diff --git a/packages/ERTP/src/typeGuards.js b/packages/ERTP/src/typeGuards.js
index c503f27bb50..2d26319aed3 100644
--- a/packages/ERTP/src/typeGuards.js
+++ b/packages/ERTP/src/typeGuards.js
@@ -124,18 +124,19 @@ export const MAX_ABSOLUTE_DECIMAL_PLACES = 100;
 
 export const AssetKindShape = M.or('nat', 'set', 'copySet', 'copyBag');
 
-export const DisplayInfoShape = M.partial(
-  harden({
+export const DisplayInfoShape = M.splitRecord(
+  {},
+  {
     decimalPlaces: M.and(
       M.gte(-MAX_ABSOLUTE_DECIMAL_PLACES),
       M.lte(MAX_ABSOLUTE_DECIMAL_PLACES),
     ),
     assetKind: AssetKindShape,
-  }),
-  harden({
+  },
+  {
     // Including this empty `rest` ensures that there are no other
     // properties beyond those in the `base` record.
-  }),
+  },
 );
 
 // //////////////////////// Interfaces /////////////////////////////////////////
diff --git a/packages/SwingSet/src/typeGuards.js b/packages/SwingSet/src/typeGuards.js
index 3ffe089b7d8..4a8ccc5bf12 100644
--- a/packages/SwingSet/src/typeGuards.js
+++ b/packages/SwingSet/src/typeGuards.js
@@ -3,16 +3,17 @@ import { M } from '@agoric/store';
 
 export const ManagerType = M.or('xs-worker', 'local'); // TODO: others
 
-const Bundle = M.split({ moduleType: M.string() }, M.partial({}));
+const Bundle = M.splitRecord({ moduleType: M.string() });
+
+const SwingsetConfigOptions = harden({
+  creationOptions: M.splitRecord({}, { critial: M.boolean() }),
+  parameters: M.recordOf(M.string(), M.any()),
+});
 
-const p1 = M.and(
-  M.partial({ creationOptions: M.partial({ critial: M.boolean() }) }),
-  M.partial({ parameters: M.recordOf(M.string(), M.any()) }),
-);
 const SwingSetConfigProperties = M.or(
-  M.split({ sourceSpec: M.string() }, p1),
-  M.split({ bundleSpec: M.string() }, p1),
-  M.split({ bundle: Bundle }, p1),
+  M.splitRecord({ sourceSpec: M.string() }, SwingsetConfigOptions),
+  M.splitRecord({ bundleSpec: M.string() }, SwingsetConfigOptions),
+  M.splitRecord({ bundle: Bundle }, SwingsetConfigOptions),
 );
 const SwingSetConfigDescriptor = M.recordOf(
   M.string(),
@@ -30,11 +31,11 @@ const SwingSetConfigDescriptor = M.recordOf(
  * in ./types-external.js
  */
 export const SwingSetConfig = M.and(
-  M.partial({ defaultManagerType: ManagerType }),
-  M.partial({ includeDevDependencies: M.boolean() }),
-  M.partial({ defaultReapInterval: M.number() }), // not in type decl
-  M.partial({ snapshotInterval: M.number() }),
-  M.partial({ vats: SwingSetConfigDescriptor }),
-  M.partial({ bootstrap: M.string() }),
-  M.partial({ bundles: SwingSetConfigDescriptor }),
+  M.splitRecord({}, { defaultManagerType: ManagerType }),
+  M.splitRecord({}, { includeDevDependencies: M.boolean() }),
+  M.splitRecord({}, { defaultReapInterval: M.number() }), // not in type decl
+  M.splitRecord({}, { snapshotInterval: M.number() }),
+  M.splitRecord({}, { vats: SwingSetConfigDescriptor }),
+  M.splitRecord({}, { bootstrap: M.string() }),
+  M.splitRecord({}, { bundles: SwingSetConfigDescriptor }),
 );
diff --git a/packages/casting/src/netconfig.js b/packages/casting/src/netconfig.js
index 6cb4d04cea1..dd27d92aae8 100644
--- a/packages/casting/src/netconfig.js
+++ b/packages/casting/src/netconfig.js
@@ -14,12 +14,12 @@ import { fit, M } from '@agoric/store';
  * @property {string[]} [peers] - a list of nodes used to start the p2p gossip (stored in a per-node “address book”, which is a file stored in that node’s data directory)
  * @property {string[]} [seeds] - nodes which tell you about other peers but don't gossip actual data
  */
-export const NetworkConfigShape = M.split(
-  {
+export const NetworkConfigShape = M.splitRecord(
+  harden({
     chainName: M.string(),
     rpcAddrs: M.arrayOf(M.string()),
-  },
-  M.partial({
+  }),
+  harden({
     apiAddrs: M.arrayOf(M.string()),
     gci: M.string(),
     peers: M.arrayOf(M.string()),
diff --git a/packages/inter-protocol/src/psm/psm.js b/packages/inter-protocol/src/psm/psm.js
index 35bc3e1df45..6cb55dd967a 100644
--- a/packages/inter-protocol/src/psm/psm.js
+++ b/packages/inter-protocol/src/psm/psm.js
@@ -276,7 +276,7 @@ export const start = async (zcf, privateArgs, baggage) => {
         wantmintedHook,
         'wantMinted',
         undefined,
-        M.split({
+        M.splitRecord({
           give: { In: anchorAmountShape },
           want: M.or({ Out: stableAmountShape }, {}),
         }),
@@ -287,7 +287,7 @@ export const start = async (zcf, privateArgs, baggage) => {
         giveMintedHook,
         'giveMinted',
         undefined,
-        M.split({
+        M.splitRecord({
           give: { In: stableAmountShape },
           want: M.or({ Out: anchorAmountShape }, {}),
         }),
diff --git a/packages/inter-protocol/src/psm/psmCharter.js b/packages/inter-protocol/src/psm/psmCharter.js
index 926aaa15ea2..3f39ff192e3 100644
--- a/packages/inter-protocol/src/psm/psmCharter.js
+++ b/packages/inter-protocol/src/psm/psmCharter.js
@@ -23,17 +23,15 @@ import { E } from '@endo/far';
  * @property {Record<string, unknown>} params
  * @property {{paramPath: { key: string }}} [path]
  */
-const ParamChangesOfferArgsShape = harden(
-  M.split(
-    {
-      deadline: TimestampShape,
-      instance: InstanceHandleShape,
-      params: M.recordOf(M.string(), M.any()),
-    },
-    M.partial({
-      path: { paramPath: { key: M.string() } },
-    }),
-  ),
+const ParamChangesOfferArgsShape = M.splitRecord(
+  {
+    deadline: TimestampShape,
+    instance: InstanceHandleShape,
+    params: M.recordOf(M.string(), M.any()),
+  },
+  {
+    path: { paramPath: { key: M.string() } },
+  },
 );
 
