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 append it to the swap memo's destination field as DESTADDR/REFUNDADDR per the Maya memo spec, via the new documented helper appendMayaRefundAddress (which replaces the destination address in the memo with DESTADDR/REFUNDADDR). Since this is the Zcash-only path, the code throws SwapCurrencyError if the transparent refund address is missing.

The refund address is deliberately NOT passed to the quote/swap endpoint. Given a refund_address, Maya builds that same DESTADDR/REFUNDADDR memo and then rejects the quote because the result overflows the source chain's memo limit (e.g. ZEC to DASH is 86/80). The shielded ZEC send instead carries the memo in the encrypted note (512 bytes), which is not bound by the 80-char transparent-memo limit that the quote endpoint pre-validates against, so the refund is injected client-side after the quote is fetched without it. Non-Zcash sources are untouched and keep defaulting to the sending address (their quote requests and memos are unchanged).

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

Verification.

• tsc --noEmit, eslint, and the mocha suite all pass (via verify-repo.sh, which also runs the webpack build).
• New unit tests in test/thorchain.test.ts pin appendMayaRefundAddress's output to the exact memo shape (=:d:DEST/REFUND:0/1/1:ej:75) and cover the destination-not-present edge case.
• Live Maya node (mayanode.mayachain.info) confirms why the endpoint cannot build the memo: BTC to ETH with refund_address returns generated memo too long for source chain: ...(96/80); the same request without it returns a valid 53-char memo.
• In-app ZEC to asset swap-to-success was driven to the success scene in the prior run (with the byte-identical memo). It could not be re-driven this pass: Maya ZEC trading is halted again (HALTZECTRADING=1, trading is halted, can't process swap) at the protocol level, and a swap during the halt fails at the quote before the refund injection runs, so it would not exercise this code anyway. Re-run the in-app smoke once Maya resumes ZEC trading.

---

Note

Medium Risk
Changes Maya Zcash swap memo construction and refund routing for a subset of swaps; wrong address formatting could misroute refunds, but scope is limited to ZEC source via the existing ZIP-321 path.

Overview
Shielded Zcash → Maya swaps now embed a transparent (t-address) refund in the swap memo as DESTADDR/REFUNDADDR, so Maya can refund when trading is halted or the swap fails—shielded sources cannot default to the sender like other chains.

Quotes still call quote/swap without refund_address, because Maya would build the same long memo and reject quotes that exceed the 80-character transparent memo limit; the shielded ZIP-321 path carries the memo in the encrypted note (512 bytes), so appendMayaRefundAddress patches the memo after quoting. Missing transparent refund address fails the swap with SwapCurrencyError.

Unit tests lock the memo shape; CHANGELOG notes the Maya behavior.

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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).

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Stale comment

Automated security triage completed on the current PR head. One net-new finding met this workflow's reporting threshold after deduplication and false-positive filtering.

  

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