feat: Advancer exo behaviors

- refs: #10390

Author: 0xpatrickdev

packages/fast-usdc/package.json

@@ -36,6 +36,7 @@
     "@agoric/notifier": "^0.6.2",
     "@agoric/orchestration": "^0.1.0",
     "@agoric/store": "^0.9.2",
+    "@agoric/vat-data": "^0.5.2",
     "@agoric/vow": "^0.1.0",
     "@agoric/zoe": "^0.26.2",
     "@endo/base64": "^1.0.8",

packages/fast-usdc/src/exos/advancer.js

@@ -1,5 +1,7 @@
+import { AmountMath, AmountShape, BrandShape } from '@agoric/ertp';
 import { assertAllDefined } from '@agoric/internal';
 import { ChainAddressShape } from '@agoric/orchestration';
+import { pickFacet } from '@agoric/vat-data';
 import { VowShape } from '@agoric/vow';
 import { makeError, q } from '@endo/errors';
 import { E } from '@endo/far';
@@ -9,116 +11,219 @@ import { addressTools } from '../utils/address.js';
 
 /**
  * @import {HostInterface} from '@agoric/async-flow';
+ * @import {NatAmount} from '@agoric/ertp';
  * @import {ChainAddress, ChainHub, Denom, DenomAmount, OrchestrationAccount} from '@agoric/orchestration';
  * @import {VowTools} from '@agoric/vow';
  * @import {Zone} from '@agoric/zone';
  * @import {CctpTxEvidence, LogFn} from '../types.js';
  * @import {StatusManager} from './status-manager.js';
- * @import {TransactionFeedKit} from './transaction-feed.js';
  */
 
+/**
+ * Expected interface from LiquidityPool
+ *
+ * @typedef {{
+ *   lookupBalance(): NatAmount;
+ *   borrowUnderlying(amount: Amount<"nat">): Promise<PaymentPKeywordRecord>;
+ *   returnUnderlying(principalPayment: Payment<"nat">, feePayment: Payment<"nat">): Promise<void>
+ * }} AssetManagerFacet
+ */
+
+/**
+ * @typedef {{
+ *  chainHub: ChainHub;
+ *  log: LogFn;
+ *  statusManager: StatusManager;
+ *  vowTools: VowTools;
+ * }} AdvancerKitCaps
+ */
+
+/** type guards internal to the AdvancerKit */
+const WatcherHandlersShape = {
+  depositHandler: M.interface('DepositHandlerI', {
+    onFulfilled: M.call(AmountShape, ChainAddressShape).returns(VowShape),
+  }),
+  transferHandler: M.interface('TransferHandlerI', {
+    // TODO confirm undefined, and not bigint (sequence)
+    onFulfilled: M.call(M.undefined(), {
+      amount: AmountShape,
+      destination: ChainAddressShape,
+    }).returns(M.undefined()),
+    onRejected: M.call(M.error(), {
+      amount: AmountShape,
+      destination: ChainAddressShape,
+    }).returns(M.undefined()),
+  }),
+};
+
 /**
  * @param {Zone} zone
- * @param {object} caps
- * @param {ChainHub} caps.chainHub
- * @param {LogFn} caps.log
- * @param {StatusManager} caps.statusManager
- * @param {VowTools} caps.vowTools
+ * @param {AdvancerKitCaps} caps
  */
-export const prepareAdvancer = (
+export const prepareAdvancerKit = (
   zone,
-  { chainHub, log, statusManager, vowTools: { watch } },
+  { chainHub, log, statusManager, vowTools: { watch, when } },
 ) => {
-  assertAllDefined({ statusManager, watch });
+  assertAllDefined({
+    chainHub,
+    statusManager,
+    watch,
+    when,
+  });
 
