diff --git a/.gitignore b/.gitignore
index 4868d9a80f4..a4204d8a812 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,8 +42,14 @@ typings/
 # Output of 'npm pack'
 *.tgz
 
-# Yarn Integrity file
-.yarn-integrity
+# Yarn (https://yarnpkg.com/getting-started/qa#which-files-should-be-gitignored)
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
 
 # dotenv environment variables file
 .env
diff --git a/a3p-integration/proposals/z:acceptance/lib/vaults.mts b/a3p-integration/proposals/z:acceptance/lib/vaults.mts
new file mode 100644
index 00000000000..b85eeb76798
--- /dev/null
+++ b/a3p-integration/proposals/z:acceptance/lib/vaults.mts
@@ -0,0 +1,213 @@
+/* eslint-disable @jessie.js/safe-await-separator */
+/* eslint-env node */
+
+import { strict as assert } from 'node:assert';
+
+import {
+  addUser,
+  agops,
+  agoric,
+  ATOM_DENOM,
+  executeOffer,
+  GOV1ADDR,
+  GOV2ADDR,
+  GOV3ADDR,
+  provisionSmartWallet,
+  waitForBlock,
+} from '@agoric/synthetic-chain';
+
+const govAccounts = [GOV1ADDR, GOV2ADDR, GOV3ADDR];
+
+export const ISTunit = 1_000_000n; // aka displayInfo: { decimalPlaces: 6 }
+
+const DEFAULT_TIMEOUT = 65000;
+
+const proposeNewAuctionParams = async (
+  address: string,
+  startFequency: any,
+  clockStep: any,
+  priceLockPeriod: any,
+) => {
+  const charterAcceptOfferId = await agops.ec(
+    'find-continuing-id',
+    '--for',
+    `${'charter\\ member\\ invitation'}`,
+    '--from',
+    address,
+  );
+
+  return executeOffer(
+    address,
+    agops.auctioneer(
+      'proposeParamChange',
+      '--charterAcceptOfferId',
+      charterAcceptOfferId,
+      '--start-frequency',
+      startFequency,
+      '--clock-step',
+      clockStep,
+      '--price-lock-period',
+      priceLockPeriod,
+    ),
+  );
+};
+
+const voteForNewParams = (accounts: string[], position: number) => {
+  console.log('ACTIONS voting for position', position, 'using', accounts);
+  return Promise.all(
+    accounts.map((account: string) =>
+      agops.ec('vote', '--forPosition', position, '--send-from', account),
+    ),
+  );
+};
+
+const paramChangeOfferGeneration = async (
+  previousOfferId: string,
+  voteDur: number,
+  debtLimit: number | bigint,
+) => {
+  const voteDurSec = BigInt(voteDur);
+  const debtLimitValue = BigInt(debtLimit) * ISTunit;
+  const toSec = (ms: number) => BigInt(Math.round(ms / 1000));
+
+  const id = `propose-${Date.now()}`;
+  const deadline = toSec(Date.now()) + voteDurSec;
+
+  const zip = (xs: any[], ys: { [x: string]: any }) =>
+    xs.map((x: any, i: string | number) => [x, ys[i]]);
+  const fromSmallCapsEntries = (txt: string) => {
+    const { body, slots } = JSON.parse(txt);
+    const theEntries = zip(JSON.parse(body.slice(1)), slots).map(
+      ([[name, ref], boardID]) => {
+        const iface = ref.replace(/^\$\d+\./, '');
+        return [name, { iface, boardID }];
+      },
+    );
+    return Object.fromEntries(theEntries);
+  };
+
+  const slots = [] as string[]; // XXX global mutable state
+  const smallCaps = {
+    Nat: (n: any) => `+${n}`,
+    // XXX mutates obj
+    ref: (obj: { ix: string; boardID: any; iface: any }) => {
+      if (obj.ix) return obj.ix;
+      const ix = slots.length;
+      slots.push(obj.boardID);
+      obj.ix = `$${ix}.Alleged: ${obj.iface}`;
+      return obj.ix;
+    },
+  };
+
+  const instance = fromSmallCapsEntries(
