diff --git a/platforms/web/src/checkout.ts b/platforms/web/src/checkout.ts
index c53c1d2a3..1eb858159 100644
--- a/platforms/web/src/checkout.ts
+++ b/platforms/web/src/checkout.ts
@@ -586,14 +586,6 @@ export class ShopifyCheckout
     }
   }
 
-  #recordNavigationSuccess(): void {
-    this.#recordNavigationDuration("success");
-  }
-
-  #recordNavigationFailure(): void {
-    this.#recordNavigationDuration("failure");
-  }
-
   #recordNavigationDuration(result: "success" | "failure"): void {
     const startedAt = this.#navigationStartedAt;
     if (startedAt === undefined) return;
@@ -822,7 +814,7 @@ export class ShopifyCheckout
       .on(Event.start, ({ params: { checkout } }) => {
         // Web cannot reliably observe cross-origin popup page-finish, so the
         // success duration ends at `ec.start`: checkout is loaded and interactive.
-        this.#recordNavigationSuccess();
+        this.#recordNavigationDuration("success");
         const snapshot = this.#recordCheckout(checkout);
         /** @ignore - Events are documented by the class @event tags. */
         this.dispatchEvent(new ShopifyCheckoutStartEvent({ checkout: snapshot }));
@@ -845,7 +837,7 @@ export class ShopifyCheckout
         this.dispatchEvent(new ShopifyCheckoutErrorEvent({ error: this.#error }));
         // `ec.error` is terminal for the embedded session. Message severity is
         // payload detail for the checkout error, not a host-side recovery signal.
-        this.#recordNavigationFailure();
+        this.#recordNavigationDuration("failure");
         this.close();
       })
       .on(Event.fulfillmentChange, ({ params: { checkout } }) => {
diff --git a/protocol/languages/typescript/src/generated/ProtocolCodecs.ts b/protocol/languages/typescript/src/generated/ProtocolCodecs.ts
index 8fc6581ca..d266693b7 100644
--- a/protocol/languages/typescript/src/generated/ProtocolCodecs.ts
+++ b/protocol/languages/typescript/src/generated/ProtocolCodecs.ts
@@ -5,6 +5,7 @@ import {
   decodeProtocolObject,
   encodeProtocolObject,
 } from '../protocol_codec_runtime';
+import {AddressChangeResultModel, AuthRequestModel, AuthResultModel, CheckoutModel, CredentialResultModel, ErrorResponseModel, InstrumentsChangeResultModel, ReadyRequestModel, ReadyResultModel, WindowOpenRequestModel, WindowOpenResultModel} from './ProtocolRenameMap';
 
 type AddressChangeResult = import('./Models').AddressChangeResult;
 type AuthRequest = import('./Models').AuthRequest;
@@ -19,45 +20,45 @@ type WindowOpenRequest = import('./Models').WindowOpenRequest;
 type WindowOpenResult = import('./Models').WindowOpenResult;
 
 export function decodeAuthRequest(value: unknown): AuthRequest {
-  return decodeProtocolObject(value, 'AuthRequest') as unknown as AuthRequest;
+  return decodeProtocolObject(value, AuthRequestModel, 'AuthRequest') as unknown as AuthRequest;
 }
 
 export function decodeCheckout(value: unknown): Checkout {
-  return decodeProtocolObject(value, 'Checkout') as unknown as Checkout;
+  return decodeProtocolObject(value, CheckoutModel, 'Checkout') as unknown as Checkout;
 }
 
 export function decodeErrorResponse(value: unknown): ErrorResponse {
-  return decodeProtocolObject(value, 'ErrorResponse') as unknown as ErrorResponse;
+  return decodeProtocolObject(value, ErrorResponseModel, 'ErrorResponse') as unknown as ErrorResponse;
 }
 
 export function decodeReadyRequest(value: unknown): ReadyRequest {
-  return decodeProtocolObject(value, 'ReadyRequest') as unknown as ReadyRequest;
+  return decodeProtocolObject(value, ReadyRequestModel, 'ReadyRequest') as unknown as ReadyRequest;
 }
 
 export function decodeWindowOpenRequest(value: unknown): WindowOpenRequest {
-  return decodeProtocolObject(value, 'WindowOpenRequest') as unknown as WindowOpenRequest;
+  return decodeProtocolObject(value, WindowOpenRequestModel, 'WindowOpenRequest') as unknown as WindowOpenRequest;
 }
 
 export function encodeAddressChangeResult(value: AddressChangeResult): unknown {
-  return encodeProtocolObject(value, 'AddressChangeResult');
+  return encodeProtocolObject(value, AddressChangeResultModel);
 }
 
 export function encodeAuthResult(value: AuthResult): unknown {
-  return encodeProtocolObject(value, 'AuthResult');
+  return encodeProtocolObject(value, AuthResultModel);
 }
 
 export function encodeCredentialResult(value: CredentialResult): unknown {
-  return encodeProtocolObject(value, 'CredentialResult');
+  return encodeProtocolObject(value, CredentialResultModel);
 }
 
 export function encodeInstrumentsChangeResult(value: InstrumentsChangeResult): unknown {
-  return encodeProtocolObject(value, 'InstrumentsChangeResult');
+  return encodeProtocolObject(value, InstrumentsChangeResultModel);
 }
 
 export function encodeReadyResult(value: ReadyResult): unknown {
-  return encodeProtocolObject(value, 'ReadyResult');
+  return encodeProtocolObject(value, ReadyResultModel);
 }
 
 export function encodeWindowOpenResult(value: WindowOpenResult): unknown {
-  return encodeProtocolObject(value, 'WindowOpenResult');
+  return encodeProtocolObject(value, WindowOpenResultModel);
 }
diff --git a/protocol/languages/typescript/src/generated/ProtocolNotifications.ts b/protocol/languages/typescript/src/generated/ProtocolNotifications.ts
index e1f16202e..ba3c711ea 100644
--- a/protocol/languages/typescript/src/generated/ProtocolNotifications.ts
+++ b/protocol/languages/typescript/src/generated/ProtocolNotifications.ts
@@ -234,19 +234,6 @@ export const requestDescriptors = {
 };
 
 export const embeddedCheckoutMethods: ReadonlySet<string> = new Set([
-  'ec.ready',
-  'ec.auth',
-  'ec.error',
-  'ec.start',
-  'ec.complete',
-  'ec.messages.change',
-  'ec.line_items.change',
-  'ec.buyer.change',
-  'ec.totals.change',
-  'ec.payment.change',
-  'ec.payment.instruments_change_request',
-  'ec.payment.credential_request',
-  'ec.window.open_request',
-  'ec.fulfillment.change',
-  'ec.fulfillment.address_change_request',
+  ...Object.values(checkoutProtocolCatalog),
+  ...Object.values(checkoutProtocolRequestCatalog),
 ]);
diff --git a/protocol/languages/typescript/src/generated/ProtocolRenameMap.ts b/protocol/languages/typescript/src/generated/ProtocolRenameMap.ts
index 968cdbcbd..123521aff 100644
--- a/protocol/languages/typescript/src/generated/ProtocolRenameMap.ts
+++ b/protocol/languages/typescript/src/generated/ProtocolRenameMap.ts
@@ -6,12 +6,94 @@
 // path needed to reach them. Extension keys (UCP additionalProperties) are
 // preserved by the walker's pass-through and are intentionally absent here.
 