 /**
diff --git a/packages/inter-protocol/src/vaultFactory/params.js b/packages/inter-protocol/src/vaultFactory/params.js
index 765b94354d0..be9d7bdfe42 100644
--- a/packages/inter-protocol/src/vaultFactory/params.js
+++ b/packages/inter-protocol/src/vaultFactory/params.js
@@ -78,16 +78,13 @@ const makeVaultParamManager = (publisherKit, initial) =>
   });
 /** @typedef {ReturnType<typeof makeVaultParamManager>} VaultParamManager */
 
-export const vaultParamPattern = M.split(
-  {
-    liquidationMargin: ratioPattern,
-    liquidationPenalty: ratioPattern,
-    interestRate: ratioPattern,
-    loanFee: ratioPattern,
-    debtLimit: amountPattern,
-  },
-  M.any(),
-);
+export const vaultParamPattern = M.splitRecord({
+  liquidationMargin: ratioPattern,
+  liquidationPenalty: ratioPattern,
+  interestRate: ratioPattern,
+  loanFee: ratioPattern,
+  debtLimit: amountPattern,
+});
 
 /**
  * @param {import('@agoric/notifier').StoredPublisherKit<GovernanceSubscriptionState>} publisherKit
diff --git a/packages/smart-wallet/src/typeGuards.js b/packages/smart-wallet/src/typeGuards.js
index 774ebc1ce0a..a8b1f324f5d 100644
--- a/packages/smart-wallet/src/typeGuards.js
+++ b/packages/smart-wallet/src/typeGuards.js
@@ -12,25 +12,25 @@ export const shape = {
   },
 
   // invitations
-  ContractInvitationSpec: M.split(
+  ContractInvitationSpec: M.splitRecord(
     {
       source: 'contract',
       instance: InstanceHandleShape,
       publicInvitationMaker: M.string(),
     },
-    M.partial({
+    {
       invitationArgs: M.array(),
-    }),
+    },
   ),
-  ContinuingInvitationSpec: M.split(
+  ContinuingInvitationSpec: M.splitRecord(
     {
       source: 'continuing',
       previousOffer: M.or(M.number(), M.string()),
       invitationMakerName: M.string(),
     },
-    M.partial({
+    {
       invitationArgs: M.array(),
-    }),
+    },
   ),
   PurseInvitationSpec: {
     source: 'purse',
@@ -39,24 +39,25 @@ export const shape = {
   },
 
   // offers
-  OfferSpec: M.split(
+  OfferSpec: M.splitRecord(
     {
       id: M.or(M.number(), M.string()),
       // TODO M.unknown() to defer validation
       invitationSpec: M.any(),
       proposal: ProposalShape,
     },
-    M.partial({ offerArgs: M.any() }),
+    { offerArgs: M.any() },
   ),
 