+    await agoric.follow('-lF', ':published.agoricNames.instance', '-o', 'text'),
+  );
+  assert(instance.VaultFactory);
+
+  const brand = fromSmallCapsEntries(
+    await agoric.follow('-lF', ':published.agoricNames.brand', '-o', 'text'),
+  );
+  assert(brand.IST);
+  assert(brand.ATOM);
+
+  const body = {
+    method: 'executeOffer',
+    offer: {
+      id,
+      invitationSpec: {
+        invitationMakerName: 'VoteOnParamChange',
+        previousOffer: previousOfferId,
+        source: 'continuing',
+      },
+      offerArgs: {
+        deadline: smallCaps.Nat(deadline),
+        instance: smallCaps.ref(instance.VaultFactory),
+        params: {
+          DebtLimit: {
+            brand: smallCaps.ref(brand.IST),
+            value: smallCaps.Nat(debtLimitValue),
+          },
+        },
+        path: {
+          paramPath: {
+            key: {
+              collateralBrand: smallCaps.ref(brand.ATOM),
+            },
+          },
+        },
+      },
+      proposal: {},
+    },
+  };
+
+  const capData = { body: `#${JSON.stringify(body)}`, slots };
+  return JSON.stringify(capData);
+};
+export const provisionWallet = async (user: string) => {
+  const userAddress = await addUser(user);
+
+  await provisionSmartWallet(
+    userAddress,
+    `20000000ubld,100000000${ATOM_DENOM}`,
+  );
+  await waitForBlock();
+};
+
+export const implementNewAuctionParams = async (
+  address: string,
+  oracles: { address: string; id: string }[],
+  startFequency: number,
+  clockStep: number,
+  priceLockPeriod: number,
+) => {
+  await waitForBlock(3);
+
+  await proposeNewAuctionParams(
+    address,
+    startFequency,
+    clockStep,
+    priceLockPeriod,
+  );
+
+  console.log('ACTIONS voting for new auction params');
+  await voteForNewParams(govAccounts, 0);
+
+  console.log('ACTIONS wait for the vote deadline to pass');
+  await new Promise(r => setTimeout(r, DEFAULT_TIMEOUT));
+};
+
+export const proposeNewDebtCeiling = async (
+  address: string,
+  debtLimit: number | bigint,
+) => {
+  const charterAcceptOfferId = await agops.ec(
+    'find-continuing-id',
+    '--for',
+    `${'charter\\ member\\ invitation'}`,
+    '--from',
+    address,
+  );
+
+  const offer = await paramChangeOfferGeneration(
+    charterAcceptOfferId,
+    30,
+    debtLimit,
+  );
+
+  console.log('ACTIONS proposing new debt ceiling', offer);
+
+  return executeOffer(address, offer);
+};
+
+export const setDebtLimit = async (
+  address: string,
+  debtLimit: number | bigint,
+) => {
+  console.log('ACTIONS Setting debt limit');
+
+  await proposeNewDebtCeiling(address, debtLimit);
+  await voteForNewParams(govAccounts, 0);
+
+  console.log('ACTIONS wait for the vote to pass');
+  await new Promise(r => setTimeout(r, DEFAULT_TIMEOUT));
+};
diff --git a/a3p-integration/proposals/z:acceptance/package.json b/a3p-integration/proposals/z:acceptance/package.json
index 0891c85d62a..0c0432f19a5 100644
--- a/a3p-integration/proposals/z:acceptance/package.json
+++ b/a3p-integration/proposals/z:acceptance/package.json
@@ -1,12 +1,13 @@
 {
   "agoricProposal": {
-    "type": "/cosmos.params.v1beta1.ParameterChangeProposal"
+    "type": "/agoric.swingset.CoreEvalProposal"
   },
   "type": "module",
   "license": "Apache-2.0",
   "dependencies": {
     "@agoric/synthetic-chain": "^0.1.0",
-    "ava": "^6.1.2"
