diff --git a/docs/protocols/http_client.md b/docs/protocols/http_client.md
index 236c67e3..2a5d76f5 100644
--- a/docs/protocols/http_client.md
+++ b/docs/protocols/http_client.md
@@ -310,6 +310,35 @@ const response = await postPingPostRequest({
 });
 ```
 
+## Error Handling
+
+Non-OK HTTP responses **throw** a typed `HttpError` instead of returning. `HttpError` extends the built-in `Error` and carries the HTTP `status`, `statusText`, and the parsed response `body`:
+
+```typescript
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown; // the parsed JSON error body, when present
+}
+```
+
+Consume it with an `instanceof` check:
+
+```typescript
+import { getGetUser, HttpError } from './__gen__/channels/http_client';
+
+try {
+  const response = await getGetUser({ baseUrl: 'https://api.example.com' });
+  // response.data is the typed, unmarshalled success payload
+} catch (error) {
+  if (error instanceof HttpError) {
+    console.error(error.status);     // e.g. 404
+    console.error(error.statusText); // e.g. 'Not Found'
+    console.error(error.body);       // parsed error body (unknown)
+  }
+}
+```
+
 ## Request/Response Hooks
 
 Customize request behavior with hooks:
@@ -451,4 +480,4 @@ if (response.status === 200) {
 } else if (response.status === 404) {
   console.log('Not found:', response.data); // NotFoundError
 }
-```
\ No newline at end of file
+```
diff --git a/examples/openapi-http-client/README.md b/examples/openapi-http-client/README.md
index df79dba4..fca69b49 100644
--- a/examples/openapi-http-client/README.md
+++ b/examples/openapi-http-client/README.md
@@ -38,22 +38,42 @@ import {GetV2ConnectReferenceIdParameters} from './generated/parameter/GetV2Conn
 
 // Body: build it with the generated request model, pass as `payload`.
 const body = new PostV2ConnectRequest({returnUrl: 'https://shop.example/return'});
-const created = await http_client.postV2Connect({server, payload: body});
+const created = await http_client.postV2Connect({baseUrl: server, payload: body});
 created.data.connectUrl; // typed
 
 // Path parameters: supply them through the generated parameter model.
 const params = new GetV2ConnectReferenceIdParameters({referenceId: 'ref_123'});
-const connect = await http_client.getV2ConnectReferenceId({server, parameters: params});
+const connect = await http_client.getV2ConnectReferenceId({baseUrl: server, parameters: params});
 connect.data.safepayAccountId; // typed
 
 // ...or, more ergonomically, pass a plain object — every parameter model also
 // exports a companion interface, and channels accept `Interface | Class` and
 // normalize internally. No need to construct the model yourself:
-await http_client.getV2ConnectReferenceId({server, parameters: {referenceId: 'ref_123'}});
+await http_client.getV2ConnectReferenceId({baseUrl: server, parameters: {referenceId: 'ref_123'}});
 ```
 
 Every function returns `HttpClientResponse<T>` where `data` is the unmarshalled, typed response model, alongside `status`, `headers`, and pagination helpers.
 
+## Error handling
+
+Non-OK responses **throw** a typed `HttpError` (exported from `generated/http_client.ts`) carrying the `status`, `statusText`, and the parsed response `body`:
+
+```ts
+import {http_client} from './generated';
+
+try {
+  await http_client.getV2ConnectReferenceId({baseUrl: server, parameters: {referenceId: 'missing'}});
+} catch (error) {
+  if (error instanceof http_client.HttpError) {
+    error.status;     // e.g. 404
+    error.statusText; // e.g. 'Not Found'
+    error.body;       // parsed JSON error body (unknown)
+  }
+}
+```
+
+The explicit `handleHttpError` cases are generated from the **error status codes the OpenAPI document declares** — `safepay-nordic-sample.json` declares `400` and `404`, so those throw with the standard reason-phrase message (`'Bad Request'`, `'Not Found'`). Any status code the document does not declare falls through to a generic `HTTP Error: <status> <statusText>` message. `HttpError` still flows through the `onError` hook and the retry logic unchanged.
+
 ## About the generated function names
 
 The operations in this document have **no `operationId`**, so names are synthesized from the HTTP method and the path, preserving word boundaries:
@@ -84,13 +104,13 @@ Call sites, before and after:
 
 ```ts
 // organization: 'flat' (default)
-await http_client.postV2Connect({server, payload});
+await http_client.postV2Connect({baseUrl: server, payload});
 
 // organization: 'tag' — grouped under the operation's OpenAPI tag (tag & leaf verbatim; here the tag is "Connect")
-await http_client.Connect.postV2Connect({server, payload});
+await http_client.Connect.postV2Connect({baseUrl: server, payload});
 
 // organization: 'path' — nested by URL path segments, HTTP method as the leaf
-await http_client.v2.connect.post({server, payload});
+await http_client.v2.connect.post({baseUrl: server, payload});
 ```
 
 See the [channels generator docs](https://the-codegen-project.org/docs/generators/channels) for the full description of each style.
diff --git a/examples/openapi-http-client/src/generated/client/SafepayApiV2SampleClient.ts b/examples/openapi-http-client/src/generated/client/SafepayApiV2SampleClient.ts
index 02eeaa0f..84b015ca 100644
--- a/examples/openapi-http-client/src/generated/client/SafepayApiV2SampleClient.ts
+++ b/examples/openapi-http-client/src/generated/client/SafepayApiV2SampleClient.ts
@@ -1,23 +1,21 @@
-import {PostV2ConnectRequest} from './../payload/PostV2ConnectRequest';
-import {PostV2ConnectResponse_200} from './../payload/PostV2ConnectResponse_200';
-import {GetV2ConnectReferenceIdResponse_200} from './../payload/GetV2ConnectReferenceIdResponse_200';
-import {GetV2UsersSafepayAccountIdBankAccountsResponse_200} from './../payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200';
+import {PostV2ConnectRequest, PostV2ConnectRequestInterface} from './../payload/PostV2ConnectRequest';
+import {PostV2ConnectResponse_200, PostV2ConnectResponse_200Interface} from './../payload/PostV2ConnectResponse_200';
+import {GetV2ConnectReferenceIdResponse_200, GetV2ConnectReferenceIdResponse_200Interface} from './../payload/GetV2ConnectReferenceIdResponse_200';
+import {GetV2UsersSafepayAccountIdBankAccountsResponse_200, GetV2UsersSafepayAccountIdBankAccountsResponse_200Interface} from './../payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200';
 import {Status} from './../payload/Status';
-import {BankAccountsItem} from './../payload/BankAccountsItem';
-import {InitializeRequest} from './../payload/InitializeRequest';
-import {InitializeModel} from './../payload/InitializeModel';
-import {GetConnectModel} from './../payload/GetConnectModel';
-import {BankAccount} from './../payload/BankAccount';
+import {BankAccount, BankAccountInterface} from './../payload/BankAccount';
+import {InitializeRequest, InitializeRequestInterface} from './../payload/InitializeRequest';
+import {InitializeModel, InitializeModelInterface} from './../payload/InitializeModel';
+import {GetConnectModel, GetConnectModelInterface} from './../payload/GetConnectModel';
 export {PostV2ConnectRequest};
 export {PostV2ConnectResponse_200};
 export {GetV2ConnectReferenceIdResponse_200};
 export {GetV2UsersSafepayAccountIdBankAccountsResponse_200};
 export {Status};
-export {BankAccountsItem};
+export {BankAccount};
 export {InitializeRequest};
 export {InitializeModel};
 export {GetConnectModel};
-export {BankAccount};
 import {GetV2ConnectReferenceIdParameters, GetV2ConnectReferenceIdParametersInterface} from './../parameter/GetV2ConnectReferenceIdParameters';
 import {GetV2UsersSafepayAccountIdBankAccountsParameters, GetV2UsersSafepayAccountIdBankAccountsParametersInterface} from './../parameter/GetV2UsersSafepayAccountIdBankAccountsParameters';
 export {GetV2ConnectReferenceIdParameters};
@@ -30,7 +28,7 @@ import * as http_client from './../http_client';
  * @class SafepayApiV2SampleClient
  *
  * A fully-typed HTTP client for the Safepay API V2 (sample). Construct it once with the shared request configuration
- * (server, auth, hooks, ...) and call the operation methods; every method
+ * (baseUrl, auth, hooks, ...) and call the operation methods; every method
  * forwards to the underlying channel function with that configuration applied.
  */
 export class SafepayApiV2SampleClient {
diff --git a/examples/openapi-http-client/src/generated/headers/PostV2ConnectHeaders.ts b/examples/openapi-http-client/src/generated/headers/PostV2ConnectHeaders.ts
index 3b43ba90..6b5a2ddd 100644
--- a/examples/openapi-http-client/src/generated/headers/PostV2ConnectHeaders.ts
+++ b/examples/openapi-http-client/src/generated/headers/PostV2ConnectHeaders.ts
@@ -1,61 +1,14 @@
-import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
-import {default as addFormats} from 'ajv-formats';
-class PostV2ConnectHeaders {
-  private _xCorrelationId?: string;
-
-  constructor(input: {
-    xCorrelationId?: string,
-  }) {
-    this._xCorrelationId = input.xCorrelationId;
-  }
 
+interface PostV2ConnectHeaders {
   /**
    * Correlation ID used for logging.
    */
-  get xCorrelationId(): string | undefined { return this._xCorrelationId; }
-  set xCorrelationId(xCorrelationId: string | undefined) { this._xCorrelationId = xCorrelationId; }
-
-  public marshal() : string {
-    let json = '{'
-    if(this.xCorrelationId !== undefined) {
-      json += `"X-Correlation-Id": ${typeof this.xCorrelationId === 'number' || typeof this.xCorrelationId === 'boolean' ? this.xCorrelationId : JSON.stringify(this.xCorrelationId)},`;
-    }
-  
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
-  }
-
-  public static unmarshal(json: string | object): PostV2ConnectHeaders {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
-    const instance = new PostV2ConnectHeaders({} as any);
-
-    if (obj["X-Correlation-Id"] !== undefined) {
-      instance.xCorrelationId = obj["X-Correlation-Id"];
-    }
-  
-  
-    return instance;
-  }
-  public static theCodeGenSchema = {"type":"object","additionalProperties":false,"properties":{"X-Correlation-Id":{"type":"string","minLength":20,"maxLength":64,"description":"Correlation ID used for logging."}},"$id":"PostV2ConnectHeaders","$schema":"http://json-schema.org/draft-07/schema"};
-  public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
-    const {data, ajvValidatorFunction} = context ?? {};
-    // Intentionally parse JSON strings to support validation of marshalled output.
-    // Example: validate({data: marshal(obj)}) works because marshal returns JSON string.
-    // Note: String 'true' will be coerced to boolean true due to JSON.parse.
-    const parsedData = typeof data === 'string' ? JSON.parse(data) : data;
-    const validate = ajvValidatorFunction ?? this.createValidator(context)
-    return {
-      valid: validate(parsedData),
-      errors: validate.errors ?? undefined,
-    };
-  }
-  public static createValidator(context?: {ajvInstance?: Ajv, ajvOptions?: AjvOptions}): ValidateFunction {
-    const {ajvInstance} = {...context ?? {}, ajvInstance: new Ajv(context?.ajvOptions ?? {})};
-    addFormats(ajvInstance);
-    ajvInstance.addVocabulary(["xml", "example"])
-    const validate = ajvInstance.compile(this.theCodeGenSchema);
-    return validate;
-  }
-
+  xMinusCorrelationMinusId?: string;
 }
-export { PostV2ConnectHeaders };
\ No newline at end of file
+export { PostV2ConnectHeaders };
+
+export function serializePostV2ConnectHeadersHeaders(headers: PostV2ConnectHeaders): Record<string, string> {
+  const result: Record<string, string> = {};
+  if (headers.xMinusCorrelationMinusId !== undefined) { result['X-Correlation-Id'] = String(headers.xMinusCorrelationMinusId); }
+  return result;
+}
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/http_client.ts b/examples/openapi-http-client/src/generated/http_client.ts
index c007a463..cde7f0b1 100644
--- a/examples/openapi-http-client/src/generated/http_client.ts
+++ b/examples/openapi-http-client/src/generated/http_client.ts
@@ -1,16 +1,15 @@
-import {PostV2ConnectRequest} from './payload/PostV2ConnectRequest';
-import {PostV2ConnectResponse_200} from './payload/PostV2ConnectResponse_200';
-import {GetV2ConnectReferenceIdResponse_200} from './payload/GetV2ConnectReferenceIdResponse_200';
-import {GetV2UsersSafepayAccountIdBankAccountsResponse_200} from './payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200';
+import {PostV2ConnectRequest, PostV2ConnectRequestInterface} from './payload/PostV2ConnectRequest';
+import {PostV2ConnectResponse_200, PostV2ConnectResponse_200Interface} from './payload/PostV2ConnectResponse_200';
+import {GetV2ConnectReferenceIdResponse_200, GetV2ConnectReferenceIdResponse_200Interface} from './payload/GetV2ConnectReferenceIdResponse_200';
+import {GetV2UsersSafepayAccountIdBankAccountsResponse_200, GetV2UsersSafepayAccountIdBankAccountsResponse_200Interface} from './payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200';
 import {Status} from './payload/Status';
-import {BankAccountsItem} from './payload/BankAccountsItem';
-import {InitializeRequest} from './payload/InitializeRequest';
-import {InitializeModel} from './payload/InitializeModel';
-import {GetConnectModel} from './payload/GetConnectModel';
-import {BankAccount} from './payload/BankAccount';
+import {BankAccount, BankAccountInterface} from './payload/BankAccount';
+import {InitializeRequest, InitializeRequestInterface} from './payload/InitializeRequest';
+import {InitializeModel, InitializeModelInterface} from './payload/InitializeModel';
+import {GetConnectModel, GetConnectModelInterface} from './payload/GetConnectModel';
 import {GetV2ConnectReferenceIdParameters, GetV2ConnectReferenceIdParametersInterface} from './parameter/GetV2ConnectReferenceIdParameters';
 import {GetV2UsersSafepayAccountIdBankAccountsParameters, GetV2UsersSafepayAccountIdBankAccountsParametersInterface} from './parameter/GetV2UsersSafepayAccountIdBankAccountsParameters';
-import {PostV2ConnectHeaders} from './headers/PostV2ConnectHeaders';
+import {PostV2ConnectHeaders, serializePostV2ConnectHeadersHeaders} from './headers/PostV2ConnectHeaders';
 
