> ## Documentation Index > Fetch the complete documentation index at: https://docs.runaether.dev/llms.txt > Use this file to discover all available pages before exploring further. # Skills > Author a SKILL.md, upload reusable skills with the CLI, let repo skills load automatically, and manage the Aether skills every workspace receives. A skill is a reusable instruction bundle the agent can load while working on a task. Each skill is a directory containing a `SKILL.md` manifest plus any supporting files. Skills come from three places: **user skills** you upload to your account, **repo skills** indexed automatically from a project's GitHub repository, and **Aether skills** the platform provides to every workspace. ## Authoring a Skill A skill is a folder whose root contains a `SKILL.md` file with YAML frontmatter. The frontmatter must include `name` and `description`, and `name` must match the skill's slug. ```markdown SKILL.md theme={"dark"} --- name: run-migrations description: How to run and verify database migrations in this project. --- # Running migrations 1. Apply pending migrations with `just migrate`. 2. Verify the schema with `just db-check`. ... ``` A **slug** is 1–64 characters, lowercase alphanumeric or dashes, starting and ending with an alphanumeric (e.g. `run-migrations`). The slug is the skill's identity — for user skills it defaults to the folder name; for repo skills it's the directory name under `.agents/skills/`. ### Bundle limits When you upload a skill, Aether enforces: | Limit | Value | | - | - | | Files per skill | 1000 | | Total uncompressed size | 50 MiB | | Per-file size | 5 MiB | Files must be valid UTF-8 text. Common build and dependency directories — `.git`, `node_modules`, `dist`, `build`, `.next`, `.cache`, `target`, `__pycache__`, `.venv` — are rejected if present, so keep the skill folder to its content. ## User Skills (CLI) Manage your saved skills with `aether skill` (aliased as `aether skills`). ### Upload one skill `push` uploads a local folder as a user skill. The slug defaults to the folder's basename; override it with `--slug`. ```bash theme={"dark"} aether skill push ./run-migrations aether skill push ./my-skill --slug run-migrations ``` If a skill with that slug already exists, the CLI prompts before overwriting. Pass `--force` to skip the prompt. ### List, show, download, delete ```bash theme={"dark"} aether skill list aether skill get run-migrations --files aether skill pull run-migrations ./local-dir aether skill delete run-migrations ``` `get --files` shows the file list; `--out ` writes the files to a directory. `pull` downloads a skill into a directory (pass `--force` to overwrite a non-empty target). `delete` prompts for confirmation unless you pass `--force`. ### Bulk import `sync` discovers skills in well-known local directories and uploads them in one pass: ```bash theme={"dark"} aether skill sync aether skill sync --dry-run ``` By default `sync` scans, in this order: * `/.agents/skills` * `/.claude/skills` * `~/.claude/skills` * `~/.agents/skills` * `~/.codex/skills` It uploads every subdirectory that has a `SKILL.md` and a valid slug. If the same slug appears in more than one source, the first match wins and later ones are skipped with a warning. Use `--dry-run` to preview what would be uploaded, `--source ` to override the search paths (repeatable), and `--force` to overwrite existing skills without prompting. ## Repo Skills When a project's linked GitHub repository contains skills under `.agents/skills//SKILL.md`, Aether indexes them from the repository's default branch and offers them to the agent automatically — no upload needed. Update the repo and the indexed skills follow. Repo skills **shadow** user skills with the same slug: if a repo defines `run-migrations` and you also have a user skill named `run-migrations`, the repo version is the one the agent uses for that project. To see the skills effective for a project (repo skills plus your non-shadowed user and Aether skills), use the [List project skills API](/api-reference/v1/skills/get-projects-by-id-skills). ## Aether Skills Aether ships its own skills to every workspace: `aether-workflow`, `aether-deep-review` (its defect-finding pull request review) plus a vendored selection of [Matt Pocock's engineering skills](https://github.com/mattpocock/skills) and Cursor's [thermo-nuclear code-quality review](https://github.com/cursor/plugins/tree/main/cursor-team-kit). They cannot be edited or deleted, but each can be turned off for your account under **Settings → Skills**; an Aether skill you turn off is left out of your workspaces and project skill lists until you turn it back on. To replace one with your own version, upload a user skill under the same slug: it shadows the Aether skill in your workspaces. The exception is `aether-workflow`, whose slug is reserved as Aether's own. ## How Skills Reach the Agent Effective skills are streamed into the workspace under `~/.aether/skills//` and symlinked into each agent's config directory (for example `~/.claude/skills`), so the running agent CLI discovers them in its native location. The skills root is wiped and rebuilt on each provision, so deleting a skill removes it from future tasks. ## API User skills are also managed over five REST endpoints: * [List project skills](/api-reference/v1/skills/get-projects-by-id-skills) * [List user skills](/api-reference/v1/skills/get-skills) * [Upload user skill](/api-reference/v1/skills/post-skills) * [Get user skill](/api-reference/v1/skills/get-skills-by-slug) * [Delete user skill](/api-reference/v1/skills/delete-skills-by-slug) Uploaded bundles are validated against the `SKILL.md` manifest rules above and encrypted at rest. Aether skills have two endpoints of their own: * [List default skills](/api-reference/v1/skills/get-default-skills) * [Enable or disable a default skill](/api-reference/v1/skills/put-default-skills-by-slug) This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.