late-media

name	late-media
description	Late.dev media upload workflow with presigned URLs, validation, and platform-specific constraints

Late.dev Media Upload Workflow

Upload Flow

1. Validate file exists, check type/size against platform limits
2. Validate content-type matches actual file magic bytes (security)
3. Get presigned URL: late-tool.mjs media presign --filename=photo.jpg --content-type=image/jpeg
4. Upload file to presigned URL via PUT (handled internally)
5. Reference publicUrl in post's mediaItems array

# Step 1: Get presigned URL
node ../../../../.founderOS/scripts/late-tool.mjs media presign \
  --filename=photo.jpg --content-type=image/jpeg
# Returns: { "publicUrl": "https://...", "uploadUrl": "https://..." }
# Note: uploadUrl is internal only — never log it

# Step 2: Reference in post
node ../../../../.founderOS/scripts/late-tool.mjs posts create \
  --accounts='["acc_123"]' \
  --text="Check this out!" \
  --media='[{"publicUrl":"https://...","type":"image"}]'

Platform Constraints

Platform	Images	Video	Other
LinkedIn	JPEG/PNG/GIF (multiple)	MP4/MOV	PDF docs (100MB, 300pp max)
X/Twitter	4 images max OR 1 video	MP4/MOV	—

Security

• Presigned URLs are bearer tokens — never persist to logs or DB
• Use immediately after creation (TTL ~15 minutes, Late.dev-controlled). If the API allows configuring TTL, request 5 minutes maximum to minimize exposure window
• Validate content-type matches file magic bytes before upload
• Max 5GB per file