify the envelope `X-Signature` *value* for these routes (set it to any one element's signature), but omitting it — or sending an empty value — rejects every element with `invalid order signature`. Instead, each element of the `orders` / `cancels` array embeds its own `"signature"` field — a 128-hex Ed25519 signature over the **ordersign typed canonical payload** for that operation: - Plain `orders` elements (no `tpsl_type`) use `op=1`. - TPSL / conditional `orders` elements (with `tpsl_type`) use `op=4` (`OpPlaceUntriggered`) — same field set as `op=1` but a different `op` value, preventing replay of a TPSL signature as a plain placeOrder. - `cancels` elements use `op=2`. The `ct` field inside every element's payload must equal the shared `X-Timestamp` header value. The whole batch consumes a single replay slot. Read-only endpoints (`GET /openOrders`, `GET /fills`, etc.) require only `X-API-Key`. In relaxed local development the gateway may run with signatures disabled; the OpenAPI `security` blocks list `signedRequest` (the three-header AND) or `{}` (empty) to reflect that. ## Account-scoped requests Public account info reads such as fills, positions, orders, open orders, and account snapshots require `address` as a **query parameter**. Signed order management requests also require `address`, and it must match the master Ethereum address returned for that API key from `POST /createApiKey`. WebSocket `placeOrder` / `cancel` / `batchPlaceOrders` / `batchCancelOrders` / `modifyOrder` use the same value in the JSON payload field `address`. ## Order execution is asynchronous `POST /placeOrder`, `POST /cancelOrder`, `POST /batchPlaceOrders`, and `POST /batchCancelOrders` are asynchronous. They return either: - **`202 Accepted`** — the common case. The signed request was validated by the gateway and forwarded to the matching engine; the body does **not** carry the order's terminal state. - **`200 OK`** — returned only when the gateway already has definitive state for the request by the time it responds (the body's `status` reflects that state, e.g. `OPEN` / `FILLED` / `CANCELED` / `REJECTED`). Clients should treat this as best-effort enrichment and not rely on it. In both cases the body echoes `orderId` / `clientId` so callers can correlate WebSocket events with the request. To observe the full order lifecycle (`OPEN`, `FILLED`, `CANCELED`, `REJECTED`, fills, rejection reasons, etc.) clients **must** subscribe to the `orders` WebSocket channel (and `userFills` for trade-level events). Treat both the `202` and `200` HTTP bodies as request acknowledgements; all definitive state lives on the WebSocket. ## Order rejection reasons When the matching engine rejects an order, the resulting `AccountUpdate` event (delivered over the WebSocket `account` channel with `type: REJECTED`) carries a `rejectionReason` enum. The same value may also appear on HTTP `OrderResponse` / `CancelOrderResponse` bodies that resolved to definitive state before returning (the `200` path described above). The complete set of reasons the matching engine can emit today is: | Value | Meaning | |------------------------------|-------------------------------------------------------------------------| | `POST_ONLY_WOULD_CROSS` | Post-only order was rejected because it would have crossed the book and taken liquidity. | | `SELF_TRADE` | Order would have matched against another resting order belonging to the same account; self-trade prevention rejected it. | | `UNDERCOLLATERALIZED` | Account has insufficient free collateral / margin to support the order. | | `COULD_NOT_FILL` | Generic "could not fill" outcome. Legacy reason — prefer the IOC/FOK-specific values below for time-in-force-driven cancels. | | `IOC_CANCELED` | An `IMMEDIATE_OR_CANCEL` order produced zero fills against the book and was canceled. | | `FOK_FAILED` | A `FILL_OR_KILL` order could not be filled in full at submission and was canceled in its entirety. | | `REDUCE_ONLY_WOULD_INCREASE` | A `reduceOnly` order was rejected because executing it would have opened or increased the account's position rather than reducing it. | | `TOO_MANY_CLIENT_IDS` | Account already has 10,000 live `clientId`s (the per-account maximum). Cancel