-  const transferHandler = zone.exo(
-    'Fast USDC Advance Transfer Handler',
-    M.interface('TransferHandlerI', {
-      // TODO confirm undefined, and not bigint (sequence)
-      onFulfilled: M.call(M.undefined(), {
-        amount: M.bigint(),
-        destination: ChainAddressShape,
-      }).returns(M.undefined()),
-      onRejected: M.call(M.error(), {
-        amount: M.bigint(),
-        destination: ChainAddressShape,
-      }).returns(M.undefined()),
-    }),
+  return zone.exoClassKit(
+    'Fast USDC Advancer',
     {
-      /**
-       * @param {undefined} result TODO confirm this is not a bigint (sequence)
-       * @param {{ destination: ChainAddress; amount: bigint; }} ctx
-       */
-      onFulfilled(result, { destination, amount }) {
-        log(
-          'Advance transfer fulfilled',
-          q({ amount, destination, result }).toString(),
-        );
-      },
-      onRejected(error) {
-        // XXX retry logic?
-        // What do we do if we fail, should we keep a Status?
-        log('Advance transfer rejected', q(error).toString());
-      },
+      advancer: M.interface('AdvancerI', {
+        handleTransactionEvent: M.callWhen(CctpTxEvidenceShape).returns(
+          M.or(M.undefined(), VowShape),
+        ),
+      }),
+      ...WatcherHandlersShape,
     },
-  );
-
-  return zone.exoClass(
-    'Fast USDC Advancer',
-    M.interface('AdvancerI', {
-      handleTransactionEvent: M.call(CctpTxEvidenceShape).returns(VowShape),
-    }),
     /**
      * @param {{
+     *   assetManagerFacet: AssetManagerFacet;
      *   localDenom: Denom;
-     *   poolAccount: HostInterface<OrchestrationAccount<{ chainId: 'agoric' }>>;
+     *   poolAccount: ERef<HostInterface<OrchestrationAccount<{chainId: 'agoric';}>>>
+     *   usdcBrand: Brand<'nat'>;
      * }} config
      */
     config => harden(config),
     {
-      /** @param {CctpTxEvidence} evidence */
-      handleTransactionEvent(evidence) {
-        // TODO EventFeed will perform input validation checks.
-        const { recipientAddress } = evidence.aux;
-        const { EUD } = addressTools.getQueryParams(recipientAddress).params;
-        if (!EUD) {
-          statusManager.observe(evidence);
-          throw makeError(
-            `recipientAddress does not contain EUD param: ${q(recipientAddress)}`,
-          );
-        }
+      advancer: {
+        /**
+         * Returns a Promise for a Vow in the happy path, or undefined
+         * when conditions are not met. Aims to perform a status update for
+         * every observed transaction.
+         *
+         * We do not expect any callers to depend on the settlement of
+         * `handleTransactionEvent` - errors caught are communicated to the
+         * `StatusManager` - so we don't need to concern ourselves with
+         * preserving the vow chain for callers.
+         *
+         * @param {CctpTxEvidence} evidence
+         */
+        async handleTransactionEvent(evidence) {
+          await null;
+          try {
+            // TODO poolAccount might be a vow we need to unwrap
+            const { assetManagerFacet, poolAccount, usdcBrand } = this.state;
+            const { recipientAddress } = evidence.aux;
+            const { EUD } =
+              addressTools.getQueryParams(recipientAddress).params;
+            if (!EUD) {
+              throw makeError(
+                `recipientAddress does not contain EUD param: ${q(recipientAddress)}`,
+              );
+            }
 
-        // TODO #10391 this can throw, and should make a status update in the catch
-        const destination = chainHub.makeChainAddress(EUD);
+            // this will throw if the bech32 prefix is not found, but is handled by the catch
+            const destination = chainHub.makeChainAddress(EUD);
 
-        /** @type {DenomAmount} */
-        const requestedAmount = harden({
-          denom: this.state.localDenom,
-          value: BigInt(evidence.tx.amount),
-        });
+            const requestedValue = BigInt(evidence.tx.amount);
+            const requestedAmount = AmountMath.make(usdcBrand, requestedValue);
+            const poolBalance = assetManagerFacet.lookupBalance();
 
