diff --git a/packages/ERTP/jsconfig.json b/packages/ERTP/jsconfig.json
index a952d3509ba..d2e659dcc2d 100644
--- a/packages/ERTP/jsconfig.json
+++ b/packages/ERTP/jsconfig.json
@@ -6,6 +6,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
     "types": [
       "node"
diff --git a/packages/SwingSet/jsconfig.json b/packages/SwingSet/jsconfig.json
index 81a97c09978..6e3990d52d7 100644
--- a/packages/SwingSet/jsconfig.json
+++ b/packages/SwingSet/jsconfig.json
@@ -6,6 +6,7 @@
     "checkJs": true,
     "noEmit": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/SwingSet/src/lib-nodejs/worker-protocol.js b/packages/SwingSet/src/lib-nodejs/worker-protocol.js
index dea9027dc6d..260b9940507 100644
--- a/packages/SwingSet/src/lib-nodejs/worker-protocol.js
+++ b/packages/SwingSet/src/lib-nodejs/worker-protocol.js
@@ -7,6 +7,7 @@ import { Transform } from 'stream';
 export function arrayEncoderStream() {
   /**
    *
+   * @this {{ push: (b: Buffer) => void }}
    * @param {*} object
    * @param {BufferEncoding} encoding
    * @param {*} callback
@@ -30,6 +31,7 @@ export function arrayEncoderStream() {
 export function arrayDecoderStream() {
   /**
    *
+   * @this {{ push: (b: Buffer) => void }}
    * @param {Buffer} buf
    * @param {BufferEncoding} encoding
    * @param {*} callback
diff --git a/packages/SwingSet/src/lib/netstring.js b/packages/SwingSet/src/lib/netstring.js
index 45142303c91..6bb4d2f5001 100644
--- a/packages/SwingSet/src/lib/netstring.js
+++ b/packages/SwingSet/src/lib/netstring.js
@@ -22,6 +22,7 @@ export function encode(data) {
 export function netstringEncoderStream() {
   /**
    *
+   * @this {{ push: (b: Buffer) => void }}
    * @param {Buffer} chunk
    * @param {BufferEncoding} encoding
    * @param {*} callback
@@ -86,6 +87,7 @@ export function netstringDecoderStream(optMaxChunkSize) {
   let buffered = Buffer.from('');
   /**
    *
+   * @this {{ push: (b: Buffer) => void }}
    * @param {Buffer} chunk
    * @param {BufferEncoding} encoding
    * @param {*} callback
diff --git a/packages/access-token/jsconfig.json b/packages/access-token/jsconfig.json
index 20b970a3dd1..5eb6e745dfa 100644
--- a/packages/access-token/jsconfig.json
+++ b/packages/access-token/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/agoric-cli/jsconfig.json b/packages/agoric-cli/jsconfig.json
index e386c8555f4..641beb64699 100644
--- a/packages/agoric-cli/jsconfig.json
+++ b/packages/agoric-cli/jsconfig.json
@@ -13,6 +13,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/agoric-cli/src/commands/oracle.js b/packages/agoric-cli/src/commands/oracle.js
index 3578b045fcf..86166d6b2ff 100644
--- a/packages/agoric-cli/src/commands/oracle.js
+++ b/packages/agoric-cli/src/commands/oracle.js
@@ -69,6 +69,7 @@ export const makeOracleCommand = async logger => {
     )
     .option('--offerId [number]', 'Offer id', Number, Date.now())
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const instance = lookupPriceAggregatorInstance(opts.pair);
@@ -104,6 +105,7 @@ export const makeOracleCommand = async logger => {
     )
     .requiredOption('--price [number]', 'price (format TODO)', String)
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       /** @type {import('../lib/psm.js').OfferSpec} */
@@ -136,6 +138,7 @@ export const makeOracleCommand = async logger => {
       ['ATOM', 'USD'],
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const { pair } = this.opts();
 
       const capDataStr = await vstorage.readLatest(
diff --git a/packages/agoric-cli/src/commands/perf.js b/packages/agoric-cli/src/commands/perf.js
