Nano Banana Pro OpenRouter Adapter

This skill is a deterministic adapter around OpenRouter image generation. It is intended for meta-skill skill_exec use, not as an open-ended agent surface.

Contract

• During MetaSkill execution, accepts only the parent-resolved, process-local provider lease. The credential, endpoint, and proxy never enter with, argv, the plan, or persisted run data. Direct standalone CLI use may still provide OPENROUTER_API_KEY.
• Does not read .env files, prompt for credentials, print credentials, or write credentials to disk.
• Uses only the model, base URL, output directory, and local path prefix passed by the caller.
• Saves generated image bytes under the supplied output directory.
• Emits one IMAGE_READY: JSON line per saved image.
• A missing/invalid required MetaSkill lease exits 78 before any provider submission. Provider failures after submission emit IMAGE_GENERATION_FAILED with exit 0 so the webpage can bind a replacement slot without auto-replay.

Meta-Skill Payload Mode

When stdin is JSON containing media_slots, image_slots, slots, or page_outline, the adapter generates image slots and preserves already downloaded images. Structured slots are preferred over free-form outline text:

{
  "requirement_framing": "...",
  "media_slots": {"slots": [{"slot_id": "hero-visual", "modality": "image"}]},
  "page_outline": "...",
  "image_download": "...",
  "include_images": "YES",
  "visual_style": "..."
}

Existing IMAGE_READY: records in image_download are preserved. If IMAGE_DOWNLOAD_INCOMPLETE: lists unfilled_slot_ids, only those slots are generated. If the caller requested images but both structured slots and outline slot parsing are empty, the adapter synthesizes minimal webpage-safe image slots from the brief instead of emitting no_image_slots_to_generate.

Plain Prompt Mode

When stdin is plain text, the adapter generates one image using that text as the prompt and the --filename stem as the slot_id.