Image Generation (AI SDK)

Official API-based image generation. Supports OpenAI, Google, DashScope (阿里通义万象) and Replicate providers.

Script Directory

Agent Execution:

1. SKILL_DIR = this SKILL.md file's directory
2. Script path = ${SKILL_DIR}/scripts/main.ts

Step 0: Load Preferences ⛔ BLOCKING

CRITICAL: This step MUST complete BEFORE any image generation. Do NOT skip or defer.

Check EXTEND.md existence (priority: project → user):

test -f .beaver-skill/beaver-image-gen/EXTEND.md && echo "project"
test -f "$HOME/.beaver-skill/beaver-image-gen/EXTEND.md" && echo "user"

Result	Action
Found	Load, parse, apply settings. If default_model.[provider] is null → ask model only (Flow 2)
Not found	⛔ Run first-time setup (below) → Save EXTEND.md → Then continue

CRITICAL: If not found, complete the full setup using AskUserQuestion BEFORE generating any images. Generation is BLOCKED until EXTEND.md is created.

Path	Location
.beaver-skill/beaver-image-gen/EXTEND.md	Project directory
$HOME/.beaver-skill/beaver-image-gen/EXTEND.md	User home

EXTEND.md Supports: Default provider | Default quality | Default aspect ratio | Default image size | Default models

Schema: references/config/preferences-schema.md

First-Time Setup (when no EXTEND.md found)

Use AskUserQuestion with ALL questions in ONE call:

1. Default Provider: Google (Recommended) | OpenAI | DashScope | Replicate
2. Default Model (per selected provider):
   • Google: gemini-3-pro-image-preview (Recommended) | gemini-3.1-flash-image-preview | gemini-3-flash-preview
   • OpenAI: gpt-image-1.5 (Recommended) | gpt-image-1
   • DashScope: z-image-turbo (Recommended) | z-image-ultra
   • Replicate: google/nano-banana-pro (Recommended) | google/nano-banana
3. Default Quality: 2k (Recommended) | normal
4. Save Location: Project .beaver-skill/ (Recommended) | User ~/.beaver-skill/

EXTEND.md template:

---
version: 1
default_provider: [selected or null]
default_quality: [selected or null]
default_aspect_ratio: null
default_image_size: null
default_model:
  google: [selected or null]
  openai: null
  dashscope: null
  replicate: null
---

If EXTEND.md exists but default_model.[current_provider] is null → ask ONLY the model question for that provider, then update EXTEND.md.

See references/config/first-time-setup.md for detailed flow diagrams.

Usage

# Basic
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image cat.png

# With aspect ratio
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A landscape" --image out.png --ar 16:9

# High quality
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --quality 2k

# From prompt files
npx -y bun ${SKILL_DIR}/scripts/main.ts --promptfiles system.md content.md --image out.png

# With reference images (Google multimodal or OpenAI edits)
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "Make blue" --image out.png --ref source.png

# With reference images (explicit provider/model)
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "Make blue" --image out.png --provider google --model gemini-3-pro-image-preview --ref source.png

# Specific provider
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --provider openai

# DashScope (阿里通义万象)
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "一只可爱的猫" --image out.png --provider dashscope

# Replicate (google/nano-banana-pro)
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --provider replicate

# Replicate with specific model
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --provider replicate --model google/nano-banana

Options

Option	Description
--prompt <text>, -p	Prompt text
--promptfiles <files...>	Read prompt from files (concatenated)
--image <path>	Output image path (required)
--provider google|openai|dashscope|replicate	Force provider (default: google)
--model <id>, -m	Model ID (Google: gemini-3-pro-image-preview, gemini-3.1-flash-image-preview; OpenAI: gpt-image-1.5)
--ar <ratio>	Aspect ratio (e.g., 16:9, 1:1, 4:3)
--size <WxH>	Size (e.g., 1024x1024)
--quality normal|2k	Quality preset (default: 2k)
--imageSize 1K|2K|4K	Image size for Google (default: from quality)
--ref <files...>	Reference images. Supported by Google multimodal (gemini-3-pro-image-preview, gemini-3-flash-preview, gemini-3.1-flash-image-preview) and OpenAI edits (GPT Image models). If provider omitted: Google first, then OpenAI
--n <count>	Number of images. Supported: OpenAI (except dall-e-3), Imagen, Replicate. Gemini multimodal and chat completions mode: warns and generates 1
--json	JSON output

