Add Swapter swap provider

[j0ntz]

CHANGELOG

Does this branch warrant an entry to the CHANGELOG?

• Yes
• No

Dependencies

none

Description

Asana task

Adds the Swapter centralized swap provider.

Recreates partner PR #455 (by @markovo4, from markovo4/edge-exchange-plugins) on an
EdgeApp branch so it can run CI, rebased from its v2.46.0 merge-base onto current
master. The plugin design, mapping and test cases are the partner's work; this branch
brings the integration up to current conventions and fixes what had gone stale.

Asana: https://app.asana.com/1/9976422036640/project/1213880789473005/task/1216571782597915

Changes on top of the partner branch

Chain mappings corrected against the live /data/coins list. Swapter has renamed
several networks since the partner branch was cut in May, and nine of the 43 non-null
mappings no longer resolve:

Edge plugin	Partner	Live network
arbitrum	ARBITRUM	ARB
optimism	OPTIMISM	OP
polygon	POLYGON	POL
solana	SOLANA	SOL
ethereumpow	ETHW	ETHEREUM POW (note the space)
bitcoinsv	BSV	(none — see below)
coreum	CORE	(none)
fio	FIO	(none)
telos	TELOS	(only TELOS(EVM); Edge's telos is EOSIO)

A stale code here is caught by no type and no test: a mainnet quote still reaches the API
and fails with Swapter's "Deposit coin and network combination does not exists.", while
a token quote throws SwapCurrencyError because /data/coins returns no ticker set for
the unknown network. Verified by driving the plugin against the live API — polygon at
POLYGON fails min-amount with HTTP 400, and at POL returns HTTP 200. Bitcoin SV is
dropped rather than remapped to Swapter's BCHSV: getChainAndTokenCodes derives the
mainnet ticker from currencyInfo.currencyCode (BSV), so that pair needs a
SPECIAL_MAINNET_CASES entry to work at all.

Max swaps now resolve. Every other central plugin routes its quote through
getMaxSwappable; this one did not, so its quoteFor !== 'from' guard threw
SwapCurrencyError for every max ("send all") swap and Swapter silently vanished from the
provider list. It now follows the nym pattern: a quote-only probe order prices fees
against the user's own refund address, so a max swap does not create an order that is
immediately abandoned, and exactly one order is created per quote.

Dropped the estimate round trip. /v2/swap/estimate was called and cleaned on every
quote, but its response was only logged — toNativeAmount comes from the create
response. The probe needs only a spendInfo to price fees, and create returns the
authoritative amounts, so neither path needs it.

Regenerated test/partnerJson/swapterMap.json from /data/coins. The partner fixture
held 292 networks, 156 of which are not Swapter networks at all (ERC20, ARBITRUMONE,
AVAXCCHAIN, and a bare A), while omitting 72 real ones — POL was absent entirely.
Every other fixture in test/partnerJson/ is a subset of its provider's mapped codes; this
one now is too (38 networks, 729 tickers).

Dropped unrelated dependency churn: a self-referential "edge-exchange-plugins": "^2.46.0"
dependency, a typescript ~4.9.5 → ^6.0.3 upgrade, a new ts-node devDependency, and
their yarn.lock fallout. This branch touches no dependency files.

Also registered swapter alphabetically in src/index.ts and dropped the whitespace-only
edits to partnerJson.test.ts.

Testing

verify-repo.sh passes (prepare, eslint, tsc, mocha — 18 partnerJson cases including 3
new Swapter ones, asserting against the regenerated live fixture).

An executed in-app swap is not part of this verification, and the plugin is unproven past
order creation. The throwaway key on the Asana task is not authorized: /v2/swap/create
and /v2/swap/estimate return HTTP 401 under every documented auth variant, and
/data/coins 401s whenever an X-API-KEY header is present at all. (/v2/swap/min-amount
is unauthenticated, which is what made the mapping verification above possible.)