-export type RenameChild =
-  | ['r', string]
-  | ['a', RenameChild]
-  | ['m', RenameChild]
-  | ['u', ...RenameChild[]];
+export type {RenameChild, RenameEntry} from '../protocol_rename_map';
 
-export type RenameEntry = [string, string] | [string, string, RenameChild];
+export const AddressChangeCheckoutModel = 0;
+export const AddressChangeResultModel = 1;
+export const AdjustmentModel = 2;
+export const AdjustmentLineItemModel = 3;
+export const AdjustmentStatusModel = 4;
+export const AppliedDiscountModel = 5;
+export const AuthModel = 6;
+export const AuthRequestModel = 7;
+export const AuthResultModel = 8;
+export const BuyerModel = 9;
+export const CapabilityElementModel = 10;
+export const CapabilityResponseSchemaModel = 11;
+export const CheckoutModel = 12;
+export const CheckoutDiscountsModel = 13;
+export const CheckoutFulfillmentModel = 14;
+export const CheckoutFulfillmentObjectModel = 15;
+export const CheckoutStatusModel = 16;
+export const CheckoutTotalModel = 17;
+export const ConstraintExpressionModel = 18;
+export const ConstraintPropertyModel = 19;
+export const ContentTypeModel = 20;
+export const ContextModel = 21;
+export const CredentialCheckoutModel = 22;
+export const CredentialResultModel = 23;
+export const DescriptionModel = 24;
+export const DiscountAllocationModel = 25;
+export const DiscountMethodModel = 26;
+export const EmbeddedColorSchemeModel = 27;
+export const EmbeddedServiceModel = 28;
+export const EmbeddedTransportConfigModel = 29;
+export const ErrorResponseModel = 30;
+export const ErrorResponseUcpModel = 31;
+export const ErrorStatusModel = 32;
+export const EventLineItemModel = 33;
+export const ExpectationModel = 34;
+export const ExpectationLineItemModel = 35;
+export const FulfillmentModel = 36;
+export const FulfillmentAvailableMethodModel = 37;
+export const FulfillmentDestinationModel = 38;
+export const FulfillmentEventModel = 39;
+export const FulfillmentGroupModel = 40;
+export const FulfillmentMethodModel = 41;
+export const FulfillmentOptionModel = 42;
+export const InstrumentsChangeCheckoutModel = 43;
+export const InstrumentsChangePaymentModel = 44;
+export const InstrumentsChangeResultModel = 45;
+export const InstrumentsChangeResultUcpModel = 46;
+export const ItemModel = 47;
+export const LineModel = 48;
+export const LineItemModel = 49;
+export const LineItemQuantityModel = 50;
+export const LineItemStatusModel = 51;
+export const LineItemTotalModel = 52;
+export const LinkModel = 53;
+export const MeasureModel = 54;
+export const MessageModel = 55;
+export const MessageTypeModel = 56;
+export const OrderModel = 57;
+export const OrderConfirmationModel = 58;
+export const OrderLineItemModel = 59;
+export const PaymentModel = 60;
+export const PaymentCredentialModel = 61;
+export const PaymentHandlerAvailableInstrumentModel = 62;
+export const PaymentHandlerElementModel = 63;
+export const PaymentHandlerResponseSchemaModel = 64;
+export const PaymentHandlerResponseSchemaAvailableInstrumentModel = 65;
+export const PolicyModel = 66;
+export const PostalAddressModel = 67;
+export const PreferredPaymentHandlerModel = 68;
+export const QuantityUnitModel = 69;
+export const ReadyCheckoutModel = 70;
+export const ReadyPaymentModel = 71;
+export const ReadyRequestModel = 72;
+export const ReadyResultModel = 73;
+export const SelectedPaymentInstrumentModel = 74;
+export const ServiceModel = 75;
+export const ServiceResponseSchemaModel = 76;
+export const SeverityModel = 77;
+export const TransportModel = 78;
+export const UcpCheckoutResponseSchemaModel = 79;
+export const UcpCheckoutResponseSchemaStatusModel = 80;
+export const UcpOrderResponseSchemaModel = 81;
+export const UnitPriceModel = 82;
+export const UpgradeModel = 83;
+export const WindowOpenRequestModel = 84;
+export const WindowOpenResultModel = 85;
 
