diff --git a/packages/zoe/contractFacet.js b/packages/zoe/contractFacet.js
index d6d6a3d11e3..e2d1e57f5e8 100644
--- a/packages/zoe/contractFacet.js
+++ b/packages/zoe/contractFacet.js
@@ -1 +1,3 @@
+// @jessie-check
+
 export * from './src/contractFacet/vatRoot.js';
diff --git a/packages/zoe/exported.js b/packages/zoe/exported.js
index 8c8d271408c..227a8133b74 100644
--- a/packages/zoe/exported.js
+++ b/packages/zoe/exported.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import './src/contractFacet/types.js';
 import './src/zoeService/types.js';
 import './src/contractSupport/types.js';
diff --git a/packages/zoe/scripts/build-bundles.js b/packages/zoe/scripts/build-bundles.js
index c0073288192..69254e341ba 100644
--- a/packages/zoe/scripts/build-bundles.js
+++ b/packages/zoe/scripts/build-bundles.js
@@ -1,4 +1,6 @@
 #! /usr/bin/env node
+// @jessie-check
+
 import '@endo/init';
 import { createBundles } from '@agoric/internal/src/node/createBundles.js';
 import url from 'url';
diff --git a/packages/zoe/src/contractFacet/evalContractCode.js b/packages/zoe/src/contractFacet/evalContractCode.js
index 3c5d8826127..b357f3d2d00 100644
--- a/packages/zoe/src/contractFacet/evalContractCode.js
+++ b/packages/zoe/src/contractFacet/evalContractCode.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 // NB: cannot import, breaks bundle building
 /* global globalThis */
 
diff --git a/packages/zoe/src/contractFacet/internal-types.js b/packages/zoe/src/contractFacet/internal-types.js
index 214cfa65a74..4de2c829bdd 100644
--- a/packages/zoe/src/contractFacet/internal-types.js
+++ b/packages/zoe/src/contractFacet/internal-types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * @typedef {( {zcf: ZCF} ) => void} TestJigSetter
  */
diff --git a/packages/zoe/src/contractFacet/offerHandlerStorage.js b/packages/zoe/src/contractFacet/offerHandlerStorage.js
index 92247ef19e4..09e2d30bd75 100644
--- a/packages/zoe/src/contractFacet/offerHandlerStorage.js
+++ b/packages/zoe/src/contractFacet/offerHandlerStorage.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { makeScalarWeakMapStore } from '@agoric/store';
 import { ToFarFunction } from '@endo/marshal';
 import { canBeDurable, provideDurableWeakMapStore } from '@agoric/vat-data';
diff --git a/packages/zoe/src/contractFacet/types.js b/packages/zoe/src/contractFacet/types.js
index 55dfbaf1609..feda8ec603a 100644
--- a/packages/zoe/src/contractFacet/types.js
+++ b/packages/zoe/src/contractFacet/types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /// <reference types="ses"/>
 
 /** @typedef {import('@agoric/ertp').IssuerOptionsRecord} IssuerOptionsRecord */
diff --git a/packages/zoe/src/contractFacet/vatRoot.js b/packages/zoe/src/contractFacet/vatRoot.js
index 881181c0d7e..befea18e9c6 100644
--- a/packages/zoe/src/contractFacet/vatRoot.js
+++ b/packages/zoe/src/contractFacet/vatRoot.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 // This is the Zoe contract facet. Each time we make a new instance of a
 // contract we will start by creating a new vat and running this code in it. In
 // order to install this code in a vat, Zoe needs to import a bundle containing
diff --git a/packages/zoe/src/contractFacet/zcfMint.js b/packages/zoe/src/contractFacet/zcfMint.js
index 5151885b105..892bcd1b49d 100644
--- a/packages/zoe/src/contractFacet/zcfMint.js
+++ b/packages/zoe/src/contractFacet/zcfMint.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { E } from '@endo/eventual-send';
 import { AmountMath } from '@agoric/ertp';
 import {
diff --git a/packages/zoe/src/contractSupport/bondingCurves.js b/packages/zoe/src/contractSupport/bondingCurves.js
index ccb1ab6a851..a7d51a536d9 100644
--- a/packages/zoe/src/contractSupport/bondingCurves.js
+++ b/packages/zoe/src/contractSupport/bondingCurves.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { Nat } from '@endo/nat';
 import { natSafeMath } from './safeMath.js';
 