an existing order or wait for one to reach a terminal state to free a slot. | | `DUPLICATE_CLIENT_ID` | The `clientId` already maps to a live order on this account. Cancel the prior order (or use atomic modify via `placeAndCancel`) before reusing the same `clientId`. | See the `RejectionReason` schema for the canonical enum. ## Rate limiting Rate-limited endpoints return `429 Too Many Requests` carrying two retry-after signals: - `Retry-After` HTTP header (integer seconds, RFC 7231 compliant). - `retryAfterMs` field in the JSON body — precise milliseconds. The body also carries a typed `reason` indicating which layer rejected (`ip`, `account_empty`, `account_partial`). See `RateLimitedError` for the schema and `TooManyRequests` for the behavioral contract. servers: - url: https://api.arcus.xyz description: Mainnet - url: https://api.testnet.arcus.xyz description: Testnet security: [] tags: - name: Onboarding description: Account and API key management. - name: Public description: >- Unauthenticated endpoints — market data, health checks, and account-scoped info reads. - name: Exchange description: > Signed order management endpoints (all are HTTP `POST`). Every request must carry the full header triple `X-API-Key` + `X-Timestamp` + `X-Signature` where `X-Signature` is an Ed25519 signature over the operation-specific signing message: `placeOrder`, `cancelOrder`, and `modifyOrder` sign the ordersign typed canonical payload (the JSON object itself, no prefix), while `cancelAllOrders` and `setLeverage` use the legacy `X-Timestamp + ACTION + canonicalJSON(body)` message (ACTION = the final camelCase path segment; the HTTP method is not signed). `X-Timestamp` is a Unix nanosecond epoch (decimal string) and must be within ±30,000 ms of server wall-clock. See the top-level **Authentication** section for full details. These endpoints also require query parameter `address` matching the key's master Ethereum address. - name: Referral description: > Affiliate / referral program endpoints. Mutating endpoints (`POST`) require the full Ed25519 signature triple and the body `address` must match the API key's master Ethereum address. Read endpoints (`GET`) are public and scoped by `?address=`, except `GET /v1/affiliate/inviteCodes` — invite codes are bearer secrets, so that read is signed too and `?address=` must match the API key's master Ethereum address. - name: Meta description: > Product / UX-level APIs served by the `api-meta` service. These live behind the same host as the rest of the API but are served by a separate deployment with its own storage and lifecycle. They share the same `X-API-Key` + Ed25519 signature scheme as Exchange endpoints; the signed `REQUEST_PATH` includes the `/v1/api-meta/...` prefix verbatim. - name: UserPreferences description: > Per-master-wallet preference store (favorited markets, dashboard layouts, theme, language, …). Reads are public and scoped by `?address=`; writes (PATCH / DELETE) require an Ed25519 signature and are bound to the address registered to `X-API-Key`. See `UserPreferenceKey` for the known keys and `UserPreferenceValue` for the type system. - name: MarketMetadata description: > Curated reference data for markets (company profile, branding, headline financials, …) refreshed from the upstream ticker feed. Reads are public; freshness is bounded by the per-row `ingestedAt` returned in the response envelope. - name: Notifications description: > Per-master-wallet inbox of "unseen events" surfaced from the matching engine: terminal resting-order fills (maker side, fully filled), liquidations, and TP/SL triggers. Reads are public and scoped by `?address=`; the `:markSeen` write requires an Ed25519 signature and is bound to the address registered to `X-API-Key`. Notifications expire after 30 days. paths: /v1/affiliate/inviteCodes: get: tags: - Referral summary: List the caller's invite codes description: Returns the caller's earned invite codes with redemption status. operationId: listInviteCodes parameters: - name: address in: query required: true schema: type: string description: Ethereum address to list invite codes for (must match signer). - name: status in: query required: false schema: type: string enum: - available - used description: >- Return only codes in this state. Omit for both. The counts in the response stay account-wide either way, so the two states can be paged independently without losing the totals. - name: limit in: query required: false schema: type: integer minimum: 1 maximum: 500 default: 100 description: >- Page size. Values above the maximum are clamped rather than rejected. - name: offset in: query required: false schema: type: integer minimum: 0 default: 0 description: Number of matching codes to skip. responses: '200': description: The caller's invite codes and earn progress. content: application/json: schema: $ref: '#/components/schemas/InviteCodesResponse' '400': description: Missing or malformed `address`, `status`, `limit`, or `offset`. content: application/json: schema: $ref: '#/components/schemas/error' '401': description: Missing or invalid API key, or signature verification failed. content: application/json: schema: $ref: '#/components/schemas/error' '403': description: '`address` does not match the API key''s account.' content: application/json: schema: $ref: '#/components/schemas/error' '429': $ref: '#/components/responses/TooManyRequests' '500': description: Internal error fetching or materializing invite codes. content: application/json: schema: $ref: '#/components/schemas/error' '503': description: Invite codes not available yet. content: application/json: schema: $ref: '#/components/schemas/error' security: - apiKey: [] timestamp: [] signature: [] components: schemas: InviteCodesResponse: type: object required: - address - lifetimeVolume - inviteCodesEarned - inviteCodesMaterialized - inviteCodesAvailable - inviteCodesUsed - volumeToNextInvite - materializationPending - codes - total - limit - offset - hasMore properties: address: type: string description: Owner's Ethereum address. lifetimeVolume: type: integer format: int64 description: Lifetime perps volume in quote quantums (1e9 = $1). inviteCodesEarned: type: integer description: Total invite codes earned (one per volume milestone). inviteCodesMaterialized: type: integer description: >- Codes that exist and are therefore redeemable. Equals `inviteCodesEarned` except while a large batch of newly earned codes is still being written — see `materializationPending`. inviteCodesAvailable: type: integer description: >- Materialized codes not yet redeemed. Account-wide, independent of the page or `status` filter. inviteCodesUsed: type: integer description: >- Materialized codes already redeemed. Account-wide, independent of the page or `status` filter. volumeToNextInvite: type: integer format: int64 description: >- Additional volume (quote quantums) until the next invite code is earned. materializationPending: type: boolean description: >- True when earned codes remain to be written. Codes are created lazily and one request writes a bounded number of them, so a trader who earned hundreds at once should call again to see the rest. codes: type: array description: The requested page, ordered oldest code first. items: $ref: '#/components/schemas/InviteCodeInfo' total: type: integer description: >- Codes matching the `status` filter across the whole account — the pagination denominator. Not the length of `codes`. limit: type: integer description: Page size actually applied, after clamping. offset: type: integer description: Offset actually applied. hasMore: type: boolean description: True when more codes match the filter beyond this page. error: type: object required: - error properties: error: type: string description: Human-readable error message. examples: - Invalid request body code: type: string description: > Machine-readable error code for generic (non-order) rejections. Present on geo-restriction blocks; clients should key product-availability UI off this rather than the human `error` string. | Value | Meaning | |------------------|---------| | `GEO_RESTRICTED` | The action is not available from the caller's country/region for this product (perps and/or spot). Reads remain available; only state-changing actions are blocked. | enum: - GEO_RESTRICTED errorSource: type: string description: > Scopes the failure to a specific operation. Present on structured order errors (place / cancel / modify flows); absent on generic HTTP errors. enum: - Order - Cancel errorType: type: string description: > Machine-readable reason for the API-layer rejection. Present alongside `errorSource` on structured order errors; absent on generic HTTP errors. | Value | Meaning | |-------------------|---------| | `Tick` | Price or size does not align to the market's tick size / step size. | | `InvalidRequest` | A request field failed validation (bad address, unknown market, invalid enum, etc.). TPSL-specific causes: `stopPrice` required when `tpslType` is set; `tpslType` must be `STOP_LOSS` or `TAKE_PROFIT`; `reduceOnly` must be `true` for TPSL orders; trigger price must not sit on the wrong side of the current oracle (would fire immediately); batch grouping/shape constraints violated (wrong order count, missing or duplicate `tpslType` legs). | | `OracleDeviation` | The order's price deviates from the current oracle price by more than the allowed threshold. Adjust the price closer to the oracle and resubmit. | | `ReduceOnly` | A reduce-only order was rejected because filling it would open or increase the account's position rather than reduce it. | | `Unavailable` | The requested operation (place / cancel) is temporarily disabled. | | `Unauthorized` | API key or trading-identity check failed. | | `Forbidden` | The authenticated key is not permitted to perform the requested operation. | | `NotImplemented` | The requested capability is not yet available on this path (e.g. TPSL over WebSocket). | | `Transmission` | The gateway accepted and validated the request but could not deliver it to the matching engine. Retry. | | `Internal` | Unexpected gateway-side failure unrelated to transmission. | enum: - Tick - InvalidRequest - OracleDeviation - ReduceOnly - Unavailable - Unauthorized - Forbidden - NotImplemented - Transmission - Internal rejectionReason: type: string description: > Machine-readable engine-level rejection code. Present on `OrderResponse` / `BatchOrderItemResponse` when `status` is `REJECTED` on the synchronous `200` path (i.e. the gateway already had a definitive engine reject before responding). Absent on `202` responses and on HTTP error bodies — in those cases rejection reasons are delivered asynchronously via the `orders` WebSocket channel. Mirror of the canonical `RejectionReason` schema in `openapi.yaml` — keep the two in lockstep (and the hardcoded list in `sdks/python/scripts/post_process_models.py`). | Value | Meaning | |------------------------------------|---------| | `POST_ONLY_WOULD_CROSS` | Post-only order would have crossed the book and taken liquidity. | | `SELF_TRADE` | Order would match against the account's own resting order; blocked by self-trade prevention. | | `UNDERCOLLATERALIZED` | Account has insufficient free collateral / margin to support the order. | | `COULD_NOT_FILL` | Generic "could not fill" (legacy; prefer `IOC_CANCELED` / `FOK_FAILED`). | | `IOC_CANCELED` | IOC order produced zero fills and was canceled. | | `FOK_FAILED` | FOK order could not be fully filled at submission. | | `REDUCE_ONLY_WOULD_INCREASE` | reduce-only order would have opened or increased the position. | | `TOO_MANY_CLIENT_IDS` | Account already has 10,000 live `clientId`s (the per-account maximum). Cancel or let existing orders reach a terminal state to free slots before placing new ones with distinct `clientId`s. | | `DUPLICATE_CLIENT_ID` | Account already has an open order with the same `clientId`. | | `POSITION_TPSL_ALREADY_EXISTS` | A position-level TPSL of the same trigger class (TP or SL) already exists for this account+market. At most one TP and one SL per market. | | `ENTRY_TPSL_CANNOT_BE_POSITION_TPSL` | A TPSL bound to an entry order (`parentOrderId` set) cannot also be a position-level TPSL; entry-linked TPSLs are sized partial legs. | | `OPEN_ORDER_CAP_EXCEEDED` | Account has reached its per-account open-order cap; cancel a resting order or let one reach a terminal state before placing another. | | `FILL_WILL_EXCEED_TRADING_BOUND` | Outside regular trading hours, the order would fill at or beyond the active off-hours trading bound. Per-order rejection; in-band trading continues. | | `OPEN_INTEREST_CAP_EXCEEDED` | Market