   // walletFactory
-  WalletBridgeMsg: M.split(
+  WalletBridgeMsg: M.splitRecord(
     {
       owner: M.string(),
       type: M.string(),
       blockHeight: M.number(),
       blockTime: M.number(),
     },
+    {},
     M.or({ action: M.string() }, { spendAction: M.string() }),
   ),
 };
diff --git a/packages/smart-wallet/src/walletFactory.js b/packages/smart-wallet/src/walletFactory.js
index 33866e85cf5..0208443cf92 100644
--- a/packages/smart-wallet/src/walletFactory.js
+++ b/packages/smart-wallet/src/walletFactory.js
@@ -17,9 +17,9 @@ import { shape } from './typeGuards.js';
 import '@agoric/vats/exported.js';
 
 const PrivateArgsShape = harden(
-  M.split(
+  M.splitRecord(
     { storageNode: M.eref(M.any()) },
-    M.partial({ bridgeManager: M.eref(M.any()) }),
+    { bridgeManager: M.eref(M.any()) },
   ),
 );
 
diff --git a/packages/vats/src/core/boot-psm.js b/packages/vats/src/core/boot-psm.js
index 7449c64c1fa..5bcc06c50e3 100644
--- a/packages/vats/src/core/boot-psm.js
+++ b/packages/vats/src/core/boot-psm.js
@@ -92,19 +92,22 @@ export const agoricNamesReserved = harden(
  *   decimalPlaces?: number
  * }} AnchorOptions
  */
-const AnchorOptionsShape = M.split(
+const AnchorOptionsShape = M.splitRecord(
   { denom: M.string() },
-  M.partial({
+  {
     keyword: M.string(),
     proposedName: M.string(),
     decimalPlaces: M.number(),
-  }),
+  },
 );
 
-export const ParametersShape = M.partial({
-  anchorAssets: M.arrayOf(AnchorOptionsShape),
-  economicCommitteeAddresses: M.recordOf(M.string(), M.string()),
-});
+export const ParametersShape = M.splitRecord(
+  {},
+  {
+    anchorAssets: M.arrayOf(AnchorOptionsShape),
+    economicCommitteeAddresses: M.recordOf(M.string(), M.string()),
+  },
+);
 
 /**
  * Build root object of the PSM-only bootstrap vat.
diff --git a/packages/zoe/src/contracts/coveredCall-durable.js b/packages/zoe/src/contracts/coveredCall-durable.js
index a2bb891aae0..e1ee291afb8 100644
--- a/packages/zoe/src/contracts/coveredCall-durable.js
+++ b/packages/zoe/src/contracts/coveredCall-durable.js
@@ -58,7 +58,7 @@ const start = async (zcf, _privateArgs, instanceBaggage) => {
   const makeOption = sellSeat => {
     fit(
       sellSeat.getProposal(),
-      M.split({ exit: { afterDeadline: M.any() } }),
+      M.splitRecord({ exit: { afterDeadline: M.any() } }),
       'exit afterDeadline',
     );
     const sellSeatExitRule = sellSeat.getProposal().exit;
diff --git a/packages/zoe/src/contracts/coveredCall.js b/packages/zoe/src/contracts/coveredCall.js
index d3dacce540d..274af6b1419 100644
--- a/packages/zoe/src/contracts/coveredCall.js
+++ b/packages/zoe/src/contracts/coveredCall.js
@@ -72,7 +72,7 @@ const start = zcf => {
   const makeOption = sellSeat => {
     fit(
       sellSeat.getProposal(),
-      M.split({ exit: { afterDeadline: M.any() } }),
+      M.splitRecord({ exit: { afterDeadline: M.any() } }),
       'exit afterDeadline',
     );
     const sellSeatExitRule = sellSeat.getProposal().exit;
diff --git a/packages/zoe/src/typeGuards.js b/packages/zoe/src/typeGuards.js
index 8fa14f7a9d4..1129190897e 100644
--- a/packages/zoe/src/typeGuards.js
+++ b/packages/zoe/src/typeGuards.js
@@ -27,10 +27,11 @@ export const TimerShape = makeHandleShape('timer');
 export const FullProposalShape = harden({
   want: AmountPatternKeywordRecordShape,
   give: AmountKeywordRecordShape,
-  // To accept only one, we could use M.or rather than M.partial,
+  // To accept only one, we could use M.or rather than M.splitRecord,
   // but the error messages would have been worse. Rather,
   // cleanProposal's assertExit checks that there's exactly one.
-  exit: M.partial(
+  exit: M.splitRecord(
+    {},
     {
       onDemand: null,
       waived: null,
@@ -43,7 +44,7 @@ export const FullProposalShape = harden({
   ),
 });
 /** @see {Proposal} type */
-export const ProposalShape = M.partial(FullProposalShape);
+export const ProposalShape = M.splitRecord({}, FullProposalShape, {});
 
 export const isOnDemandExitRule = exit => {
   const [exitKey] = Object.getOwnPropertyNames(exit);
@@ -68,7 +69,7 @@ export const isAfterDeadlineExitRule = exit => {
   return exitKey === 'afterDeadline';
 };
 
-export const InvitationElementShape = M.split({
+export const InvitationElementShape = M.splitRecord({
   description: M.string(),
   handle: InvitationHandleShape,
   instance: InstanceHandleShape,