+    "ava": "^6.1.2",
+    "tsx": "^4.17.0"
   },
   "ava": {
     "concurrency": 1,
@@ -18,5 +19,8 @@
   "scripts": {
     "agops": "yarn --cwd /usr/src/agoric-sdk/ --silent agops"
   },
-  "packageManager": "yarn@4.2.2"
+  "packageManager": "yarn@4.2.2",
+  "devDependencies": {
+    "typescript": "^5.5.4"
+  }
 }
diff --git a/a3p-integration/proposals/z:acceptance/scripts/test-vaults.mts b/a3p-integration/proposals/z:acceptance/scripts/test-vaults.mts
new file mode 100755
index 00000000000..a4e5e7f9e5f
--- /dev/null
+++ b/a3p-integration/proposals/z:acceptance/scripts/test-vaults.mts
@@ -0,0 +1,83 @@
+#!/usr/bin/env tsx
+/* eslint-disable @jessie.js/safe-await-separator */
+
+import {
+  adjustVault,
+  agops,
+  agoric,
+  closeVault,
+  getUser,
+  GOV1ADDR,
+  GOV2ADDR,
+  newOfferId,
+  openVault,
+} from '@agoric/synthetic-chain';
+import assert from 'node:assert/strict';
+import {
+  implementNewAuctionParams,
+  ISTunit,
+  provisionWallet,
+  setDebtLimit,
+} from '../lib/vaults.mjs';
+
+const START_FREQUENCY = 600; // StartFrequency: 600s (auction runs every 10m)
+const CLOCK_STEP = 20; // ClockStep: 20s (ensures auction completes in time)
+const PRICE_LOCK_PERIOD = 300;
+const oraclesAddresses = [GOV1ADDR, GOV2ADDR];
+
+const oracles = [] as { address: string; id: string }[];
+for (const oracle of oraclesAddresses) {
+  const offerId = await newOfferId();
+  oracles.push({ address: oracle, id: offerId });
+}
+
+// console.log('Ensure user2 provisioned');
+// await provisionWallet('user2');
+
+// console.log('Ensure auction params have changed');
+// await implementNewAuctionParams(
+//   GOV1ADDR,
+//   oracles,
+//   START_FREQUENCY,
+//   CLOCK_STEP,
+//   PRICE_LOCK_PERIOD,
+// );
+
+// const govParams = await agoric.follow('-lF', ':published.auction.governance');
+// assert.equal(govParams.current.ClockStep.value.relValue, CLOCK_STEP.toString());
+// assert.equal(
+//   govParams.current.StartFrequency.value.relValue,
+//   START_FREQUENCY.toString(),
+// );
+
+console.log('Ensure debt ceiling changes');
+const limit = 45_000_000n;
+await setDebtLimit(GOV1ADDR, limit);
+const params = await agoric.follow(
+  '-lF',
+  ':published.vaultFactory.managers.manager0.governance',
+);
+assert.equal(params.current.DebtLimit.value.value, String(limit * ISTunit));
+
+console.log('Open Vaults');
+const currentVaults = await agops.vaults('list', '--from', GOV1ADDR);
+assert.equal(currentVaults.length, 0);
+
+const vaults = [
+  { mint: 5.0, collateral: 9.0 },
+  { mint: 6.0, collateral: 10.0 },
+];
+
+for (const vault of vaults) {
+  await openVault(GOV1ADDR, vault.mint, vault.collateral);
+}
+
+await adjustVault(GOV1ADDR, 'vault0', { wantCollateral: 1.0 });
+await adjustVault(GOV1ADDR, 'vault0', { wantMinted: 1.0 });
+await closeVault(GOV1ADDR, 'vault1', 6.06);
+
+const user2 = await getUser('user2');
+await openVault(user2, 7, 11);
+await adjustVault(user2, 'vault2', { giveMinted: 1.5 });
+await adjustVault(user2, 'vault2', { giveCollateral: 2.0 });
+await closeVault(user2, 'vault2', 5.75);
diff --git a/a3p-integration/proposals/z:acceptance/test.sh b/a3p-integration/proposals/z:acceptance/test.sh
index 7e4b0145a04..75549f654c4 100755
--- a/a3p-integration/proposals/z:acceptance/test.sh
+++ b/a3p-integration/proposals/z:acceptance/test.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-
