Cloud Storage

Manage files across cloud providers with authentication, cost awareness, and multi-provider operations.

When to Use

User needs to upload, download, sync, or manage files across cloud storage providers. Agent handles multi-provider operations with cost awareness.

Quick Reference

Topic	File
Provider-specific patterns	providers.md
Authentication setup	auth.md
Cost calculation	costs.md

Scope

This skill covers operational cloud storage tasks across providers:

• S3, GCS, Azure Blob, Backblaze B2, Cloudflare R2
• Google Drive, Dropbox, OneDrive, iCloud

For storage architecture decisions, see storage skill. For S3-specific deep patterns, see s3 skill.

Critical Rules

1. Verify operations completed — API 200 ≠ success; check file exists with correct size/checksum
2. Calculate ALL costs before large transfers — egress fees often exceed storage costs; check costs.md
3. Never delete without backup verification — confirm backup exists AND is restorable before removing source
4. Handle partial failures — long operations fail mid-way; implement checkpoints and resume logic
5. Rate limits vary wildly — Google 750GB/day upload, Dropbox batch limits, S3 3500 PUT/s per prefix

Authentication Traps

• OAuth tokens expire — refresh before long operations, not during
• Service account ≠ user account — different quotas, permissions, audit trails
• Wrong region/endpoint — S3 bucket in eu-west-1 won't work with s3.amazonaws.com
• MFA required — some operations need session tokens, plan for interactive auth

Multi-Provider Gotchas

Concept	Translates differently
Shared folder	Drive "Shared with me" ≠ Dropbox "Team Folders" ≠ OneDrive "SharePoint"
File ID	Drive uses IDs; Dropbox uses paths; S3 uses keys
Versioning	S3 explicit enable; Drive automatic; Dropbox 180 days
Permissions	S3 ACLs + policies; Drive roles; Dropbox link-based

Before Any Bulk Operation

• Estimated time calculated (size ÷ bandwidth)
• Rate limits checked for both source AND destination
• Cost estimate including egress + API calls
• Checkpoint/resume strategy for failures
• Verification method defined (checksum, count, spot-check)