diff --git a/packages/zoe/src/contractSupport/index.js b/packages/zoe/src/contractSupport/index.js
index ca7d654ca7a..5eac279b893 100644
--- a/packages/zoe/src/contractSupport/index.js
+++ b/packages/zoe/src/contractSupport/index.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 export {
   getInputPrice,
   getOutputPrice,
diff --git a/packages/zoe/src/contractSupport/priceAuthorityInitial.js b/packages/zoe/src/contractSupport/priceAuthorityInitial.js
index a15cef6b326..e41734877f8 100644
--- a/packages/zoe/src/contractSupport/priceAuthorityInitial.js
+++ b/packages/zoe/src/contractSupport/priceAuthorityInitial.js
@@ -1,4 +1,6 @@
 // @ts-check
+// @jessie-check
+
 import { E } from '@endo/far';
 import { Far } from '@endo/marshal';
 
diff --git a/packages/zoe/src/contractSupport/priceQuote.js b/packages/zoe/src/contractSupport/priceQuote.js
index 3ba149e36ac..71422ed682d 100644
--- a/packages/zoe/src/contractSupport/priceQuote.js
+++ b/packages/zoe/src/contractSupport/priceQuote.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { AmountMath } from '@agoric/ertp';
 import { Nat } from '@endo/nat';
 import { E } from '@endo/eventual-send';
diff --git a/packages/zoe/src/contractSupport/types.js b/packages/zoe/src/contractSupport/types.js
index 6808eb5f65a..c1341d1768c 100644
--- a/packages/zoe/src/contractSupport/types.js
+++ b/packages/zoe/src/contractSupport/types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /// <reference types="ses"/>
 
 /**
diff --git a/packages/zoe/src/handleWarning.js b/packages/zoe/src/handleWarning.js
index 321f5d520aa..c0e2388da1a 100644
--- a/packages/zoe/src/handleWarning.js
+++ b/packages/zoe/src/handleWarning.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Don't trigger Node.js's UnhandledPromiseRejectionWarning.
  * This does not suppress any error messages.
diff --git a/packages/zoe/src/internal-types.js b/packages/zoe/src/internal-types.js
index ce79d5e5dff..f1ac110d697 100644
--- a/packages/zoe/src/internal-types.js
+++ b/packages/zoe/src/internal-types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * @typedef {object} SeatData
  * @property {ProposalRecord} proposal
diff --git a/packages/zoe/src/issuerRecord.js b/packages/zoe/src/issuerRecord.js
index 137a0915390..aaa2e467eab 100644
--- a/packages/zoe/src/issuerRecord.js
+++ b/packages/zoe/src/issuerRecord.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Put together information about the issuer in a standard format that
  * is synchronously accessible.
diff --git a/packages/zoe/src/makeHandle.js b/packages/zoe/src/makeHandle.js
index fa87b4217b2..5af62d1b6cf 100644
--- a/packages/zoe/src/makeHandle.js
+++ b/packages/zoe/src/makeHandle.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { assert } from '@agoric/assert';
 import { initEmpty, makeExo } from '@agoric/store';
 import { prepareExoClass } from '@agoric/vat-data';
diff --git a/packages/zoe/src/typeGuards.js b/packages/zoe/src/typeGuards.js
index fa0bf9b9c14..9176f9556a9 100644
--- a/packages/zoe/src/typeGuards.js
+++ b/packages/zoe/src/typeGuards.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import {
   AmountShape,
   AssetKindShape,
diff --git a/packages/zoe/src/types.js b/packages/zoe/src/types.js
index 73166c6b4b7..76b37719701 100644
--- a/packages/zoe/src/types.js
+++ b/packages/zoe/src/types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /// <reference types="ses"/>
 
 /**
diff --git a/packages/zoe/src/zoeService/createZCFVat.js b/packages/zoe/src/zoeService/createZCFVat.js
index fefd654ba87..e1437e7b7e6 100644
--- a/packages/zoe/src/zoeService/createZCFVat.js
+++ b/packages/zoe/src/zoeService/createZCFVat.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { E } from '@endo/eventual-send';
 
 const { Fail, quote: q } = assert;
diff --git a/packages/zoe/src/zoeService/internal-types.js b/packages/zoe/src/zoeService/internal-types.js
index 892b226b8ed..9a5a9e51918 100644
--- a/packages/zoe/src/zoeService/internal-types.js
+++ b/packages/zoe/src/zoeService/internal-types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Create a purse for a new issuer
  *
diff --git a/packages/zoe/src/zoeService/invitationQueries.js b/packages/zoe/src/zoeService/invitationQueries.js
index 06c515bd1d2..dd6bc544923 100644
--- a/packages/zoe/src/zoeService/invitationQueries.js
+++ b/packages/zoe/src/zoeService/invitationQueries.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { assert, details as X } from '@agoric/assert';
 import { E } from '@endo/eventual-send';
 