 // ============================================================================
 // Common Types - Shared across all HTTP client functions
@@ -27,26 +26,6 @@ export interface HttpResponse {
   json: () => Record<any, any> | Promise<Record<any, any>>;
 }
 
-/**
- * Pagination info extracted from response
- */
-export interface PaginationInfo {
-  /** Total number of items (if available from headers like X-Total-Count) */
-  totalCount?: number;
-  /** Total number of pages (if available) */
-  totalPages?: number;
-  /** Current page/offset */
-  currentOffset?: number;
-  /** Items per page */
-  limit?: number;
-  /** Next cursor (for cursor-based pagination) */
-  nextCursor?: string;
-  /** Previous cursor */
-  prevCursor?: string;
-  /** Whether there are more items */
-  hasMore?: boolean;
-}
-
 /**
  * Rich response wrapper returned by HTTP client functions
  */
@@ -61,16 +40,27 @@ export interface HttpClientResponse<T> {
   headers: Record<string, string>;
   /** Raw JSON response before deserialization */
   rawData: Record<string, any>;
-  /** Pagination info extracted from response (if applicable) */
-  pagination?: PaginationInfo;
-  /** Fetch the next page (if pagination is configured and more data exists) */
-  getNextPage?: () => Promise<HttpClientResponse<T>>;
-  /** Fetch the previous page (if pagination is configured) */
-  getPrevPage?: () => Promise<HttpClientResponse<T>>;
-  /** Check if there's a next page */
-  hasNextPage?: () => boolean;
-  /** Check if there's a previous page */
-  hasPrevPage?: () => boolean;
+}
+
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP `status`, `statusText`, and the parsed response `body`
+ * (when the error response had a JSON body). Thrown by `handleHttpError` and
+ * routed through the `onError` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
 }
 
 /**
@@ -181,69 +171,6 @@ const API_KEY_DEFAULTS = {
   in: 'header' as 'header' | 'query' | 'cookie'
 } as const;
 
-// ============================================================================
-// Pagination Types
-// ============================================================================
-
-/**
- * Where to place pagination parameters
- */
-export type PaginationLocation = 'query' | 'header';
-
-/**
- * Offset-based pagination configuration
- */
-export interface OffsetPagination {
-  type: 'offset';
-  in?: PaginationLocation;  // Where to place params (default: 'query')
-  offset: number;
-  limit: number;
-  offsetParam?: string;  // Param name for offset (default: 'offset' for query, 'X-Offset' for header)
-  limitParam?: string;   // Param name for limit (default: 'limit' for query, 'X-Limit' for header)
-}
-
-/**
- * Cursor-based pagination configuration
- */
-export interface CursorPagination {
-  type: 'cursor';
-  in?: PaginationLocation;  // Where to place params (default: 'query')
-  cursor?: string;
-  limit?: number;
-  cursorParam?: string;  // Param name for cursor (default: 'cursor' for query, 'X-Cursor' for header)
-  limitParam?: string;   // Param name for limit (default: 'limit' for query, 'X-Limit' for header)
-}
-
-/**
- * Page-based pagination configuration
- */
-export interface PagePagination {
-  type: 'page';
-  in?: PaginationLocation;  // Where to place params (default: 'query')
-  page: number;
-  pageSize: number;
-  pageParam?: string;     // Param name for page (default: 'page' for query, 'X-Page' for header)
-  pageSizeParam?: string; // Param name for page size (default: 'pageSize' for query, 'X-Page-Size' for header)
-}
-
-/**
- * Range-based pagination (typically used with headers)
- * Follows RFC 7233 style: Range: items=0-24
- */
-export interface RangePagination {
-  type: 'range';
-  in?: 'header';  // Range pagination is typically header-only
-  start: number;
-  end: number;
-  unit?: string;        // Range unit (default: 'items')
-  rangeHeader?: string; // Header name (default: 'Range')
-}
-
-/**
- * Union type for all pagination methods
- */
-export type PaginationConfig = OffsetPagination | CursorPagination | PagePagination | RangePagination;
-
 // ============================================================================
 // Retry Configuration
 // ============================================================================
@@ -301,15 +228,11 @@ export interface HttpHooks {
  * Base context shared by all HTTP client functions
  */
 export interface HttpClientContext {
-  server?: string;
-  path?: string;
+  baseUrl?: string;
 
   // Authentication - grouped for better autocomplete
   auth?: AuthConfig;
 
-  // Pagination configuration
-  pagination?: PaginationConfig;
-
   // Retry configuration
   retry?: RetryConfig;
 
@@ -319,8 +242,8 @@ export interface HttpClientContext {
   // Additional options
   additionalHeaders?: Record<string, string | string[]>;
 
-  // Query parameters
-  queryParams?: Record<string, string | number | boolean | undefined>;
+  // Extra query parameters not covered by the typed parameters interface
+  additionalQueryParams?: Record<string, string | number | boolean | undefined>;
 }
 
 // ============================================================================
@@ -412,94 +335,6 @@ function applyAuth(
   return { headers, url };
 }
 
-/**
- * Apply pagination parameters to URL and/or headers based on configuration
- */
-function applyPagination(
-  pagination: PaginationConfig | undefined,
-  url: string,
-  headers: Record<string, string | string[]>
-): { url: string; headers: Record<string, string | string[]> } {
-  if (!pagination) return { url, headers };
-
-  const location = pagination.in ?? 'query';
-  const isHeader = location === 'header';
-
-  // Helper to get default param names based on location
-  const getDefaultName = (queryName: string, headerName: string) =>
-    isHeader ? headerName : queryName;
-
-  const queryParams = new URLSearchParams();
-  const headerParams: Record<string, string> = {};
-
-  const addParam = (name: string, value: string) => {
-    if (isHeader) {
-      headerParams[name] = value;
-    } else {
-      queryParams.append(name, value);
-    }
-  };
-
-  switch (pagination.type) {
-    case 'offset':
-      addParam(
-        pagination.offsetParam ?? getDefaultName('offset', 'X-Offset'),
-        String(pagination.offset)
-      );
-      addParam(
-        pagination.limitParam ?? getDefaultName('limit', 'X-Limit'),
-        String(pagination.limit)
-      );
-      break;
-
-    case 'cursor':
-      if (pagination.cursor) {
-        addParam(
-          pagination.cursorParam ?? getDefaultName('cursor', 'X-Cursor'),
-          pagination.cursor
-        );
-      }
-      if (pagination.limit !== undefined) {
-        addParam(
-          pagination.limitParam ?? getDefaultName('limit', 'X-Limit'),
-          String(pagination.limit)
-        );
-      }
-      break;
-
-    case 'page':
-      addParam(
-        pagination.pageParam ?? getDefaultName('page', 'X-Page'),
-        String(pagination.page)
-      );
-      addParam(
-        pagination.pageSizeParam ?? getDefaultName('pageSize', 'X-Page-Size'),
-        String(pagination.pageSize)
-      );
-      break;
-
-    case 'range': {
-      // Range pagination is always header-based (RFC 7233 style)
-      const unit = pagination.unit ?? 'items';
-      const headerName = pagination.rangeHeader ?? 'Range';
-      headerParams[headerName] = `${unit}=${pagination.start}-${pagination.end}`;
-      break;
-    }
-  }
-
-  // Apply query params to URL
-  const queryString = queryParams.toString();
-  if (queryString) {
-    const separator = url.includes('?') ? '&' : '?';
-    url = `${url}${separator}${queryString}`;
-  }
-
-  // Merge header params
-  const updatedHeaders = { ...headers, ...headerParams };
-
-  return { url, headers: updatedHeaders };
-}
-
 /**
  * Apply query parameters to URL
  */
@@ -602,20 +437,18 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
   switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
+    case 400:
+      throw new HttpError("Bad Request", status, statusText, body);
     case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
+      throw new HttpError("Not Found", status, statusText, body);
     default:
-      throw new Error(`HTTP Error: ${status} ${statusText}`);
+      throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);
   }
 }
 
@@ -642,199 +475,6 @@ function extractHeaders(response: HttpResponse): Record<string, string> {
   return headers;
 }
 