+set -ueo pipefail
 # Place here any test that should be executed using the executed proposal.
 # The effects of this step are not persisted in further proposal layers.
 
@@ -10,7 +10,11 @@ yarn ava initial.test.js
 GLOBIGNORE=initial.test.js
 yarn ava ./*.test.js
 
-./create-kread-item-test.sh
+npm install -g tsx
+scripts/test-vaults.mts
+
+# DEBUGGING
+# ./create-kread-item-test.sh
 
-./state-sync-snapshots-test.sh
-./genesis-test.sh
+# ./state-sync-snapshots-test.sh
+# ./genesis-test.sh
diff --git a/a3p-integration/proposals/z:acceptance/tsconfig.json b/a3p-integration/proposals/z:acceptance/tsconfig.json
index 02e3bea3c6d..795ebdd04fc 100644
--- a/a3p-integration/proposals/z:acceptance/tsconfig.json
+++ b/a3p-integration/proposals/z:acceptance/tsconfig.json
@@ -2,11 +2,14 @@
   "compilerOptions": {
     "noEmit": true,
     "target": "esnext",
-    "module": "esnext",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
     "allowJs": true,
     "checkJs": true,
     "strict": false,
     "strictNullChecks": true,
-    "noImplicitThis": true
+    "noImplicitThis": true,
+    // XXX synthetic-chain has some errors
+    "skipLibCheck": true,
   }
 }
diff --git a/a3p-integration/proposals/z:acceptance/yarn.lock b/a3p-integration/proposals/z:acceptance/yarn.lock
index 708f6030037..376240ba41f 100644
--- a/a3p-integration/proposals/z:acceptance/yarn.lock
+++ b/a3p-integration/proposals/z:acceptance/yarn.lock
@@ -26,6 +26,174 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@esbuild/aix-ppc64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/aix-ppc64@npm:0.23.1"
+  conditions: os=aix & cpu=ppc64
+  languageName: node
+  linkType: hard
+
+"@esbuild/android-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/android-arm64@npm:0.23.1"
+  conditions: os=android & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/android-arm@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/android-arm@npm:0.23.1"
+  conditions: os=android & cpu=arm
+  languageName: node
+  linkType: hard
+
+"@esbuild/android-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/android-x64@npm:0.23.1"
+  conditions: os=android & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/darwin-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/darwin-arm64@npm:0.23.1"
+  conditions: os=darwin & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/darwin-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/darwin-x64@npm:0.23.1"
+  conditions: os=darwin & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/freebsd-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/freebsd-arm64@npm:0.23.1"
+  conditions: os=freebsd & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/freebsd-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/freebsd-x64@npm:0.23.1"
+  conditions: os=freebsd & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-arm64@npm:0.23.1"
+  conditions: os=linux & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-arm@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-arm@npm:0.23.1"
+  conditions: os=linux & cpu=arm
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-ia32@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-ia32@npm:0.23.1"
+  conditions: os=linux & cpu=ia32
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-loong64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-loong64@npm:0.23.1"
+  conditions: os=linux & cpu=loong64
