gemini-to-seedream-migration（Gemini TO seedream 迁移）

Gemini to SeeDream v4.5 Migration

Migrate AI image generation from Google Gemini 2.5 Flash Image to BytePlus SeeDream v4.5 with this proven, production-ready workflow.

Quick Start

Migration Overview:

• Replace Gemini SDK with BytePlus REST API
• Update environment variables and validation
• Migrate API routes to new client
• Test and validate changes
• Update documentation

Benefits:

• Higher resolution support (up to 4K vs 2K)
• Better control over image dimensions and generation
• Built-in prompt optimization for quality improvement
• Potentially lower costs (check BytePlus pricing)
• Broader format support (adds BMP, TIFF, GIF)

Prerequisites:

• Existing project using Google Gemini 2.5 Flash Image
• BytePlus API key (get from https://console.byteplus.com/ark/region:ark+ap-southeast-1/apiKey)
• TypeScript/JavaScript project with image generation endpoints

Time Estimate: 3-4 hours for complete migration

Core Migration Workflow

Phase 1: Environment Setup

Replace Gemini environment variables with BytePlus configuration.

Step 1.1: Update.env.example

Find and remove Gemini configuration:

# REMOVE
GEMINI_API_KEY=your_google_ai_api_key_here

Add BytePlus configuration:

# ADD
BYTEPLUS_API_KEY=your_byteplus_api_key_here

Step 1.2: Update Environment Validator

If you have environment validation (recommended), update it to check for BYTEPLUS_API_KEY instead of GEMINI_API_KEY.

Example changes:

// OLD
{
  name: 'GEMINI_API_KEY',
  required: true,
  description: 'Google AI API key for image generation',
  setupUrl: 'https://aistudio.google.com/app/apikey',
}

// NEW
{
  name: 'BYTEPLUS_API_KEY',
  required: true,
  description: 'BytePlus SeeDream API key for image generation',
  setupUrl: 'https://console.byteplus.com/ark/region:ark+ap-southeast-1/apiKey',
}

Step 1.3: Add API Key to Local Environment

Add to your .env.local:

BYTEPLUS_API_KEY=your_actual_byteplus_api_key

Step 1.4: Verify Environment

Test that validation detects the new key correctly:

npm run validate  # or your validation command

Phase 2: Create BytePlus Client

Create a reusable REST API client for BytePlus SeeDream v4.5.

Step 2.1: Create Client File

Create lib/byteplus-client.ts (or appropriate path for your project).

See references/client-template.ts for a fully commented, production-ready template.

Key implementation points:

• Use native fetch API (no SDK required)
• Convert base64 to data URI format: data:image/png;base64,${base64String}
• Add comprehensive error handling for all HTTP status codes
• Validate API key before making requests
• Include verbose logging for debugging
• Return consistent interface matching your app's expectations

Step 2.2: Configure Model Parameters

Choose appropriate parameters for your use case:

Model ID: seedream-4-5-251128 (latest as of Dec 2025)

Size options:

• Fixed pixels: 2048x2560 (portrait), 2560x2048 (landscape), 2048x2048 (square)
• Semantic: 2K, 4K (model determines exact dimensions)

Prompt optimization:

• mode: "standard" - Higher quality, slower (~45-60s)
• mode: "fast" - Good quality, faster (~15-30s)

Other settings:

• sequential_image_generation: "disabled" - Single image output
• watermark: false - No watermark
• response_format: "b64_json" - Base64 response

Step 2.3: Test Client

Create a simple test to verify the client works:

const result = await generateImageWithByteplus({
  prompt: "A simple test image of a red circle",
  images: [] // or test images
})

console.log(result.imageUrl ? "Success!" : result.error)

Phase 3: Migrate API Routes

Replace Gemini SDK calls with BytePlus client in all API routes.

Step 3.1: Remove Gemini Imports

In each API route file:

// REMOVE
import { GoogleGenAI } from "@google/genai"

Add BytePlus import:

// ADD
import { generateImageWithByteplus } from "@/lib/byteplus-client"

Step 3.2: Replace Generation Calls

Before (Gemini SDK):

const genAI = new GoogleGenAI({ apiKey: process.env.GEMINI_API_KEY! })

const result = await genAI.models.generateContent({
  model: "gemini-2.5-flash-image",
  contents: [{
    role: "user",
    parts: [
      { text: prompt },
      { inlineData: { mimeType: "image/png", data: base64Image1 } },
      { inlineData: { mimeType: "image/jpeg", data: base64Image2 } }
    ]
  }],
  config: {
    responseModalities: ["IMAGE"],
    imageConfig: { aspectRatio: "4:5" }
  }
})

// Extract image from candidates
const imagePart = result.candidates[0].content.parts.find(p => p.inlineData)
const base64Image = `data:${imagePart.inlineData.mimeType};base64,${imagePart.inlineData.data}`

After (BytePlus REST):

const result = await generateImageWithByteplus({
  prompt: prompt,
  images: [
    { data: base64Image1, mimeType: "image/png" },
    { data: base64Image2, mimeType: "image/jpeg" }
  ]
})

if (result.error) {
  return NextResponse.json({ error: result.error }, { status: 500 })
}

// Image already in data URI format
const base64Image = result.imageUrl

Step 3.3: Handle Response Differences

BytePlus doesn't return text alongside images. If your frontend expects both:

return NextResponse.json({
  imageUrl: result.imageUrl,
  text: "", // BytePlus doesn't generate text
  usage: result.usage
})

Step 3.4: Update Logging

Replace Gemini-specific log messages:

// OLD
console.log("[v0] Gemini API key available:", !!process.env.GEMINI_API_KEY)
console.log("[v0] Calling Gemini API...")