-/**
- * Extract pagination info from response headers
- */
-function extractPaginationInfo(
-  headers: Record<string, string>,
-  currentPagination?: PaginationConfig
-): PaginationInfo | undefined {
-  const info: PaginationInfo = {};
-  let hasPaginationInfo = false;
-
-  // Common total count headers
-  const totalCount = headers['x-total-count'] || headers['x-total'] || headers['total-count'];
-  if (totalCount) {
-    info.totalCount = parseInt(totalCount, 10);
-    hasPaginationInfo = true;
-  }
-
-  // Total pages
-  const totalPages = headers['x-total-pages'] || headers['x-page-count'];
-  if (totalPages) {
-    info.totalPages = parseInt(totalPages, 10);
-    hasPaginationInfo = true;
-  }
-
-  // Next cursor
-  const nextCursor = headers['x-next-cursor'] || headers['x-cursor-next'];
-  if (nextCursor) {
-    info.nextCursor = nextCursor;
-    info.hasMore = true;
-    hasPaginationInfo = true;
-  }
-
-  // Previous cursor
-  const prevCursor = headers['x-prev-cursor'] || headers['x-cursor-prev'];
-  if (prevCursor) {
-    info.prevCursor = prevCursor;
-    hasPaginationInfo = true;
-  }
-
-  // Has more indicator
-  const hasMore = headers['x-has-more'] || headers['x-has-next'];
-  if (hasMore) {
-    info.hasMore = hasMore.toLowerCase() === 'true' || hasMore === '1';
-    hasPaginationInfo = true;
-  }
-
-  // Parse Link header (RFC 5988)
-  const linkHeader = headers['link'];
-  if (linkHeader) {
-    const links = parseLinkHeader(linkHeader);
-    if (links.next) {
-      info.hasMore = true;
-      hasPaginationInfo = true;
-    }
-  }
-
-  // Include current pagination state
-  if (currentPagination) {
-    switch (currentPagination.type) {
-      case 'offset':
-        info.currentOffset = currentPagination.offset;
-        info.limit = currentPagination.limit;
-        break;
-      case 'cursor':
-        info.limit = currentPagination.limit;
-        break;
-      case 'page':
-        info.currentOffset = (currentPagination.page - 1) * currentPagination.pageSize;
-        info.limit = currentPagination.pageSize;
-        break;
-      case 'range':
-        info.currentOffset = currentPagination.start;
-        info.limit = currentPagination.end - currentPagination.start + 1;
-        break;
-    }
-    hasPaginationInfo = true;
-  }
-
-  // Calculate hasMore based on total count
-  if (info.hasMore === undefined && info.totalCount !== undefined &&
-      info.currentOffset !== undefined && info.limit !== undefined) {
-    info.hasMore = info.currentOffset + info.limit < info.totalCount;
-  }
-
-  return hasPaginationInfo ? info : undefined;
-}
-
-/**
- * Parse RFC 5988 Link header
- */
-function parseLinkHeader(header: string): Record<string, string> {
-  const links: Record<string, string> = {};
-  const parts = header.split(',');
-
-  for (const part of parts) {
-    const match = part.match(/<([^>]+)>;\s*rel="?([^";\s]+)"?/);
-    if (match) {
-      links[match[2]] = match[1];
-    }
-  }
-
-  return links;
-}
-
-/**
- * Create pagination helper functions for the response
- */
-function createPaginationHelpers<T, TContext extends HttpClientContext>(
-  currentConfig: TContext,
-  paginationInfo: PaginationInfo | undefined,
-  requestFn: (config: TContext) => Promise<HttpClientResponse<T>>
-): Pick<HttpClientResponse<T>, 'getNextPage' | 'getPrevPage' | 'hasNextPage' | 'hasPrevPage'> {
-  const helpers: Pick<HttpClientResponse<T>, 'getNextPage' | 'getPrevPage' | 'hasNextPage' | 'hasPrevPage'> = {};
-
-  if (!currentConfig.pagination) {
-    return helpers;
-  }
-
-  const pagination = currentConfig.pagination;
-
-  helpers.hasNextPage = () => {
-    if (paginationInfo?.hasMore !== undefined) return paginationInfo.hasMore;
-    if (paginationInfo?.nextCursor) return true;
-    if (paginationInfo?.totalCount !== undefined &&
-        paginationInfo.currentOffset !== undefined &&
-        paginationInfo.limit !== undefined) {
-      return paginationInfo.currentOffset + paginationInfo.limit < paginationInfo.totalCount;
-    }
-    return false;
-  };
-
-  helpers.hasPrevPage = () => {
-    if (paginationInfo?.prevCursor) return true;
-    if (paginationInfo?.currentOffset !== undefined) {
-      return paginationInfo.currentOffset > 0;
-    }
-    return false;
-  };
-
-  helpers.getNextPage = async () => {
-    let nextPagination: PaginationConfig;
-
-    switch (pagination.type) {
-      case 'offset':
-        nextPagination = { ...pagination, offset: pagination.offset + pagination.limit };
-        break;
-      case 'cursor':
-        if (!paginationInfo?.nextCursor) throw new Error('No next cursor available');
-        nextPagination = { ...pagination, cursor: paginationInfo.nextCursor };
-        break;
-      case 'page':
-        nextPagination = { ...pagination, page: pagination.page + 1 };
-        break;
-      case 'range':
-        const rangeSize = pagination.end - pagination.start + 1;
-        nextPagination = { ...pagination, start: pagination.end + 1, end: pagination.end + rangeSize };
-        break;
-      default:
-        throw new Error('Unsupported pagination type');
-    }
-
-    return requestFn({ ...currentConfig, pagination: nextPagination });
-  };
-
-  helpers.getPrevPage = async () => {
-    let prevPagination: PaginationConfig;
-
-    switch (pagination.type) {
-      case 'offset':
-        prevPagination = { ...pagination, offset: Math.max(0, pagination.offset - pagination.limit) };
-        break;
-      case 'cursor':
-        if (!paginationInfo?.prevCursor) throw new Error('No previous cursor available');
-        prevPagination = { ...pagination, cursor: paginationInfo.prevCursor };
-        break;
-      case 'page':
-        prevPagination = { ...pagination, page: Math.max(1, pagination.page - 1) };
-        break;
-      case 'range':
-        const size = pagination.end - pagination.start + 1;
-        const newStart = Math.max(0, pagination.start - size);
-        prevPagination = { ...pagination, start: newStart, end: newStart + size - 1 };
-        break;
-      default:
-        throw new Error('Unsupported pagination type');
-    }
-
-    return requestFn({ ...currentConfig, pagination: prevPagination });
-  };
-
-  return helpers;
-}
-
 /**
  * Builds a URL with path parameters replaced
  * @param server - Base server URL
@@ -1025,8 +665,8 @@ async function handleTokenRefresh(
 // ============================================================================
 
 export interface PostV2ConnectContext extends HttpClientContext {
-  payload: PostV2ConnectRequest;
-  requestHeaders?: { marshal: () => string };
+  payload: PostV2ConnectRequestInterface | PostV2ConnectRequest;
+  requestHeaders?: PostV2ConnectHeaders;
 }
 
 /**
@@ -1035,8 +675,7 @@ export interface PostV2ConnectContext extends HttpClientContext {
 async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientResponse<PostV2ConnectResponse_200>> {
   // Apply defaults
   const config = {
-    path: '/v2/connect',
-    server: 'localhost:3000',
+    baseUrl: 'http://localhost:3000',
     ...context,
   };
 
@@ -1046,18 +685,11 @@ async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientR
   }
 
   // Build headers
-  let headers = context.requestHeaders
-    ? applyTypedHeaders(context.requestHeaders, config.additionalHeaders)
-    : { 'Content-Type': 'application/json', ...config.additionalHeaders } as Record<string, string | string[]>;
+  let headers = { 'Content-Type': 'application/json', ...config.additionalHeaders, ...(context.requestHeaders ? serializePostV2ConnectHeadersHeaders(context.requestHeaders) : {}) } as Record<string, string | string[]>;
 
   // Build URL
-  let url = `${config.server}${config.path}`;
-  url = applyQueryParams(config.queryParams, url);
-
-  // Apply pagination (can affect URL and/or headers)
-  const paginationResult = applyPagination(config.pagination, url, headers);
-  url = paginationResult.url;
-  headers = paginationResult.headers;
+  let url = `${config.baseUrl}/v2/connect`;
+  url = applyQueryParams(config.additionalQueryParams, url);
 
   // Apply authentication
   const authResult = applyAuth(config.auth, headers, url);
@@ -1065,7 +697,8 @@ async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientR
   url = authResult.url;
 
   // Prepare body
-  const body = context.payload?.marshal();
+  const payload = context.payload instanceof PostV2ConnectRequest ? context.payload : new PostV2ConnectRequest(context.payload);
+  const body = payload?.marshal();
 
   // Determine request function
   const makeRequest = config.hooks?.makeRequest ?? defaultMakeRequest;
@@ -1114,7 +747,8 @@ async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientR
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1123,17 +757,13 @@ async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientR
 
     // Extract response metadata
     const responseHeaders = extractHeaders(response);
-    const paginationInfo = extractPaginationInfo(responseHeaders, config.pagination);
 
-    // Build response wrapper with pagination helpers
     const result: HttpClientResponse<PostV2ConnectResponse_200> = {
       data: responseData,
       status: response.status,
       statusText: response.statusText,
       headers: responseHeaders,
       rawData,
-      pagination: paginationInfo,
-      ...createPaginationHelpers(config, paginationInfo, postV2Connect),
     };
 
     return result;
@@ -1149,7 +779,6 @@ async function postV2Connect(context: PostV2ConnectContext): Promise<HttpClientR
 
 export interface GetV2ConnectReferenceIdContext extends HttpClientContext {
   parameters: GetV2ConnectReferenceIdParametersInterface | GetV2ConnectReferenceIdParameters;
-  requestHeaders?: { marshal: () => string };
 }
 
 /**
@@ -1158,8 +787,7 @@ export interface GetV2ConnectReferenceIdContext extends HttpClientContext {
 async function getV2ConnectReferenceId(context: GetV2ConnectReferenceIdContext): Promise<HttpClientResponse<GetV2ConnectReferenceIdResponse_200>> {
   // Apply defaults
   const config = {
-    path: '/v2/connect/{referenceId}',
-    server: 'localhost:3000',
+    baseUrl: 'http://localhost:3000',
     ...context,
   };
 
@@ -1171,18 +799,11 @@ async function getV2ConnectReferenceId(context: GetV2ConnectReferenceIdContext):
   }
 
   // Build headers
-  let headers = context.requestHeaders
-    ? applyTypedHeaders(context.requestHeaders, config.additionalHeaders)
-    : { 'Content-Type': 'application/json', ...config.additionalHeaders } as Record<string, string | string[]>;
+  let headers = { 'Content-Type': 'application/json', ...config.additionalHeaders } as Record<string, string | string[]>;
 
   // Build URL
-  let url = buildUrlWithParameters(config.server, '/v2/connect/{referenceId}', parameters);
-  url = applyQueryParams(config.queryParams, url);
-
-  // Apply pagination (can affect URL and/or headers)
-  const paginationResult = applyPagination(config.pagination, url, headers);
-  url = paginationResult.url;
-  headers = paginationResult.headers;
+  let url = buildUrlWithParameters(config.baseUrl, '/v2/connect/{referenceId}', parameters);
+  url = applyQueryParams(config.additionalQueryParams, url);
 
   // Apply authentication
   const authResult = applyAuth(config.auth, headers, url);
@@ -1239,7 +860,8 @@ async function getV2ConnectReferenceId(context: GetV2ConnectReferenceIdContext):
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1248,17 +870,13 @@ async function getV2ConnectReferenceId(context: GetV2ConnectReferenceIdContext):
 
     // Extract response metadata
     const responseHeaders = extractHeaders(response);
-    const paginationInfo = extractPaginationInfo(responseHeaders, config.pagination);
 
-    // Build response wrapper with pagination helpers
     const result: HttpClientResponse<GetV2ConnectReferenceIdResponse_200> = {
       data: responseData,
       status: response.status,
       statusText: response.statusText,
       headers: responseHeaders,
       rawData,
-      pagination: paginationInfo,
-      ...createPaginationHelpers(config, paginationInfo, getV2ConnectReferenceId),
     };
 
     return result;
@@ -1274,7 +892,6 @@ async function getV2ConnectReferenceId(context: GetV2ConnectReferenceIdContext):
 
 export interface GetV2UsersSafepayAccountIdBankAccountsContext extends HttpClientContext {
   parameters: GetV2UsersSafepayAccountIdBankAccountsParametersInterface | GetV2UsersSafepayAccountIdBankAccountsParameters;
-  requestHeaders?: { marshal: () => string };
 }
 
 /**
@@ -1283,8 +900,7 @@ export interface GetV2UsersSafepayAccountIdBankAccountsContext extends HttpClien
 async function getV2UsersSafepayAccountIdBankAccounts(context: GetV2UsersSafepayAccountIdBankAccountsContext): Promise<HttpClientResponse<GetV2UsersSafepayAccountIdBankAccountsResponse_200>> {
   // Apply defaults
   const config = {
-    path: '/v2/users/{safepayAccountId}/bank-accounts',
-    server: 'localhost:3000',
+    baseUrl: 'http://localhost:3000',
     ...context,
   };
 