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-mips64el@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-mips64el@npm:0.23.1"
+  conditions: os=linux & cpu=mips64el
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-ppc64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-ppc64@npm:0.23.1"
+  conditions: os=linux & cpu=ppc64
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-riscv64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-riscv64@npm:0.23.1"
+  conditions: os=linux & cpu=riscv64
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-s390x@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-s390x@npm:0.23.1"
+  conditions: os=linux & cpu=s390x
+  languageName: node
+  linkType: hard
+
+"@esbuild/linux-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/linux-x64@npm:0.23.1"
+  conditions: os=linux & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/netbsd-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/netbsd-x64@npm:0.23.1"
+  conditions: os=netbsd & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/openbsd-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/openbsd-arm64@npm:0.23.1"
+  conditions: os=openbsd & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/openbsd-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/openbsd-x64@npm:0.23.1"
+  conditions: os=openbsd & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/sunos-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/sunos-x64@npm:0.23.1"
+  conditions: os=sunos & cpu=x64
+  languageName: node
+  linkType: hard
+
+"@esbuild/win32-arm64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/win32-arm64@npm:0.23.1"
+  conditions: os=win32 & cpu=arm64
+  languageName: node
+  linkType: hard
+
+"@esbuild/win32-ia32@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/win32-ia32@npm:0.23.1"
+  conditions: os=win32 & cpu=ia32
+  languageName: node
+  linkType: hard
+
+"@esbuild/win32-x64@npm:0.23.1":
+  version: 0.23.1
+  resolution: "@esbuild/win32-x64@npm:0.23.1"
+  conditions: os=win32 & cpu=x64
+  languageName: node
+  linkType: hard
+
 "@isaacs/cliui@npm:^8.0.2":
   version: 8.0.2
   resolution: "@isaacs/cliui@npm:8.0.2"
@@ -772,6 +940,89 @@ __metadata:
   languageName: node
   linkType: hard
 
+"esbuild@npm:~0.23.0":
+  version: 0.23.1
+  resolution: "esbuild@npm:0.23.1"
+  dependencies:
+    "@esbuild/aix-ppc64": "npm:0.23.1"
+    "@esbuild/android-arm": "npm:0.23.1"
+    "@esbuild/android-arm64": "npm:0.23.1"
+    "@esbuild/android-x64": "npm:0.23.1"
+    "@esbuild/darwin-arm64": "npm:0.23.1"
+    "@esbuild/darwin-x64": "npm:0.23.1"
+    "@esbuild/freebsd-arm64": "npm:0.23.1"
+    "@esbuild/freebsd-x64": "npm:0.23.1"
+    "@esbuild/linux-arm": "npm:0.23.1"
+    "@esbuild/linux-arm64": "npm:0.23.1"
+    "@esbuild/linux-ia32": "npm:0.23.1"
+    "@esbuild/linux-loong64": "npm:0.23.1"
+    "@esbuild/linux-mips64el": "npm:0.23.1"
+    "@esbuild/linux-ppc64": "npm:0.23.1"
+    "@esbuild/linux-riscv64": "npm:0.23.1"
+    "@esbuild/linux-s390x": "npm:0.23.1"
+    "@esbuild/linux-x64": "npm:0.23.1"
+    "@esbuild/netbsd-x64": "npm:0.23.1"
+    "@esbuild/openbsd-arm64": "npm:0.23.1"
+    "@esbuild/openbsd-x64": "npm:0.23.1"
+    "@esbuild/sunos-x64": "npm:0.23.1"
+    "@esbuild/win32-arm64": "npm:0.23.1"
+    "@esbuild/win32-ia32": "npm:0.23.1"
+    "@esbuild/win32-x64": "npm:0.23.1"
+  dependenciesMeta:
+    "@esbuild/aix-ppc64":
+      optional: true
+    "@esbuild/android-arm":
+      optional: true
