feat: support multiple images in Buffer posts

[omarherri]

Feature request: support multiple images in Buffer posts

Creating a post through the Buffer n8n node currently exposes one image URL and sends exactly one image asset. This prevents workflows from submitting a post with multiple images while preserving their order and per-image metadata.

Proposed behavior

• Keep the existing first-image fields so saved workflows remain compatible.
• Add an optional Additional Images collection with an Add Image button.
• Each additional image has:
  • Image URL (required)
  • Alt Text (optional)
  • Image Thumbnail URL (optional)
• Send all images in one ordered assets array, with each image's metadata kept together.
• Reuse HTTP/HTTPS URL validation and identify the failing additional image in errors.
• Leave text-only and video posts unchanged.

The implementation is ready on combindma/buffer-n8n feat/multiple-image-posts, commit 0f1ef5e. A pull request could not be opened because this repository limits pull requests to collaborators.

Evidence and validation

• npm test -- --runInBand: 21 suites, 207 tests passed.
• npm run lint: passed.
• npm run build: passed.
• n8n 2.37.10 local manual execution: one GraphQL mutation with three ordered image assets; alt text and thumbnail URLs remained associated with the correct image.
• The screenshot below shows the actual n8n fields and successful local mock API output. It does not represent a live Buffer post.

Suggested PR checklist

• Link this issue in the PR body.
• Include a screenshot of the node form showing the existing first-image fields and at least two Additional Images entries.
• Include request evidence showing one post request and an ordered assets array with three distinct image URLs.
• Include evidence that alt text and thumbnail URLs stay paired with their image.
• Add or update tests for single-image compatibility, three-image ordering, invalid additional URLs, text-only posts, and video posts.
• Run npm test, npm run lint, and npm run build, and report the actual results.
• Test a safe Buffer channel using three distinct public images; document the channel/post type, queue or scheduled mode, and resulting post URL or execution evidence.
• Check Buffer's current per-network image count, format, size, and carousel limitations before describing support.
• Explain that the node does not currently expose saveToDraft, if the test plan references drafts.