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.

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 no-destination-field 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 swap memo construction for Zcash-only sources and affects refund routing on failure; scope is narrow and covered by tests, but incorrect memo shape would break refunds or swaps.

Overview
Shielded Zcash swaps through Maya now embed a transparent (t-address) refund in the swap memo so Maya can refund when trading halts or the swap fails—shielded sources have no transparent send address Maya can default to.

After quoting without refund_address (passing it makes Mayanode reject quotes that exceed Zcash’s 80-character transparent-memo limit), the client fetches the wallet’s transparent address and appends it to memo field 2 as DESTADDR/REFUNDADDR via appendMayaRefundAddress, then carries that memo in the shielded ZIP-321 note (512-byte limit). Non-Zcash sources and Thorchain behavior are unchanged.

Debug ZIP-321 logging is removed; unit tests cover the memo transformation.

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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).

[peachbits]

This blob is pretty ugly. The memo is created by the quote/swap endpoint and it accepts a refund address argument so let's pass it to taht and use the memo they return.

[j0ntz]

Passing the refund address to the quote/swap endpoint is what the original PR did, and it breaks every ZEC swap. Given refund_address, Maya builds the same DESTADDR/REFUNDADDR memo and then rejects the quote because the result overflows the source chain's memo limit. Reproduced live today against mayanode:

• BTC->ETH with refund: generated memo too long for source chain: =:e:0x742d...f44e/bc1q...5mdq::ej:75 (96/80)
• ZEC->DASH with refund is 86/80 (captured live in the prior run's window when ZEC trading was open).

The reason it still works on-chain is that the shielded ZEC send carries the memo in the encrypted note (512 bytes), which is not bound by the 80-char transparent-memo limit that Maya's quote endpoint pre-validates against. So the endpoint cannot return a usable memo for a shielded ZEC source; the refund has to be appended client-side after the quote is fetched without it.

I've addressed the readability concern: the inline blob is now a single call to a named, documented helper appendMayaRefundAddress (src/swap/defi/thorchain/thorchainCommon.ts), with the endpoint/80-char rationale on its docstring, plus unit tests in test/thorchain.test.ts pinning the exact memo output. Leaving this thread open for your call on the approach.

[cursor]

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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