`GeminiTitanExchangeOptions.sandbox` missing from both SDK `GeminiTitan` constructors

[realfishsam]

Gap

GeminiTitanExchange in core accepts a sandbox: boolean option to route requests to Gemini Titan's sandbox environment. Neither SDK exposes this option in the GeminiTitan constructor, forcing all SDK calls to the production environment.

Core

core/src/exchanges/gemini-titan/index.ts:39

export interface GeminiTitanExchangeOptions {
    credentials?: ExchangeCredentials;
    sandbox?: boolean;
}

core/src/exchanges/gemini-titan/index.ts:45

constructor(credentials?: ExchangeCredentials | GeminiTitanExchangeOptions)

TypeScript SDK

sdks/typescript/pmxt/client.ts:2803

class GeminiTitan extends Exchange {
    constructor(options?: ExchangeOptions) { super("gemini-titan", options); }
}

ExchangeOptions has no sandbox field.

Python SDK

sdks/python/pmxt/_exchanges.py:435

class GeminiTitan(Exchange):
    def __init__(
        self,
        api_key: Optional[str] = None,
        api_secret: Optional[str] = None,
        base_url: Optional[str] = None,
        auto_start_server: Optional[bool] = None,
        pmxt_api_key: Optional[str] = None,
    ): ...

No sandbox parameter.

Evidence

GeminiTitanExchangeOptions.sandbox is defined in gemini-titan/index.ts:39. When true, it switches the exchange to use Gemini's sandbox API endpoints.

Impact

Developers integrating with Gemini Titan cannot use the sandbox environment via the SDK. All trading operations (order creation, cancellation) go to production, making safe end-to-end testing impossible through the SDK.

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Found by automated Core-to-SDK surface coverage audit