// NEW
console.log("[v0] BytePlus API key available:", !!process.env.BYTEPLUS_API_KEY)
console.log("[v0] Calling BytePlus SeeDream v4.5 API...")

Phase 4: Dependency Cleanup

Remove Gemini SDK from project dependencies.

Step 4.1: Uninstall Gemini SDK

npm uninstall @google/genai

This automatically updates package.json and package-lock.json.

Step 4.2: Verify Removal

Check that Gemini is no longer referenced:

grep -i "genai\|gemini" package.json

Expected: No matches (empty output).

Step 4.3: Rebuild

npm install
npx tsc --noEmit  # Verify no type errors

Phase 5: Testing & Validation

See references/testing-checklist.md for comprehensive testing guide.

Quick validation:

1. Environment validation passes: npm run validate
2. TypeScript compiles: npx tsc --noEmit
3. Linting passes: npm run lint
4. Build succeeds: npm run build
5. Manual API test generates images correctly

Test scenarios:

• Happy path: Valid images + prompt → generates image
• Invalid API key → Returns 401 with clear message
• Missing images → Returns 400 error
• Rate limit → Returns 429 with retry message
• Service error → Returns 500 with retry message

Phase 6: Documentation Updates

Update all documentation to reflect BytePlus instead of Gemini.

Files to update:

• README.md - Replace "Gemini 2.5 Flash" with "BytePlus SeeDream v4.5"
• SETUP.md - Update API key setup instructions
• ARCHITECTURE.md - Update AI integration section
• Any troubleshooting guides - Update error codes and debugging steps

Search for remaining references:

grep -ri "gemini\|google ai" *.md docs/*.md

Key Differences: Gemini vs BytePlus

See references/api-comparison.md for detailed parameter mapping.

Quick comparison:

Common Pitfalls

See references/troubleshooting.md for detailed solutions.

Common mistakes:

1. Forgetting data URI format - BytePlus requires data:image/png;base64,... not plain base64
2. Wrong model ID - Use seedream-4-5-251128 not seedream-4.5
3. Missing error handling - Handle all HTTP status codes (400, 401, 429, 500)
4. Not validating API key - Check key exists before making requests
5. Incorrect image format - Ensure images are in supported formats (PNG/JPEG/WEBP)

Quick Reference

Gemini SDK Pattern

import { GoogleGenAI } from "@google/genai"

const genAI = new GoogleGenAI({ apiKey: process.env.GEMINI_API_KEY! })

const result = await genAI.models.generateContent({
  model: "gemini-2.5-flash-image",
  contents: [{
    role: "user",
    parts: [
      { text: prompt },
      { inlineData: { mimeType, data: base64String } }
    ]
  }],
  config: {
    responseModalities: ["IMAGE"],
    imageConfig: { aspectRatio: "4:5" }
  }
})

BytePlus REST Pattern

import { generateImageWithByteplus } from "@/lib/byteplus-client"

const result = await generateImageWithByteplus({
  prompt: prompt,
  images: [{ data: base64String, mimeType: "image/png" }]
})

if (result.error) {
  // Handle error
}

Error Handling

See references/error-handling.md for comprehensive guide.

HTTP Status Codes:

• 400 - Invalid request (check image format, size, aspect ratio)
• 401 - Authentication failed (invalid API key)
• 429 - Rate limit exceeded (implement backoff)
• 500 - Service error (retry with exponential backoff)

Example error handler:

if (!response.ok) {
  switch (response.status) {
    case 400:
      return { error: "Invalid image or prompt" }
    case 401:
      return { error: "BytePlus API authentication failed" }
    case 429:
      return { error: "Rate limit exceeded, please try again later" }
    case 500:
      return { error: "BytePlus service error, please retry" }
    default:
      return { error: "Failed to generate image" }
  }
}

Success Criteria

Migration complete when:

• ✅ All API routes use BytePlus instead of Gemini
• ✅ Environment validation passes
• ✅ TypeScript compilation passes (npx tsc --noEmit)
• ✅ Linting passes (npm run lint)
• ✅ Build succeeds
• ✅ Generated images meet quality expectations
• ✅ All error scenarios handled gracefully
• ✅ Documentation updated
• ✅ Production deployment stable

Additional Resources

• BytePlus API Documentation: https://docs.byteplus.com/en/docs/ModelArk/1666945
• API Console: https://console.byteplus.com/ark/region:ark+ap-southeast-1/apiKey
• Model Pricing: https://docs.byteplus.com/en/docs/ModelArk/1099320#image-generation
• Prompt Guide: https://docs.byteplus.com/en/docs/ModelArk/1829186

Troubleshooting

For common issues and solutions, see references/troubleshooting.md.

For API parameter details, see references/api-comparison.md.

For comprehensive testing checklist, see references/testing-checklist.md.