diff --git a/src/products/dto/product-ai.dto.ts b/src/products/dto/product-ai.dto.ts
index c3981d1..97cc6da 100644
--- a/src/products/dto/product-ai.dto.ts
+++ b/src/products/dto/product-ai.dto.ts
@@ -1,10 +1,15 @@
-import { IsEnum, IsString, MinLength } from 'class-validator';
+import { IsEnum, IsOptional, IsString, MinLength } from 'class-validator';
 
 export enum ProductAiLanguage {
   en = 'en',
   fa = 'fa',
 }
 
+export enum ProductAiFillField {
+  summary = 'summary',
+  description = 'description',
+}
+
 export class CreateProductByAiDto {
   @IsString()
   @MinLength(1)
@@ -17,3 +22,25 @@ export class CreateProductByAiDto {
   @IsEnum(ProductAiLanguage)
   language!: ProductAiLanguage;
 }
+
+export class FillProductFieldByAiDto {
+  @IsEnum(ProductAiFillField)
+  field!: ProductAiFillField;
+
+  /** Editable user prompt shown in the dashboard modal. */
+  @IsString()
+  @MinLength(10)
+  prompt!: string;
+
+  @IsOptional()
+  @IsString()
+  title?: string;
+
+  @IsOptional()
+  @IsString()
+  nameFa?: string;
+
+  @IsOptional()
+  @IsString()
+  categoryId?: string;
+}
diff --git a/src/products/product-ai.service.ts b/src/products/product-ai.service.ts
index a62cdc0..3e5e8ca 100644
--- a/src/products/product-ai.service.ts
+++ b/src/products/product-ai.service.ts
@@ -7,7 +7,7 @@ import { ContentStatus, TechnicalFieldType } from '@prisma/client';
 import { AuthUser } from '../auth/auth.types';
 import { CategoryTechnicalFormService } from '../categories/category-technical-form.service';
 import { PrismaService } from '../prisma/prisma.service';
-import { CreateProductByAiDto, ProductAiLanguage } from './dto/product-ai.dto';
+import { CreateProductByAiDto, FillProductFieldByAiDto, ProductAiFillField, ProductAiLanguage } from './dto/product-ai.dto';
 import { ProductTechnicalInfoService } from './product-technical-info.service';
 import { ProductsService } from './products.service';
 import {
@@ -112,6 +112,91 @@ export class ProductAiService {
     };
   }
 
+  async fillField(
+    businessIdRaw: string,
+    dto: FillProductFieldByAiDto,
+    _actor: AuthUser,
+  ) {
+    const businessId = BigInt(businessIdRaw);
+
+    const title = dto.title?.trim() ?? '';
+    const nameFa = dto.nameFa?.trim() ?? '';
+    if (!title && !nameFa) {
+      throw new BadRequestException('Enter a product name before using AI fill');
+    }
+
+    let categoryName = '';
+    if (dto.categoryId?.trim()) {
+      const category = await this.prisma.category.findFirst({
+        where: {
+          id: BigInt(dto.categoryId),
+          businessId,
+          isActive: true,
+        },
+        select: { name: true, nameFa: true },
+      });
+      if (category) {
+        categoryName = category.nameFa?.trim() || category.name;
+      }
+    }
+
+    const provider = resolveAiProvider(this.config);
+    const isSummary = dto.field === ProductAiFillField.summary;
+
+    const systemPrompt = isSummary
+      ? `You write short e-commerce product listing summaries for Iranian stores.
+Return ONLY valid JSON: { "text": "..." }
+Follow the user's instructions for language and tone.
+Keep the summary to 1–3 sentences. No HTML. No markdown.
+Prefer a technical, informative style: what the product is and why its traits matter.
+Never write sales CTAs, discounts, "buy now", or vague praise like "excellent choice" / "amazing experience".`
+      : `You write e-commerce product descriptions as HTML for Iranian stores.
+Return ONLY valid JSON: { "html": "..." }
+Allowed tags only: p, ul, ol, li, strong, em, br.
+Follow the user's instructions for language and tone.
+Prefer a technical, informative structure: what it is, key traits/composition, typical use.
+Never write sales CTAs, discounts, or vague marketing slogans.
+Aim for 2–4 short paragraphs and optionally a bullet list. No scripts, styles, or markdown.`;
+
+    const userPrompt = JSON.stringify({
+      instructions: dto.prompt.trim(),
+      product: {
+        title: title || null,
+        nameFa: nameFa || null,
+        category: categoryName || null,
+      },
+    });
+
+    let content: string;
+    try {
+      content = await requestAiJsonCompletion(provider, systemPrompt, userPrompt, 0.5);
+    } catch (err) {
+      const message = err instanceof Error ? err.message : 'AI request failed';
+      throw new BadRequestException(message);
+    }
+
+    let parsed: { text?: unknown; html?: unknown };
+    try {
+      parsed = JSON.parse(content) as { text?: unknown; html?: unknown };
+    } catch {
+      throw new BadRequestException('AI returned invalid JSON');
+    }
+
+    if (isSummary) {
+      const text = String(parsed.text ?? '').trim();
+      if (!text) {
+        throw new BadRequestException('AI returned an empty summary');
+      }
+      return { field: ProductAiFillField.summary, text };
+    }
+
+    const html = String(parsed.html ?? '').trim();
+    if (!html) {
+      throw new BadRequestException('AI returned an empty description');
+    }
+    return { field: ProductAiFillField.description, html };
+  }
+
   private async generateDraft(input: {
     categoryName: string;
     productName: string;
diff --git a/src/products/products.controller.ts b/src/products/products.controller.ts
index 5213e49..262205c 100644
--- a/src/products/products.controller.ts
+++ b/src/products/products.controller.ts
@@ -15,7 +15,7 @@ import { CurrentUser } from '../auth/decorators/current-user.decorator';
 import { RequireBusinessPermission } from '../auth/decorators/require-business-permission.decorator';
 import { BusinessPermissionGuard } from '../auth/guards/business-permission.guard';
 import { JwtAuthGuard } from '../auth/guards/jwt-auth.guard';
-import { CreateProductByAiDto } from './dto/product-ai.dto';
+import { CreateProductByAiDto, FillProductFieldByAiDto } from './dto/product-ai.dto';
 import { CreateProductDto, ListProductsDto, ListPublicProductsDto, UpdateProductDto } from './dto/product.dto';
 import { ReplaceProductVariationValuesDto } from './dto/product-variation-values.dto';
 import { ReplaceProductTechnicalInfoDto } from './dto/product-technical-info.dto';
@@ -54,6 +54,16 @@ export class ProductsController {
     return this.aiService.createFromAi(businessId, dto, user);
   }
 
+  @Post('ai-fill')
+  @RequireBusinessPermission('products.create')
+  fillFieldByAi(
+    @Param('businessId') businessId: string,
+    @Body() dto: FillProductFieldByAiDto,
+    @CurrentUser() user: AuthUser,
+  ) {
+    return this.aiService.fillField(businessId, dto, user);
+  }
+
   @Get(':productId')
   @RequireBusinessPermission('products.read')
   getOne(
diff --git a/src/storage/s3-storage.driver.ts b/src/storage/s3-storage.driver.ts
index fa08447..1101f6f 100644
--- a/src/storage/s3-storage.driver.ts
+++ b/src/storage/s3-storage.driver.ts
@@ -46,6 +46,8 @@ export class S3StorageDriver {
         Key: key,
         Body: input.body,
         ContentType: input.contentType,
+        // Stable public media URLs — let browsers/CDN cache aggressively.
+        CacheControl: 'public, max-age=31536000, immutable',
       }),
     );