index c06aadbbe9b..efba4c05855 100644
--- a/packages/agoric-cli/src/commands/perf.js
+++ b/packages/agoric-cli/src/commands/perf.js
@@ -45,6 +45,7 @@ export const makePerfCommand = async logger => {
     )
     .option('--home [string]', 'directory for config and data')
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
       logger.warn({ opts });
       const payloadStr = await fs.readFileSync(opts.executeOffer).toString();
diff --git a/packages/agoric-cli/src/commands/psm.js b/packages/agoric-cli/src/commands/psm.js
index 8e96b431077..f20a176fdbf 100644
--- a/packages/agoric-cli/src/commands/psm.js
+++ b/packages/agoric-cli/src/commands/psm.js
@@ -126,6 +126,7 @@ export const makePsmCommand = async logger => {
       ['IST', 'AUSD'],
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const { pair } = this.opts();
       const { governance } = await getGovernanceState(pair);
       console.log('psm governance params', Object.keys(governance));
@@ -159,6 +160,7 @@ export const makePsmCommand = async logger => {
     .option('--feePct [%]', 'Gas fee percentage', Number)
     .option('--offerId [number]', 'Offer id', Number, Date.now())
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
       console.warn('running with options', opts);
       const instance = await lookupPsmInstance(opts.pair);
@@ -172,6 +174,7 @@ export const makePsmCommand = async logger => {
     .description('join the economic committee')
     .option('--offerId [number]', 'Offer id', Number, Date.now())
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const { economicCommittee } = agoricNames.instance;
@@ -202,6 +205,7 @@ export const makePsmCommand = async logger => {
     .description('prepare an offer to accept the charter invitation')
     .option('--offerId [number]', 'Offer id', Number, Date.now())
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const { psmCharter } = agoricNames.instance;
@@ -255,6 +259,7 @@ export const makePsmCommand = async logger => {
       1,
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const psmInstance = lookupPsmInstance(opts.pair);
@@ -312,6 +317,7 @@ export const makePsmCommand = async logger => {
       1,
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const psmInstance = lookupPsmInstance(opts.pair);
@@ -366,6 +372,7 @@ export const makePsmCommand = async logger => {
       Number,
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const questionHandleCapDataStr = await vstorage.readLatest(
diff --git a/packages/agoric-cli/src/commands/wallet.js b/packages/agoric-cli/src/commands/wallet.js
index 62fea897697..3fcfd2e22dc 100644
--- a/packages/agoric-cli/src/commands/wallet.js
+++ b/packages/agoric-cli/src/commands/wallet.js
@@ -53,6 +53,7 @@ export const makeWalletCommand = async () => {
         spend,
         home,
         keyringBackend: backend,
+        // @ts-expect-error this implicit any
       } = this.opts();
       const tx = `provision-one ${nickname} ${account} SMART_WALLET`;
       if (spend) {
@@ -102,6 +103,7 @@ export const makeWalletCommand = async () => {
         offer,
         home,
         keyringBackend: backend,
+        // @ts-expect-error this implicit any
       } = this.opts();
 
       execSwingsetTransaction(
@@ -131,6 +133,7 @@ export const makeWalletCommand = async () => {
       normalizeAddress,
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const opts = this.opts();
 
       const { agoricNames, fromBoard, vstorage } = await makeRpcUtils({
@@ -176,6 +179,7 @@ export const makeWalletCommand = async () => {
       normalizeAddress,
     )
     .action(async function () {
