---
name: tryghost-add-private-feature-flag
description: "Use when adding a new private (developer experiments) feature flag to Ghost, including the backend registration and settings UI toggle."
license: "MIT"
metadata:
  decimalai-skill-id: "a07e960b-ec9f-4ab2-b263-a4849328b8eb"
  decimalai-version-id: "05f87038-621b-463b-95a6-34df576a1933"
  decimalai-version: "3"
  decimalai-body-sha256: "11118b5462a2f0f4e1010c053909cddc00fc9837f76bdccf33d8fb8d1b3494e9"
  decimalai-name: "tryghost/add-private-feature-flag"
  decimalai-format: "1"
  decimalai-invocation: "model"
  decimalai-category: "coding"
  decimalai-source: "https://app.decimal.ai/s/tryghost-add-private-feature-flag@3/SKILL.md"
---
# Add Private Feature Flag

## Overview

Adds a new private feature flag to Ghost. Private flags appear in Labs settings under the "Private features" tab, visible only when developer experiments are enabled.

Read and follow the canonical [feature flag guide](../../../docs/practices/feature-flags.md)
before adding a flag. The guide covers when a Labs flag is appropriate, safe
gating across server and Admin, testing, and the cleanup lifecycle.

For Admin 7 milestone flags, also use the
[Admin 7 feature flags skill](../admin7-feature-flags/SKILL.md) for naming
and shared presentation guidance.

## Steps

1. **Add the flag to `ghost/core/shared/labs.js`**
   - Add the flag name (camelCase string) to the `PRIVATE_FEATURES` array.

2. **Add a UI toggle in `apps/admin/src/settings/advanced/labs/private-features.tsx`**
   - Add a new entry to the `features` array with `title`, `description`, and `flag` (must match the string in `labs.js`).

3. **Run tests and update the config API snapshot**
   - Unit: `cd ghost && pnpm test:single test/unit/shared/labs.test.js`
   - Update snapshots: `cd ghost && pnpm test:single test/e2e-api/admin/config.test.js -u && pnpm test:single test/e2e-api/admin/settings.test.js -u`
   - Review both snapshot diffs to confirm only your new flag was added.

## Notes

- No database migration is needed. Labs flags are stored in a single JSON `labs` setting.
- The flag name must be identical in `labs.js`, `private-features.tsx`, and the snapshots.
- Flags are camelCase strings (e.g. `welcomeEmailDesignCustomization`).
- For public beta flags (visible to all users), add to `PUBLIC_BETA_FEATURES` in `labs.js` instead and add the toggle to `apps/admin/src/settings/advanced/labs/beta-features.tsx`.