-export const renameMap: Record<string, RenameEntry[]> = {"AddressChangeCheckout":[["fulfillment","fulfillment",["r","CheckoutFulfillmentObject"]]],"AddressChangeResult":[["checkout","checkout",["r","AddressChangeCheckout"]],["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]],"Adjustment":[["line_items","lineItems",["a",["r","AdjustmentLineItem"]]],["occurred_at","occurredAt"],["totals","totals",["a",["r","LineItemTotal"]]]],"AdjustmentLineItem":[["measure","measure",["r","Measure"]]],"AuthResult":[["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]],"Buyer":[["first_name","firstName"],["last_name","lastName"],["phone_number","phoneNumber"]],"Checkout":[["buyer","buyer",["r","Buyer"]],["context","context",["r","Context"]],["continue_url","continueUrl"],["expires_at","expiresAt"],["fulfillment","fulfillment",["r","CheckoutFulfillment"]],["line_items","lineItems",["a",["r","LineItem"]]],["messages","messages",["a",["r","Message"]]],["order","order",["r","OrderConfirmation"]],["payment","payment",["r","Payment"]],["policies","policies",["a",["r","Policy"]]],["totals","totals",["a",["r","CheckoutTotal"]]],["ucp","ucp",["r","UcpCheckoutResponseSchema"]]],"CheckoutFulfillment":[["available_methods","availableMethods",["a",["r","FulfillmentAvailableMethod"]]],["methods","methods",["a",["r","FulfillmentMethod"]]]],"CheckoutFulfillmentObject":[["available_methods","availableMethods",["a",["r","FulfillmentAvailableMethod"]]],["methods","methods",["a",["r","FulfillmentMethod"]]]],"CheckoutTotal":[["display_text","displayText"],["lines","lines",["a",["r","Line"]]]],"Context":[["address_country","addressCountry"],["address_region","addressRegion"],["postal_code","postalCode"]],"CredentialCheckout":[["payment","payment",["r","Payment"]]],"CredentialResult":[["checkout","checkout",["r","CredentialCheckout"]],["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]],"EmbeddedTransportConfig":[["color_scheme","colorScheme"]],"ErrorResponse":[["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]],["ucp","ucp",["r","ErrorResponseUcp"]]],"ErrorResponseUcp":[["map_order","mapOrder"],["payment_handlers","paymentHandlers",["m",["a",["r","PaymentHandlerResponseSchema"]]]]],"Expectation":[["destination","destination",["r","PostalAddress"]],["fulfillable_on","fulfillableOn"],["line_items","lineItems"],["method_type","methodType"]],"Fulfillment":[["events","events",["a",["r","FulfillmentEvent"]]],["expectations","expectations",["a",["r","Expectation"]]]],"FulfillmentAvailableMethod":[["fulfillable_on","fulfillableOn"],["line_item_ids","lineItemIds"]],"FulfillmentDestination":[["address","address",["r","PostalAddress"]],["address_country","addressCountry"],["address_locality","addressLocality"],["address_region","addressRegion"],["extended_address","extendedAddress"],["first_name","firstName"],["last_name","lastName"],["phone_number","phoneNumber"],["postal_code","postalCode"],["street_address","streetAddress"]],"FulfillmentEvent":[["line_items","lineItems"],["occurred_at","occurredAt"],["tracking_number","trackingNumber"],["tracking_url","trackingUrl"]],"FulfillmentGroup":[["line_item_ids","lineItemIds"],["options","options",["a",["r","FulfillmentOption"]]],["selected_option_id","selectedOptionId"]],"FulfillmentMethod":[["destinations","destinations",["a",["r","FulfillmentDestination"]]],["groups","groups",["a",["r","FulfillmentGroup"]]],["line_item_ids","lineItemIds"],["selected_destination_id","selectedDestinationId"]],"FulfillmentOption":[["earliest_fulfillment_time","earliestFulfillmentTime"],["latest_fulfillment_time","latestFulfillmentTime"],["totals","totals",["a",["r","LineItemTotal"]]]],"InstrumentsChangeCheckout":[["payment","payment",["r","InstrumentsChangePayment"]]],"InstrumentsChangePayment":[["instruments","instruments",["a",["r","SelectedPaymentInstrument"]]],["selected_instrument_id","selectedInstrumentId"]],"InstrumentsChangeResult":[["checkout","checkout",["r","InstrumentsChangeCheckout"]],["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]],"InstrumentsChangeResultUcp":[["map_order","mapOrder"],["payment_handlers","paymentHandlers",["m",["a",["r","PaymentHandlerElement"]]]]],"Item":[["image_url","imageUrl"],["quantity_unit","quantityUnit",["r","QuantityUnit"]],["unit_price","unitPrice",["r","UnitPrice"]]],"Line":[["display_text","displayText"]],"LineItem":[["item","item",["r","Item"]],["parent_id","parentId"],["totals","totals",["a",["r","LineItemTotal"]]]],"LineItemTotal":[["display_text","displayText"]],"Measure":[["display_text","displayText"]],"Message":[["content_type","contentType"],["image_url","imageUrl"]],"Order":[["adjustments","adjustments",["a",["r","Adjustment"]]],["checkout_id","checkoutId"],["fulfillment","fulfillment",["r","Fulfillment"]],["line_items","lineItems",["a",["r","OrderLineItem"]]],["messages","messages",["a",["r","Message"]]],["permalink_url","permalinkUrl"],["policies","policies",["a",["r","Policy"]]],["totals","totals",["a",["r","CheckoutTotal"]]],["ucp","ucp",["r","UcpOrderResponseSchema"]]],"OrderConfirmation":[["permalink_url","permalinkUrl"]],"OrderLineItem":[["item","item",["r","Item"]],["parent_id","parentId"],["totals","totals",["a",["r","LineItemTotal"]]]],"Payment":[["instruments","instruments",["a",["r","SelectedPaymentInstrument"]]]],"PaymentHandlerElement":[["available_instruments","availableInstruments"]],"PaymentHandlerResponseSchema":[["available_instruments","availableInstruments"]],"Policy":[["applies_to","appliesTo"]],"PostalAddress":[["address_country","addressCountry"],["address_locality","addressLocality"],["address_region","addressRegion"],["extended_address","extendedAddress"],["first_name","firstName"],["last_name","lastName"],["phone_number","phoneNumber"],["postal_code","postalCode"],["street_address","streetAddress"]],"QuantityUnit":[["display_text","displayText"]],"ReadyCheckout":[["fulfillment","fulfillment",["r","CheckoutFulfillmentObject"]],["payment","payment",["r","ReadyPayment"]]],"ReadyPayment":[["instruments","instruments",["a",["r","SelectedPaymentInstrument"]]],["selected_instrument_id","selectedInstrumentId"]],"ReadyResult":[["checkout","checkout",["r","ReadyCheckout"]],["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]],"SelectedPaymentInstrument":[["billing_address","billingAddress",["r","PostalAddress"]],["handler_id","handlerId"]],"ServiceResponseSchema":[["config","config",["r","EmbeddedTransportConfig"]]],"UcpCheckoutResponseSchema":[["map_order","mapOrder"],["payment_handlers","paymentHandlers",["m",["a",["r","PaymentHandlerResponseSchema"]]]],["services","services",["m",["a",["r","ServiceResponseSchema"]]]]],"UcpOrderResponseSchema":[["map_order","mapOrder"],["payment_handlers","paymentHandlers",["m",["a",["r","PaymentHandlerResponseSchema"]]]]],"UnitPrice":[["measure","measure",["r","Measure"]],["reference","reference",["r","Measure"]]],"WindowOpenResult":[["ucp","ucp",["r","InstrumentsChangeResultUcp"]],["continue_url","continueUrl"],["messages","messages",["a",["r","Message"]]]]};
+export const renameFields = ["address","address_country","address_locality","address_region","adjustments","applies_to","available_instruments","available_methods","billing_address","buyer","checkout","checkout_id","color_scheme","config","content_type","context","continue_url","destination","destinations","display_text","earliest_fulfillment_time","events","expectations","expires_at","extended_address","first_name","fulfillable_on","fulfillment","groups","handler_id","image_url","instruments","item","last_name","latest_fulfillment_time","line_item_ids","line_items","lines","map_order","measure","messages","method_type","methods","occurred_at","options","order","parent_id","payment","payment_handlers","permalink_url","phone_number","policies","postal_code","quantity_unit","reference","selected_destination_id","selected_instrument_id","selected_option_id","services","street_address","totals","tracking_number","tracking_url","ucp","unit_price"];
+export const encodedRenameMap = "y#=#1&,#!b#P2!J$#Y%F$#%M!_$#V#I#X!!!!%b#P2!J$#Y%;!C!T!!!.+#+1#72!9!=#0F$#SJ$#YO#]Q#_U$#e_$#3b#r!$)$#GL$#K$)$#GL$#K!$5!G$#R!!!%#!%!V!#Q#_&,#8b#P2!J$#Y!!!!!#.!%2!J$#Yb#A$H!R%$#c!!&3#f<!F!K!!$7$#I8$#D$<!E!,!#f#!$!%!:!;!C!T!V!^!&F!M!`!a!%E!N$#L[!&4$#H>$#JE!Y!%6!D!_$#V#Q#N$A$#mZ!&,#Mb#P2!J$#Y$H!R%$#b%@!W#hc#u#5!%B#QP!_$#V!!#5!!#5!$0!@!!+&$#$-!=#FF$#^J$#YS!U$#e_$#3b#t#S!%B#QP!_$#V#A$#m!!#(!#(!!#'!+#!$!%!:!;!C!T!V!^!!#5!$=#1Q#j$A$#mZ!!&,#ib#P2!J$#Y$*#f?!!#/#?!!%H!R%$#c]%$#o!$H!R%$#c$I#XX#X!!%b#P2!J$#Y";
diff --git a/protocol/languages/typescript/src/protocol_codec_runtime.d.ts b/protocol/languages/typescript/src/protocol_codec_runtime.d.ts
index b974ac8ac..593138d69 100644
--- a/protocol/languages/typescript/src/protocol_codec_runtime.d.ts
+++ b/protocol/languages/typescript/src/protocol_codec_runtime.d.ts
@@ -6,6 +6,6 @@ export declare class ProtocolValidationError extends TypeError {
     readonly reason: ProtocolValidationReason;
     constructor(modelPath: string, reason: ProtocolValidationReason);
 }
-export declare function decodeProtocolObject(value: unknown, modelName: string): JSONRecord;
-export declare function encodeProtocolObject(value: unknown, modelName: string): unknown;
+export declare function decodeProtocolObject(value: unknown, modelId: number, modelName: string): JSONRecord;
+export declare function encodeProtocolObject(value: unknown, modelId: number): unknown;
 export {};
diff --git a/protocol/languages/typescript/src/protocol_codec_runtime.ts b/protocol/languages/typescript/src/protocol_codec_runtime.ts
index 940336c98..73ec32b8b 100644
--- a/protocol/languages/typescript/src/protocol_codec_runtime.ts
+++ b/protocol/languages/typescript/src/protocol_codec_runtime.ts
@@ -1,8 +1,15 @@
-import {renameMap} from './generated/ProtocolRenameMap';
-import type {RenameChild, RenameEntry} from './generated/ProtocolRenameMap';
+import {
+  CheckoutModel,
+  ErrorResponseModel,
+  FulfillmentOptionModel,
+  ReadyRequestModel,
+  WindowOpenRequestModel,
+  encodedRenameMap,
+  renameFields,
+} from './generated/ProtocolRenameMap';
+import {decodeRenameMap, type RenameChild} from './protocol_rename_map';
 
 type JSONRecord = Record<string, unknown>;
-type Direction = 'decode' | 'encode';
 
 export type ProtocolValidationReason = 'missing_required' | 'invalid_type';
 
@@ -26,16 +33,32 @@ export class ProtocolValidationError extends TypeError {
   }
 }
 