+      // @ts-expect-error this implicit any
       const { from } = this.opts();
       const spec = `:published.wallet.${from}`;
 
diff --git a/packages/assert/jsconfig.json b/packages/assert/jsconfig.json
index 5b49fdf922e..c427eff5cfb 100644
--- a/packages/assert/jsconfig.json
+++ b/packages/assert/jsconfig.json
@@ -3,9 +3,8 @@
   "compilerOptions": {
     "target": "esnext",
     "module": "esnext",
-
     "noEmit": true,
-/*
+    /*
     // The following flags are for creating .d.ts files:
     "noEmit": false,
     "declaration": true,
@@ -13,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/cache/jsconfig.json b/packages/cache/jsconfig.json
index 574efb7853d..c0220e6dd95 100644
--- a/packages/cache/jsconfig.json
+++ b/packages/cache/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/casting/jsconfig.json b/packages/casting/jsconfig.json
index 574efb7853d..c0220e6dd95 100644
--- a/packages/casting/jsconfig.json
+++ b/packages/casting/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/cosmic-proto/tsconfig.json b/packages/cosmic-proto/tsconfig.json
index 88079b96a95..0e93484c29e 100644
--- a/packages/cosmic-proto/tsconfig.json
+++ b/packages/cosmic-proto/tsconfig.json
@@ -7,6 +7,7 @@
     "allowSyntheticDefaultImports": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
     "outDir": "dist"
   },
diff --git a/packages/cosmic-swingset/jsconfig.json b/packages/cosmic-swingset/jsconfig.json
index 1ea05b00f4c..8c6d9976bf4 100644
--- a/packages/cosmic-swingset/jsconfig.json
+++ b/packages/cosmic-swingset/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/deploy-script-support/jsconfig.json b/packages/deploy-script-support/jsconfig.json
index 6de2c49ef46..1bc5745423f 100644
--- a/packages/deploy-script-support/jsconfig.json
+++ b/packages/deploy-script-support/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/deployment/jsconfig.json b/packages/deployment/jsconfig.json
index 20b970a3dd1..5eb6e745dfa 100644
--- a/packages/deployment/jsconfig.json
+++ b/packages/deployment/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/governance/jsconfig.json b/packages/governance/jsconfig.json
index 858ad6a85b1..242b11f4bbb 100644
--- a/packages/governance/jsconfig.json
+++ b/packages/governance/jsconfig.json
@@ -6,6 +6,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/inter-protocol/jsconfig.json b/packages/inter-protocol/jsconfig.json
index a6d0d34134e..dc34fe095bf 100644
--- a/packages/inter-protocol/jsconfig.json
+++ b/packages/inter-protocol/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/internal/jsconfig.json b/packages/internal/jsconfig.json
index 37469ecb668..cf1e13ca5ce 100644
--- a/packages/internal/jsconfig.json
+++ b/packages/internal/jsconfig.json
@@ -7,6 +7,7 @@
     "downlevelIteration": true,
     "noImplicitAny": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
     "types": [
       "node"
diff --git a/packages/notifier/jsconfig.json b/packages/notifier/jsconfig.json
index f0ab26f7584..1635d0e0d5e 100644
--- a/packages/notifier/jsconfig.json
+++ b/packages/notifier/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/pegasus/jsconfig.json b/packages/pegasus/jsconfig.json
index 0f3b5a4bfc9..f54cbf215f6 100644
--- a/packages/pegasus/jsconfig.json
+++ b/packages/pegasus/jsconfig.json
@@ -3,9 +3,8 @@
   "compilerOptions": {
     "target": "esnext",
     "module": "esnext",
-
     "noEmit": true,
-/*
+    /*
     // The following flags are for creating .d.ts files:
     "noEmit": false,
     "declaration": true,
@@ -13,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/smart-wallet/jsconfig.json b/packages/smart-wallet/jsconfig.json
