SDK drift: Escrow.approveTx's amount_wei serializes as a JSON string in TypeScript but as a JSON number in Python #1923

Drift

For the same semantic amount_wei value passed to Escrow.approveTx/Escrow.approve_tx, the two SDKs put different JSON types on the wire: TypeScript always serializes it as a string, Python always serializes it as a number.

TypeScript SDK

sdks/typescript/pmxt/escrow.ts:51-62 — normalizeAmountWei(amountWei: bigint | undefined): string | undefined always returns amountWei.toString().
sdks/typescript/pmxt/escrow.ts:120-133 — approveTx() puts that string directly into the request body: ...(approvalAmount === undefined ? {} : { amount_wei: approvalAmount }), so e.g. 1000000n is sent as "amount_wei": "1000000".

Python SDK

sdks/python/pmxt/escrow.py:46-56 — _amount_wei(value: int | None) -> int | None returns the raw int unchanged (no string conversion).
sdks/python/pmxt/escrow.py:114-123 — approve_tx() puts that int directly into the request body: **({} if approval_amount is None else {"amount_wei": approval_amount}), so e.g. 1000000 is sent as "amount_wei": 1000000 (a JSON number).

Expected

Both SDKs should serialize amount_wei on the wire the same way (either both as a string or both as a number), matching whatever the hosted trading API actually expects.

Impact

A server integration for the /v0/escrow/approve endpoint must accept amount_wei as either a JSON string or a JSON number depending on which SDK the caller used, since the two SDKs never agree. This is the same category of bug as #1713 (which covers amount on deposit_tx/withdraw_tx) but for a different field (amount_wei) on a different method (approveTx/approve_tx); #1025 only covers the language-level type annotation (bigint vs int), not the actual wire serialization format.

Found by automated SDK cross-language drift audit