+    "@esbuild/android-arm64":
+      optional: true
+    "@esbuild/android-x64":
+      optional: true
+    "@esbuild/darwin-arm64":
+      optional: true
+    "@esbuild/darwin-x64":
+      optional: true
+    "@esbuild/freebsd-arm64":
+      optional: true
+    "@esbuild/freebsd-x64":
+      optional: true
+    "@esbuild/linux-arm":
+      optional: true
+    "@esbuild/linux-arm64":
+      optional: true
+    "@esbuild/linux-ia32":
+      optional: true
+    "@esbuild/linux-loong64":
+      optional: true
+    "@esbuild/linux-mips64el":
+      optional: true
+    "@esbuild/linux-ppc64":
+      optional: true
+    "@esbuild/linux-riscv64":
+      optional: true
+    "@esbuild/linux-s390x":
+      optional: true
+    "@esbuild/linux-x64":
+      optional: true
+    "@esbuild/netbsd-x64":
+      optional: true
+    "@esbuild/openbsd-arm64":
+      optional: true
+    "@esbuild/openbsd-x64":
+      optional: true
+    "@esbuild/sunos-x64":
+      optional: true
+    "@esbuild/win32-arm64":
+      optional: true
+    "@esbuild/win32-ia32":
+      optional: true
+    "@esbuild/win32-x64":
+      optional: true
+  bin:
+    esbuild: bin/esbuild
+  checksum: 10c0/08c2ed1105cc3c5e3a24a771e35532fe6089dd24a39c10097899072cef4a99f20860e41e9294e000d86380f353b04d8c50af482483d7f69f5208481cce61eec7
+  languageName: node
+  linkType: hard
+
 "escalade@npm:^3.1.1":
   version: 3.1.1
   resolution: "escalade@npm:3.1.1"
@@ -951,6 +1202,25 @@ __metadata:
   languageName: node
   linkType: hard
 
+"fsevents@npm:~2.3.3":
+  version: 2.3.3
+  resolution: "fsevents@npm:2.3.3"
+  dependencies:
+    node-gyp: "npm:latest"
+  checksum: 10c0/a1f0c44595123ed717febbc478aa952e47adfc28e2092be66b8ab1635147254ca6cfe1df792a8997f22716d4cbafc73309899ff7bfac2ac3ad8cf2e4ecc3ec60
+  conditions: os=darwin
+  languageName: node
+  linkType: hard
+
+"fsevents@patch:fsevents@npm%3A~2.3.3#optional!builtin<compat/fsevents>":
+  version: 2.3.3
+  resolution: "fsevents@patch:fsevents@npm%3A2.3.3#optional!builtin<compat/fsevents>::version=2.3.3&hash=df0bf1"
+  dependencies:
+    node-gyp: "npm:latest"
+  conditions: os=darwin
+  languageName: node
+  linkType: hard
+
 "gauge@npm:^3.0.0":
   version: 3.0.2
   resolution: "gauge@npm:3.0.2"
@@ -989,6 +1259,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"get-tsconfig@npm:^4.7.5":
+  version: 4.7.6
+  resolution: "get-tsconfig@npm:4.7.6"
+  dependencies:
+    resolve-pkg-maps: "npm:^1.0.0"
+  checksum: 10c0/2240e1b13e996dfbb947d177f422f83d09d1f93c9ce16959ebb3c2bdf8bdf4f04f98eba043859172da1685f9c7071091f0acfa964ebbe4780394d83b7dc3f58a
+  languageName: node
+  linkType: hard
+
 "github-from-package@npm:0.0.0":
   version: 0.0.0
   resolution: "github-from-package@npm:0.0.0"
@@ -1932,6 +2211,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"resolve-pkg-maps@npm:^1.0.0":
+  version: 1.0.0
+  resolution: "resolve-pkg-maps@npm:1.0.0"
+  checksum: 10c0/fb8f7bbe2ca281a73b7ef423a1cbc786fb244bd7a95cbe5c3fba25b27d327150beca8ba02f622baea65919a57e061eb5005204daa5f93ed590d9b77463a567ab
+  languageName: node
+  linkType: hard
+
 "retry@npm:^0.12.0":
   version: 0.12.0
   resolution: "retry@npm:0.12.0"
@@ -1963,6 +2249,8 @@ __metadata:
   dependencies:
     "@agoric/synthetic-chain": "npm:^0.1.0"
     ava: "npm:^6.1.2"
+    tsx: "npm:^4.17.0"
+    typescript: "npm:^5.5.4"
   languageName: unknown
   linkType: soft
 
@@ -2298,6 +2586,22 @@ __metadata:
   languageName: node
   linkType: hard
 
+"tsx@npm:^4.17.0":