index 92298f10852..c5ba4d5cace 100644
--- a/packages/smart-wallet/jsconfig.json
+++ b/packages/smart-wallet/jsconfig.json
@@ -6,6 +6,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/smart-wallet/src/smartWallet.js b/packages/smart-wallet/src/smartWallet.js
index 4810758a09d..c1e17a1844c 100644
--- a/packages/smart-wallet/src/smartWallet.js
+++ b/packages/smart-wallet/src/smartWallet.js
@@ -232,9 +232,8 @@ const behaviorGuards = {
 const behavior = {
   helper: {
     /**
-     * @this {{ state: State, facets: typeof behavior }}
      * @param {RemotePurse} purse
-     * @param {Amount} balance
+     * @param {Amount<any>} balance
      * @param {'init'} [init]
      */
     updateBalance(purse, balance, init) {
@@ -252,9 +251,6 @@ const behavior = {
       helper.publishCurrentState();
     },
 
-    /**
-     * @this {{ state: State, facets: typeof behavior }}
-     */
     publishCurrentState() {
       const {
         brandDescriptors,
@@ -275,7 +271,6 @@ const behavior = {
 
     /** @type {(desc: Omit<BrandDescriptor, 'displayInfo'>, purse: RemotePurse) => Promise<void>} */
     async addBrand(desc, purseRef) {
-      /** @type {State} */
       const {
         address,
         brandDescriptors,
@@ -332,10 +327,7 @@ const behavior = {
       const payments = paymentQueues.has(desc.brand)
         ? paymentQueues.get(desc.brand)
         : [];
-      const deposits = payments.map(p =>
-        // @ts-expect-error deposit does take a FarRef<Payment>
-        E(purse).deposit(p),
-      );
+      const deposits = payments.map(p => E(purse).deposit(p));
       Promise.all(deposits).catch(err =>
         console.error('ERROR depositing queued payments', err),
       );
@@ -350,11 +342,11 @@ const behavior = {
      *
      * If the purse doesn't exist, we hold the payment until it does.
      *
+     * @this {SmartWalletThis}
      * @param {import('@endo/far').FarRef<Payment>} payment
      * @returns {Promise<Amount>} amounts for deferred deposits will be empty
      */
     async receive(payment) {
-      /** @type {State} */
       const { brandPurses, paymentQueues: queues } = this.state;
       const brand = await E(payment).getAllegedBrand();
 
@@ -385,13 +377,13 @@ const behavior = {
     /**
      * Take an offer description provided in capData, augment it with payments and call zoe.offer()
      *
+     * @this {SmartWalletThis}
      * @param {import('./offers.js').OfferSpec} offerSpec
      * @returns {Promise<void>} when the offer has been sent to Zoe; payouts go into this wallet's purses
      * @throws if any parts of the offer can be determined synchronously to be invalid
      */
     async executeOffer(offerSpec) {
       const { facets } = this;
-      /** @type {State} */
       const {
         address,
         zoe,
@@ -443,6 +435,7 @@ const behavior = {
   self: {
     /**
      *
+     * @this {SmartWalletThis}
      * @param {import('@endo/marshal').CapData<string>} actionCapData of type BridgeAction
      * @param {boolean} [canSpend=false]
      * @returns {Promise<void>}
@@ -465,29 +458,33 @@ const behavior = {
         },
       );
     },
-    /** @returns {SmartWalletBehavior['deposit']} */
+    /** @this {SmartWalletThis} */
     getDepositFacet() {
       return this.facets.deposit;
     },
-    /** @returns {SmartWalletBehavior['offers']} */
+    /** @this {SmartWalletThis} */
     getOffersFacet() {
       return this.facets.offers;
     },
-    /** @returns {StoredSubscriber<CurrentWalletRecord>} */
+    /** @this {SmartWalletThis} */