-        // TODO #10391 ensure there's enough funds in poolAccount
+            if (!AmountMath.isGTE(poolBalance, requestedAmount)) {
+              log(
+                `Insufficient pool funds`,
+                `Requested ${q(requestedAmount)} but only have ${q(poolBalance)}`,
+              );
+              statusManager.observe(evidence);
+              return;
+            }
 
-        const transferV = E(this.state.poolAccount).transfer(
-          destination,
-          requestedAmount,
-        );
+            try {
+              // mark as Advanced since `transferV` initiates the advance
+              // will throw if we've already .skipped or .advanced this evidence
+              statusManager.advance(evidence);
+            } catch (e) {
+              // only anticipated error is `assertNotSeen`, so
+              // intercept the catch so we don't call .skip which
+              // also performs this check
+              log('Advancer error:', q(e).toString());
+              return;
+            }
 
-        // mark as Advanced since `transferV` initiates the advance
-        statusManager.advance(evidence);
+            try {
+              // should LiquidityPool return a vow here?
+              const { USDC: advancePmtP } =
+                await assetManagerFacet.borrowUnderlying(requestedAmount);
 
-        return watch(transferV, transferHandler, {
-          destination,
-          amount: requestedAmount.value,
-        });
+              // do we actually need to await here?
+              const advancePmt = await advancePmtP;
+              const depositV = E(poolAccount).deposit(advancePmt);
+              return watch(depositV, this.facets.depositHandler, destination);
+            } catch (e) {
+              // TODO how should we think about failure here?
+              log('Ruh roh', q(e).toString());
+              throw e;
+            }
+          } catch (e) {
+            log('Advancer error:', q(e).toString());
+            statusManager.observe(evidence);
+          }
+        },
+      },
+      depositHandler: {
+        /**
+         * @param {NatAmount} amount amount returned from deposit
+         * @param {ChainAddress} destination
+         */
+        onFulfilled(amount, destination) {
+          const { localDenom, poolAccount } = this.state;
+          const transferV = E(poolAccount).transfer(
+            destination,
+            /** @type {DenomAmount} */ ({
+              denom: localDenom,
+              value: amount.value,
+            }),
+          );
+          return watch(transferV, this.facets.transferHandler, {
+            destination,
+            amount,
+          });
+        },
+        // xxx return payment on rejected
+      },
+      transferHandler: {
+        /**
+         * @param {undefined} result TODO confirm this is not a bigint (sequence)
+         * @param {{ destination: ChainAddress; amount: NatAmount; }} ctx
+         */
+        onFulfilled(result, { destination, amount }) {
+          // TODO vstorage update?
+          log(
+            'Advance transfer fulfilled',
+            q({ amount, destination, result }).toString(),
+          );
+        },
+        onRejected(error) {
+          // XXX retry logic?
+          // What do we do if we fail, should we keep a Status?
+          log('Advance transfer rejected', q(error).toString());
+        },
       },
     },
     {
       stateShape: harden({
+        assetManagerFacet: M.remotable(),
         localDenom: M.string(),
-        poolAccount: M.remotable(),
+        poolAccount: M.or(VowShape, M.remotable()),
+        usdcBrand: BrandShape,
       }),
     },
   );
 };
+harden(prepareAdvancerKit);
+
+/**
+ * @param {Zone} zone
+ * @param {AdvancerKitCaps} caps
+ */
+export const prepareAdvancer = (zone, caps) => {
+  const makeAdvancerKit = prepareAdvancerKit(zone, caps);
+  return pickFacet(makeAdvancerKit, 'advancer');
+};
 harden(prepareAdvancer);

packages/fast-usdc/src/fast-usdc.contract.js

@@ -72,11 +72,7 @@ export const contract = async (zcf, privateArgs, zone, tools) => {
   // Connect evidence stream to advancer
   void observeIteration(subscribeEach(feedKit.public.getEvidenceStream()), {
     updateState(evidence) {
-      try {
-        advancer.handleTransactionEvent(evidence);
-      } catch (err) {
-        trace('🚨 Error handling transaction event', err);
-      }
+      void advancer.handleTransactionEvent(evidence);
     },
   });
   const makeLiquidityPoolKit = prepareLiquidityPoolKit(