is at its operator-set open-interest cap and the order's next fill would have increased open interest. OI-neutral and OI-reducing orders still match. | | `ORDER_WILL_TAKE_LIQUIDITY_DURING_MARKET_HALT` | Deprecated — no longer emitted; replaced by `FILL_WILL_EXCEED_TRADING_BOUND`. | | `ORDER_NOT_FOUND` | `cancelOrder` referenced an order not on the orderbook (already filled, canceled, never placed, or owned by another account). | | `ORDER_NOT_FOUND_FOR_MODIFY` | `modifyOrder` referenced an order not on the regular orderbook; TPSL and untriggered orders cannot be modified. | | `MODIFY_CHANGED_IMMUTABLE_FIELD` | `modifyOrder` attempted to change an immutable field (`side`, `timeInForce`, `reduceOnly`, or `orderType`). | | `MODIFY_ZERO_SIZE` | `modifyOrder` specified a new size of zero or less. | enum: - POST_ONLY_WOULD_CROSS - SELF_TRADE - UNDERCOLLATERALIZED - COULD_NOT_FILL - IOC_CANCELED - FOK_FAILED - REDUCE_ONLY_WOULD_INCREASE - TOO_MANY_CLIENT_IDS - DUPLICATE_CLIENT_ID - POSITION_TPSL_ALREADY_EXISTS - ENTRY_TPSL_CANNOT_BE_POSITION_TPSL - OPEN_ORDER_CAP_EXCEEDED - ORDER_WILL_TAKE_LIQUIDITY_DURING_MARKET_HALT - ORDER_NOT_FOUND - ORDER_NOT_FOUND_FOR_MODIFY - MODIFY_CHANGED_IMMUTABLE_FIELD - MODIFY_ZERO_SIZE - FILL_WILL_EXCEED_TRADING_BOUND - OPEN_INTEREST_CAP_EXCEEDED InviteCodeInfo: type: object required: - code - status properties: code: type: string pattern: ^[0-9A-Z]{6}$ description: >- The invite code: exactly 6 uppercase base36 characters (A-Z, 0-9). Always treat this as a string — codes are zero-padded, so roughly one in 2,160 is all digits and would lose its leading zeros if parsed as a number. status: type: string enum: - available - used redeemedBy: type: string description: Redeemer's Ethereum address. Present only when `status` is `used`. redeemedAt: type: integer format: int64 description: >- Redemption time in epoch milliseconds. Present only when `status` is `used`. RateLimitedError: description: > 429 response body shape. Extends the generic `Error` with two rate-limit-specific fields: - `reason` — which limiter rejected the request. Stable string enum; new values may be added in future versions, so clients should treat unknown values as opaque. - `retryAfterMs` — precise milliseconds the client should wait before retrying. The HTTP `Retry-After` header carries the same information rounded up to whole seconds (RFC 7231); prefer this field when sub-second precision matters. type: object required: - error properties: error: type: string example: rate limited reason: type: string enum: - ip - account_empty - account_partial - unknown description: | Layer that rejected the request: * `ip` — per-IP weight bucket exhausted. * `account_empty` — per-subaccount pool fully exhausted; the drip-throttle has no token available either. * `account_partial` — pool has some credit but not enough for this batch. Split the request into smaller chunks to drain the remaining headroom. * `unknown` — defensive fallback; clients should retry per `retryAfterMs` and report the occurrence. retryAfterMs: type: integer format: int64 minimum: 0 description: >- Milliseconds to wait before retrying. Matches the precise wait the rate limiter computed (the `Retry-After` header rounds up to the next whole second). clientId: type: string description: > Echo of the request's client-supplied `clientId`, so the client can correlate the rejection to a specific order request. Present only on single-order endpoints (placeOrder, modifyOrder, cancelOrder) when the request carried a `clientId`. Omitted on batch endpoints (see `clientIds`) and when the request had none. clientIds: type: array items: type: string description: > Echo of every client-supplied `clientId` in a batch request (batchPlaceOrders, batchCancelOrders), positionally aligned with the submitted `orders` / `cancels` array. A batch is rejected all-or-nothing, so every listed order was rejected; the echo lets a client submitting multiple batches concurrently correlate the 429 to a specific batch. An entry is empty when that element carried no `clientId` (e.g. a cancel-by-orderId). Omitted on single-order endpoints (see `clientId`). responses: TooManyRequests: description: > Rate limit exceeded. Two