+  version: 4.17.0
+  resolution: "tsx@npm:4.17.0"
+  dependencies:
+    esbuild: "npm:~0.23.0"
+    fsevents: "npm:~2.3.3"
+    get-tsconfig: "npm:^4.7.5"
+  dependenciesMeta:
+    fsevents:
+      optional: true
+  bin:
+    tsx: dist/cli.mjs
+  checksum: 10c0/ad720b81d6447c7695d24c27947fa1a2b6db9d2ef03216389edd6fa0006aa479bc0d8348a1ac9975a08edef4ce791ff5629a24d8dccbb0987f42e5407785cfa4
+  languageName: node
+  linkType: hard
+
 "tunnel-agent@npm:^0.6.0":
   version: 0.6.0
   resolution: "tunnel-agent@npm:0.6.0"
@@ -2314,6 +2618,26 @@ __metadata:
   languageName: node
   linkType: hard
 
+"typescript@npm:^5.5.4":
+  version: 5.5.4
+  resolution: "typescript@npm:5.5.4"
+  bin:
+    tsc: bin/tsc
+    tsserver: bin/tsserver
+  checksum: 10c0/422be60f89e661eab29ac488c974b6cc0a660fb2228003b297c3d10c32c90f3bcffc1009b43876a082515a3c376b1eefcce823d6e78982e6878408b9a923199c
+  languageName: node
+  linkType: hard
+
+"typescript@patch:typescript@npm%3A^5.5.4#optional!builtin<compat/typescript>":
+  version: 5.5.4
+  resolution: "typescript@patch:typescript@npm%3A5.5.4#optional!builtin<compat/typescript>::version=5.5.4&hash=b45daf"
+  bin:
+    tsc: bin/tsc
+    tsserver: bin/tsserver
+  checksum: 10c0/10dd9881baba22763de859e8050d6cb6e2db854197495c6f1929b08d1eb2b2b00d0b5d9b0bcee8472f1c3f4a7ef6a5d7ebe0cfd703f853aa5ae465b8404bc1ba
+  languageName: node
+  linkType: hard
+
 "unicorn-magic@npm:^0.1.0":
   version: 0.1.0
   resolution: "unicorn-magic@npm:0.1.0"
diff --git a/packages/SwingSet/src/types-external.js b/packages/SwingSet/src/types-external.js
index a90c4ab2b7a..f1ada6e5ddb 100644
--- a/packages/SwingSet/src/types-external.js
+++ b/packages/SwingSet/src/types-external.js
@@ -287,7 +287,7 @@ export {};
  * Vat Creation and Management
  *
  * @typedef { string } BundleID
- * @typedef {any} BundleCap
+ * @typedef {import('./vats/plugin-manager.js').Device<'BundleCap'>} BundleCap
  * @typedef { { moduleFormat: 'endoZipBase64', endoZipBase64: string, endoZipBase64Sha512: string } } EndoZipBase64Bundle
  *
  * @typedef { unknown } Meter
diff --git a/packages/zoe/tools/fakeVatAdmin.js b/packages/zoe/tools/fakeVatAdmin.js
index b174a067309..914d33b0e31 100644
--- a/packages/zoe/tools/fakeVatAdmin.js
+++ b/packages/zoe/tools/fakeVatAdmin.js
@@ -18,8 +18,7 @@ import zcfBundle from '../bundles/bundle-contractFacet.js';
 // this simulates a bundlecap, which is normally a swingset "device node"
 /** @typedef { import('@agoric/swingset-vat').BundleCap } BundleCap */
 /** @type {() => BundleCap} */
-const fakeBundleCap = () => makeHandle('FakeBundleCap');
-const bogusBundleCap = () => makeHandle('BogusBundleCap');
+const fakeBundleCap = () => /** @type {any} */ (makeHandle('BundleCap'));
 export const zcfBundleCap = fakeBundleCap();
 
 /**
@@ -56,13 +55,13 @@ function makeFakeVatAdmin(testContextSetter = undefined, makeRemote = x => x) {
   const admin = Far('vatAdmin', {
     getBundleCap: bundleID => {
       if (!idToBundleCap.has(bundleID)) {
-        idToBundleCap.init(bundleID, bogusBundleCap());
+        idToBundleCap.init(bundleID, fakeBundleCap());
       }
       return Promise.resolve(idToBundleCap.get(bundleID));
     },
     waitForBundleCap: bundleID => {
       if (!idToBundleCap.has(bundleID)) {
-        idToBundleCap.init(bundleID, bogusBundleCap());
+        idToBundleCap.init(bundleID, fakeBundleCap());
       }
       return Promise.resolve(idToBundleCap.get(bundleID));
     },