     getCurrentSubscriber() {
       return this.state.currentPublishKit.subscriber;
     },
-    /** @returns {StoredSubscriber<UpdateRecord>} */
+    /** @this {SmartWalletThis} */
     getUpdatesSubscriber() {
-      /** @type {{state: State}} */
-      // @ts-expect-error
-      const { state } = this;
-      return state.updatePublishKit.subscriber;
+      return this.state.updatePublishKit.subscriber;
     },
   },
 };
 /** @typedef {typeof behavior} SmartWalletBehavior */
+// XXX defineVirtualFarClassKit should infer this
+/** @typedef {{ facets: SmartWalletBehavior, state: State }} SmartWalletThis */
 
+// TODO type facets (runs into problems with 'this')
+/**
+ *
+ * @param {{ state: State, facets: * }} param0
+ */
 const finish = ({ state, facets }) => {
   /** @type {State} */
   const { invitationBrand, invitationIssuer, invitationPurse, bank } = state;
diff --git a/packages/solo/jsconfig.json b/packages/solo/jsconfig.json
index 51992bfe6ff..35c0b15aadd 100644
--- a/packages/solo/jsconfig.json
+++ b/packages/solo/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/sparse-ints/jsconfig.json b/packages/sparse-ints/jsconfig.json
index 20b970a3dd1..5eb6e745dfa 100644
--- a/packages/sparse-ints/jsconfig.json
+++ b/packages/sparse-ints/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/stat-logger/jsconfig.json b/packages/stat-logger/jsconfig.json
index 20b970a3dd1..5eb6e745dfa 100644
--- a/packages/stat-logger/jsconfig.json
+++ b/packages/stat-logger/jsconfig.json
@@ -12,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/store/jsconfig.json b/packages/store/jsconfig.json
index f49e23ca966..f05b5057347 100644
--- a/packages/store/jsconfig.json
+++ b/packages/store/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/store/src/patterns/interface-tools.js b/packages/store/src/patterns/interface-tools.js
index e7340c48caa..931ef0a6d03 100644
--- a/packages/store/src/patterns/interface-tools.js
+++ b/packages/store/src/patterns/interface-tools.js
@@ -137,7 +137,7 @@ const defendMethod = (method, methodGuard, label) => {
  *
  * @param {string} methodTag
  * @param {WeakMap} contextMap
- * @param {Method} behaviorMethod
+ * @param {CallableFunction} behaviorMethod
  * @param {boolean} [thisfulMethods]
  * @param {MethodGuard} [methodGuard]
  */
@@ -195,7 +195,7 @@ const bindMethod = (
 };
 
 /**
- * @template {Record<string | symbol, Method>} T
+ * @template {Record<string | symbol, CallableFunction>} T
  * @param {string} tag
  * @param {WeakMap} contextMap
  * @param {T} behaviorMethods
@@ -280,13 +280,13 @@ export const initEmpty = () => emptyRecord;
  */
 
 /**
- * @template A
- * @template S
- * @template {{}} T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string | symbol, CallableFunction>} T methods
  * @param {string} tag
  * @param {any} interfaceGuard
  * @param {(...args: A[]) => S} init
- * @param {T} methods
+ * @param {T & ThisType<T & { state: S }>} methods
  * @param {object} [options]
  * @returns {(...args: A[]) => (T & import('@endo/eventual-send').RemotableBrand<{}, T>)}
  */
@@ -330,13 +330,13 @@ export const defineHeapFarClass = (
 harden(defineHeapFarClass);
 
 /**
- * @template A
- * @template S
- * @template {Record<string, any>} F
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string, Record<string | symbol, CallableFunction>>} F methods
  * @param {string} tag
  * @param {any} interfaceGuardKit
  * @param {(...args: A[]) => S} init
- * @param {F} methodsKit
+ * @param {F & { [K in keyof F]: ThisType<F[K] & { state: S }> }} methodsKit
  * @param {object} [options]
  * @returns {(...args: A[]) => F}
