Add transparent refund address for shielded Zcash Maya swaps

[j0ntz]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Description

Asana: https://app.asana.com/0/1215088146871429/1214541361005860

Problem. When Edge sends a shielded-Zcash swap to Maya, the swap memo carries no refund address. Maya cannot refund a shielded source and rejects the refund:

can't refund ZEC from shielded source without a refund address
fail to refund for halted trading

For every chain except Zcash, Maya defaults the refund to the sending address, which is correct. A shielded ZEC source has no transparent sending address to refund to, so the integrator must supply a transparent (t-address) refund address in the swap memo.

Fix. In the shared Thorchain/Maya common code, when the source wallet is Zcash, fetch the wallet's transparent address (getAddress(fromWallet, 'transparentAddress'), the same helper already used for the ZEC receive side) and pass it as refund_address to the quote/swap endpoint. The node bakes it into the swap memo's destination field per the Maya memo spec (SWAP:ASSET:DESTADDR/REFUNDADDR:...). For ZEC the memo then flows into the existing ZIP-321 shielded-memo path unchanged. Non-Zcash sources are untouched and keep defaulting to the sending address (refund_address is only added when present, so their quote requests are byte-for-byte identical).

The change lives entirely in the dependency; no gui-side wiring is required.

Verification.

• tsc --noEmit, eslint, and yarn test all pass.
• Verified the mechanism directly against the live Maya node (mayanode.mayachain.info): the same quote/swap request returns memo =:e:0x04c5... without refund_address and =:e:0x04c5.../bc1q... with it, confirming the node appends the refund address to the destination field exactly as this change relies on.
• In-app ZEC to asset swap-to-success could not be driven on the sim: Maya ZEC trading is currently halted (trading is halted, can't process swap) at the protocol level, so no ZEC quote/swap can be produced regardless of wallet funding. Re-run the in-app smoke once Maya resumes ZEC trading.

---

Note

Medium Risk
Changes Maya/Thorchain ZEC swap memo construction and refund routing; mistakes could misdirect refunds, but the change is narrowly scoped to ZEC sources and post-quote memo mutation only.

Overview
Shielded Zcash → Maya swaps now carry a transparent t-address refund in the swap memo so Maya can refund when the source is shielded (it cannot default to the sender like other chains).

For ZEC source wallets, the plugin loads transparentAddress via the same getAddress helper used elsewhere. The refund is not sent on quote/swap—that would blow past Zcash’s 80-character transparent-memo limit and fail quoting. After the quote returns, the ZEC / ZIP-321 path rewrites memo field 3 from DESTADDR to DESTADDR/REFUNDADDR before the memo is encoded into the shielded note (which is not subject to that limit). Non-ZEC swaps are unchanged.

CHANGELOG documents the Maya behavior under Unreleased.

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[j0ntz]

📸 Test evidence — in-app Maya shielded-ZEC swap order (verification followup)

agent proof 1214541361005860 02 maya zec order

Captured by the agent's in-app test run (build-and-test).

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[j0ntz]

📸 Test evidence (in-app, after fix)

agent proof 1214541361005860 04 zec dash fixed order

agent proof 1214541361005860 05 zec dash swap success

agent proof 1214541361005860 06 btc eth unaffected order

Captured by the agent's in-app test run (build-and-test).