@@ -1296,18 +912,11 @@ async function getV2UsersSafepayAccountIdBankAccounts(context: GetV2UsersSafepay
   }
 
   // Build headers
-  let headers = context.requestHeaders
-    ? applyTypedHeaders(context.requestHeaders, config.additionalHeaders)
-    : { 'Content-Type': 'application/json', ...config.additionalHeaders } as Record<string, string | string[]>;
+  let headers = { 'Content-Type': 'application/json', ...config.additionalHeaders } as Record<string, string | string[]>;
 
   // Build URL
-  let url = buildUrlWithParameters(config.server, '/v2/users/{safepayAccountId}/bank-accounts', parameters);
-  url = applyQueryParams(config.queryParams, url);
-
-  // Apply pagination (can affect URL and/or headers)
-  const paginationResult = applyPagination(config.pagination, url, headers);
-  url = paginationResult.url;
-  headers = paginationResult.headers;
+  let url = buildUrlWithParameters(config.baseUrl, '/v2/users/{safepayAccountId}/bank-accounts', parameters);
+  url = applyQueryParams(config.additionalQueryParams, url);
 
   // Apply authentication
   const authResult = applyAuth(config.auth, headers, url);
@@ -1364,7 +973,8 @@ async function getV2UsersSafepayAccountIdBankAccounts(context: GetV2UsersSafepay
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1373,17 +983,13 @@ async function getV2UsersSafepayAccountIdBankAccounts(context: GetV2UsersSafepay
 
     // Extract response metadata
     const responseHeaders = extractHeaders(response);
-    const paginationInfo = extractPaginationInfo(responseHeaders, config.pagination);
 
-    // Build response wrapper with pagination helpers
     const result: HttpClientResponse<GetV2UsersSafepayAccountIdBankAccountsResponse_200> = {
       data: responseData,
       status: response.status,
       statusText: response.statusText,
       headers: responseHeaders,
       rawData,
-      pagination: paginationInfo,
-      ...createPaginationHelpers(config, paginationInfo, getV2UsersSafepayAccountIdBankAccounts),
     };
 
     return result;
diff --git a/examples/openapi-http-client/src/generated/payload/BankAccount.ts b/examples/openapi-http-client/src/generated/payload/BankAccount.ts
index b56919e9..7a5a699f 100644
--- a/examples/openapi-http-client/src/generated/payload/BankAccount.ts
+++ b/examples/openapi-http-client/src/generated/payload/BankAccount.ts
@@ -1,17 +1,18 @@
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface BankAccountInterface {
+  id?: string
+  iban?: string
+  isDefault?: boolean
+  additionalProperties?: Record<string, any>
+}
 class BankAccount {
   private _id?: string;
   private _iban?: string;
   private _isDefault?: boolean;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    id?: string,
-    iban?: string,
-    isDefault?: boolean,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: BankAccountInterface) {
     this._id = input.id;
     this._iban = input.iban;
     this._isDefault = input.isDefault;
@@ -30,50 +31,57 @@ class BankAccount {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.id !== undefined) {
-      json += `"id": ${typeof this.id === 'number' || typeof this.id === 'boolean' ? this.id : JSON.stringify(this.id)},`;
+      json["id"] = this.id;
     }
     if(this.iban !== undefined) {
-      json += `"iban": ${typeof this.iban === 'number' || typeof this.iban === 'boolean' ? this.iban : JSON.stringify(this.iban)},`;
+      json["iban"] = this.iban;
     }
     if(this.isDefault !== undefined) {
-      json += `"isDefault": ${typeof this.isDefault === 'number' || typeof this.isDefault === 'boolean' ? this.isDefault : JSON.stringify(this.isDefault)},`;
+      json["isDefault"] = this.isDefault;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["id","iban","isDefault","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): BankAccount {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): BankAccount {
     const instance = new BankAccount({} as any);
 
     if (obj["id"] !== undefined) {
-      instance.id = obj["id"];
+      instance.id = obj["id"] as string;
     }
     if (obj["iban"] !== undefined) {
-      instance.iban = obj["iban"];
+      instance.iban = obj["iban"] as string;
     }
     if (obj["isDefault"] !== undefined) {
-      instance.isDefault = obj["isDefault"];
+      instance.isDefault = obj["isDefault"] as boolean;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["id","iban","isDefault","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
-  public static theCodeGenSchema = {"type":"object","properties":{"id":{"type":"string"},"iban":{"type":"string"},"isDefault":{"type":"boolean"}},"$id":"BankAccount","$schema":"http://json-schema.org/draft-07/schema"};
+
+  public static unmarshal(json: string | object): BankAccount {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return BankAccount.fromJson(obj as Record<string, unknown>);
+  }
+  public static theCodeGenSchema = {"type":"object","properties":{"id":{"type":"string"},"iban":{"type":"string"},"isDefault":{"type":"boolean"}}};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
     // Intentionally parse JSON strings to support validation of marshalled output.
@@ -95,4 +103,4 @@ class BankAccount {
   }
 
 }
-export { BankAccount };
\ No newline at end of file
+export { BankAccount, BankAccountInterface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/GetConnectModel.ts b/examples/openapi-http-client/src/generated/payload/GetConnectModel.ts
index 392f53fa..4b973dd0 100644
--- a/examples/openapi-http-client/src/generated/payload/GetConnectModel.ts
+++ b/examples/openapi-http-client/src/generated/payload/GetConnectModel.ts
@@ -1,18 +1,19 @@
 import {Status} from './Status';
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface GetConnectModelInterface {
+  referenceId?: string
+  safepayAccountId?: string
+  status?: Status
+  additionalProperties?: Record<string, any>
+}
 class GetConnectModel {
   private _referenceId?: string;
   private _safepayAccountId?: string;
   private _status?: Status;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    referenceId?: string,
-    safepayAccountId?: string,
-    status?: Status,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: GetConnectModelInterface) {
     this._referenceId = input.referenceId;
     this._safepayAccountId = input.safepayAccountId;
     this._status = input.status;
@@ -31,49 +32,56 @@ class GetConnectModel {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.referenceId !== undefined) {
-      json += `"referenceId": ${typeof this.referenceId === 'number' || typeof this.referenceId === 'boolean' ? this.referenceId : JSON.stringify(this.referenceId)},`;
+      json["referenceId"] = this.referenceId;
     }
     if(this.safepayAccountId !== undefined) {
-      json += `"safepayAccountId": ${typeof this.safepayAccountId === 'number' || typeof this.safepayAccountId === 'boolean' ? this.safepayAccountId : JSON.stringify(this.safepayAccountId)},`;
+      json["safepayAccountId"] = this.safepayAccountId;
     }
     if(this.status !== undefined) {
-      json += `"status": ${typeof this.status === 'number' || typeof this.status === 'boolean' ? this.status : JSON.stringify(this.status)},`;
+      json["status"] = this.status;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["referenceId","safepayAccountId","status","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): GetConnectModel {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): GetConnectModel {
     const instance = new GetConnectModel({} as any);
 
     if (obj["referenceId"] !== undefined) {
-      instance.referenceId = obj["referenceId"];
+      instance.referenceId = obj["referenceId"] as string;
     }
     if (obj["safepayAccountId"] !== undefined) {
-      instance.safepayAccountId = obj["safepayAccountId"];
+      instance.safepayAccountId = obj["safepayAccountId"] as string;
     }
     if (obj["status"] !== undefined) {
-      instance.status = obj["status"];
+      instance.status = obj["status"] as Status;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["referenceId","safepayAccountId","status","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): GetConnectModel {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return GetConnectModel.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","properties":{"referenceId":{"type":"string"},"safepayAccountId":{"type":"string"},"status":{"type":"string","enum":["pending","connected","expired"]}},"$id":"GetConnectModel","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -96,4 +104,4 @@ class GetConnectModel {
   }
 
 }
-export { GetConnectModel };
\ No newline at end of file
+export { GetConnectModel, GetConnectModelInterface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/GetV2ConnectReferenceIdResponse_200.ts b/examples/openapi-http-client/src/generated/payload/GetV2ConnectReferenceIdResponse_200.ts
index 01d4e656..f1b9bf12 100644
--- a/examples/openapi-http-client/src/generated/payload/GetV2ConnectReferenceIdResponse_200.ts
+++ b/examples/openapi-http-client/src/generated/payload/GetV2ConnectReferenceIdResponse_200.ts
@@ -1,18 +1,19 @@
 import {Status} from './Status';
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface GetV2ConnectReferenceIdResponse_200Interface {
+  referenceId?: string
+  safepayAccountId?: string
+  status?: Status
+  additionalProperties?: Record<string, any>
+}
 class GetV2ConnectReferenceIdResponse_200 {
   private _referenceId?: string;
   private _safepayAccountId?: string;
   private _status?: Status;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    referenceId?: string,
-    safepayAccountId?: string,
-    status?: Status,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: GetV2ConnectReferenceIdResponse_200Interface) {
     this._referenceId = input.referenceId;
     this._safepayAccountId = input.safepayAccountId;
     this._status = input.status;
@@ -31,49 +32,56 @@ class GetV2ConnectReferenceIdResponse_200 {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.referenceId !== undefined) {
-      json += `"referenceId": ${typeof this.referenceId === 'number' || typeof this.referenceId === 'boolean' ? this.referenceId : JSON.stringify(this.referenceId)},`;
+      json["referenceId"] = this.referenceId;
     }
     if(this.safepayAccountId !== undefined) {
-      json += `"safepayAccountId": ${typeof this.safepayAccountId === 'number' || typeof this.safepayAccountId === 'boolean' ? this.safepayAccountId : JSON.stringify(this.safepayAccountId)},`;
+      json["safepayAccountId"] = this.safepayAccountId;
     }
     if(this.status !== undefined) {
-      json += `"status": ${typeof this.status === 'number' || typeof this.status === 'boolean' ? this.status : JSON.stringify(this.status)},`;
+      json["status"] = this.status;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["referenceId","safepayAccountId","status","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): GetV2ConnectReferenceIdResponse_200 {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): GetV2ConnectReferenceIdResponse_200 {
     const instance = new GetV2ConnectReferenceIdResponse_200({} as any);
 
     if (obj["referenceId"] !== undefined) {
-      instance.referenceId = obj["referenceId"];
+      instance.referenceId = obj["referenceId"] as string;
     }
     if (obj["safepayAccountId"] !== undefined) {
-      instance.safepayAccountId = obj["safepayAccountId"];
+      instance.safepayAccountId = obj["safepayAccountId"] as string;
     }
     if (obj["status"] !== undefined) {
-      instance.status = obj["status"];
+      instance.status = obj["status"] as Status;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["referenceId","safepayAccountId","status","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): GetV2ConnectReferenceIdResponse_200 {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return GetV2ConnectReferenceIdResponse_200.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","properties":{"referenceId":{"type":"string"},"safepayAccountId":{"type":"string"},"status":{"type":"string","enum":["pending","connected","expired"]}},"$id":"getV2ConnectReferenceId_Response_200","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -96,4 +104,4 @@ class GetV2ConnectReferenceIdResponse_200 {
   }
 
 }
-export { GetV2ConnectReferenceIdResponse_200 };
\ No newline at end of file
+export { GetV2ConnectReferenceIdResponse_200, GetV2ConnectReferenceIdResponse_200Interface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200.ts b/examples/openapi-http-client/src/generated/payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200.ts
index 39d1abf3..80cb4534 100644
--- a/examples/openapi-http-client/src/generated/payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200.ts
+++ b/examples/openapi-http-client/src/generated/payload/GetV2UsersSafepayAccountIdBankAccountsResponse_200.ts
@@ -1,61 +1,69 @@
-import {BankAccountsItem} from './BankAccountsItem';
+import {BankAccount} from './BankAccount';
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface GetV2UsersSafepayAccountIdBankAccountsResponse_200Interface {
+  bankAccounts?: BankAccount[]
+  additionalProperties?: Record<string, any>
+}
 class GetV2UsersSafepayAccountIdBankAccountsResponse_200 {
-  private _bankAccounts?: BankAccountsItem[];
+  private _bankAccounts?: BankAccount[];
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    bankAccounts?: BankAccountsItem[],
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: GetV2UsersSafepayAccountIdBankAccountsResponse_200Interface) {
     this._bankAccounts = input.bankAccounts;
     this._additionalProperties = input.additionalProperties;
   }
 