  */
diff --git a/packages/store/test/test-heap-classes.js b/packages/store/test/test-heap-classes.js
index a9c92663721..a8c99ca6cdf 100644
--- a/packages/store/test/test-heap-classes.js
+++ b/packages/store/test/test-heap-classes.js
@@ -24,10 +24,10 @@ test('test defineHeapFarClass', t => {
   const makeUpCounter = defineHeapFarClass(
     'UpCounter',
     UpCounterI,
+    /** @param {number} x */
     (x = 0) => ({ x }),
     {
       incr(y = 1) {
-        // @ts-expect-error TS doesn't know that `this` is a `Context`
         const { state } = this;
         state.x += y;
         return state.x;
@@ -51,11 +51,11 @@ test('test defineHeapFarClassKit', t => {
   const makeCounterKit = defineHeapFarClassKit(
     'Counter',
     { up: UpCounterI, down: DownCounterI },
+    /** @param {number} x */
     (x = 0) => ({ x }),
     {
       up: {
         incr(y = 1) {
-          // @ts-expect-error xxx this.state
           const { state } = this;
           state.x += y;
           return state.x;
@@ -63,7 +63,6 @@ test('test defineHeapFarClassKit', t => {
       },
       down: {
         decr(y = 1) {
-          // @ts-expect-error xxx this.state
           const { state } = this;
           state.x -= y;
           return state.x;
diff --git a/packages/swing-store/jsconfig.json b/packages/swing-store/jsconfig.json
index ccb9a505c7c..30cb7b373db 100644
--- a/packages/swing-store/jsconfig.json
+++ b/packages/swing-store/jsconfig.json
@@ -11,6 +11,7 @@
     "emitDeclarationOnly": true,
 */
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/swingset-runner/jsconfig.json b/packages/swingset-runner/jsconfig.json
index 3c39b292fd6..4ce8d1400d2 100644
--- a/packages/swingset-runner/jsconfig.json
+++ b/packages/swingset-runner/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/telemetry/jsconfig.json b/packages/telemetry/jsconfig.json
index 4bbf8dfc50c..d8f08ac74d1 100644
--- a/packages/telemetry/jsconfig.json
+++ b/packages/telemetry/jsconfig.json
@@ -7,6 +7,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/ui-components/jsconfig.json b/packages/ui-components/jsconfig.json
index 58a8c8a9324..68bf2bb305a 100644
--- a/packages/ui-components/jsconfig.json
+++ b/packages/ui-components/jsconfig.json
@@ -3,9 +3,8 @@
   "compilerOptions": {
     "target": "esnext",
     "module": "esnext",
-
     "noEmit": true,
-/*
+    /*
     // The following flags are for creating .d.ts files:
     "noEmit": false,
     "declaration": true,
@@ -13,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
     "jsx": "react",
   },
diff --git a/packages/vat-data/src/far-class-utils.js b/packages/vat-data/src/far-class-utils.js
index 515c0317d90..a3ddfd79ddd 100644
--- a/packages/vat-data/src/far-class-utils.js
+++ b/packages/vat-data/src/far-class-utils.js
@@ -45,11 +45,13 @@ harden(defineVirtualFarClass);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template A,S,T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string, Record<string | symbol, CallableFunction>>} T facets
  * @param {string} tag
  * @param {any} interfaceGuardKit
  * @param {(...args: A[]) => S} init
- * @param {T} facets
+ * @param {T & { [K in keyof T]: ThisType<T[K] & { facets: T, state: S }> }} facets
  * @param {DefineKindOptions<unknown>} [options]
  * @returns {(...args: A[]) => (T & RemotableBrand<{}, T>)}
  */
@@ -71,11 +73,13 @@ harden(defineVirtualFarClassKit);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template A,S,T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string | symbol, CallableFunction>} T methods
  * @param {DurableKindHandle} kindHandle
