flag-prerequisites

Add, remove, or inspect feature-level prerequisites on a GrowthBook feature flag. A feature-level prerequisite is a boolean gate: if the specified prerequisite flag is off for a user, the current flag skips all its rules and returns its defaultValue for that user.

Feature-level prerequisites are boolean-flag-only. The prerequisite flag must have valueType: "boolean". The gate condition is always "prerequisite flag is on" ({"value": true}) — no custom conditions. If the user wants a more nuanced dependency (e.g. gate on a string flag's value, or gate a single rule rather than the whole flag), route to flag-targeting.

This is distinct from rule-level prerequisites (which gate a single rule and support richer conditions) — feature-level prerequisites apply to every rule on the flag simultaneously.

All API calls go through the bundled helper: ${CLAUDE_PLUGIN_ROOT}/scripts/gb-call. It needs GB_API_KEY set in env or written to ~/.config/growthbook/.env by /growthbook:gb-setup.

Workflow

Path A — Add a prerequisite

Fetch the flag's current prerequisites:
```
gb-call GET /api/v2/features/<flag-id>
```
Capture the existing prerequisites array. The PUT below replaces the full array, so you need the current contents to avoid overwriting existing prerequisites.