-  get bankAccounts(): BankAccountsItem[] | undefined { return this._bankAccounts; }
-  set bankAccounts(bankAccounts: BankAccountsItem[] | undefined) { this._bankAccounts = bankAccounts; }
+  get bankAccounts(): BankAccount[] | undefined { return this._bankAccounts; }
+  set bankAccounts(bankAccounts: BankAccount[] | undefined) { this._bankAccounts = bankAccounts; }
 
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.bankAccounts !== undefined) {
-      let bankAccountsJsonValues: any[] = [];
-      for (const unionItem of this.bankAccounts) {
-        bankAccountsJsonValues.push(`${unionItem && typeof unionItem === 'object' && 'marshal' in unionItem && typeof unionItem.marshal === 'function' ? unionItem.marshal() : JSON.stringify(unionItem)}`);
-      }
-      json += `"bankAccounts": [${bankAccountsJsonValues.join(',')}],`;
+      json["bankAccounts"] = this.bankAccounts.map((item: any) =>
+        item && typeof item === 'object' && 'toJson' in item && typeof item.toJson === 'function'
+          ? item.toJson()
+          : item
+      );
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["bankAccounts","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): GetV2UsersSafepayAccountIdBankAccountsResponse_200 {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): GetV2UsersSafepayAccountIdBankAccountsResponse_200 {
     const instance = new GetV2UsersSafepayAccountIdBankAccountsResponse_200({} as any);
 
     if (obj["bankAccounts"] !== undefined) {
       instance.bankAccounts = obj["bankAccounts"] == null
         ? undefined
-        : obj["bankAccounts"].map((item: any) => BankAccountsItem.unmarshal(item));
+        : (obj["bankAccounts"] as Record<string, unknown>[]).map((item: Record<string, unknown>) => BankAccount.fromJson(item));
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["bankAccounts","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): GetV2UsersSafepayAccountIdBankAccountsResponse_200 {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return GetV2UsersSafepayAccountIdBankAccountsResponse_200.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","properties":{"bankAccounts":{"type":"array","items":{"type":"object","properties":{"id":{"type":"string"},"iban":{"type":"string"},"isDefault":{"type":"boolean"}}}}},"$id":"getV2UsersSafepayAccountIdBankAccounts_Response_200","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -78,4 +86,4 @@ class GetV2UsersSafepayAccountIdBankAccountsResponse_200 {
   }
 
 }
-export { GetV2UsersSafepayAccountIdBankAccountsResponse_200 };
\ No newline at end of file
+export { GetV2UsersSafepayAccountIdBankAccountsResponse_200, GetV2UsersSafepayAccountIdBankAccountsResponse_200Interface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/InitializeModel.ts b/examples/openapi-http-client/src/generated/payload/InitializeModel.ts
index 9d12907a..dce7b9c9 100644
--- a/examples/openapi-http-client/src/generated/payload/InitializeModel.ts
+++ b/examples/openapi-http-client/src/generated/payload/InitializeModel.ts
@@ -1,15 +1,16 @@
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface InitializeModelInterface {
+  referenceId?: string
+  connectUrl?: string
+  additionalProperties?: Record<string, any>
+}
 class InitializeModel {
   private _referenceId?: string;
   private _connectUrl?: string;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    referenceId?: string,
-    connectUrl?: string,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: InitializeModelInterface) {
     this._referenceId = input.referenceId;
     this._connectUrl = input.connectUrl;
     this._additionalProperties = input.additionalProperties;
@@ -24,43 +25,50 @@ class InitializeModel {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.referenceId !== undefined) {
-      json += `"referenceId": ${typeof this.referenceId === 'number' || typeof this.referenceId === 'boolean' ? this.referenceId : JSON.stringify(this.referenceId)},`;
+      json["referenceId"] = this.referenceId;
     }
     if(this.connectUrl !== undefined) {
-      json += `"connectUrl": ${typeof this.connectUrl === 'number' || typeof this.connectUrl === 'boolean' ? this.connectUrl : JSON.stringify(this.connectUrl)},`;
+      json["connectUrl"] = this.connectUrl;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["referenceId","connectUrl","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): InitializeModel {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): InitializeModel {
     const instance = new InitializeModel({} as any);
 
     if (obj["referenceId"] !== undefined) {
-      instance.referenceId = obj["referenceId"];
+      instance.referenceId = obj["referenceId"] as string;
     }
     if (obj["connectUrl"] !== undefined) {
-      instance.connectUrl = obj["connectUrl"];
+      instance.connectUrl = obj["connectUrl"] as string;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["referenceId","connectUrl","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): InitializeModel {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return InitializeModel.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","properties":{"referenceId":{"type":"string"},"connectUrl":{"type":"string","format":"uri"}},"$id":"InitializeModel","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -83,4 +91,4 @@ class InitializeModel {
   }
 
 }
-export { InitializeModel };
\ No newline at end of file
+export { InitializeModel, InitializeModelInterface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/InitializeRequest.ts b/examples/openapi-http-client/src/generated/payload/InitializeRequest.ts
index d4a50a50..af34d425 100644
--- a/examples/openapi-http-client/src/generated/payload/InitializeRequest.ts
+++ b/examples/openapi-http-client/src/generated/payload/InitializeRequest.ts
@@ -1,15 +1,16 @@
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface InitializeRequestInterface {
+  returnUrl: string
+  skipKyc?: boolean
+  additionalProperties?: Record<string, any>
+}
 class InitializeRequest {
   private _returnUrl: string;
   private _skipKyc?: boolean;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    returnUrl: string,
-    skipKyc?: boolean,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: InitializeRequestInterface) {
     this._returnUrl = input.returnUrl;
     this._skipKyc = input.skipKyc;
     this._additionalProperties = input.additionalProperties;
@@ -24,43 +25,50 @@ class InitializeRequest {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.returnUrl !== undefined) {
-      json += `"returnUrl": ${typeof this.returnUrl === 'number' || typeof this.returnUrl === 'boolean' ? this.returnUrl : JSON.stringify(this.returnUrl)},`;
+      json["returnUrl"] = this.returnUrl;
     }
     if(this.skipKyc !== undefined) {
-      json += `"skipKyc": ${typeof this.skipKyc === 'number' || typeof this.skipKyc === 'boolean' ? this.skipKyc : JSON.stringify(this.skipKyc)},`;
+      json["skipKyc"] = this.skipKyc;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["returnUrl","skipKyc","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): InitializeRequest {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): InitializeRequest {
     const instance = new InitializeRequest({} as any);
 
     if (obj["returnUrl"] !== undefined) {
-      instance.returnUrl = obj["returnUrl"];
+      instance.returnUrl = obj["returnUrl"] as string;
     }
     if (obj["skipKyc"] !== undefined) {
-      instance.skipKyc = obj["skipKyc"];
+      instance.skipKyc = obj["skipKyc"] as boolean;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["returnUrl","skipKyc","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): InitializeRequest {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return InitializeRequest.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","required":["returnUrl"],"properties":{"returnUrl":{"type":"string","format":"uri"},"skipKyc":{"type":"boolean"}},"$id":"InitializeRequest","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -83,4 +91,4 @@ class InitializeRequest {
   }
 
 }
-export { InitializeRequest };
\ No newline at end of file
+export { InitializeRequest, InitializeRequestInterface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/PostV2ConnectRequest.ts b/examples/openapi-http-client/src/generated/payload/PostV2ConnectRequest.ts
index b7d2c2bb..e2caea1b 100644
--- a/examples/openapi-http-client/src/generated/payload/PostV2ConnectRequest.ts
+++ b/examples/openapi-http-client/src/generated/payload/PostV2ConnectRequest.ts
@@ -1,15 +1,16 @@
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface PostV2ConnectRequestInterface {
+  returnUrl: string
+  skipKyc?: boolean
+  additionalProperties?: Record<string, any>
+}
 class PostV2ConnectRequest {
   private _returnUrl: string;
   private _skipKyc?: boolean;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    returnUrl: string,
-    skipKyc?: boolean,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: PostV2ConnectRequestInterface) {
     this._returnUrl = input.returnUrl;
     this._skipKyc = input.skipKyc;
     this._additionalProperties = input.additionalProperties;
@@ -24,43 +25,50 @@ class PostV2ConnectRequest {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.returnUrl !== undefined) {
-      json += `"returnUrl": ${typeof this.returnUrl === 'number' || typeof this.returnUrl === 'boolean' ? this.returnUrl : JSON.stringify(this.returnUrl)},`;
+      json["returnUrl"] = this.returnUrl;
     }
     if(this.skipKyc !== undefined) {
-      json += `"skipKyc": ${typeof this.skipKyc === 'number' || typeof this.skipKyc === 'boolean' ? this.skipKyc : JSON.stringify(this.skipKyc)},`;
+      json["skipKyc"] = this.skipKyc;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["returnUrl","skipKyc","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): PostV2ConnectRequest {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): PostV2ConnectRequest {
     const instance = new PostV2ConnectRequest({} as any);
 
     if (obj["returnUrl"] !== undefined) {
-      instance.returnUrl = obj["returnUrl"];
+      instance.returnUrl = obj["returnUrl"] as string;
     }
     if (obj["skipKyc"] !== undefined) {
-      instance.skipKyc = obj["skipKyc"];
+      instance.skipKyc = obj["skipKyc"] as boolean;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["returnUrl","skipKyc","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): PostV2ConnectRequest {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return PostV2ConnectRequest.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","required":["returnUrl"],"properties":{"returnUrl":{"type":"string","format":"uri"},"skipKyc":{"type":"boolean"}},"$id":"PostV2ConnectRequest","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -83,4 +91,4 @@ class PostV2ConnectRequest {
   }
 
 }
-export { PostV2ConnectRequest };
\ No newline at end of file
+export { PostV2ConnectRequest, PostV2ConnectRequestInterface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/generated/payload/PostV2ConnectResponse_200.ts b/examples/openapi-http-client/src/generated/payload/PostV2ConnectResponse_200.ts
index 5b9942a4..a2e05fbc 100644
--- a/examples/openapi-http-client/src/generated/payload/PostV2ConnectResponse_200.ts
+++ b/examples/openapi-http-client/src/generated/payload/PostV2ConnectResponse_200.ts
@@ -1,15 +1,16 @@
 import {Ajv, Options as AjvOptions, ErrorObject, ValidateFunction} from 'ajv';
 import {default as addFormats} from 'ajv-formats';
+interface PostV2ConnectResponse_200Interface {
+  referenceId?: string
+  connectUrl?: string
+  additionalProperties?: Record<string, any>
+}
 class PostV2ConnectResponse_200 {
   private _referenceId?: string;
   private _connectUrl?: string;
   private _additionalProperties?: Record<string, any>;
 
-  constructor(input: {
-    referenceId?: string,
-    connectUrl?: string,
-    additionalProperties?: Record<string, any>,
-  }) {
+  constructor(input: PostV2ConnectResponse_200Interface) {
     this._referenceId = input.referenceId;
     this._connectUrl = input.connectUrl;
     this._additionalProperties = input.additionalProperties;
@@ -24,43 +25,50 @@ class PostV2ConnectResponse_200 {
   get additionalProperties(): Record<string, any> | undefined { return this._additionalProperties; }
   set additionalProperties(additionalProperties: Record<string, any> | undefined) { this._additionalProperties = additionalProperties; }
 