Environment Variables

Variable	Description
OPENAI_API_KEY	OpenAI API key
GOOGLE_API_KEY	Google API key
DASHSCOPE_API_KEY	DashScope API key (阿里云)
REPLICATE_API_TOKEN	Replicate API token
OPENAI_IMAGE_MODEL	OpenAI model override
GOOGLE_IMAGE_MODEL	Google model override
DASHSCOPE_IMAGE_MODEL	DashScope model override (default: z-image-turbo)
REPLICATE_IMAGE_MODEL	Replicate model override (default: google/nano-banana-pro)
OPENAI_BASE_URL	Custom OpenAI endpoint
GOOGLE_BASE_URL	Custom Google endpoint
DASHSCOPE_BASE_URL	Custom DashScope endpoint
REPLICATE_BASE_URL	Custom Replicate endpoint

Load Priority: CLI args > EXTEND.md > env vars > <cwd>/.beaver-skill/.env > ~/.beaver-skill/.env

Model Resolution

Model priority (highest → lowest), applies to all providers:

1. CLI flag: --model <id>
2. EXTEND.md: default_model.[provider]
3. Env var: <PROVIDER>_IMAGE_MODEL (e.g., GOOGLE_IMAGE_MODEL)
4. Built-in default

EXTEND.md overrides env vars. If both EXTEND.md default_model.google: "gemini-3-pro-image-preview" and env var GOOGLE_IMAGE_MODEL=gemini-3.1-flash-image-preview exist, EXTEND.md wins.

Agent MUST display model info before each generation:

• Show: Using [provider] / [model]
• Show switch hint: Switch model: --model <id> | EXTEND.md default_model.[provider] | env <PROVIDER>_IMAGE_MODEL

Replicate Models

Supported model formats:

• owner/name (recommended for official models), e.g. google/nano-banana-pro
• owner/name:version (community models by version), e.g. stability-ai/sdxl:<version>

Examples:

# Use Replicate default model
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --provider replicate

# Override model explicitly
npx -y bun ${SKILL_DIR}/scripts/main.ts --prompt "A cat" --image out.png --provider replicate --model google/nano-banana

Provider Selection

1. --ref provided + no --provider → auto-select Google first, then OpenAI, then Replicate
2. --provider specified → use it (if --ref, must be google, openai, or replicate)
3. Only one API key available → use that provider
4. Multiple available → default to Google

Quality Presets

Preset	Google imageSize	OpenAI Size	Use Case
normal	1K	1024px	Quick previews
2k (default)	2K	2048px	Covers, illustrations, infographics

Google imageSize: Can be overridden with --imageSize 1K|2K|4K

Aspect Ratios

Supported: 1:1, 16:9, 9:16, 4:3, 3:4, 2.35:1

• Google multimodal: uses imageConfig.aspectRatio
• Google Imagen: uses aspectRatio parameter
• OpenAI: maps to closest supported size

Generation Mode

Default: Sequential generation (one image at a time). This ensures stable output and easier debugging.

Parallel Generation: Only use when user explicitly requests parallel/concurrent generation.

Mode	When to Use
Sequential (default)	Normal usage, single images, small batches
Parallel	User explicitly requests, large batches (10+)

Parallel Settings (when requested):

Setting	Value
Recommended concurrency	4 subagents
Max concurrency	8 subagents
Use case	Large batch generation when user requests parallel

Agent Implementation (parallel mode only):

# Launch multiple generations in parallel using Task tool
# Each Task runs as background subagent with run_in_background=true
# Collect results via TaskOutput when all complete

Error Handling

• Missing API key → error with setup instructions
• Generation failure → auto-retry once
• Invalid aspect ratio → warning, proceed with default
• Reference images with unsupported provider/model → error with fix hint (switch to Google multimodal: gemini-3-pro-image-preview, gemini-3.1-flash-image-preview; or OpenAI GPT Image edits)

Extension Support

Custom configurations via EXTEND.md. See Preferences section for paths and supported options.