Gpt image 2 support

[yangjunx21]

Summary

Lets the agent call gpt-image-2 (or OpenRouter image models) on demand to generate bitmap assets (logos, hero images, illustrations) while producing a design, and embeds them seamlessly in preview + exports. Off by default; users opt in from Settings.

Type of change

• New feature

Linked issue

Checklist

• I read docs/VISION.md, docs/PRINCIPLES.md, and CLAUDE.md before starting
• Commits are signed with DCO (git commit -s)
• pnpm lint && pnpm typecheck && pnpm test passes locally
• Added/updated tests for the change
• Added a changeset (pnpm changeset) if user-visible
• Updated docs if behavior changed

Dependency additions (if any)

Screenshots / recordings (UI changes)

[github-actions]

Findings

• [Major] Enabled image generation silently degrades by disabling the image tool when credentials are missing. This violates the project rule to avoid silent fallbacks and can produce non-image outputs without explicit user-facing failure. Evidence: apps/desktop/src/main/image-generation-settings.ts:124, apps/desktop/src/main/index.ts:378, apps/desktop/src/main/index.ts:433.
  Suggested fix:

  const cfg = getCachedConfig();
  const imageConfig = cfg ? resolveImageGenerationConfig(cfg) : null;
  if (cfg?.imageGeneration?.enabled === true && imageConfig === null) {
    throw new CodesignError(
      'Image generation is enabled but credentials are missing or invalid. Update Settings > Image Generation.',
      ERROR_CODES.PROVIDER_AUTH_MISSING,
    );
  }

Summary

• Review mode: initial
• Not found in repo/docs: docs/VISION.md, docs/PRINCIPLES.md.

Testing

• Not run (automation)

open-codesign Bot

[github-actions]

[Major] This branch silently disables generate_image_asset when image generation is enabled but credentials are unavailable (resolveImageGenerationConfig returns null). That is a silent fallback rather than a surfaced error.

Suggested fix:

const cfg = getCachedConfig();
const imageConfig = cfg ? resolveImageGenerationConfig(cfg) : null;
if (cfg?.imageGeneration?.enabled === true && imageConfig === null) {
  throw new CodesignError(
    'Image generation is enabled but credentials are missing or invalid. Update Settings > Image Generation.',
    ERROR_CODES.PROVIDER_AUTH_MISSING,
  );
}