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A2a Assets

Documents
a2a-assets

A2a Assets is an Agent Skill for documents published in the BuilderIO/agent-native repository on GitHub: a SKILL.md instruction file an AI agent can load to do this task.

Use Assets from other apps or MCP hosts to generate, refine, export, and insert brand images or videos.

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How to use this skill

Bring this guide into your coding agent with a prompt tailored to the tool you use.

  1. Open your project in Codex.
  2. Copy and paste the prompt below.
  3. Review files and risks before approving any action.
Prompt to paste
Inspect the Agent Skill at https://github.com/BuilderIO/agent-native/blob/HEAD/templates/assets/.agents/skills/a2a-assets/SKILL.md and all supporting files. Report provenance, permissions, scripts, dependencies, and security risks. Propose an exact installation into .agents/skills/a2a-assets, but wait for my approval before writing files or running scripts.

Copying this prompt does not install or run the skill. Review third-party files before use.

Assets MCP Tool

Use the Assets MCP tool surface when another app or external host needs brand imagery, video, or reusable source media and Assets owns the library. Prefer the pure MCP generate-asset flow for human-in-the-loop generation because it can return the inline picker. A2A remains useful for unattended cross-app delegation, but A2A replies cannot render MCP App pickers.

Caller Flow

  1. For human selection, call generate-asset with the brief, callerAppId, and libraryId when known. It will match the library, generate candidates, and return the Assets picker filtered to the new run IDs.
  2. For unattended A2A-style work, call match-library or list-libraries when the library is ambiguous, then call generate-image-batch with one slot per destination, such as one hero per slide. Pass source: "a2a" and callerAppId with the calling app id (slides, design, content, mail) so the Assets audit log can group cross-agent generations.
  3. Treat image batches as complete when the action returns. Use returned successful images entries directly; only regenerate slots that returned ok: false.
  4. For social/blog/diagram slots, call list-generation-presets and pass the matching presetId so output rules travel with the run.
  5. When a human designer needs to continue the work, create or update a generation session and preserve the returned sessionId.
  6. For video, call generate-video and then refresh-generation-run until the run completes.
  7. Preserve returned assetId, runId, previewUrl, downloadUrl, and embedPath exactly.
  8. Insert chosen/exported URLs into the caller's artifact. Design callers should call insert-asset after the picker returns a selected asset.
  9. On feedback, call refine-image with the prior assetId, source: "a2a", and the same callerAppId, then replace only the affected destination.

Audit Trail

Every Assets generation writes an image_generation_runs row with the prompt, compiled prompt, model, aspect ratio, references, source app, owner, org, status, error, output assets, and refinement lineage. Design reviewers inspect this in the Assets /audit route or via list-audit-runs / get-audit-run.

Preview Rules

Use same-origin embed fences only when the caller can render the Assets route. Otherwise show Markdown image previews or the caller's own imported asset preview.