-  public marshal() : string {
-    let json = '{'
+  public toJson(): Record<string, unknown> {
+    const json: Record<string, unknown> = {};
     if(this.referenceId !== undefined) {
-      json += `"referenceId": ${typeof this.referenceId === 'number' || typeof this.referenceId === 'boolean' ? this.referenceId : JSON.stringify(this.referenceId)},`;
+      json["referenceId"] = this.referenceId;
     }
     if(this.connectUrl !== undefined) {
-      json += `"connectUrl": ${typeof this.connectUrl === 'number' || typeof this.connectUrl === 'boolean' ? this.connectUrl : JSON.stringify(this.connectUrl)},`;
+      json["connectUrl"] = this.connectUrl;
     }
-    if(this.additionalProperties !== undefined) { 
-      for (const [key, value] of this.additionalProperties.entries()) {
+    if(this.additionalProperties !== undefined) {
+      for (const [key, value] of Object.entries(this.additionalProperties)) {
         //Only unwrap those that are not already a property in the JSON object
         if(["referenceId","connectUrl","additionalProperties"].includes(String(key))) continue;
-        json += `"${key}": ${typeof value === 'number' || typeof value === 'boolean' ? value : JSON.stringify(value)},`;
+        json[key] = value;
       }
     }
-    //Remove potential last comma 
-    return `${json.charAt(json.length-1) === ',' ? json.slice(0, json.length-1) : json}}`;
+    return json;
   }
 
-  public static unmarshal(json: string | object): PostV2ConnectResponse_200 {
-    const obj = typeof json === "object" ? json : JSON.parse(json);
+  public marshal(): string {
+    return JSON.stringify(this.toJson());
+  }
+
+  public static fromJson(obj: Record<string, unknown>): PostV2ConnectResponse_200 {
     const instance = new PostV2ConnectResponse_200({} as any);
 
     if (obj["referenceId"] !== undefined) {
-      instance.referenceId = obj["referenceId"];
+      instance.referenceId = obj["referenceId"] as string;
     }
     if (obj["connectUrl"] !== undefined) {
-      instance.connectUrl = obj["connectUrl"];
+      instance.connectUrl = obj["connectUrl"] as string;
     }
-  
-    instance.additionalProperties = new Map();
+
+    instance.additionalProperties = {};
     const propsToCheck = Object.entries(obj).filter((([key,]) => {return !["referenceId","connectUrl","additionalProperties"].includes(key);}));
     for (const [key, value] of propsToCheck) {
-      instance.additionalProperties.set(key, value as any);
+      instance.additionalProperties[key] = value as any;
     }
     return instance;
   }
+
+  public static unmarshal(json: string | object): PostV2ConnectResponse_200 {
+    const obj = typeof json === "object" ? json : JSON.parse(json);
+    return PostV2ConnectResponse_200.fromJson(obj as Record<string, unknown>);
+  }
   public static theCodeGenSchema = {"type":"object","properties":{"referenceId":{"type":"string"},"connectUrl":{"type":"string","format":"uri"}},"$id":"postV2Connect_Response_200","$schema":"http://json-schema.org/draft-07/schema"};
   public static validate(context?: {data: any, ajvValidatorFunction?: ValidateFunction, ajvInstance?: Ajv, ajvOptions?: AjvOptions}): { valid: boolean; errors?: ErrorObject[]; } {
     const {data, ajvValidatorFunction} = context ?? {};
@@ -83,4 +91,4 @@ class PostV2ConnectResponse_200 {
   }
 
 }
-export { PostV2ConnectResponse_200 };
\ No newline at end of file
+export { PostV2ConnectResponse_200, PostV2ConnectResponse_200Interface };
\ No newline at end of file
diff --git a/examples/openapi-http-client/src/index.ts b/examples/openapi-http-client/src/index.ts
index 1de8caaf..21bf836d 100644
--- a/examples/openapi-http-client/src/index.ts
+++ b/examples/openapi-http-client/src/index.ts
@@ -51,7 +51,7 @@ async function main() {
   // reuses `server`/`auth` and returns an HttpClientResponse<T> whose `data` is
   // the unmarshalled, fully typed response model.
   const safepay = new SafepayApiV2SampleClient({
-    server,
+    baseUrl: server,
     auth: {type: 'bearer', token: process.env.SAFEPAY_TOKEN ?? ''}
   });
 
@@ -76,7 +76,26 @@ async function main() {
 
   // The standalone channel functions remain available for one-off calls where
   // constructing a client is unnecessary.
-  await http_client.postV2Connect({server, payload: connectBody});
+  await http_client.postV2Connect({baseUrl: server, payload: connectBody});
+
+  // Error handling: non-OK responses throw a typed `HttpError`. Because the
+  // OpenAPI document declares 400/404 responses, those codes get explicit cases
+  // with standard reason-phrase messages ('Bad Request', 'Not Found'); any
+  // undeclared code uses the generic `HTTP Error: <status> <statusText>` form.
+  try {
+    await safepay.getV2ConnectReferenceId({parameters: {referenceId: 'does-not-exist'}});
+  } catch (error) {
+    if (error instanceof http_client.HttpError) {
+      console.log('Request failed with HttpError:', {
+        status: error.status,
+        statusText: error.statusText,
+        message: error.message,
+        body: error.body
+      });
+    } else {
+      throw error;
+    }
+  }
 }
 
 main().catch((error) => {
diff --git a/src/codegen/generators/typescript/channels/openapi.ts b/src/codegen/generators/typescript/channels/openapi.ts
index cf8b6caa..f1d0abce 100644
--- a/src/codegen/generators/typescript/channels/openapi.ts
+++ b/src/codegen/generators/typescript/channels/openapi.ts
@@ -113,7 +113,11 @@ export async function generateTypeScriptChannelsForOpenAPI(
   // Generate common types once (stateless check)
   // Pass security schemes to generate only relevant auth types
   if (protocolCodeFunctions['http_client'].length === 0 && renders.length > 0) {
-    const commonTypesCode = renderHttpCommonTypes(securitySchemes);
+    const errorStatusCodes = collectErrorStatusCodes(openapiDocument);
+    const commonTypesCode = renderHttpCommonTypes({
+      securitySchemes,
+      errorStatusCodes
+    });
     protocolCodeFunctions['http_client'].unshift(commonTypesCode);
   }
 
@@ -130,6 +134,58 @@ export async function generateTypeScriptChannelsForOpenAPI(
   });
 }
 
+/**
+ * Collect the error status codes declared across every operation in the
+ * document. Numeric response keys >= 400 and the literal 'default' are gathered
+ * and deduped; 2xx/3xx keys are ignored. These drive the explicit cases in the
+ * shared, document-wide `handleHttpError`. Handles OpenAPI 2.0/3.0/3.1
+ * uniformly (response keys are strings in all three).
+ */
+function collectResponseErrorCodes(
+  responses: Record<string, unknown> | undefined,
+  codes: Set<number | 'default'>
+): void {
+  if (!responses) {
+    return;
+  }
+
+  for (const statusCode of Object.keys(responses)) {
+    if (statusCode === 'default') {
+      codes.add('default');
+      continue;
+    }
+    const numericCode = Number(statusCode);
+    if (Number.isInteger(numericCode) && numericCode >= 400) {
+      codes.add(numericCode);
+    }
+  }
+}
+
+function collectErrorStatusCodes(
+  openapiDocument: OpenAPIDocument
+): (number | 'default')[] {
+  const codes = new Set<number | 'default'>();
+
+  for (const pathItem of Object.values(openapiDocument.paths ?? {})) {
+    if (!pathItem) {
+      continue;
+    }
+
+    for (const method of HTTP_METHODS) {
+      // eslint-disable-next-line security/detect-object-injection
+      const operation = (pathItem as Record<string, unknown>)[method] as
+        | OpenAPIOperation
+        | undefined;
+      collectResponseErrorCodes(
+        operation?.responses as Record<string, unknown> | undefined,
+        codes
+      );
+    }
+  }
+
+  return [...codes];
+}
+
 /**
  * Process all OpenAPI operations and generate HTTP client functions.
  */
diff --git a/src/codegen/generators/typescript/channels/protocols/http/client.ts b/src/codegen/generators/typescript/channels/protocols/http/client.ts
index 8a5a02ed..457c4767 100644
--- a/src/codegen/generators/typescript/channels/protocols/http/client.ts
+++ b/src/codegen/generators/typescript/channels/protocols/http/client.ts
@@ -367,7 +367,8 @@ ${parameterNormalization}${oauth2ValidateBlock}  // Build headers
 ${oauth2TokenBlock}
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
diff --git a/src/codegen/generators/typescript/channels/protocols/http/common-types.ts b/src/codegen/generators/typescript/channels/protocols/http/common-types.ts
index 8dedf8bd..c52b1acd 100644
--- a/src/codegen/generators/typescript/channels/protocols/http/common-types.ts
+++ b/src/codegen/generators/typescript/channels/protocols/http/common-types.ts
@@ -12,6 +12,94 @@ import {
   renderSecurityTypes
 } from './security';
 
+/**
+ * Standard HTTP reason phrases used to bake a message into each generated
+ * `handleHttpError` case. Keyed by status code; deterministic and
+ * collision-free across operations that declare the same code.
+ */
+const HTTP_REASON_PHRASES: Record<number, string> = {
+  400: 'Bad Request',
+  401: 'Unauthorized',
+  402: 'Payment Required',
+  403: 'Forbidden',
+  404: 'Not Found',
+  405: 'Method Not Allowed',
+  406: 'Not Acceptable',
+  407: 'Proxy Authentication Required',
+  408: 'Request Timeout',
+  409: 'Conflict',
+  410: 'Gone',
+  411: 'Length Required',
+  412: 'Precondition Failed',
+  413: 'Payload Too Large',
+  414: 'URI Too Long',
+  415: 'Unsupported Media Type',
+  416: 'Range Not Satisfiable',
+  417: 'Expectation Failed',
+  418: "I'm a Teapot",
+  421: 'Misdirected Request',
+  422: 'Unprocessable Entity',
+  423: 'Locked',
+  424: 'Failed Dependency',
+  425: 'Too Early',
+  426: 'Upgrade Required',
+  428: 'Precondition Required',
+  429: 'Too Many Requests',
+  431: 'Request Header Fields Too Large',
+  451: 'Unavailable For Legal Reasons',
+  500: 'Internal Server Error',
+  501: 'Not Implemented',
+  502: 'Bad Gateway',
+  503: 'Service Unavailable',
+  504: 'Gateway Timeout',
+  505: 'HTTP Version Not Supported',
+  506: 'Variant Also Negotiates',
+  507: 'Insufficient Storage',
+  508: 'Loop Detected',
+  510: 'Not Extended',
+  511: 'Network Authentication Required'
+};
+
+/**
+ * Build the body of the generated `handleHttpError` function from the set of
+ * error status codes the input document declares. Numeric codes become explicit
+ * `case` statements throwing an `HttpError` with the standard reason phrase; a
+ * `default` case throws the generic `HTTP Error: <status> <statusText>` form.
+ * When no numeric codes are declared (e.g. the AsyncAPI path) only the default
+ * throw is emitted.
+ */
+function renderHandleHttpErrorBody(
+  errorStatusCodes: (number | 'default')[]
+): string {
+  const defaultThrow =
+    'throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);';
+
+  const numericCodes = errorStatusCodes
+    .filter((code): code is number => typeof code === 'number')
+    .filter((code, index, all) => all.indexOf(code) === index)
+    .sort((first, second) => first - second);
+
+  if (numericCodes.length === 0) {
+    return `  ${defaultThrow}`;
+  }
+
+  const cases = numericCodes
+    .map((code) => {
+      // eslint-disable-next-line security/detect-object-injection
+      const phrase = HTTP_REASON_PHRASES[code] ?? `HTTP Error: ${code}`;
+      return `    case ${code}:\n      throw new HttpError(${JSON.stringify(
+        phrase
+      )}, status, statusText, body);`;
+    })
+    .join('\n');
+
+  return `  switch (status) {
+${cases}
+    default:
+      ${defaultThrow}
+  }`;
+}
+
 /**
  * Generates common types and helper functions shared across all HTTP client functions.
  * This should be called once per protocol generation to avoid code duplication.
@@ -19,10 +107,17 @@ import {
  * @param securitySchemes - Optional security schemes extracted from OpenAPI.
  *                          When provided, only relevant auth types are generated.
  *                          When undefined/empty, all auth types are generated for backward compatibility.
+ * @param errorStatusCodes - Error status codes declared by the input document.
+ *                          Each numeric code becomes an explicit `handleHttpError`
+ *                          case; when empty only the default handler is emitted.
  */
-export function renderHttpCommonTypes(
-  securitySchemes?: SecuritySchemeOptions[]
-): string {
+export function renderHttpCommonTypes({
+  securitySchemes,
+  errorStatusCodes = []
+}: {
+  securitySchemes?: SecuritySchemeOptions[];
+  errorStatusCodes?: (number | 'default')[];
+} = {}): string {
   const requirements = analyzeSecuritySchemes(securitySchemes);
   const securityTypes = renderSecurityTypes(securitySchemes, requirements);
   const applyAuthCases = renderApplyAuthCases(requirements);
@@ -86,6 +181,27 @@ export interface HttpClientResponse<T> {
   rawData: Record<string, any>;
 }
 
