Musher Configuration

Environment variables, credential storage, and file locations for the musher CLI.

Environment Variables

Variable	Description	Default
`MUSHER_API_KEY`	API key for authentication (overrides stored credentials)	None
`MUSHER_API_URL`	Base URL for the Musher API	`https://api.musher.dev`

Example

export MUSHER_API_KEY="mush_sk_abc123..."
musher publish

Credential Storage

When you run musher login, your API key is stored securely. The CLI checks for credentials in this order:

Environment variable — MUSHER_API_KEY (highest priority)
OS keyring — the system's native credential store
Fallback file — ~/.config/musher/api-key

OS Keyring

The CLI uses your operating system's native credential manager:

Platform	Keyring Backend
macOS	Keychain
Linux	secret-service (GNOME Keyring, KWallet)
Windows	Credential Manager

The keyring service name is dev.musher.musher. If no keyring is available (e.g., in a headless server), credentials fall back to the config file.

File Locations

Purpose	Path
Configuration	`~/.config/musher/`
Logs	`~/.local/state/musher/logs/musher.log`
Pack cache	`~/.cache/musher/pack/`
OCI store	`~/.local/share/musher/oci/`

These follow the XDG Base Directory convention on Linux and macOS. On macOS, ~/.config is used rather than ~/Library.

musher.yaml Reference

The musher.yaml file defines a bundle and lives in your project directory — it is not a global configuration file.

Top-Level Fields

Field	Type	Required	Description
`kind`	`string`	Yes	Always `"bundle"`
`namespace`	`string`	Yes	Organization namespace to publish under
`slug`	`string`	Yes	URL-safe bundle identifier (lowercase, hyphens)
`version`	`string`	Yes	Version string for this release
`name`	`string`	Yes	Human-readable display name
`description`	`string`	No	Short description of the bundle
`keywords`	`string[]`	No	Tags for discovery and search
`assets`	`object[]`	Yes	Array of asset definitions

Asset Fields

Field	Type	Required	Description
`id`	`string`	Yes	Unique identifier within the bundle
`src`	`string`	Yes	Source file path relative to `musher.yaml`
`kind`	`string`	Yes	Asset type (e.g., `skill`, `prompt`, `rule`, `config`)
`installs`	`object[]`	No	Install mappings for target runners

Install Mapping Fields

Field	Type	Required	Description
`harness`	`string`	Yes	Target runner identifier
`path`	`string`	Yes	Destination path in the runner's workspace

Full Example

musher.yaml

kind: bundle
namespace: acme
slug: code-review-kit
version: 1.0.0
name: Code Review Kit
description: Skills, prompts, and rules for consistent code reviews.
keywords:
  - code-review
  - skills

assets:
  - id: code-review-skill
    src: skills/code-review/SKILL.md
    kind: skill
    installs:
      - harness: claude-code
        path: .claude/skills/code-review/SKILL.md

  - id: pr-summary-prompt
    src: prompts/pr-summary.md
    kind: prompt
    installs:
      - harness: claude-code
        path: .claude/rules/pr-summary.md

  - id: review-standards
    src: rules/review-standards.md
    kind: rule
    installs:
      - harness: claude-code
        path: .claude/rules/review-standards.md

Supported Harnesses

Harness	Description	Typical Install Paths
`claude-code`	Claude Code (Anthropic's CLI)	`.claude/skills//SKILL.md`, `.claude/rules/.md`, `CLAUDE.md`

The harness value determines which runner knows how to install the asset. Each runner expects files in specific locations — the path field in your install mapping should match the runner's conventions.