> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lucenthq.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Feature flag filters

> Filter Signals by the evaluated feature flags seen in each session.

Signals can filter sessions by feature flag values. Use this to compare a
release, experiment, or rollout against the rest of your traffic.

## How it works

Lucent reads evaluated flag values from session metadata. Values can come from:

* Lucent SDK user properties
* replay integrations that export feature flag metadata
* imported session metadata added by your application or provider

Lucent filters on the value attached to the session.

## Send flags with the Lucent SDK

Pass evaluated flag values into Lucent as user properties.

<Tabs>
  <Tab title="React">
    ```tsx theme={null}
    <LucentIdentify
      userId={user?.id}
      email={user?.email}
      properties={{
        featureFlags: {
          "new-checkout-flow": flags.newCheckoutFlow,
          "pricing-page-redesign": flags.pricingPageRedesign,
          "paywall-test": flags.paywallTest,
        },
      }}
    />
    ```
  </Tab>

  <Tab title="Vanilla JS">
    ```ts theme={null}
    tracker.identify({
      id: "user_123",
      email: "jane@example.com",
      properties: {
        featureFlags: {
          "new-checkout-flow": launchDarkly.variation("new-checkout-flow"),
          "pricing-page-redesign": statsig.checkGate("pricing-page-redesign"),
          "paywall-test": growthbook.getFeatureValue("paywall-test", "control"),
        },
      },
    });
    ```
  </Tab>
</Tabs>

## Filter in Signals

<Steps>
  <Step title="Open Signals">
    Go to **Signals** in the Lucent dashboard.
  </Step>

  <Step title="Add a feature flag filter">
    Choose a flag key and value, such as `new-checkout-flow = variant-a`.
  </Step>

  <Step title="Compare sessions">
    Review sessions and issues from the selected flag cohort.
  </Step>
</Steps>