SDK drift: Python's `validate_economics` silently auto-derives `typed_data` from `build_response`; TypeScript requires it explicitly with no fallback

[realfishsam]

Drift

TypeScript's validateEconomics takes typedData as a required positional parameter with no default and no fallback-extraction logic. Python's validate_economics treats typed_data as optional — when omitted (None), it reaches into build_response["typed_data"] and uses that value instead of failing, unlike its sibling required args (route/build_request/build_response), which fail immediately when missing.

TypeScript SDK

sdks/typescript/pmxt/hosted-typed-data.ts:402-407 — typedData: TypedData is a required positional parameter; the function body has no fallback-extraction logic.

Python SDK

sdks/python/pmxt/_hosted_typeddata.py:256-274:

def validate_economics(
    typed_data: dict[str, Any] | None = None,
    route: str | None = None,
    build_request: dict[str, Any] | None = None,
    build_response: dict[str, Any] | None = None,
) -> None:
    ...
    if typed_data is None:
        candidate = _value(build_response, "typed_data")
        if candidate is _MISSING or candidate is None:
            _economic_fail("typed_data missing")
        typed_data = candidate

Expected

Both SDKs should require the same set of arguments with the same fallback behavior — either TypeScript should support the same build_response-derived fallback, or Python should not silently auto-derive typed_data and should instead require it explicitly like its sibling parameters.

Impact

This is distinct from existing issue #1120 (which is only about nullability/omission being allowed, not about an active fallback-extraction behavior). A Python caller relying on this convenience (passing only route/build_request/build_response and omitting typed_data) has no equivalent call shape in TypeScript at all — porting such code to TypeScript would require an explicit code change, not just a syntax translation.

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Found by automated SDK cross-language drift audit