-const REQUIRED_FIELDS: Record<string, readonly string[]> = {
-  Checkout: ['currency', 'id', 'line_items', 'links', 'status', 'totals', 'ucp'],
-  ErrorResponse: ['messages', 'ucp'],
-  ReadyRequest: ['delegate'],
-  WindowOpenRequest: ['url'],
+type RenameLookup = Map<string, [string, RenameChild?]>;
+
+const renameMap = decodeRenameMap(encodedRenameMap).map(entries => {
+  const decode: RenameLookup = new Map();
+  const encode: RenameLookup = new Map();
+  for (const [fieldIndex, child] of entries) {
+    const protocolName = renameFields[fieldIndex]!;
+    const javascriptName = protocolName.replace(/_([a-z])/g, (_, letter: string) =>
+      letter.toUpperCase(),
+    );
+    decode.set(protocolName, [javascriptName, child]);
+    encode.set(javascriptName, [protocolName, child]);
+  }
+  return [decode, encode];
+});
+
+const REQUIRED_FIELDS: Record<number, readonly string[]> = {
+  [CheckoutModel]: ['currency', 'id', 'line_items', 'links', 'status', 'totals', 'ucp'],
+  [ErrorResponseModel]: ['messages', 'ucp'],
+  [ReadyRequestModel]: ['delegate'],
+  [WindowOpenRequestModel]: ['url'],
 };
 
-const REQUIRED_STRING_FIELDS: Record<string, readonly string[]> = {
-  Checkout: ['currency', 'id'],
-  WindowOpenRequest: ['url'],
+const REQUIRED_STRING_FIELDS: Record<number, readonly string[]> = {
+  [CheckoutModel]: ['currency', 'id'],
+  [WindowOpenRequestModel]: ['url'],
 };
 
 const NESTED_REQUIRED_STRING_FIELDS: Record<string, readonly string[]> = {
@@ -45,55 +68,47 @@ const NESTED_REQUIRED_STRING_FIELDS: Record<string, readonly string[]> = {
 
 export function decodeProtocolObject(
   value: unknown,
+  modelId: number,
   modelName: string,
 ): JSONRecord {
   const input = requireObject(value, modelName);
-  requireFields(input, REQUIRED_FIELDS[modelName] ?? [], modelName);
-  requireStringFields(input, REQUIRED_STRING_FIELDS[modelName] ?? [], modelName);
+  requireFields(input, REQUIRED_FIELDS[modelId] ?? [], modelName);
+  requireStringFields(input, REQUIRED_STRING_FIELDS[modelId] ?? [], modelName);
   requireNestedFields(input, modelName);
-  return walkObject(input, renameMap[modelName], 'decode', modelName) as JSONRecord;
+  return walkObject(input, renameMap[modelId], true, modelId) as JSONRecord;
 }
 
-export function encodeProtocolObject(
-  value: unknown,
-  modelName: string,
-): unknown {
-  return walkObject(value, renameMap[modelName], 'encode', modelName);
+export function encodeProtocolObject(value: unknown, modelId: number): unknown {
+  return walkObject(value, renameMap[modelId], false, modelId);
 }
 
 function walkObject(
   value: unknown,
-  entries: RenameEntry[] | undefined,
-  direction: Direction,
-  modelName?: string,
+  entries: RenameLookup[] | undefined,
+  decode: boolean,
+  modelId?: number,
 ): unknown {
   const input =
-    direction === 'decode' && modelName === 'FulfillmentOption'
+    decode && modelId === FulfillmentOptionModel
       ? normalizeLegacyFulfillmentOptionDescription(value)
       : value;
-  if (!isObjectRecord(input) || (!entries && direction === 'encode')) {
+  if (!isObjectRecord(input) || (!entries && !decode)) {
     return input;
   }
 
-  const sourceIndex = direction === 'decode' ? 0 : 1;
-  const targetIndex = direction === 'decode' ? 1 : 0;
-
-  const entryBySource = new Map<string, RenameEntry>();
-  for (const entry of entries ?? []) {
-    entryBySource.set(entry[sourceIndex], entry);
-  }
+  const entryBySource = entries?.[decode ? 0 : 1];
 
   const output: JSONRecord = {};
   for (const [key, item] of Object.entries(input)) {
     // Structured clone preserves undefined-valued own properties whereas JSON
     // omits them. Only normalize objects being walked as protocol models; an
     // unknown extension value is passed through without changing its contents.
-    if (direction === 'decode' && item === undefined) {
+    if (decode && item === undefined) {
       continue;
     }
-    const entry = entryBySource.get(key);
+    const entry = entryBySource?.get(key);
     if (entry) {
-      output[entry[targetIndex]] = walkChild(item, entry[2], direction);
+      output[entry[0]] = walkChild(item, entry[1], decode);
     } else {
       output[key] = item;
     }
@@ -104,36 +119,36 @@ function walkObject(
 function walkChild(
   value: unknown,
   child: RenameChild | undefined,
-  direction: Direction,
+  decode: boolean,
 ): unknown {
   if (!child) {
     return value;
   }
 
   switch (child[0]) {
-    case 'r':
-      return walkObject(value, renameMap[child[1]], direction, child[1]);
-    case 'a':
+    case 0:
+      return walkObject(value, renameMap[child[1]], decode, child[1]);
+    case 1:
       return Array.isArray(value)
-        ? value.map(item => walkChild(item, child[1], direction))
+        ? value.map(item => walkChild(item, child[1], decode))
         : value;
-    case 'm':
+    case 2:
       return isObjectRecord(value)
-        ? mapValues(value, child[1], direction)
+        ? mapValues(value, child[1], decode)
         : value;
-    case 'u':
-      return walkUnion(value, child.slice(1) as RenameChild[], direction);
+    case 3:
+      return walkUnion(value, child.slice(1) as RenameChild[], decode);
   }
 }
 
 function mapValues(
   value: JSONRecord,
   child: RenameChild,
-  direction: Direction,
+  decode: boolean,
 ): JSONRecord {
   const output: JSONRecord = {};
   for (const [key, item] of Object.entries(value)) {
-    output[key] = walkChild(item, child, direction);
+    output[key] = walkChild(item, child, decode);
   }
   return output;
 }
@@ -141,17 +156,17 @@ function mapValues(
 function walkUnion(
   value: unknown,
   members: RenameChild[],
-  direction: Direction,
+  decode: boolean,
 ): unknown {
   if (Array.isArray(value)) {
-    const arrayMember = members.find(member => member[0] === 'a');
-    return arrayMember ? walkChild(value, arrayMember, direction) : value;
+    const arrayMember = members.find(member => member[0] === 1);
+    return arrayMember ? walkChild(value, arrayMember, decode) : value;
   }
   if (isObjectRecord(value)) {
     const objectMember = members.find(
-      member => member[0] === 'r' || member[0] === 'm',
+      member => member[0] === 0 || member[0] === 2,
     );
-    return objectMember ? walkChild(value, objectMember, direction) : value;
+    return objectMember ? walkChild(value, objectMember, decode) : value;
   }
   return value;
 }
diff --git a/protocol/languages/typescript/src/protocol_rename_map.d.ts b/protocol/languages/typescript/src/protocol_rename_map.d.ts
new file mode 100644
index 000000000..c57bbb28d
--- /dev/null
+++ b/protocol/languages/typescript/src/protocol_rename_map.d.ts
@@ -0,0 +1,3 @@
+export type RenameChild = [0, number] | [1, RenameChild] | [2, RenameChild] | [3, ...RenameChild[]];
+export type RenameEntry = [number] | [number, RenameChild];
+export declare function decodeRenameMap(encoded: string): RenameEntry[][];
diff --git a/protocol/languages/typescript/src/protocol_rename_map.ts b/protocol/languages/typescript/src/protocol_rename_map.ts
new file mode 100644
index 000000000..660da0930
--- /dev/null
+++ b/protocol/languages/typescript/src/protocol_rename_map.ts
@@ -0,0 +1,33 @@
+export type RenameChild =
+  | [0, number]
+  | [1, RenameChild]
+  | [2, RenameChild]
+  | [3, ...RenameChild[]];
+
+export type RenameEntry = [number] | [number, RenameChild];
+
+export function decodeRenameMap(encoded: string): RenameEntry[][] {
+  let offset = 0;
+  const readSymbol = (): number => {
+    const code = encoded.charCodeAt(offset++);
+    return code - 33 - (code > 34 ? 1 : 0) - (code > 92 ? 1 : 0);
+  };
+  const readValue = (): number => {
+    const value = readSymbol();
+    return value === 91 ? readValue() * 91 + readSymbol() : value;
+  };
+  const readChild = (type = readValue() - 1): RenameChild => {
+    if (type === 0) return [type, readValue()];
+    if (type === 3) {
+      return [type, ...Array.from({length: readValue()}, () => readChild())];
+    }
+    return [type as 1 | 2, readChild()];
+  };
+  return Array.from({length: readValue()}, () =>
+    Array.from({length: readValue()}, () => {
+      const field = readValue();
+      const type = readValue();
+      return type === 0 ? [field] : [field, readChild(type - 1)];
+    }),
+  );
+}
diff --git a/protocol/languages/typescript/test/codec-runtime.test.ts b/protocol/languages/typescript/test/codec-runtime.test.ts
index c008d0fbc..bb31c6cc3 100644
--- a/protocol/languages/typescript/test/codec-runtime.test.ts
+++ b/protocol/languages/typescript/test/codec-runtime.test.ts
@@ -1,6 +1,11 @@
 import {expect, test} from 'vitest';
 
