Step zero — from nothing to your first trade

Gemini uses a venue-custodied cash account. You do not need a crypto wallet or gas asset for this lane.

1. Create the account. Sign up at gemini.com, complete the venue’s regulated identity checks, and accept its current prediction-market terms. Expect government-ID KYC.
2. Create credentials. In your venue account’s API settings, create a Trader API key and secret. Enable a time-based nonce, disable heartbeat, and use Unrestricted trusted-IP mode while Predictefy egress is not pinned. Predictefy uses the credential in-process and never retains it.
3. Fund it. Deposit USD through Gemini’s own supported bank or card rail; no chain or crypto collateral applies. Start with enough to meet the selected instrument’s published quantityMinimum plus fees. The repo sources establish no universal deposit minimum.
4. Allow time. Setup is about 10 minutes after approval; KYC may take a day.
5. Check access. Gemini controls product and geographic eligibility, so confirm both before funding.

What you need first

• Production status: Armed for build, submit, and cancel as verified on 2026-08-15.
• Wallet and chain: No wallet or chain transaction signs the order body. Gemini request auth is the only signature.
• Venue account: Yes. Use a funded Gemini account and accept the current prediction-market terms.
• Credentials: A caller-owned Trader API key and secret. Keep them in your process and send them only for submit, cancel, or refresh; Predictefy uses them in-process and never retains them.
• Funding: Fund the venue-custodied Gemini account through Gemini’s own rails. The funding registry pins no chain or collateral token for this lane.

Gemini is a strict server-built, per-request HMAC transit lane. It is source-ready but default off behind GEMINI_EXECUTION_ENABLED=true; check GET /v1/exec/venues before integrating.

Production update — 2026-08-15

The default-off wording above records Gemini’s 2026-08-11 source-ready phase. Production now advertises build, submit, and cancel for Gemini. Continue to check the live capability endpoint before every integration because arming can change independently of this page.

Build accepts no credential and performs no venue request. Send asset (the Core outcome id), or outcome + outcomeSide, with these plain fields:

Field	Type	Required	Meaning
isBuy	boolean	yes	true → Gemini buy; false → sell
price	number in (0,1)	yes	Limit price, persisted as a decimal string
size	number greater than zero	yes	Contract quantity, persisted as a decimal string
timeInForce	good-til-cancel, immediate-or-cancel, or fill-or-kill	no	Defaults to good-til-cancel
makerOrCancel	boolean	no	true requires maker-only behavior

The catalog supplies the exact Gemini instrument symbol and yes/no outcome. The stored version-1 artifact contains only { venue, buildVersion, request, body }, where request is pinned to /v1/prediction-markets/order and body is the documented venue shape: symbol, orderType: "limit", side, quantity, price, outcome, timeInForce, and optional makerOrCancel: true. Stop-limit is not supported. Notional is quantity × price and passes the same build and submit caps as every other order lane. Gemini also publishes instrument-specific quantityIncrement, quantityMinimum, priceIncrement, and priceMinimum values in contract metadata; choose aligned inputs or Gemini will reject the order without placing it.

Submit { executionId, apiKey, apiSecret }. Master API keys must also supply account with the Gemini account name (for example, primary); account-scoped keys omit it. Only after version, shape, request-path, notional, and artifact-bounds checks pass does Predictefy read the credentials. It constructs { request, nonce, account, ...body } when account is present (otherwise { request, nonce, ...body }), base64-encodes the JSON, computes the hex HMAC-SHA384 with apiSecret, and sends one empty-body POST with Gemini’s three auth headers. Credentials and generated headers are excluded from both persisted artifacts and logs.

Gemini account and key prerequisites

Complete these yourself; Predictefy never changes account settings or accepts terms for you.

• Accept the current prediction-market terms once via Gemini’s POST /v1/prediction-markets/terms/accept flow.
• Use a third-party key with the Trader role.
• Enable Uses a time based nonce. Counter-nonce keys are unsafe for a stateless relay because a relay request can race and regress the caller’s own bot. Gemini requires epoch seconds within plus or minus 30 seconds. A rejection returns 409 GEMINI_TIME_NONCE_REQUIRED with the fix.
• Disable Requires Heartbeat. Thirty seconds of authenticated silence cancels that session’s open orders. If Gemini exposes this setting in an error, Predictefy returns 409 GEMINI_HEARTBEAT_KEY_UNSUPPORTED.
• Gemini trading keys require trusted-IP configuration. Predictefy does not provide pinned egress, so this lane requires choosing Unrestricted and accepting that it removes the IP allowlist layer of protection.

Gemini holds the account balance, just as a venue holds other venue-account balances; this is fund custody by Gemini, not custody by Predictefy. Predictefy never holds those funds and never retains the API key or secret. The same private REST family supports cancel and status: cancel builds a new zero-notional artifact containing the stored integer orderId, while status refresh signs /orders/active and then /orders/history with the caller’s transient credentials. No automatic background poll is possible because no credential is retained.