Function createFlagGuard

createFlagGuard(flag: string, options?: FlagGuardOptions): MiddlewareFunction
Creates a middleware function that guards a route based on a feature flag.

Resolves IFeatureFlags from the service registry per request, evaluates the flag, and either calls next() (flag on) or short-circuits to a redirect / 404 (flag off).

When the CAPABILITIES.FEATURE_FLAGS capability is unregistered, the registry's error propagates — the guard does not fail silently.
Parameters
- flag: string
  Flag name to evaluate.
- Optionaloptions: FlagGuardOptions
  Guard options (fallback URL, status code, context override).
Returns MiddlewareFunction
A middleware function.
Example
```
app.get('/dashboard', [
  createFlagGuard('new-dashboard', { fallback: '/old' }),
  () => c.text('New dashboard'),
]);
```
Throws
If CAPABILITIES.FEATURE_FLAGS is not registered.

Since
0.1.0
- Defined in packages/feature-flags-plugin/src/middleware/feature-flag-middleware.ts:40