 import {EmbeddedCheckoutProtocol} from '../src/embedded_checkout_protocol';
+import {
+  CheckoutModel,
+  InstrumentsChangeResultUcpModel,
+  PostalAddressModel,
+} from '../src/generated/ProtocolRenameMap';
 import {
   decodeProtocolObject,
   encodeProtocolObject,
@@ -21,7 +26,7 @@ const wire = {
 };
 
 test('camelizes known schema fields on decode', () => {
-  const decoded = decodeProtocolObject(wire, 'Checkout') as Record<
+  const decoded = decodeProtocolObject(wire, CheckoutModel, 'Checkout') as Record<
     string,
     unknown
   >;
@@ -31,7 +36,7 @@ test('camelizes known schema fields on decode', () => {
 });
 
 test('preserves unknown extension keys unchanged on decode', () => {
-  const decoded = decodeProtocolObject(wire, 'Checkout') as Record<
+  const decoded = decodeProtocolObject(wire, CheckoutModel, 'Checkout') as Record<
     string,
     unknown
   >;
@@ -42,8 +47,8 @@ test('preserves unknown extension keys unchanged on decode', () => {
 });
 
 test('round-trips extension keys through decode + encode', () => {
-  const decoded = decodeProtocolObject(wire, 'Checkout');
-  const encoded = encodeProtocolObject(decoded, 'Checkout') as Record<
+  const decoded = decodeProtocolObject(wire, CheckoutModel, 'Checkout');
+  const encoded = encodeProtocolObject(decoded, CheckoutModel) as Record<
     string,
     unknown
   >;
@@ -56,6 +61,7 @@ test('round-trips extension keys through decode + encode', () => {
 test('renames fields inside array elements', () => {
   const decoded = decodeProtocolObject(
     {...wire, line_items: [{parent_id: 'parent-1', quantity: 2}]},
+    CheckoutModel,
     'Checkout',
   ) as Record<string, Array<Record<string, unknown>>>;
 
@@ -67,6 +73,7 @@ test('renames fields inside array elements', () => {
 test('renames fields inside map values', () => {
   const decoded = decodeProtocolObject(
     {payment_handlers: {stripe: [{available_instruments: ['card']}]}},
+    InstrumentsChangeResultUcpModel,
     'InstrumentsChangeResultUcp',
   ) as Record<string, Record<string, Array<Record<string, unknown>>>>;
 
@@ -75,9 +82,19 @@ test('renames fields inside map values', () => {
   expect('available_instruments' in handler).toBe(false);
 });
 
+test('decodes compact rename entries for later model IDs', () => {
+  const decoded = decodeProtocolObject(
+    {street_address: '151 O’Connor St', address_country: 'CA'},
+    PostalAddressModel,
+    'PostalAddress',
+  );
+
+  expect(decoded).toEqual({streetAddress: '151 O’Connor St', addressCountry: 'CA'});
+});
+
 test('throws when a required string field is not a string', () => {
   expectValidationError(
-    () => decodeProtocolObject({...wire, currency: 123}, 'Checkout'),
+    () => decodeProtocolObject({...wire, currency: 123}, CheckoutModel, 'Checkout'),
     'Checkout.currency',
     'invalid_type',
   );
@@ -98,10 +115,10 @@ test('treats structured-cloned undefined properties as absent without changing e
   };
 
   expect(Object.hasOwn(checkout, 'order')).toBe(true);
-  expect(decodeProtocolObject(checkout, 'Checkout')).toStrictEqual(
-    decodeProtocolObject(omitted, 'Checkout'),
+  expect(decodeProtocolObject(checkout, CheckoutModel, 'Checkout')).toStrictEqual(
+    decodeProtocolObject(omitted, CheckoutModel, 'Checkout'),
   );
-  const decoded = decodeProtocolObject(checkout, 'Checkout');
+  const decoded = decodeProtocolObject(checkout, CheckoutModel, 'Checkout');
   expect(decoded).not.toHaveProperty('order');
   expect(decoded).not.toHaveProperty('fulfillment');
   expect(decoded.buyer).not.toHaveProperty('firstName');
@@ -118,8 +135,8 @@ test('decodes direct objects and JSON-serialized delivery the same way', () => {
   });
   const serializedCheckout = JSON.parse(JSON.stringify(checkout));
 
-  expect(decodeProtocolObject(checkout, 'Checkout')).toStrictEqual(
-    decodeProtocolObject(serializedCheckout, 'Checkout'),
+  expect(decodeProtocolObject(checkout, CheckoutModel, 'Checkout')).toStrictEqual(
+    decodeProtocolObject(serializedCheckout, CheckoutModel, 'Checkout'),
   );
 });
 
@@ -134,6 +151,7 @@ test('preserves schema-valid null instead of treating it as absent', () => {
         methods: undefined,
       },
     },
+    CheckoutModel,
     'Checkout',
   );
 
@@ -146,7 +164,12 @@ test.each(['currency', 'totals', 'ucp'])(
   'rejects an undefined required Checkout.%s',
   field => {
     expectValidationError(
-      () => decodeProtocolObject({...wire, [field]: undefined}, 'Checkout'),
+      () =>
+        decodeProtocolObject(
+          {...wire, [field]: undefined},
+          CheckoutModel,
+          'Checkout',
+        ),
       `Checkout.${field}`,
       'missing_required',
     );
@@ -157,23 +180,27 @@ test('rejects undefined and malformed required fields inside a present order', (
   const permalink_url = 'https://example.test/orders/order-1';
 
   expectValidationError(
-    () => decodeProtocolObject(
-      {...wire, order: {id: undefined, permalink_url}},
-      'Checkout',
-    ),
+    () =>
+      decodeProtocolObject(
+        {...wire, order: {id: undefined, permalink_url}},
+        CheckoutModel,
+        'Checkout',
+      ),
     'Checkout.order.id',
     'missing_required',
   );
   expectValidationError(
-    () => decodeProtocolObject(
-      {...wire, order: {id: 'order-1', permalink_url: undefined}},
-      'Checkout',
-    ),
+    () =>
+      decodeProtocolObject(
+        {...wire, order: {id: 'order-1', permalink_url: undefined}},
+        CheckoutModel,
+        'Checkout',
+      ),
     'Checkout.order.permalink_url',
     'missing_required',
   );
   expectValidationError(
-    () => decodeProtocolObject({...wire, order: 123}, 'Checkout'),
+    () => decodeProtocolObject({...wire, order: 123}, CheckoutModel, 'Checkout'),
     'Checkout.order',
     'invalid_type',
   );
@@ -181,7 +208,12 @@ test('rejects undefined and malformed required fields inside a present order', (
 
