[turnipdabeets]

💡 Motivation and Context

Brings Flutter to parity with posthog-ios 4.0 (PostHogSDK.shared.onFeatureFlags(_:)) and posthog-android 4.0 (PostHog.onFeatureFlags(callback), PostHog/posthog-android#878). Until now Flutter only had PostHogConfig.onFeatureFlags, which is fixed at setup() and can't be removed.

final subscription = Posthog().onFeatureFlags((loaded) {
  if (loaded.variants['new-checkout'] == 'test') { /* ... */ }
});
subscription.unsubscribe();

Same semantics as iOS and Android:

• Runs after every load (startup, bootstrap, reloadFeatureFlags(), identify()/group()/reset()), with errorsLoading and the last known flags on failure.
• If flags already loaded, a new listener gets the current values once, shortly after registering. Skipped if a newer load reaches it first.
• Can register before setup() and survives close()/setup(). reset() and close() drop the cached load, so a new listener never gets the previous user's flags.

Implementation: a Dart-side registry (FeatureFlagsListeners, @internal). Each platform delivers to it next to the existing config callback: method channel (iOS/Android/macOS), desktop client (Windows/Linux), and posthog-js on web. No native changes, since native already forwards every load.

Web now registers its posthog-js onFeatureFlags listener even without config.onFeatureFlags, and unsubscribes it on close() and before re-registering on repeated setup(). Before, every setup() added another JS listener, so the config callback ran once per setup() call.

A throwing listener is logged and doesn't stop the others. Web skips registration when the page's posthog object has no onFeatureFlags (test stubs), instead of throwing during setup().

Stacked on #664 (needs PostHogFeatureFlagsLoaded).

💚 How did you test it?

• test/feature_flags_listeners_test.dart: delivery until unsubscribe, one replay, replay skipped when a newer load wins, no replay after clear, unsubscribe during delivery, a throwing listener.
• One wiring test per platform: method channel (posthog_flutter_io_test), desktop (posthog_flutter_desktop_test), web (posthog_flutter_web_setup_test, also covers repeated setup delivering once).
• posthog_test: no replay of flags loaded before reset() / close().
• Mutation-checked: removing the reset clear, the newer-load check, the desktop delivery, or the web re-setup unsubscribe each fails its test.
• flutter analyze clean, flutter test and flutter test --platform chrome test/posthog_flutter_web_setup_test.dart pass.

📝 Checklist

• All commits are signed (see Commit signing)
• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Claude Code wrote this while aligning the flags API across iOS 4, Android 4 and Flutter 6. Kept the listener in Dart instead of adding a native subscribe/unsubscribe channel method: native already pushes every load to Dart, so a Dart registry covers all five platforms with one implementation.

🤖 Generated with Claude Code

[posthog]

PostHog Review · Standard · reviewed 34d79f4: 2 Should fix.

See this review and its findings in PostHog Review. Comment @posthog review --deep for a Deep review. A Deep review takes longer and looks deeper than a Standard review.

[github-actions]

posthog-flutter Compliance Report

Date: 2026-10-30 16:30:49 UTC
Duration: 96883ms

✅ All Tests Passed!

45/45 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	144ms
Format Validation.Event Has Uuid	✅	119ms
Format Validation.Event Has Lib Properties	✅	116ms
Format Validation.Distinct Id Is String	✅	116ms
Format Validation.Token Is Present	✅	115ms
Format Validation.Custom Properties Preserved	✅	118ms
Format Validation.Event Has Timestamp	✅	117ms
Retry Behavior.Retries On 503	✅	5329ms
Retry Behavior.Does Not Retry On 400	✅	2119ms
Retry Behavior.Does Not Retry On 401	✅	2118ms
Retry Behavior.Respects Retry After Header	✅	8126ms
Retry Behavior.Implements Backoff	✅	15449ms
Retry Behavior.Retries On 500	✅	5226ms
Retry Behavior.Retries On 502	✅	5228ms
Retry Behavior.Retries On 504	✅	5227ms
Retry Behavior.Max Retries Respected	✅	15448ms
Deduplication.Generates Unique Uuids	✅	126ms
Deduplication.Preserves Uuid On Retry	✅	5225ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10337ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5231ms
Deduplication.No Duplicate Events In Batch	✅	125ms
Deduplication.Different Events Have Different Uuids	✅	117ms
Compression.Sends Gzip When Enabled	✅	117ms
Batch Format.Uses Proper Batch Structure	✅	114ms
Batch Format.Flush With No Events Sends Nothing	✅	108ms
Batch Format.Multiple Events Batched Together	✅	124ms
Error Handling.Does Not Retry On 403	✅	2116ms
Error Handling.Does Not Retry On 413	✅	2118ms
Error Handling.Retries On 408	✅	5225ms

Feature_Flags Tests

✅ 16/16 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	13ms
Request Payload.Flags Request Uses V2 Query Param	✅	10ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	10ms
Request Payload.Flags Request Omits Authorization Header	✅	10ms
Request Payload.Token In Flags Body Matches Init	✅	10ms
Request Payload.Groups Round Trip	✅	10ms
Request Payload.Groups Default To Empty Object	✅	10ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	✅	11ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	10ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	9ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	11ms
Request Lifecycle.No Flags Request On Init Alone	✅	4ms
Request Lifecycle.No Flags Request On Normal Capture	✅	113ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	19ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	10ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	116ms

[dustinbyrne]

The subscription API and ordinary delivery/replay paths look sound. Two dispatch-boundary cases remain: a config callback can restore an invalidated snapshot after reset/close, and a synchronous config-callback exception prevents runtime subscribers from receiving the load. Both reproduce through the public Dart API and IO channel harness.

AI-assisted review.

[posthog]

PostHog Review · Standard · reviewed d4105d9: 3 Should fix.

[dustinbyrne]

The previous web-loader, stale-native-notification and synchronous-replay findings are resolved in the focused regressions. Two runtime subscription routes remain incomplete: native auto-init does not activate the bridge when subscription is the first Dart operation, and Android manual reloads update neither subscribers nor their replay snapshot. Both reproduce independently; native 4.0 build availability remains a separate prerequisite.

AI-assisted review.