diff --git a/VEZA_INTEGRATION_PERFECTION_TODOLIST_TEMPLATE.json b/VEZA_INTEGRATION_PERFECTION_TODOLIST_TEMPLATE.json
index 289f8c12f..2b262e634 100644
--- a/VEZA_INTEGRATION_PERFECTION_TODOLIST_TEMPLATE.json
+++ b/VEZA_INTEGRATION_PERFECTION_TODOLIST_TEMPLATE.json
@@ -355,7 +355,8 @@
       "description": "L'interface ApiError frontend est incomplète par rapport aux erreurs retournées par le backend.",
       "priority": "P1",
       "priority_rank": 9,
-      "status": "todo",
+      "status": "completed",
+      "completed_at": "2025-01-27T13:45:00Z",
       "estimated_hours": 1.5,
       "side": "frontend_only",
       "files_to_modify": [
@@ -1090,13 +1091,13 @@
   },
   "progress_tracking": {
     "total_tasks": 32,
-    "completed": 8,
+    "completed": 9,
     "in_progress": 0,
-    "todo": 24,
+    "todo": 23,
     "blocked": 0,
-    "completion_percentage": 25,
-    "last_updated": "2025-01-27T13:30:00Z",
+    "completion_percentage": 28,
+    "last_updated": "2025-01-27T13:45:00Z",
     "estimated_completion_date": null,
-    "estimated_hours_remaining": 36
+    "estimated_hours_remaining": 34.5
   }
 }
diff --git a/apps/web/src/schemas/apiSchemas.ts b/apps/web/src/schemas/apiSchemas.ts
index d0f0b7cc1..857ea7877 100644
--- a/apps/web/src/schemas/apiSchemas.ts
+++ b/apps/web/src/schemas/apiSchemas.ts
@@ -182,18 +182,22 @@ export type AuditLog = z.infer<typeof auditLogSchema>;
 
 /**
  * ApiError schema
+ * INT-TYPE-006: Aligned with backend error format (handlers/error_response.go)
+ * Backend ErrorDetail: { field, message }
  */
 export const apiErrorSchema = z.object({
-  code: z.number().int(),
+  code: z.number().int(), // ErrorCode (1000-9999) or HTTP status code
   message: z.string(),
+  // INT-TYPE-006: details matches backend ErrorDetail[] structure
   details: z.array(z.object({
-    field: z.string(),
-    message: z.string(),
+    field: z.string(), // Field name from ErrorDetail.Field
+    message: z.string(), // Error message from ErrorDetail.Message
+    value: z.string().optional(), // Optional value that failed validation
   })).optional(),
-  request_id: z.string().optional(),
-  timestamp: isoDateSchema,
-  context: z.record(z.any()).optional(),
-  retry_after: z.number().int().positive().optional(),
+  request_id: z.string().optional(), // Request ID for tracking
+  timestamp: isoDateSchema, // ISO8601 timestamp
+  context: z.record(z.any()).optional(), // Additional context (user_id, etc.)
+  retry_after: z.number().int().positive().optional(), // Seconds before retry (for 429)
 });
 
 export type ApiError = z.infer<typeof apiErrorSchema>;
diff --git a/apps/web/src/types/api.ts b/apps/web/src/types/api.ts
index a9f6666e0..e5994c546 100644
--- a/apps/web/src/types/api.ts
+++ b/apps/web/src/types/api.ts
@@ -251,18 +251,20 @@ export interface ApiResponse<T> {
 }
 
 // Types pour les erreurs API
-// Aligné avec FRONTEND_INTEGRATION.md
+// INT-TYPE-006: ApiError interface aligned with backend error format (handlers/error_response.go)
+// Backend format: { error: { code, message, details, request_id, timestamp, context } }
 export interface ApiError {
   code: number; // Code numérique (1000, 2000, etc.) ou code HTTP (429, 503, 502)
   message: string;
+  // INT-TYPE-006: details array matches backend ErrorDetail[] structure
   details?: Array<{
-    field: string;
-    message: string;
-    value?: string; // FE-TYPE-005: Added to match backend ValidationError DTO
+    field: string; // Field name (from ErrorDetail.Field)
+    message: string; // Error message (from ErrorDetail.Message)
+    value?: string; // Optional value that failed validation
   }>;
-  request_id?: string;
-  timestamp: string;
-  context?: Record<string, any>;
+  request_id?: string; // Request ID for tracking (from X-Request-ID header)
+  timestamp: string; // ISO8601 timestamp
+  context?: Record<string, any>; // Additional context (user_id, etc.)
   retry_after?: number; // Nombre de secondes avant de pouvoir réessayer (pour 429)
 }
 
diff --git a/apps/web/src/types/index.ts b/apps/web/src/types/index.ts
index bcb2bd16e..759ed2954 100644
--- a/apps/web/src/types/index.ts
+++ b/apps/web/src/types/index.ts
@@ -97,10 +97,20 @@ export interface LibraryItem {
   is_favorite: boolean;
 }
 
+// INT-TYPE-006: ApiError interface aligned with backend error format
+// Backend format: { error: { code, message, details, request_id, timestamp, context } }
 export interface ApiError {
+  code: number; // Code numérique (1000, 2000, etc.) ou code HTTP (429, 503, 502)
   message: string;
-  code?: string;
-  details?: Record<string, unknown>;
+  details?: Array<{
+    field: string;
+    message: string;
+    value?: string; // Optional value that failed validation
+  }>;
+  request_id?: string;
+  timestamp: string;
+  context?: Record<string, any>; // Additional context (user_id, etc.)
+  retry_after?: number; // Nombre de secondes avant de pouvoir réessayer (pour 429)
 }
 
 export interface PaginatedResponse<T> {