signals are returned, designed to coexist with both naive HTTP clients and rate-limit-aware SDK clients: - `Retry-After` header (integer seconds, RFC 7231 compliant). Rounds up — clients that obey this header sleep at least as long as required. Safe for generic HTTP libraries to read. - JSON body `retryAfterMs` (precise milliseconds, matches the server's internal computation). Sophisticated clients should prefer this over the header to avoid the round-up overshoot. - JSON body `reason` indicates which rate-limit layer rejected: `ip` (per-IP weight bucket), `account_empty` (per-subaccount pool fully exhausted, in drip throttle), `account_partial` (pool has some credit but not enough for this batch — split the request smaller to drain), or `unknown` (defensive fallback). - JSON body `clientId` (single-order endpoints) or `clientIds` (batch endpoints) echoes the request's client-supplied order identifier(s) so the client can correlate the rejection to a specific order request. headers: Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/RateLimitedError' example: error: rate limited reason: account_empty retryAfterMs: 850 clientId: my-order-42 headers: RetryAfter: description: Seconds the client should wait before retrying the request. schema: type: integer minimum: 1 example: 1 securitySchemes: apiKey: type: apiKey in: header name: X-API-Key description: > Hex-encoded Ed25519 public key (64 chars). The public key IS the API key — register it via `POST /createApiKey`. Required on every authenticated request, both read-only and signed. timestamp: type: apiKey in: header name: X-Timestamp description: > Unix time in **nanoseconds** as a decimal string (e.g. `"1713825891591000000"`). Millisecond or second epochs are rejected with `401 Unauthorized`. Must be within ±30,000 ms (`MaxTimestampDriftMs`, the drift window stays configured in milliseconds) of server wall-clock, or the request is rejected with `401 Unauthorized`. Required on all mutating / credential-creating endpoints. This same value must appear as the `ct` field in the ordersign typed canonical payload (single-order endpoints) or in each element's `ct` field (batch endpoints). signature: type: apiKey in: header name: X-Signature description: > Lowercase hex-encoded Ed25519 signature (128 chars). **Single-order endpoints** (`placeOrder`, `cancelOrder`, `modifyOrder`, and other non-batch mutating routes) sign over the **ordersign typed canonical payload** — a compact, key-sorted JSON object built from parsed request fields using engine-native integer values: ``` placeOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,"g":N,"m":N,"op":1,"p":N,"q":N,"r":0|1,"s":N,"t":N,"v":1} cancelOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,[,"id":"…"],"m":N,"op":2,"v":1} modifyOrder: {"ad":"0x…","ai":N,[,"c":"…"],"ct":N,"g":N,"id":"…","m":N,"op":3,"p":N,"q":N,"r":0|1,"s":N,"t":N,"v":1} ``` `ct` must equal the `X-Timestamp` header value. Keys in brackets are conditional (omitted when empty). `op` values: `1`=place, `2`=cancel, `3`=modify. See the `ordersign` package for field definitions and reference signing code. Other signed routes (e.g. `createApiKey`, `tokens`, `userPreferences`) still use the legacy scheme: `signing_message = X-Timestamp + ACTION + canonicalJSON(body)`, where `ACTION` is the camelCase final path segment. **Batch endpoints (`batchPlaceOrders`, `batchCancelOrders`) do NOT use this header.** They authenticate with per-element typed ordersign signatures embedded in the request body (see the global auth description and the per-field `signature` descriptions on `OrderRequest` / `CancelOrderRequest`). Read endpoints are authenticated by `?address=` (and optionally `X-API-Key`) only — no signature is required. The one exception is `GET /v1/affiliate/inviteCodes`, which returns bearer secrets and therefore requires the full header triple; with no body its signing message is `X-Timestamp + ACTION`. `canonicalJSON(body)` is the JSON body with object keys sorted lexicographically at every level and no whitespace; the server canonicalizes the received body before verifying, so only the bytes signed over must be canonical. Required on all mutating / credential-creating endpoints. ````