  * @param {any} interfaceGuard
  * @param {(...args: A[]) => S} init
- * @param {T} methods
+ * @param {T & ThisType<T & { state: S }>} methods
  * @param {DefineKindOptions<unknown>} [options]
  * @returns {(...args: A[]) => (T & RemotableBrand<{}, T>)}
  */
@@ -97,11 +101,13 @@ harden(defineDurableFarClass);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template A,S,T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string, Record<string | symbol, CallableFunction>>} T facets
  * @param {DurableKindHandle} kindHandle
  * @param {any} interfaceGuardKit
  * @param {(...args: A[]) => S} init
- * @param {T} facets
+ * @param {T & { [K in keyof T]: ThisType<T[K] & { facets: T, state: S }> }} facets
  * @param {DefineKindOptions<unknown>} [options]
  * @returns {(...args: A[]) => (T & RemotableBrand<{}, T>)}
  */
@@ -123,12 +129,14 @@ harden(defineDurableFarClassKit);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template A,S,T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string | symbol, CallableFunction>} T methods
  * @param {Baggage} baggage
  * @param {string} kindName
  * @param {any} interfaceGuard
  * @param {(...args: A[]) => S} init
- * @param {T} methods
+ * @param {T & ThisType<T & { state: S }>} methods
  * @param {DefineKindOptions<unknown>} [options]
  * @returns {(...args: A[]) => (T & RemotableBrand<{}, T>)}
  */
@@ -151,12 +159,14 @@ harden(vivifyFarClass);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template A,S,T
+ * @template A args to init
+ * @template S state from init
+ * @template {Record<string, Record<string | symbol, CallableFunction>>} T facets
  * @param {Baggage} baggage
  * @param {string} kindName
  * @param {any} interfaceGuardKit
  * @param {(...args: A[]) => S} init
- * @param {T} facets
+ * @param {T & { [K in keyof T]: ThisType<T[K] & { facets: T, state: S }> }} facets
  * @param {DefineKindOptions<unknown>} [options]
  * @returns {(...args: A[]) => (T & RemotableBrand<{}, T>)}
  */
@@ -179,7 +189,8 @@ harden(vivifyFarClassKit);
 
 // TODO interfaceGuard type https://github.com/Agoric/agoric-sdk/issues/6206
 /**
- * @template T,M
+ * @template T
+ * @template {Record<string | symbol, CallableFunction>} M methods
  * @param {Baggage} baggage
  * @param {string} kindName
  * @param {any} interfaceGuard
@@ -211,7 +222,7 @@ harden(vivifyFarInstance);
 
 /**
  * @deprecated Use vivifyFarInstance instead.
- * @template T
+ * @template {Record<string | symbol, CallableFunction>} T methods
  * @param {Baggage} baggage
  * @param {string} kindName
  * @param {T} methods
diff --git a/packages/vat-data/test/test-durable-classes.js b/packages/vat-data/test/test-durable-classes.js
index 230962e1196..0509ade09da 100644
--- a/packages/vat-data/test/test-durable-classes.js
+++ b/packages/vat-data/test/test-durable-classes.js
@@ -28,10 +28,10 @@ test('test defineDurableFarClass', t => {
   const makeUpCounter = defineDurableFarClass(
     upCounterKind,
     UpCounterI,
+    /** @param {number} x */
     (x = 0) => ({ x }),
     {
       incr(y = 1) {
-        // @ts-expect-error TS doesn't know that `this` is a `Context`
         const { state } = this;
         state.x += y;
         return state.x;
@@ -87,6 +87,7 @@ test('test defineDurableFarClassKit', t => {
     message:
       'In "decr" method of (Counter down) arg 0: string "foo" - Must be a number',
   });
+  // @ts-expect-error the type violation is what we're testing
   t.throws(() => upCounter.decr(3), {
     message: 'upCounter.decr is not a function',
   });
