Prerequisite: If you haven't already, also read .ai/principles/distilled/permissions-fundamentals.md - it contains foundational rules that apply to all permissions work.

Permissions REST GPAT Principles

Checklist

Permission Definition Files

Generate raw permission definition files using the bin/permission command rather than creating them manually.
Place raw permission definition files at exactly config/authz/permissions/<resource>/<action>.yml; DO NOT add extra directories between the base path and the filename.
Name permissions based on what the endpoint modifies or returns, not the route structure (e.g., DELETE /projects/:id/jobs/:job_id/artifacts → delete_job_artifact).
Use a single read_<resource> permission for both list and show (GET) operations on the same resource.
Include the parent resource in the permission name for nested resources (e.g., create_pipeline_schedule_variable).
Create specific permissions for special actions (cancel, retry, download, trigger); DO NOT collapse them into a generic update permission.
Use a single update_<resource> permission covering all attribute updates; DO NOT create per-attribute permissions such as update_issue_title.
Set feature_category in the resource .metadata.yml to a valid entry from config/feature_categories.yml; look at existing endpoints in the same API file for the correct value.
Run bundle exec rake gitlab:permissions:validate (or rely on the Lefthook pre-push hook) to catch naming and structure violations before pushing.

Assignable Permissions

Place assignable permission YAML files at exactly config/authz/permission_groups/assignable_permissions/<category>/<resource>/<action>.yml; DO NOT add extra directories.
Ensure every raw permission listed in an assignable permission's permissions array already exists as a raw permission definition file before referencing it.
Select boundaries based only on the organizational levels the bundled raw permissions actually support; DO NOT include boundaries where the permissions do not apply.
Include project in boundaries when raw permissions cover /projects/:id/... endpoints; include group for /groups/:id/... endpoints; include user for /users/:id/... or personal-namespace operations; use instance sparingly and only for admin-facing permissions.
Create a category .metadata.yml only when titleization produces an incorrect display name (e.g., ci_cd → "CI/CD"); DO NOT create one when the folder name titleizes correctly.
Create a resource .metadata.yml only when the resource name contains an acronym, brand name, or awkward pluralization; DO NOT create one when the directory name titleizes and pluralizes correctly.
Use <actions> interpolation in a resource .metadata.yml description so the action list stays in sync automatically.
DO NOT remove an assignable permission while the underlying API functionality still exists; removal is a breaking change that silently drops all access for tokens holding that permission.
DO NOT rename an assignable permission without following the three-step migration process: add the new YAML, queue a rename_granular_scope_permission batched background migration, mark the old permission deprecated: true, finalize the migration in a later milestone, then delete the deprecated file using bundle exec rake gitlab:permissions:assignable:cleanup_deprecated.
DO NOT add raw permissions to an existing assignable permission except when adding support for new API endpoints.
DO NOT remove raw permissions from an assignable permission without using a rename migration to split the old permission into the retained and moved parts.
Changing boundary_type between project and group is safe; changing to or from user or instance is a breaking change requiring token holders to recreate scopes.
Renaming a raw permission requires only updating the raw permission YAML and any referencing assignable permission YAMLs; DO NOT create a database migration for raw permission renames.

REST API Endpoint Decorators

Add route_setting :authorization immediately before every HTTP method definition (get, post, put, delete), even when multiple endpoints share the same permission.
Use boundary_type: :project | :group | :user | :instance for single-boundary endpoints; use the boundaries array for endpoints that support multiple boundary types.
Use the boundary option (a callable returning the boundary object) only when the boundary cannot be determined through standard parameter lookup.
Use boundary_param when the request parameter containing the boundary identifier is not the default :id.
When using boundaries array, include a boundary_type key in each entry and optionally a boundary_param; the system evaluates boundaries in priority order project > group > user > instance and uses the first resolvable boundary.
Use skip_granular_token_authorization: true only for endpoints that are publicly accessible, authenticate by means other than PATs, or where authentication is optional; DO NOT use it to bypass permission checks on authenticated endpoints.
Add permissions that represent read-only access to publicly visible data to config/authz/roles/public_anonymous.yml under the matching project: or group: boundary so that granular PATs without an explicit scope can access them on public resources; DO NOT add user or instance boundary permissions to this file.

Testing

Add the 'authorizing granular token permissions' shared example for every endpoint, providing boundary_object, user, and request let-bindings.
Set boundary_object to match the boundary_type: project → project, group → group, :user → :user, :instance → :instance.
Ensure the user is a member of the namespace (project or group) when the boundary object is a project or group.

Job Token Permissions

Ensure all new job token permissions are opt-in and disabled by default.
Tag @gitlab-com/gl-security/product-security/appsec for security review before merging any new job token permission.
Update all three locations when adding a new job token permission: lib/ci/job_token/policies.rb, app/validators/json_schemas/ci_job_token_policies.json, and app/assets/javascripts/token_access/constants.js.
Add route_setting :authentication, job_token_allowed: true and route_setting :authorization, job_token_policies: <policy> to each endpoint that should accept job token authentication.
Use :read_* policies for GET (read) operations and :admin_* policies for POST/PUT/DELETE (write/delete) operations on job token endpoints.
Use the allow_public_access_for_enabled_project_features parameter on route_setting :authorization to allow job token access based on project feature visibility, providing backward compatibility.
Use the 'enforcing job token policies' shared RSpec example to test job token authorization, passing the required policy and optionally allow_public_access_for_enabled_project_features and expected_success_status.
Regenerate the fine-grained permissions documentation after adding job token support to a new endpoint by running bundle exec rake ci:job_tokens:compile_docs.

Authoritative sources

For the full picture, see:

doc/development/permissions/granular_access/rest_api_implementation_guide.md
doc/development/permissions/granular_access/job_tokens.md
doc/development/permissions/job_tokens.md
doc/development/permissions/granular_access/permission_definitions.md
doc/development/permissions/granular_access/assignable_permissions.md