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP \`status\`, \`statusText\`, and the parsed response \`body\`
+ * (when the error response had a JSON body). Thrown by \`handleHttpError\` and
+ * routed through the \`onError\` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
+}
+
 /**
  * HTTP request parameters passed to the request hook
  */
@@ -342,21 +458,12 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
-  switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
-    case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
-    default:
-      throw new Error(\`HTTP Error: \${status} \${statusText}\`);
-  }
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
+${renderHandleHttpErrorBody(errorStatusCodes)}
 }
 
 /**
diff --git a/test/codegen/generators/typescript/__snapshots__/channels.spec.ts.snap b/test/codegen/generators/typescript/__snapshots__/channels.spec.ts.snap
index 99e26dd5..3f0096a5 100644
--- a/test/codegen/generators/typescript/__snapshots__/channels.spec.ts.snap
+++ b/test/codegen/generators/typescript/__snapshots__/channels.spec.ts.snap
@@ -44,6 +44,27 @@ export interface HttpClientResponse<T> {
   rawData: Record<string, any>;
 }
 
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP \`status\`, \`statusText\`, and the parsed response \`body\`
+ * (when the error response had a JSON body). Thrown by \`handleHttpError\` and
+ * routed through the \`onError\` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
+}
+
 /**
  * HTTP request parameters passed to the request hook
  */
@@ -392,20 +413,20 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
   switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
+    case 400:
+      throw new HttpError("Bad Request", status, statusText, body);
     case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
+      throw new HttpError("Not Found", status, statusText, body);
+    case 405:
+      throw new HttpError("Method Not Allowed", status, statusText, body);
     default:
-      throw new Error(\`HTTP Error: \${status} \${statusText}\`);
+      throw new HttpError(\`HTTP Error: \${status} \${statusText}\`, status, statusText, body);
   }
 }
 
@@ -703,7 +724,8 @@ async function addPet(context: AddPetContext): Promise<HttpClientResponse<Pet>>
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -814,7 +836,8 @@ async function updatePet(context: UpdatePetContext): Promise<HttpClientResponse<
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -927,7 +950,8 @@ async function findPetsByStatusAndCategory(context: FindPetsByStatusAndCategoryC
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1580,6 +1604,27 @@ export interface HttpClientResponse<T> {
   rawData: Record<string, any>;
 }
 
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP \`status\`, \`statusText\`, and the parsed response \`body\`
+ * (when the error response had a JSON body). Thrown by \`handleHttpError\` and
+ * routed through the \`onError\` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
+}
+
 /**
  * HTTP request parameters passed to the request hook
  */
@@ -1954,21 +1999,12 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
-  switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
-    case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
-    default:
-      throw new Error(\`HTTP Error: \${status} \${statusText}\`);
-  }
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
+  throw new HttpError(\`HTTP Error: \${status} \${statusText}\`, status, statusText, body);
 }
 
 /**
@@ -2262,7 +2298,8 @@ async function getPingRequest(context: GetPingRequestContext = {}): Promise<Http
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
diff --git a/test/codegen/generators/typescript/channels.spec.ts b/test/codegen/generators/typescript/channels.spec.ts
index e1f2f0da..b690b94d 100644
--- a/test/codegen/generators/typescript/channels.spec.ts
+++ b/test/codegen/generators/typescript/channels.spec.ts
@@ -511,6 +511,16 @@ describe('channels', () => {
         expect(generatedChannels.files.length).toBeGreaterThan(0);
         expect(generatedChannels.result).toMatchSnapshot('http_client-index');
         expect(generatedChannels.protocolFiles['http_client']).toMatchSnapshot('http_client-protocol-code');
+
+        // AsyncAPI declares no error responses, so handleHttpError is
+        // default-only (no explicit numeric cases / switch), but the typed
+        // HttpError class is still exported.
+        const httpProtocolCode = generatedChannels.protocolFiles['http_client'];
+        expect(httpProtocolCode).toContain('export class HttpError extends Error');
+        expect(httpProtocolCode).toContain(
+          'function handleHttpError(status: number, statusText: string, body?: unknown): never {\n  throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);\n}'
+        );
+        expect(httpProtocolCode).not.toMatch(/case \d+:/);
       });
     });
 
@@ -791,6 +801,29 @@ describe('channels', () => {
         expect(httpProtocolCode).toContain('unmarshal(JSON.stringify(rawData))');
         expect(httpProtocolCode).not.toMatch(/unmarshal\(rawData\)/);
 
+        // Error handling is input-driven: openapi-3.json declares 400/404/405
+        // across its operations, so handleHttpError emits an explicit case per
+        // code (aggregated document-wide) throwing a typed HttpError with the
+        // standard reason phrase. The typed HttpError class is always exported.
+        expect(httpProtocolCode).toContain('export class HttpError extends Error');
+        expect(httpProtocolCode).toContain(
+          'case 400:\n      throw new HttpError("Bad Request", status, statusText, body);'
+        );
+        expect(httpProtocolCode).toContain(
+          'case 404:\n      throw new HttpError("Not Found", status, statusText, body);'
+        );
+        expect(httpProtocolCode).toContain(
+          'case 405:\n      throw new HttpError("Method Not Allowed", status, statusText, body);'
+        );
+        // Undeclared codes fall through to the generic default handler.
+        expect(httpProtocolCode).toContain(
+          'throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);'
+        );
+        // The per-operation error branch parses and forwards the error body.
+        expect(httpProtocolCode).toContain(
+          'const errorBody = await response.json().catch(() => undefined);'
+        );
+
         // Operations with path parameters must expose their parameter model name via
         // parameterType so downstream consumers (e.g. README generation) know the
         // operation requires a `parameters` argument. Operations without parameters
diff --git a/test/codegen/generators/typescript/channels/protocols/http/fetch-security.spec.ts b/test/codegen/generators/typescript/channels/protocols/http/fetch-security.spec.ts
index b3d7778e..5c19c5d8 100644
--- a/test/codegen/generators/typescript/channels/protocols/http/fetch-security.spec.ts
+++ b/test/codegen/generators/typescript/channels/protocols/http/fetch-security.spec.ts
@@ -16,7 +16,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       // Should include ApiKeyAuth interface
       expect(result).toContain('export interface ApiKeyAuth');
@@ -44,7 +44,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       expect(result).toContain('export interface BearerAuth');
       expect(result).toContain("type: 'bearer'");
@@ -63,7 +63,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       expect(result).toContain('export interface BasicAuth');
       expect(result).toContain("type: 'basic'");
@@ -87,7 +87,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       expect(result).toContain('export interface OAuth2Auth');
       expect(result).toContain("type: 'oauth2'");
@@ -116,7 +116,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       expect(result).toContain('export interface ApiKeyAuth');
       expect(result).toContain('export interface BearerAuth');
@@ -142,7 +142,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
     });
 
     it('should generate all auth types when empty security schemes array provided', () => {
-      const result = renderHttpCommonTypes([]);
+      const result = renderHttpCommonTypes({securitySchemes: []});
 
       expect(result).toContain('export interface BearerAuth');
       expect(result).toContain('export interface BasicAuth');
@@ -160,7 +160,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       // The generated interface should have name and in pre-set
       expect(result).toContain('X-Petstore-Key');
@@ -181,7 +181,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       expect(result).toContain('export interface OAuth2Auth');
       expect(result).toContain('https://example.com/authorize');
@@ -197,7 +197,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       // OpenID Connect should be treated similar to OAuth2
       expect(result).toContain('export interface OAuth2Auth');
@@ -210,9 +210,9 @@ describe('HTTP Fetch Generator - Security Types', () => {
       // A bearer-only spec narrows AuthConfig to BearerAuth. The generated
       // helpers must not reference the other auth types, otherwise the output
       // fails to type-check (fields/discriminants that no longer exist).
-      const result = renderHttpCommonTypes([
+      const result = renderHttpCommonTypes({securitySchemes: [
         {name: 'bearerAuth', type: 'http', httpScheme: 'bearer'}
-      ]);
+      ]});
 
       expect(result).toContain("case 'bearer':");
       expect(result).not.toContain("case 'basic'");
@@ -255,7 +255,7 @@ describe('HTTP Fetch Generator - Security Types', () => {
         }
       ];
 
-      const result = renderHttpCommonTypes(securitySchemes);
+      const result = renderHttpCommonTypes({securitySchemes});
 
       // Should only have one ApiKeyAuth interface
       const apiKeyInterfaceMatches = result.match(
diff --git a/test/runtime/typescript/src/openapi/channels/http_client.ts b/test/runtime/typescript/src/openapi/channels/http_client.ts
index b356f6c5..5a2dc4ed 100644
--- a/test/runtime/typescript/src/openapi/channels/http_client.ts
+++ b/test/runtime/typescript/src/openapi/channels/http_client.ts
@@ -41,6 +41,27 @@ export interface HttpClientResponse<T> {
   rawData: Record<string, any>;
 }
 
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP `status`, `statusText`, and the parsed response `body`
+ * (when the error response had a JSON body). Thrown by `handleHttpError` and
+ * routed through the `onError` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
+}
+
 /**
  * HTTP request parameters passed to the request hook
  */
@@ -389,20 +410,20 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
   switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
+    case 400:
+      throw new HttpError("Bad Request", status, statusText, body);
     case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
+      throw new HttpError("Not Found", status, statusText, body);
+    case 405:
+      throw new HttpError("Method Not Allowed", status, statusText, body);
     default:
-      throw new Error(`HTTP Error: ${status} ${statusText}`);
+      throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);
   }
 }
 
@@ -700,7 +721,8 @@ async function addPet(context: AddPetContext): Promise<HttpClientResponse<APet>>
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -811,7 +833,8 @@ async function updatePet(context: UpdatePetContext): Promise<HttpClientResponse<
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -924,7 +947,8 @@ async function findPetsByStatusAndCategory(context: FindPetsByStatusAndCategoryC
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
diff --git a/test/runtime/typescript/src/request-reply/channels/http_client.ts b/test/runtime/typescript/src/request-reply/channels/http_client.ts
index 17b02755..10189682 100644
--- a/test/runtime/typescript/src/request-reply/channels/http_client.ts
+++ b/test/runtime/typescript/src/request-reply/channels/http_client.ts
@@ -42,6 +42,27 @@ export interface HttpClientResponse<T> {
   rawData: Record<string, any>;
 }
 
