TrueGrowth/openspec/changes/archive/2026-04-29-add-gpt-image-edit-support/proposal.md

Change: Add GPT Image edit support

Why

Official GPT Image editing uses /images/edits with a different request contract from text-to-image generation. The first GPT Image compatibility phase intentionally shipped only /images/generations; users now need image-to-image/edit support without replacing the existing Tuzi/basic compatibility fallback.

What Changes

• Add an official GPT Image edit request schema for /images/edits.
• Let image invocation planning prefer a request schema when the current request requires edit semantics.
• Extend the image adapter request shape with lightweight edit fields while keeping TaskType.IMAGE.
• Extend the GPT Image adapter to build official multipart edit requests from reference images.
• Keep Tuzi/basic GPT Image compatibility on the existing default adapter path.
• Add tests for generation-vs-edit routing, request bodies, and adapter selection.

Non-Goals

• Do not add TaskType.IMAGE_EDIT.
• Do not add a public edit_image MCP tool in this change.
• Do not build full mask drawing UI in this change.
• Do not convert all image providers to a common image.generate / image.edit abstraction.

Impact

• Affected specs:
  • provider-routing
  • image-generation
• Affected code:
  • packages/drawnix/src/services/provider-routing/types.ts
  • packages/drawnix/src/services/provider-routing/invocation-planner.ts
  • packages/drawnix/src/services/provider-routing/settings-repository.ts
  • packages/drawnix/src/services/provider-routing/binding-inference.ts
  • packages/drawnix/src/services/provider-routing/endpoint-binding-inference.ts
  • packages/drawnix/src/services/model-adapters/types.ts
  • packages/drawnix/src/services/model-adapters/context.ts
  • packages/drawnix/src/services/model-adapters/gpt-image-adapter.ts
  • packages/drawnix/src/services/generation-api-service.ts