Skills

Custom Skills are versioned zip bundles stored in S3-compatible storage. An Agent or Session resolves every reference to an immutable Skill Version before execution.

POST   /v1/skills
GET    /v1/skills
GET    /v1/skills/{skill_id}
DELETE /v1/skills/{skill_id}
POST   /v1/skills/{skill_id}/versions
GET    /v1/skills/{skill_id}/versions
GET    /v1/skills/{skill_id}/versions/{version}
GET    /v1/skills/{skill_id}/versions/{version}/content
DELETE /v1/skills/{skill_id}/versions/{version}

Skills routes require configured Files storage and, in strict mode, anthropic-beta: skills-2025-10-02.

Bundle contract

Create and Version uploads accept a zip archive or path-qualified multipart files smaller than 30 MB. A bundle contains one top-level directory and a root SKILL.md; validation rejects traversal, absolute paths, links, duplicate paths, and invalid frontmatter metadata.

Agent references use the documented custom union. An omitted Version or latest is replaced by a concrete ready Version before the Agent Version or Session snapshot is stored. Active Agent and Session pins prevent deleting an archive that is still executable.

Runtime behavior

Docker-backed cloud Sessions initially expose only Skill name, description, and instruction path metadata. A private Skill dispatcher selects the immutable bundle, returns Launching skill: <name>, and injects the complete main instruction file on demand. Supporting files and scripts remain available through ordinary sandbox tools.

Primary and self Agent bundles use /workspace/skills/<name>/; external roster Agents use isolated namespaces below /workspace/skills/.agents/.

Anthropic-managed Skills, GitHub repository auto-loading, self-hosted runtime activation, and current remote-sandbox activation are not implemented.