Driving the real plugin against the live API with that key gives:

GET  /data/coins            -> HTTP 401   (warn + empty ticker map, as designed)
POST /v2/swap/min-amount    -> HTTP 200   {"amount":"0.00116310"}
POST /v2/swap/create        -> HTTP 401   {"info":{"type":"float","refundAddress":"bc1q…"},
                                           "deposit":{"coin":"BTC","network":"BTC","amount":0.1},
                                           "withdraw":{"coin":"ETH","network":"ETH","address":"0x71C7…"}}
=> Error: Swapter returned error code 401

So request construction and the mapping are confirmed end-to-end, and auth is the only
thing between this and an executed swap. A valid Swapter partner key is needed to
sign this off; until then the create response cleaner (asSwapterCreateResponse) has
never seen a real payload and is trusted from the published docs alone.

Review-round changes (addressing @peachbits)

• ceil for the below-limit native minimum (never understate Swapter's floor) and floor for the payout toNativeAmount (never over-promise the receive amount), replacing round.
• Rate selection follows the sibling convention: try a fixed-rate order, fall back to float. Dropped the userSettings.swapType selection (the GUI never passes it, which pinned the plugin to float). Swapter 500s type: 'fixed' for pairs it cannot fix, so that create error is suppressed and the float fallback runs.
• Fallback correctness: fall back to float only when Swapter rejected the fixed create with no order (a SwapterCreateRejected sentinel), so a create-then-parse-failure never spawns a second order; unsupported-pair errors propagate directly with no retry; rethrow the fixed error only when float was also cleanly rejected, else surface the float error so a live order is not masked.
• skipChecks: true on the max-fee probe so EVM max swaps no longer fail with SpendToSelfError (matches the NYM fix).
• SPECIAL_MAINNET_CASES pins native TON to Swapter's GRAM coin (audited all mapped networks; TON was the only native-coin mismatch).
• Deposit-echo assertion (suggested) left out: Swapter float64-parses the deposit, so a strict eq would false-reject 18-decimal orders, and no enforced max exists to guard.

Follow-ups

• Verified a real swap end-to-end with a working test key (ETH on Arbitrum to LTC, executed in-app to the success scene). asSwapterCreateResponse validated against live create responses.
• Consider a mapctl synchronizer for Swapter. /data/coins needs no API key, so it is a
  clean fit, and it would catch renames like POLYGON → POL automatically instead of
  silently dropping a chain. Not done here: mapctl update-mappings constructs every
  provider's synchronizer eagerly and aborts without all of their API keys, so the
  generated-mapping path could not be run or validated in this environment.
• swapter is registered but is not yet enabled anywhere — the info server serves no
  Swapter init options, so the GUI needs SWAPTER_INIT before it can surface.

---

Note

Medium Risk
New third-party swap path that creates real deposit orders and builds spends from API responses; behavior aligns with other CEX plugins but live create payloads were not verified with an authorized key, and stale network mappings can fail silently at quote time.

Overview
Adds Swapter as a new centralized swap provider: plugin registration, Edge→Swapter chain mapping, and partner JSON tests backed by a regenerated /data/coins fixture.

Quoting follows the same central-plugin pattern as peers: getMaxSwappable with a fee probe (user refund address, skipChecks so EVM max swaps don’t hit spend-to-self), then /v2/swap/min-amount and /v2/swap/create for a single real order—no separate estimate call. It tries fixed rate first and falls back to float only when create is rejected without an order; unsupported pairs map to SwapCurrencyError. Supported assets are refreshed hourly from public /data/coins (no API key on that route). Network codes were corrected against the live API (e.g. POL, ARB, AVAX_C, ETHEREUM POW); native TON uses SPECIAL_MAINNET_CASES (GRAM on Swapter). Only from / max (rewritten to from) quotes are supported.

SWAPTER_INIT is added for tests; the plugin is registered but not enabled in production until init options are served.

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[j0ntz]

📸 Test evidence — in-app Swapter swap (ETH→LTC) executed, followup with working key bdd7a874

agent proof 1216571782597915 01 swapter quote

agent proof 1216571782597915 02 swap success

agent proof 1216571782597915 03 txn details

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

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Cursor Bugbot has reviewed your changes using high effort and found 4 potential issues.

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[j0ntz]

📸 Test evidence (review-round re-verification, HEAD 441a45e)

swapter quote

swap success

txn details

max skipchecks

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