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 `$CORE_SCRIPT` for scripts) replaced with the lower-priority content |
Multiple composing presets chain recursively. For example, a security preset with `prepend` and a compliance preset with `append` will produce: security header + core content + compliance footer.
> Community presets are independently created and maintained by their respective authors. Maintainers only verify that catalog entries are complete and correctly formatted — they do **not review, audit, endorse, or support the preset code itself**. Review preset source code before installation and use at your own discretion.
| `SPECKIT_PRESET_CATALOG_URL` | Override the full catalog stack with a single URL (replaces all defaults) | Built-in default stack |
| `GH_TOKEN` / `GITHUB_TOKEN` | GitHub token for authenticated requests to GitHub-hosted URLs (`raw.githubusercontent.com`, `github.com`, `api.github.com`, `codeload.github.com`). Required when your catalog JSON or preset ZIPs are hosted in a private GitHub repository. | None |
#### Example: Using a private GitHub-hosted catalog
```bash
# Authenticate with a token (gh CLI, PAT, or GITHUB_TOKEN in CI)
exportGITHUB_TOKEN=$(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.