 test('requires the version of a present ucp object', () => {
   expectValidationError(
-    () => decodeProtocolObject({...wire, ucp: {version: undefined}}, 'Checkout'),
+    () =>
+      decodeProtocolObject(
+        {...wire, ucp: {version: undefined}},
+        CheckoutModel,
+        'Checkout',
+      ),
     'Checkout.ucp.version',
     'missing_required',
   );
@@ -196,7 +228,7 @@ test.each([
   ['ucp.version', {ucp: {version: {value: '2026-04-08'}}}],
 ])('rejects non-string Checkout.%s', (field, nested) => {
   expectValidationError(
-    () => decodeProtocolObject({...wire, ...nested}, 'Checkout'),
+    () => decodeProtocolObject({...wire, ...nested}, CheckoutModel, 'Checkout'),
     `Checkout.${field}`,
     'invalid_type',
   );
@@ -205,7 +237,7 @@ test.each([
 test('does not accept inherited required fields', () => {
   const inheritedCheckout = Object.create(wire) as Record<string, unknown>;
   expectValidationError(
-    () => decodeProtocolObject(inheritedCheckout, 'Checkout'),
+    () => decodeProtocolObject(inheritedCheckout, CheckoutModel, 'Checkout'),
     'Checkout.currency',
     'missing_required',
   );
@@ -216,7 +248,12 @@ test('does not accept inherited required fields', () => {
   >;
   inheritedOrder.permalink_url = 'https://example.test/orders/order-1';
   expectValidationError(
-    () => decodeProtocolObject({...wire, order: inheritedOrder}, 'Checkout'),
+    () =>
+      decodeProtocolObject(
+        {...wire, order: inheritedOrder},
+        CheckoutModel,
+        'Checkout',
+      ),
     'Checkout.order.id',
     'missing_required',
   );
@@ -225,7 +262,12 @@ test('does not accept inherited required fields', () => {
 test('does not include a value in its validation error', () => {
   const malformedValue = {private_url: 'https://example.test/private/order-123'};
   expectValidationError(
-    () => decodeProtocolObject({...wire, currency: malformedValue}, 'Checkout'),
+    () =>
+      decodeProtocolObject(
+        {...wire, currency: malformedValue},
+        CheckoutModel,
+        'Checkout',
+      ),
     'Checkout.currency',
     'invalid_type',
   );
diff --git a/protocol/languages/typescript/test/payloads.test.ts b/protocol/languages/typescript/test/payloads.test.ts
index 64091a9f1..297f167d9 100644
--- a/protocol/languages/typescript/test/payloads.test.ts
+++ b/protocol/languages/typescript/test/payloads.test.ts
@@ -4,6 +4,7 @@ import {describe, expect, test} from 'vitest';
 import {EmbeddedCheckoutProtocol} from '../src/embedded_checkout_protocol';
 import {Convert} from '../src/generated/Models';
 import {decodeCheckout, decodeErrorResponse} from '../src/generated/ProtocolCodecs';
+import {CheckoutModel} from '../src/generated/ProtocolRenameMap';
 import {encodeProtocolObject} from '../src/protocol_codec_runtime';
 
 function fixture(name: string) {
@@ -52,7 +53,7 @@ describe('pinned protocol payloads', () => {
       expect(location.address!.postalCode).toBe('10002');
     }
     expect(checkout.fulfillment!.methods![0].destinations![0].type).toBe('shipping_address');
-    expect(encodeProtocolObject(checkout, 'Checkout')).toEqual(wire);
+    expect(encodeProtocolObject(checkout, CheckoutModel)).toEqual(wire);
     expect(JSON.parse(Convert.checkoutToJson(converted))).toEqual(wire);
     expect(checkout.ucp.mapOrder).toEqual(
       customFulfillment ? {payment_handlers: ['com.example.wallet']} : undefined,
diff --git a/protocol/languages/typescript/test/rename-map-encoding.test.ts b/protocol/languages/typescript/test/rename-map-encoding.test.ts
new file mode 100644
index 000000000..d9b61fe2b
--- /dev/null
+++ b/protocol/languages/typescript/test/rename-map-encoding.test.ts
@@ -0,0 +1,141 @@
+import {afterEach, expect, test, vi} from 'vitest';
+
+import {encodeRenameMap} from '../../../scripts/generate_typescript_rename_map.mjs';
+import type {RenameEntry} from '../src/generated/ProtocolRenameMap';
+import {decodeRenameMap} from '../src/protocol_rename_map';
+
+const fields = ['nested_value', 'reference_value', 'array_values', 'map_values', 'union_value', 'map_union_value'];
+const entries: RenameEntry[][] = [
+  [
+    [1, [0, 1]],
+    [2, [1, [0, 1]]],
+    [3, [2, [0, 1]]],
+    [4, [3, [1, [0, 1]], [0, 1]]],
+    [5, [3, [2, [0, 1]], [1, [0, 1]]]],
+  ],
+  [[0]],
+];
+
+afterEach(() => {
+  vi.doUnmock('../src/generated/ProtocolRenameMap');
+  vi.resetModules();
+  vi.restoreAllMocks();
+});
+
+test('decodes all child variants from generator output', () => {
+  const encoded = encodeRenameMap(entries);
+  expect(decodeRenameMap(encoded)).toEqual(entries);
+  expect(decodeRenameMap(encoded)).toEqual(entries);
+});
+
+test.each([0, 1, 89, 90, 91, 92, 182, 8280, 8281, Number.MAX_SAFE_INTEGER])(
+  'preserves encoded integer %s',
+  value => {
+    const map: RenameEntry[][] = [[[value, [0, value]]]];
+    expect(decodeRenameMap(encodeRenameMap(map))).toEqual(map);
+  },
+);
+
+test.each([
+  [0, '!'],
+  [90, '}'],
+  [91, '~#!'],
+  [92, '~##'],
+  [8280, '~}}'],
+  [8281, '~~#!!'],
+] as const)('uses the expected wire representation for %s', (value, symbol) => {
+  const map: RenameEntry[][] = [[[value]]];
+  const encoded = `##${symbol}!`;
+  expect(encodeRenameMap(map)).toBe(encoded);
+  expect(decodeRenameMap(encoded)).toEqual(map);
+});
+
+test.each([91, 92, 182])('supports %s models and entries', count => {
+  const map: RenameEntry[][] = Array.from({length: count}, () => []);
+  map[count - 1] = Array.from({length: count}, (_, field) => [field]);
+  expect(decodeRenameMap(encodeRenameMap(map))).toEqual(map);
+});
+
+test.each([-1, 1.5, NaN, Infinity, Number.MAX_SAFE_INTEGER + 1])(
+  'rejects invalid encoded integer %s',
+  value => {
+    expect(() => encodeRenameMap([[[value]]])).toThrow('Invalid rename map integer');
+  },
+);
+
+test('renames synthetic references, arrays, maps and both union branches', async () => {
+  vi.doMock('../src/generated/ProtocolRenameMap', () => ({
+    CheckoutModel: -1,
+    ErrorResponseModel: -2,
+    FulfillmentOptionModel: -3,
+    ReadyRequestModel: -4,
+    WindowOpenRequestModel: -5,
+    encodedRenameMap: encodeRenameMap(entries),
+    renameFields: fields,
+  }));
+  const {decodeProtocolObject, encodeProtocolObject} = await import('../src/protocol_codec_runtime');
+  for (const arrayUnion of [false, true]) {
+    const wire = {
+      reference_value: {nested_value: 'reference'},
+      array_values: [{nested_value: 'array'}],
+      map_values: {key: {nested_value: 'map'}},
+      union_value: arrayUnion ? [{nested_value: 'union'}] : {nested_value: 'union'},
+      map_union_value: {key: {nested_value: 'map union'}},
+      extension_data: {nested_value: 'unchanged'},
+    };
+    const expected = {
+      referenceValue: {nestedValue: 'reference'},
+      arrayValues: [{nestedValue: 'array'}],
+      mapValues: {key: {nestedValue: 'map'}},
+      unionValue: arrayUnion ? [{nestedValue: 'union'}] : {nestedValue: 'union'},
+      mapUnionValue: {key: {nestedValue: 'map union'}},
+      extension_data: {nested_value: 'unchanged'},
+    };
+    expect(decodeProtocolObject(wire, 0, 'Synthetic')).toEqual(expected);
+    expect(encodeProtocolObject(expected, 0)).toEqual(wire);
+  }
+});
+
+test('renames fields through model and field IDs beyond the single-symbol range', async () => {
+  const largeMap: RenameEntry[][] = Array.from({length: 93}, () => []);
+  largeMap[0] = [[91, [0, 92]]];
+  largeMap[92] = [[92]];
+  vi.doMock('../src/generated/ProtocolRenameMap', () => ({
+    CheckoutModel: -1,
+    ErrorResponseModel: -2,
+    FulfillmentOptionModel: -3,
+    ReadyRequestModel: -4,
+    WindowOpenRequestModel: -5,
+    encodedRenameMap: encodeRenameMap(largeMap),
+    renameFields: Array.from({length: 93}, (_, index) => `field_${index}_name`),
+  }));
+  const {decodeProtocolObject, encodeProtocolObject} = await import('../src/protocol_codec_runtime');
+  const wire = {field_91_name: {field_92_name: 'value'}};
+  const expected = {field_91Name: {field_92Name: 'value'}};
+  expect(decodeProtocolObject(wire, 0, 'Synthetic')).toEqual(expected);
+  expect(encodeProtocolObject(expected, 0)).toEqual(wire);
+});
+
+test('reuses derived names across repeated objects and both directions', async () => {
+  vi.doMock('../src/generated/ProtocolRenameMap', () => ({
+    CheckoutModel: -1,
+    ErrorResponseModel: -2,
+    FulfillmentOptionModel: -3,
+    ReadyRequestModel: -4,
+    WindowOpenRequestModel: -5,
+    encodedRenameMap: encodeRenameMap(entries),
+    renameFields: fields,
+  }));
+  const {decodeProtocolObject, encodeProtocolObject} = await import('../src/protocol_codec_runtime');
+  const replace = vi.spyOn(String.prototype, 'replace');
+  const wire = {array_values: Array.from({length: 100}, () => ({nested_value: 'value'}))};
+  const decoded = decodeProtocolObject(wire, 0, 'Synthetic');
+  const encoded = encodeProtocolObject(decoded, 0);
+  const repeated = decodeProtocolObject(wire, 0, 'Synthetic');
+  const conversions = replace.mock.calls.length;
+  replace.mockRestore();
+  expect(conversions).toBe(0);
+  expect(decoded).toEqual({arrayValues: Array.from({length: 100}, () => ({nestedValue: 'value'}))});
+  expect(repeated).toEqual(decoded);
+  expect(encoded).toEqual(wire);
+});
diff --git a/protocol/languages/typescript/test/spec-metadata.test.ts b/protocol/languages/typescript/test/spec-metadata.test.ts
index 14c635ef3..6e8c3d6ea 100644
--- a/protocol/languages/typescript/test/spec-metadata.test.ts
+++ b/protocol/languages/typescript/test/spec-metadata.test.ts
@@ -55,12 +55,28 @@ describe('spec metadata', () => {
     });
   });
 
