Presets are stackable, priority-ordered collections of template and command overrides for Spec Kit. They let you customize both the artifacts produced by the Spec-Driven Development workflow (specs, plans, tasks, checklists, constitutions) and the commands that guide the LLM in creating them — without forking or modifying core files.
## How It Works
When Spec Kit needs a template (e.g. `spec-template`), it walks a resolution stack:
Template resolution happens **at runtime** — although preset files are copied into `.specify/presets/<id>/` during installation, Spec Kit walks the resolution stack on every template lookup rather than merging templates into a single location.
For detailed resolution and command registration flows, see [ARCHITECTURE.md](ARCHITECTURE.md).
## Command Overrides
Presets can also override the commands that guide the SDD workflow. Templates define *what* gets produced (specs, plans, constitutions); commands define *how* the LLM produces them (the step-by-step instructions).
Unlike templates, command overrides are applied **at install time**. When a preset includes `type: "command"` entries, the commands are registered into all detected agent directories (`.claude/commands/`, `.gemini/commands/`, etc.) in the correct format (Markdown or TOML with appropriate argument placeholders). When the preset is removed, the registered commands are cleaned up.
Multiple presets can be installed simultaneously. The `--priority` flag controls which one wins when two presets provide the same template (lower number = higher precedence):
```bash
specify preset add enterprise-safe --priority 10# base layer
Presets **override by default**, they don't merge. If two presets both provide `spec-template` with the default `replace` strategy, the one with the lowest priority number wins entirely. However, presets can use **composition strategies** to augment rather than replace content.
### Composition Strategies
Presets can declare a `strategy` per template to control how content is combined. The `name` field identifies which template to compose with in the priority stack, while `file` points to the actual content file (which can differ from the convention path `templates/<name>.md`):
```yaml
provides:
templates:
- type:"template"
name:"spec-template"
file:"templates/spec-addendum.md"
strategy:"append"# adds content after the core template
```
| Strategy | Description |
|----------|-------------|
| `replace` (default) | Fully replaces the lower-priority template |
| `prepend` | Places content **before** the resolved lower-priority template, separated by a blank line |
| `append` | Places content **after** the resolved lower-priority template, separated by a blank line |
| `wrap` | Content contains `{CORE_TEMPLATE}` placeholder (or `$CORE_SCRIPT` for scripts) replaced with the lower-priority content |
Multiple composing presets chain recursively. For example, a security preset with `prepend` and a compliance preset with `append` will produce: security header + core content + compliance footer.
> Community presets are independently created and maintained by their respective authors. GitHub and the Spec Kit maintainers may review pull requests that add entries to the community catalog for formatting, catalog structure, or policy compliance, but they do **not review, audit, endorse, or support the preset code itself**. Review preset source code before installation and use at your own discretion.
| `SPECKIT_PRESET_CATALOG_URL` | Override the full catalog stack with a single URL (replaces all defaults) | Built-in default stack |
| `GH_TOKEN` / `GITHUB_TOKEN` | GitHub token for authenticated requests to GitHub-hosted URLs (`raw.githubusercontent.com`, `github.com`, `api.github.com`, `codeload.github.com`). Required when your catalog JSON or preset ZIPs are hosted in a private GitHub repository. | None |
#### Example: Using a private GitHub-hosted catalog
```bash
# Authenticate with a token (gh CLI, PAT, or GITHUB_TOKEN in CI)
exportGITHUB_TOKEN=$(gh auth token)
# Search a private catalog added via `specify preset catalog add`
specify preset search my-template
# Install from a private catalog
specify preset add my-template
```
The token is attached automatically to requests targeting GitHub domains. Non-GitHub catalog URLs are always fetched without credentials.