+/**
+ * Error thrown for non-OK HTTP responses.
+ *
+ * Carries the HTTP `status`, `statusText`, and the parsed response `body`
+ * (when the error response had a JSON body). Thrown by `handleHttpError` and
+ * routed through the `onError` hook / retry logic unchanged.
+ */
+export class HttpError extends Error {
+  status: number;
+  statusText: string;
+  body?: unknown;
+
+  constructor(message: string, status: number, statusText: string, body?: unknown) {
+    super(message);
+    this.name = 'HttpError';
+    this.status = status;
+    this.statusText = statusText;
+    this.body = body;
+  }
+}
+
 /**
  * HTTP request parameters passed to the request hook
  */
@@ -416,21 +437,12 @@ async function executeWithRetry(
 }
 
 /**
- * Handle HTTP error status codes with standardized messages
+ * Handle HTTP error status codes by throwing a typed HttpError.
+ * Explicit cases are generated from the error status codes declared by the
+ * input document; undeclared codes fall through to the default handler.
  */
-function handleHttpError(status: number, statusText: string): never {
-  switch (status) {
-    case 401:
-      throw new Error('Unauthorized');
-    case 403:
-      throw new Error('Forbidden');
-    case 404:
-      throw new Error('Not Found');
-    case 500:
-      throw new Error('Internal Server Error');
-    default:
-      throw new Error(`HTTP Error: ${status} ${statusText}`);
-  }
+function handleHttpError(status: number, statusText: string, body?: unknown): never {
+  throw new HttpError(`HTTP Error: ${status} ${statusText}`, status, statusText, body);
 }
 
 /**
@@ -727,7 +739,8 @@ async function postPingPostRequest(context: PostPingPostRequestContext): Promise
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -835,7 +848,8 @@ async function getPingGetRequest(context: GetPingGetRequestContext = {}): Promis
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -946,7 +960,8 @@ async function putPingPutRequest(context: PutPingPutRequestContext): Promise<Htt
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1054,7 +1069,8 @@ async function deletePingDeleteRequest(context: DeletePingDeleteRequestContext =
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1165,7 +1181,8 @@ async function patchPingPatchRequest(context: PatchPingPatchRequestContext): Pro
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1273,7 +1290,8 @@ async function headPingHeadRequest(context: HeadPingHeadRequestContext = {}): Pr
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1381,7 +1399,8 @@ async function optionsPingOptionsRequest(context: OptionsPingOptionsRequestConte
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1489,7 +1508,8 @@ async function getMultiStatusResponse(context: GetMultiStatusResponseContext = {
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1604,7 +1624,8 @@ async function getGetUserItem(context: GetGetUserItemContext): Promise<HttpClien
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
@@ -1721,7 +1742,8 @@ async function putUpdateUserItem(context: PutUpdateUserItemContext): Promise<Htt
 
     // Handle error responses
     if (!response.ok) {
-      handleHttpError(response.status, response.statusText);
+      const errorBody = await response.json().catch(() => undefined);
+      handleHttpError(response.status, response.statusText, errorBody);
     }
 
     // Parse response
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/api_auth.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/api_auth.spec.ts
index 97a8143c..194fb18d 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/api_auth.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/api_auth.spec.ts
@@ -186,7 +186,7 @@ describe('HTTP Client - API Key and Basic Authentication', () => {
           });
           throw new Error('Expected request to fail with 401 status');
         } catch (error) {
-          expect(error.message).toBe('Unauthorized');
+          expect(error.message).toBe('HTTP Error: 401 Unauthorized');
         }
       });
     });
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/hooks.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/hooks.spec.ts
index 3864aad5..cffc0671 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/hooks.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/hooks.spec.ts
@@ -251,7 +251,9 @@ describe('HTTP Client - Hooks', () => {
         }
 
         expect(onErrorCalled).toBe(true);
-        expect(capturedError?.message).toBe('Not Found');
+        // AsyncAPI-generated client declares no error responses, so the
+        // default-only handleHttpError uses the generic message form.
+        expect(capturedError?.message).toBe('HTTP Error: 404 Not Found');
       });
     });
 
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/methods.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/methods.spec.ts
index 9a061a9a..6fc26250 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/methods.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/methods.spec.ts
@@ -10,6 +10,7 @@ import {
   patchPingPatchRequest,
   headPingHeadRequest,
   optionsPingOptionsRequest,
+  HttpError,
 } from '../../../../src/request-reply/channels/http_client';
 
 jest.setTimeout(15000);
@@ -319,6 +320,10 @@ describe('HTTP Client - HTTP Methods', () => {
   });
 
   describe('error handling across methods', () => {
+    // The request-reply client is AsyncAPI-generated, which declares no error
+    // responses, so handleHttpError is default-only: every error throws a typed
+    // HttpError carrying status/statusText/body, with the default message form
+    // `HTTP Error: <status> <statusText>`.
     it('should handle 404 for PUT', async () => {
       const { app, router, port } = createTestServer();
 
@@ -329,10 +334,16 @@ describe('HTTP Client - HTTP Methods', () => {
       });
 
       return runWithServer(app, port, async (_server, actualPort) => {
-        await expect(putPingPutRequest({
+        const error = await putPingPutRequest({
           baseUrl: `http://localhost:${actualPort}`,
           payload: requestMessage
-        })).rejects.toThrow('Not Found');
+        }).catch((e) => e);
+
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(404);
+        expect(error.statusText).toBeDefined();
+        expect(error.body).toEqual({ error: 'Not Found' });
+        expect(error.message).toBe('HTTP Error: 404 Not Found');
       });
     });
 
@@ -344,9 +355,15 @@ describe('HTTP Client - HTTP Methods', () => {
       });
 
       return runWithServer(app, port, async (_server, actualPort) => {
-        await expect(deletePingDeleteRequest({
+        const error = await deletePingDeleteRequest({
           baseUrl: `http://localhost:${actualPort}`
-        })).rejects.toThrow('Internal Server Error');
+        }).catch((e) => e);
+
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(500);
+        expect(error.statusText).toBeDefined();
+        expect(error.body).toEqual({ error: 'Internal Server Error' });
+        expect(error.message).toBe('HTTP Error: 500 Internal Server Error');
       });
     });
 
@@ -360,10 +377,16 @@ describe('HTTP Client - HTTP Methods', () => {
       });
 
       return runWithServer(app, port, async (_server, actualPort) => {
-        await expect(patchPingPatchRequest({
+        const error = await patchPingPatchRequest({
           baseUrl: `http://localhost:${actualPort}`,
           payload: requestMessage
-        })).rejects.toThrow('Forbidden');
+        }).catch((e) => e);
+
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(403);
+        expect(error.statusText).toBeDefined();
+        expect(error.body).toEqual({ error: 'Forbidden' });
+        expect(error.message).toBe('HTTP Error: 403 Forbidden');
       });
     });
   });
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_implicit_flow.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_implicit_flow.spec.ts
index 287cbe16..1f587fac 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_implicit_flow.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_implicit_flow.spec.ts
@@ -202,7 +202,7 @@ describe('HTTP Client - OAuth2 Pre-obtained Access Token', () => {
           });
           throw new Error('Expected to fail');
         } catch (error) {
-          expect(error.message).toBe('Unauthorized');
+          expect(error.message).toBe('HTTP Error: 401 Unauthorized');
         }
       });
     });
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_refresh_token.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_refresh_token.spec.ts
index ee2b9183..f0259961 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_refresh_token.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/oauth2_refresh_token.spec.ts
@@ -153,7 +153,9 @@ describe('HTTP Client - OAuth2 Refresh Token Flow', () => {
           });
           throw new Error('Expected request to fail with 401 status');
         } catch (error) {
-          // Request should fail with the original 401 error since refresh failed
+          // Refresh was attempted (all credentials present) but failed, so the
+          // OAuth2 refresh branch throws its own 'Unauthorized' error before
+          // handleHttpError is reached.
           expect(error.message).toBe('Unauthorized');
         }
       });
@@ -188,7 +190,7 @@ describe('HTTP Client - OAuth2 Refresh Token Flow', () => {
         } catch (error) {
           // The request should fail with the original 401 error
           // since refresh can't be performed without clientId
-          expect(error.message).toBe('Unauthorized');
+          expect(error.message).toBe('HTTP Error: 401 Unauthorized');
         }
       });
     });
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/openapi.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/openapi.spec.ts
index 2316c9d3..4e6fa404 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/openapi.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/openapi.spec.ts
@@ -4,6 +4,7 @@ import {
   addPet,
   updatePet,
   findPetsByStatusAndCategory,
+  HttpError,
 } from '../../../../src/openapi/channels/http_client';
 import { APet } from '../../../../src/openapi/payloads/APet';
 import { FindPetsByStatusAndCategoryParameters } from '../../../../src/openapi/parameters/FindPetsByStatusAndCategoryParameters';
@@ -101,27 +102,37 @@ describe('HTTP Client - OpenAPI Generated', () => {
   });
 
   describe('error handling', () => {
-    it('should throw error for 400 response', async () => {
+    // The OpenAPI client is input-driven: error status codes declared anywhere
+    // in openapi-3.json (400, 404, 405) become explicit cases in the shared
+    // handleHttpError, each throwing a typed HttpError whose message is the
+    // standard HTTP reason phrase for that code.
+    it('should throw a typed HttpError with the reason phrase for a declared 400', async () => {
       const { app, router, port } = createTestServer();
 
       router.post('/pet', (req, res) => {
-        res.status(400).json({ error: 'Bad Request' });
+        res.status(400).json({ error: 'invalid pet' });
       });
 
       return runWithServer(app, port, async (_server, actualPort) => {
         const pet = new APet({ name: 'Test', photoUrls: [] });
-        await expect(addPet({
+        const error = await addPet({
           payload: pet,
           baseUrl: `http://localhost:${actualPort}`
-        })).rejects.toThrow();
+        }).catch((e) => e);
+
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(400);
+        // 400 is declared in the input -> explicit case with reason phrase
+        expect(error.message).toBe('Bad Request');
+        expect(error.body).toEqual({ error: 'invalid pet' });
       });
     });
 
-    it('should throw error for 404 response', async () => {
+    it('should throw a typed HttpError with the reason phrase for a declared 404', async () => {
       const { app, router, port } = createTestServer();
 
       router.get('/pet/findByStatus/:status/:categoryId', (req, res) => {
-        res.status(404).json({ error: 'Not Found' });
+        res.status(404).json({ error: 'no pets' });
       });
 
       return runWithServer(app, port, async (_server, actualPort) => {
@@ -130,10 +141,16 @@ describe('HTTP Client - OpenAPI Generated', () => {
           categoryId: 999
         });
 
-        await expect(findPetsByStatusAndCategory({
+        const error = await findPetsByStatusAndCategory({
           parameters: params,
           baseUrl: `http://localhost:${actualPort}`
-        })).rejects.toThrow('Not Found');
+        }).catch((e) => e);
+
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(404);
+        // 404 is declared in the input -> explicit case with reason phrase
+        expect(error.message).toBe('Not Found');
+        expect(error.body).toEqual({ error: 'no pets' });
       });
     });
   });
diff --git a/test/runtime/typescript/test/channels/request_reply/http_client/retry.spec.ts b/test/runtime/typescript/test/channels/request_reply/http_client/retry.spec.ts
index 083d0c8b..b6974e74 100644
--- a/test/runtime/typescript/test/channels/request_reply/http_client/retry.spec.ts
+++ b/test/runtime/typescript/test/channels/request_reply/http_client/retry.spec.ts
@@ -4,6 +4,7 @@ import { createTestServer, runWithServer } from './test-utils';
 import {
   getPingGetRequest,
   RetryConfig,
+  HttpError,
 } from '../../../../src/request-reply/channels/http_client';
 
 jest.setTimeout(15000);
@@ -142,11 +143,13 @@ describe('HTTP Client - Retry Logic', () => {
           retryableStatusCodes: [500]
         };
 
-        await expect(getPingGetRequest({
+        const error = await getPingGetRequest({
           baseUrl: `http://localhost:${actualPort}`,
           retry
-        })).rejects.toThrow('Internal Server Error');
+        }).catch((e) => e);
 
+        expect(error).toBeInstanceOf(HttpError);
+        expect(error.status).toBe(500);
         expect(requestCount).toBe(3);
       });
     });