-  test('embedded methods cover notifications and requests', () => {
-    expect(embeddedCheckoutMethods.has('ec.start')).toBe(true);
+  test('embedded methods exactly cover notifications and requests', () => {
     expect(embeddedCheckoutMethods.has('ec.ready')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.auth')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.error')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.start')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.complete')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.messages.change')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.line_items.change')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.buyer.change')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.totals.change')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.payment.change')).toBe(true);
     expect(
       embeddedCheckoutMethods.has('ec.payment.instruments_change_request'),
     ).toBe(true);
+    expect(
+      embeddedCheckoutMethods.has('ec.payment.credential_request'),
+    ).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.window.open_request')).toBe(true);
+    expect(embeddedCheckoutMethods.has('ec.fulfillment.change')).toBe(true);
+    expect(
+      embeddedCheckoutMethods.has('ec.fulfillment.address_change_request'),
+    ).toBe(true);
     expect(embeddedCheckoutMethods.size).toBe(15);
   });
 });
diff --git a/protocol/scripts/generate_typescript_codecs.mjs b/protocol/scripts/generate_typescript_codecs.mjs
index 9e2d779c3..123b80b79 100644
--- a/protocol/scripts/generate_typescript_codecs.mjs
+++ b/protocol/scripts/generate_typescript_codecs.mjs
@@ -38,13 +38,13 @@ function codecModels() {
 
 function renderDecodeFunction(modelName) {
   return `export function decode${modelName}(value: unknown): ${modelName} {
-  return decodeProtocolObject(value, '${modelName}') as unknown as ${modelName};
+  return decodeProtocolObject(value, ${modelName}Model, '${modelName}') as unknown as ${modelName};
 }`;
 }
 
 function renderEncodeFunction(modelName) {
   return `export function encode${modelName}(value: ${modelName}): unknown {
-  return encodeProtocolObject(value, '${modelName}');
+  return encodeProtocolObject(value, ${modelName}Model);
 }`;
 }
 
@@ -61,6 +61,7 @@ import {
   decodeProtocolObject,
   encodeProtocolObject,
 } from '../protocol_codec_runtime';
+import {${allModels.map(modelName => `${modelName}Model`).join(', ')}} from './ProtocolRenameMap';
 
 ${typeAliases}
 
diff --git a/protocol/scripts/generate_typescript_notifications.mjs b/protocol/scripts/generate_typescript_notifications.mjs
index e5fa7d481..ced23312c 100644
--- a/protocol/scripts/generate_typescript_notifications.mjs
+++ b/protocol/scripts/generate_typescript_notifications.mjs
@@ -134,7 +134,6 @@ function modelImports(notifications, requests) {
 
 function renderModule(notifications, requests) {
   const typeNames = modelImports(notifications, requests);
-  const allMethods = EC_METHODS.map(entry => entry.method);
   const codecNames = new Set();
   for (const notification of notifications) {
     codecNames.add(`decode${notification.typeName}`);
@@ -283,7 +282,8 @@ ${requests
 };
 
 export const embeddedCheckoutMethods: ReadonlySet<string> = new Set([
-${allMethods.map(method => `  '${method}',`).join('\n')}
+  ...Object.values(checkoutProtocolCatalog),
+  ...Object.values(checkoutProtocolRequestCatalog),
 ]);
 `;
 }
diff --git a/protocol/scripts/generate_typescript_rename_map.mjs b/protocol/scripts/generate_typescript_rename_map.mjs
index 23b10298a..ee04420ae 100644
--- a/protocol/scripts/generate_typescript_rename_map.mjs
+++ b/protocol/scripts/generate_typescript_rename_map.mjs
@@ -142,7 +142,15 @@ function buildRenameMap(typeMap, contains) {
       if (prop.json === prop.js && !child) {
         continue;
       }
-      entries.push(child ? [prop.json, prop.js, child] : [prop.json, prop.js]);
+      const derivedName = prop.json.replace(/_([a-z])/g, (_, letter) =>
+        letter.toUpperCase(),
+      );
+      if (derivedName !== prop.js) {
+        throw new Error(
+          `Cannot derive TypeScript property ${prop.js} from ${prop.json}`,
+        );
+      }
+      entries.push(child ? [prop.json, child] : [prop.json]);
     }
     if (entries.length > 0) {
       renameMap[name] = entries;
@@ -151,15 +159,84 @@ function buildRenameMap(typeMap, contains) {
   return renameMap;
 }
 