diff --git a/packages/zoe/src/zoeService/makeInvitation.js b/packages/zoe/src/zoeService/makeInvitation.js
index fa4c5c5a69b..cb59e7c549f 100644
--- a/packages/zoe/src/zoeService/makeInvitation.js
+++ b/packages/zoe/src/zoeService/makeInvitation.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { provideDurableMapStore } from '@agoric/vat-data';
 import {
   AssetKind,
diff --git a/packages/zoe/src/zoeService/offer/burnInvitation.js b/packages/zoe/src/zoeService/offer/burnInvitation.js
index 89cf58375e4..eb5b36e90c5 100644
--- a/packages/zoe/src/zoeService/offer/burnInvitation.js
+++ b/packages/zoe/src/zoeService/offer/burnInvitation.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { Fail, assert, details as X } from '@agoric/assert';
 import { E } from '@endo/eventual-send';
 
diff --git a/packages/zoe/src/zoeService/offer/offer.js b/packages/zoe/src/zoeService/offer/offer.js
index 106d2d9da78..f34d578e171 100644
--- a/packages/zoe/src/zoeService/offer/offer.js
+++ b/packages/zoe/src/zoeService/offer/offer.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { passStyleOf } from '@endo/marshal';
 import { mustMatch } from '@agoric/store';
 import { E } from '@endo/eventual-send';
diff --git a/packages/zoe/src/zoeService/types.js b/packages/zoe/src/zoeService/types.js
index 5b991fed4cb..8e4dbc7ce96 100644
--- a/packages/zoe/src/zoeService/types.js
+++ b/packages/zoe/src/zoeService/types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /// <reference types="ses"/>
 
 /**
diff --git a/packages/zoe/src/zoeService/zoe.js b/packages/zoe/src/zoeService/zoe.js
index c1ccdadf007..6e1edcb6b24 100644
--- a/packages/zoe/src/zoeService/zoe.js
+++ b/packages/zoe/src/zoeService/zoe.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Zoe uses ERTP, the Electronic Rights Transfer Protocol
  *
diff --git a/packages/zoe/tools/fakeVatAdmin.js b/packages/zoe/tools/fakeVatAdmin.js
index dc29f18b4f7..8587db4e19a 100644
--- a/packages/zoe/tools/fakeVatAdmin.js
+++ b/packages/zoe/tools/fakeVatAdmin.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { Fail } from '@agoric/assert';
 import { E } from '@endo/eventual-send';
 import { makePromiseKit } from '@endo/promise-kit';
diff --git a/packages/zoe/tools/internal-types.js b/packages/zoe/tools/internal-types.js
index d0055738b60..750c189be4b 100644
--- a/packages/zoe/tools/internal-types.js
+++ b/packages/zoe/tools/internal-types.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * @typedef {object} ManualTimerAdmin
  * @property {(msg?: string) => void | Promise<void>} tick Advance the timer by one tick.
diff --git a/packages/zoe/tools/manualPriceAuthority.js b/packages/zoe/tools/manualPriceAuthority.js
index a5f7c532850..f2be0391472 100644
--- a/packages/zoe/tools/manualPriceAuthority.js
+++ b/packages/zoe/tools/manualPriceAuthority.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 import { AmountMath, makeIssuerKit, AssetKind } from '@agoric/ertp';
 import { E } from '@endo/eventual-send';
 import { Far } from '@endo/marshal';
diff --git a/packages/zoe/tools/prepare-test-env-ava.js b/packages/zoe/tools/prepare-test-env-ava.js
index a6e6520dde0..3441cba85b1 100644
--- a/packages/zoe/tools/prepare-test-env-ava.js
+++ b/packages/zoe/tools/prepare-test-env-ava.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Prepare global environment for zoe tests.
  *
diff --git a/packages/zoe/tools/prepare-test-env.js b/packages/zoe/tools/prepare-test-env.js
index 31f9979d4b8..5602959ea06 100644
--- a/packages/zoe/tools/prepare-test-env.js
+++ b/packages/zoe/tools/prepare-test-env.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * Prepare global environment for zoe tests.
  *
diff --git a/packages/zoe/tools/types-ambient.js b/packages/zoe/tools/types-ambient.js
index 177aa3e8d03..d26802fad91 100644
--- a/packages/zoe/tools/types-ambient.js
+++ b/packages/zoe/tools/types-ambient.js
@@ -1,3 +1,5 @@
+// @jessie-check
+
 /**
  * @typedef {object} PriceQuote
  * @property {Amount<'set'>} quoteAmount