diff --git a/packages/vat-data/test/test-virtual-classes.js b/packages/vat-data/test/test-virtual-classes.js
index b8b199e8efa..d4015cc126f 100644
--- a/packages/vat-data/test/test-virtual-classes.js
+++ b/packages/vat-data/test/test-virtual-classes.js
@@ -82,6 +82,7 @@ test('test defineVirtualFarClassKit', t => {
     message:
       'In "decr" method of (Counter down) arg 0: string "foo" - Must be a number',
   });
+  // @ts-expect-error the type violation is what we're testing
   t.throws(() => upCounter.decr(3), {
     message: 'upCounter.decr is not a function',
   });
diff --git a/packages/vat-data/test/test-vivify.js b/packages/vat-data/test/test-vivify.js
index c82b9d8e150..8b8090eb860 100644
--- a/packages/vat-data/test/test-vivify.js
+++ b/packages/vat-data/test/test-vivify.js
@@ -33,7 +33,6 @@ test('test vivifyFarClass', t => {
     (x = 0) => ({ x }),
     {
       incr(y = 1) {
-        // @ts-expect-error TS doesn't know that `this` is a `Context`
         const { state } = this;
         state.x += y;
         return state.x;
@@ -90,6 +89,7 @@ test('test vivifyFarClassKit', t => {
     message:
       'In "decr" method of (Counter down) arg 0: string "foo" - Must be a number',
   });
+  // @ts-expect-error the type violation is what we're testing
   t.throws(() => upCounter.decr(3), {
     message: 'upCounter.decr is not a function',
   });
diff --git a/packages/vats/jsconfig.json b/packages/vats/jsconfig.json
index fc0786fb00d..9f590bf1928 100644
--- a/packages/vats/jsconfig.json
+++ b/packages/vats/jsconfig.json
@@ -5,6 +5,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/wallet/api/jsconfig.json b/packages/wallet/api/jsconfig.json
index 0f3b5a4bfc9..1e3864ec1d2 100644
--- a/packages/wallet/api/jsconfig.json
+++ b/packages/wallet/api/jsconfig.json
@@ -3,16 +3,10 @@
   "compilerOptions": {
     "target": "esnext",
     "module": "esnext",
-
     "noEmit": true,
-/*
-    // The following flags are for creating .d.ts files:
-    "noEmit": false,
-    "declaration": true,
-    "emitDeclarationOnly": true,
-*/
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/web-components/jsconfig.json b/packages/web-components/jsconfig.json
index 5a183cba851..022b6f00d70 100644
--- a/packages/web-components/jsconfig.json
+++ b/packages/web-components/jsconfig.json
@@ -3,9 +3,8 @@
   "compilerOptions": {
     "target": "esnext",
     "module": "esnext",
-
     "noEmit": true,
-/*
+    /*
     // The following flags are for creating .d.ts files:
     "noEmit": false,
     "declaration": true,
@@ -13,6 +12,7 @@
 */
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/zoe/jsconfig.json b/packages/zoe/jsconfig.json
index df25dccaf78..b778899ba5e 100644
--- a/packages/zoe/jsconfig.json
+++ b/packages/zoe/jsconfig.json
@@ -6,6 +6,7 @@
     "noEmit": true,
     "downlevelIteration": true,
     "strictNullChecks": true,
+    "noImplicitThis": true,
     "moduleResolution": "node",
   },
   "include": [
diff --git a/packages/zoe/test/swingsetTests/upgradeCoveredCall/coveredCall-durable-V3.js b/packages/zoe/test/swingsetTests/upgradeCoveredCall/coveredCall-durable-V3.js
index a4c6c847e76..41fd30ca40b 100644
--- a/packages/zoe/test/swingsetTests/upgradeCoveredCall/coveredCall-durable-V3.js
+++ b/packages/zoe/test/swingsetTests/upgradeCoveredCall/coveredCall-durable-V3.js
@@ -39,7 +39,6 @@ const vivify = async (zcf, _privateArgs, instanceBaggage) => {
     sellSeat => ({ sellSeat }),
     {
       handle(buySeat) {
-        // @ts-expect-error TS doesn't understand context
         const { state } = this;
         assert(!state.sellSeat.hasExited(), sellSeatExpiredMsg);
         try {