vercel__flags/packages/adapter-posthog/CHANGELOG.md

@flags-sdk/posthog

1.0.1

Patch Changes

• #452 58e1f5b Thanks @luismeyer! - Replace @vercel/edge-config with @vercel/global-config.

  Rename the Edge Config adapter package to @flags-sdk/global-config and rename repository-owned Edge Config files, exports, types, options, variables, and environment variables to Global Config.

  The previous Edge Config names remain available as deprecated aliases, and the previous environment variables are still honored as fallbacks, so existing code keeps working without changes.

1.0.0

Major Changes

• #436 aec3c03 Thanks @dferber90! - Modernize the PostHog adapter. This release is breaking in five ways:

  • Environment variables were renamed. NEXT_PUBLIC_POSTHOG_KEY → POSTHOG_PROJECT_API_KEY and NEXT_PUBLIC_POSTHOG_HOST → POSTHOG_HOST.
  • Local vs. remote evaluation is now an explicit choice. The default adapter evaluates remotely unless you set POSTHOG_SECRET_KEY.
  • The three adapter methods collapsed into a single callable adapter. isFeatureEnabled() / featureFlagValue() / featureFlagPayload() become postHogAdapter and postHogAdapter.payload.
  • A flag's key is used as the PostHog flag key verbatim. The old "read until the first ." convention is gone.
  • The per-call sendFeatureFlagEvents option and the featureFlagPayload getValue mapper are removed.

  It also upgrades posthog-node from v4.11.1 to v5.45.0 (which raises the required Node.js version), adds bulk evaluation support, drops posthog-node's runtime deprecation warnings, and removes the unused @vercel/edge-config dependency.

  This release requires flags@^4.2.0, which is where the uninvoked-adapter shorthand and bulk evaluation landed.

  Environment variables

  The adapter runs server-side only, so its credentials were never meant to be exposed to the browser. The NEXT_PUBLIC_ prefixed variables are renamed accordingly, and the project API key variable now says which key it wants:

  - NEXT_PUBLIC_POSTHOG_KEY=phc_...
  - NEXT_PUBLIC_POSTHOG_HOST=https://us.i.posthog.com
  + POSTHOG_PROJECT_API_KEY=phc_...
  + POSTHOG_HOST=https://us.i.posthog.com
  

  POSTHOG_HOST is also what getProviderData derives the app host from, and POSTHOG_PERSONAL_API_KEY / POSTHOG_PROJECT_ID are unchanged.

  Explicit local vs. remote evaluation

  Previously the default postHogAdapter passed POSTHOG_PERSONAL_API_KEY into the runtime posthog-node client. When that variable was set, this enabled local evaluation and started a feature-flag poller in every warm server process — on serverless that could generate a large, traffic-independent volume of PostHog feature flag requests, as a side effect of a credential you may only have set for the Flags Explorer.

  The default adapter now evaluates flags remotely unless you opt in to local evaluation by setting POSTHOG_SECRET_KEY (a phs_... project secret key). When set, posthog-node polls flag definitions and evaluates flags in-process. When using createPostHogAdapter, control it explicitly via postHogOptions (secretKey + enableLocalEvaluation).

  POSTHOG_PERSONAL_API_KEY continues to be used only by getProviderData (Flags Explorer discovery) and no longer affects runtime evaluation.

  Single callable adapter

  The three adapter methods (isFeatureEnabled, featureFlagValue, featureFlagPayload) are collapsed into a single callable adapter, matching @flags-sdk/vercel. Pass it uninvoked or invoked, and use .payload for a flag's attached payload:

  // before
  import { postHogAdapter } from "@flags-sdk/posthog";
  
  flag({ key: "my-flag", adapter: postHogAdapter.isFeatureEnabled() });
  flag({ key: "my-flag", adapter: postHogAdapter.featureFlagValue() });
  flag({
    key: "my-flag",
    adapter: postHogAdapter.featureFlagPayload((v) => v),
  });
  
  // after
  import { postHogAdapter } from "@flags-sdk/posthog";
  
  flag({ key: "my-flag", adapter: postHogAdapter }); // or postHogAdapter()
  flag({ key: "my-flag", adapter: postHogAdapter.payload }); // or .payload()
  

  isFeatureEnabled and featureFlagValue merged into the value adapter, which returns whatever PostHog evaluated the flag to: a boolean for a boolean flag, the variant string for a multivariate flag. Type the flag (flag<boolean>, flag<string>) to describe the value you expect.

  Note that isFeatureEnabled used to coerce a multivariate flag's variant to true. Nothing coerces now, so a flag that previously read true via isFeatureEnabled will read e.g. 'variant-a'. Declaring flag<boolean> only changes the TypeScript type — if you relied on the boolean, narrow the value in your own decide or at the call site.

  A flag's key is now used as the PostHog feature flag key verbatim. The previous convention of trimming everything after the first . (so my-flag.variant read the PostHog flag my-flag) has been removed; use the exact PostHog flag key as your flag key.

  Upgraded posthog-node, migrated to evaluateFlags, added bulk evaluation

  posthog-node is upgraded from v4.11.1 to v5.45.0. Internally the adapter now uses its evaluateFlags instead of the deprecated isFeatureEnabled / getFeatureFlag / getFeatureFlagPayload methods, removing the deprecation warnings those log at runtime.

  The adapter also implements bulkDecide, so evaluate() resolves flags that share an identify source through a single evaluateFlags call — one /flags request when evaluating remotely, one in-process evaluation when evaluating locally. Flag values and flag payloads are batched separately, so a flag and its payload still resolve through two calls.

  The per-call sendFeatureFlagEvents option and the featureFlagPayload getValue mapper are removed (neither has an evaluateFlags equivalent); map payloads in your own flag code instead.

  Node.js version requirement

  posthog-node@5.45.0 requires Node.js ^20.20.0 || >=22.22.0, and this adapter now declares the same engines constraint.

  Removed @vercel/edge-config dependency

  The adapter never used it. It is dropped from dependencies (and from the package keywords), so installs no longer pull it in.

0.2.2

Patch Changes

• 5f3757a: drop tsconfig dependency

0.2.1

Patch Changes

• ff052f0: upgrade internal @vercel/edge-config dependency to v1.4.3

0.2.0

Minor Changes

• 5586443: List flags includes inactive ones to discover all flags

0.1.0

Minor Changes

• 44bada7: Publish PostHog adapter

0.1.0

Minor Changes

• postHogAdapter: Default adapter is available
• postHogAdapter.isFeatureEnabled: Check if a feature flag is enabled
• postHogAdapter.featureFlagValue: Get the value of a feature flag
• postHogAdapter.featureFlagPayload: Get the payload of a feature flag
• postHogAdapter.client: Access the PostHog client