+function indexChild(child, indexes) {
+  switch (child[0]) {
+    case "r":
+      return [0, indexes[child[1]]];
+    case "a":
+      return [1, indexChild(child[1], indexes)];
+    case "m":
+      return [2, indexChild(child[1], indexes)];
+    case "u":
+      return [3, ...child.slice(1).map(member => indexChild(member, indexes))];
+  }
+}
+
+const RENAME_ALPHABET = Array.from({length: 94}, (_, index) =>
+  String.fromCharCode(index + 33),
+)
+  .filter(character => character !== '"' && character !== "\\")
+  .join("");
+
+export function encodeRenameMap(renameMap) {
+  const values = [renameMap.length];
+  const encodeChild = child => {
+    const [type, ...members] = child;
+    values.push(type + 1);
+    if (type === 0) {
+      values.push(members[0]);
+    } else if (type === 3) {
+      values.push(members.length);
+      members.forEach(encodeChild);
+    } else {
+      encodeChild(members[0]);
+    }
+  };
+  for (const entries of renameMap) {
+    values.push(entries.length);
+    for (const [field, child] of entries) {
+      values.push(field);
+      if (child) {
+        encodeChild(child);
+      } else {
+        values.push(0);
+      }
+    }
+  }
+  const encodeValue = value => {
+    if (!Number.isSafeInteger(value) || value < 0) {
+      throw new Error(`Invalid rename map integer ${value}`);
+    }
+    return value < 91
+      ? RENAME_ALPHABET[value]
+      : RENAME_ALPHABET[91] + encodeValue(Math.floor(value / 91)) + RENAME_ALPHABET[value % 91];
+  };
+  return values.map(encodeValue).join("");
+}
+
 async function main() {
   const typeMap = parseTypeMap(await fs.readFile(MODELS, "utf8"));
   const contains = computeContainsRename(typeMap);
   const renameMap = buildRenameMap(typeMap, contains);
-  const sorted = Object.fromEntries(
-    Object.keys(renameMap)
-      .sort()
-      .map(key => [key, renameMap[key]]),
+  const names = Object.keys(typeMap).sort();
+  const indexes = Object.fromEntries(names.map((name, index) => [name, index]));
+  const fields = [
+    ...new Set(Object.values(renameMap).flatMap(entries => entries.map(entry => entry[0]))),
+  ].sort();
+  const fieldIndexes = Object.fromEntries(
+    fields.map((field, index) => [field, index]),
+  );
+  const indexedMap = names.map(name =>
+    (renameMap[name] ?? []).map(([wireName, child]) =>
+      child
+        ? [fieldIndexes[wireName], indexChild(child, indexes)]
+        : [fieldIndexes[wireName]],
+    ),
   );
+  const modelIds = names
+    .map(name => `export const ${name}Model = ${indexes[name]};`)
+    .join("\n");
+  const encodedMap = encodeRenameMap(indexedMap);
   const body = `// This file is generated by protocol/scripts/generate_typescript_rename_map.mjs.
 // Do not edit directly.
 //
@@ -168,17 +245,12 @@ async function main() {
 // path needed to reach them. Extension keys (UCP additionalProperties) are
 // preserved by the walker's pass-through and are intentionally absent here.
 
-export type RenameChild =
-  | ['r', string]
-  | ['a', RenameChild]
-  | ['m', RenameChild]
-  | ['u', ...RenameChild[]];
+export type {RenameChild, RenameEntry} from '../protocol_rename_map';
 
-export type RenameEntry = [string, string] | [string, string, RenameChild];
+${modelIds}
 
-export const renameMap: Record<string, RenameEntry[]> = ${JSON.stringify(
-    sorted,
-  )};
+export const renameFields = ${JSON.stringify(fields)};
+export const encodedRenameMap = ${JSON.stringify(encodedMap)};
 `;
   await fs.writeFile(OUTPUT, body);
   const count = Object.values(renameMap).reduce(
diff --git a/telemetry/languages/typescript/src/client.ts b/telemetry/languages/typescript/src/client.ts
index 28dca3f27..a5a7e8c14 100644
--- a/telemetry/languages/typescript/src/client.ts
+++ b/telemetry/languages/typescript/src/client.ts
@@ -66,27 +66,27 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
   }
 
   recordError(metric: TelemetryErrorMetric): void {
-    this.#recordCounter('checkout_kit_error', this.#attributes({
+    this.#recordCounter('checkout_kit_error', {
       category: metric.category,
       stage: metric.stage,
       code: metric.code,
       retryable: metric.retryable,
       is_retry: metric.isRetry ?? false,
-    }));
+    });
   }
 
   recordProtocolDecodeError(metric: TelemetryProtocolDecodeErrorMetric): void {
-    this.#recordCounter('checkout_kit_protocol_decode_error', this.#attributes({
+    this.#recordCounter('checkout_kit_protocol_decode_error', {
       method: toProtocolMethod(metric.method),
       failure_type: metric.failureType,
-    }));
+    });
   }
 
   recordNavigationRetry(metric: TelemetryNavigationRetryMetric): void {
-    this.#recordCounter('checkout_kit_navigation_retry', this.#attributes({
+    this.#recordCounter('checkout_kit_navigation_retry', {
       reason: metric.reason,
       result: metric.result,
-    }));
+    });
   }
 
   recordNavigationDuration(metric: TelemetryNavigationDurationMetric): void {
@@ -104,8 +104,8 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
     });
   }
 
-  flush(options: FlushOptions = {}, ignoreBackoff = false): Promise<boolean> {
-    if (this.#stopped) return Promise.resolve(false);
+  async flush(options: FlushOptions = {}, ignoreBackoff = false): Promise<boolean> {
+    if (this.#stopped) return false;
     const inFlight = this.#flushInProgress;
     if (inFlight) {
       if (this.#measurements.length === 0) return inFlight;
@@ -124,13 +124,13 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
       });
     }
     if (this.#measurements.length === 0) {
-      return Promise.resolve(true);
+      return true;
     }
     // A keepalive flush is a page-terminal moment (pagehide/unload): skipping
     // it because of backoff would silently drop the buffered measurements.
     const bypassBackoff = ignoreBackoff || options.keepalive === true;
     if (!bypassBackoff && Date.now() < this.#nextExportAllowedAtMs) {
-      return Promise.resolve(false);
+      return false;
     }
     const measurements = this.#measurements;
     this.#measurements = [];
@@ -166,7 +166,7 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
     this.#record({
       type: 'counter',
       name,
-      attributes,
+      attributes: this.#attributes(attributes),
       timeUnixNano: this.#now(),
     });
   }
@@ -196,6 +196,7 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
     if (options.keepalive !== true) {
       this.#activeRequest = controller;
     }
+    let succeeded = false;
     try {
       const response = await this.#fetch(this.#endpoint, {
         method: 'POST',
@@ -210,21 +211,14 @@ class DefaultCheckoutKitTelemetry implements CheckoutKitTelemetryClient {
         referrerPolicy: 'no-referrer',
         signal: controller.signal,
       });
-      const succeeded = response.ok;
-      if (!this.#stopped) {
-        if (!succeeded) this.#restoreMeasurements(measurements);
-        this.#updateExportBackoff(succeeded);
-      }
-      return succeeded;
-    } catch {
-      if (!this.#stopped) {
-        this.#restoreMeasurements(measurements);
-        this.#updateExportBackoff(false);
-      }
-      return false;
-    } finally {
-      if (this.#activeRequest === controller) this.#activeRequest = undefined;
+      succeeded = response.ok;
+    } catch {}
+    if (!this.#stopped) {
+      if (!succeeded) this.#restoreMeasurements(measurements);
+      this.#updateExportBackoff(succeeded);
     }
+    if (this.#activeRequest === controller) this.#activeRequest = undefined;
+    return succeeded;
   }
 
   #updateExportBackoff(succeeded: boolean): void {
diff --git a/telemetry/languages/typescript/test/client.test.ts b/telemetry/languages/typescript/test/client.test.ts
index 3275cbcc5..73fb579cb 100644
--- a/telemetry/languages/typescript/test/client.test.ts
+++ b/telemetry/languages/typescript/test/client.test.ts
@@ -112,6 +112,9 @@ describe('CheckoutKitTelemetry', () => {
     await expect(telemetry.flush()).resolves.toBe(false);
     const body = JSON.parse(fetch.mock.calls[0]![1].body as string);
     expect(body.resourceMetrics[0].scopeMetrics[0].metrics).toHaveLength(1);
+
+    await expect(telemetry.shutdown()).resolves.toBe(false);
+    expect(fetch).toHaveBeenCalledTimes(2);
   });
 
   it('clamps pending measurement capacity to one', async () => {