fix(push): re-register the device token on opt-in (#675)

[dmarchuk]

Problem

The opt-in half of #675. After a logout unregisterPushNotificationToken() clears the stored device token, optIn() only flips consent back on. It never refetches the FCM token or re-registers the device, so a user who opts out and back in stays unsubscribed and Workflows can't target them until the next app launch re-runs registration (or onNewToken happens to fire).

Change

Adds an onOptIn() lifecycle hook to PostHogIntegration (default no-op). PostHog.optIn() now notifies every integration, mirroring how onRemoteConfig is dispatched. PostHogPushSubscriptionIntegration.onOptIn() refetches the FCM token and re-registers the device, reusing the same executor and token fetcher as install.

The push integration is only registered when capturePushNotificationSubscriptions is enabled, so the refetch is gated to auto-capture apps. Manual push mode is unchanged: the host owns the token lifecycle.

How tested

• Unit test: onOptIn refetches the token and re-registers the device (a second registration after install), in PostHogPushSubscriptionIntegrationTest.
• Emulator E2E against a local stack with a real FCM token (Firebase on the sample's classpath, adb reverse to the backend). The app auto-registered its FCM token on launch, opt out cleared it, then opt in refetched the FCM token and re-registered the device (POST /api/push_subscriptions, 200). Rebuilt with the opt-in dispatch disabled and the same opt-in produced no re-register.
• The iOS counterpart (fix(push): re-register the device token on opt-in (#746) posthog-ios#760) is confirmed the same way on a real device.

Not in this PR

The strand-the-unregister-DELETE half of #675 is fixed separately in #688. This PR is independent and targets main.

Note

Draft. Directed by @dmarchuk; implemented and verified locally by Claude while @ioannisj is out.

[github-actions]

posthog-android Compliance Report

Date: 2026-08-11 10:58:50 UTC
Duration: 118404ms

✅ All Tests Passed!

46/46 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	401ms
Format Validation.Event Has Uuid	✅	30ms
Format Validation.Event Has Lib Properties	✅	29ms
Format Validation.Distinct Id Is String	✅	23ms
Format Validation.Token Is Present	✅	24ms
Format Validation.Custom Properties Preserved	✅	23ms
Format Validation.Event Has Timestamp	✅	36ms
Retry Behavior.Retries On 503	✅	7029ms
Retry Behavior.Does Not Retry On 400	✅	4022ms
Retry Behavior.Does Not Retry On 401	✅	4025ms
Retry Behavior.Respects Retry After Header	✅	7025ms
Retry Behavior.Implements Backoff	✅	17033ms
Retry Behavior.Retries On 500	✅	7019ms
Retry Behavior.Retries On 502	✅	7017ms
Retry Behavior.Retries On 504	✅	7020ms
Retry Behavior.Max Retries Respected	✅	17021ms
Deduplication.Generates Unique Uuids	✅	38ms
Deduplication.Preserves Uuid On Retry	✅	7018ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	12031ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	7019ms
Deduplication.No Duplicate Events In Batch	✅	45ms
Deduplication.Different Events Have Different Uuids	✅	22ms
Compression.Sends Gzip When Enabled	✅	18ms
Batch Format.Uses Proper Batch Structure	✅	21ms
Batch Format.Flush With No Events Sends Nothing	✅	12ms
Batch Format.Multiple Events Batched Together	✅	32ms
Error Handling.Does Not Retry On 403	✅	4021ms
Error Handling.Does Not Retry On 413	✅	4020ms
Error Handling.Retries On 408	✅	5026ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	34ms
Request Payload.Flags Request Uses V2 Query Param	✅	26ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	20ms
Request Payload.Flags Request Omits Authorization Header	✅	27ms
Request Payload.Token In Flags Body Matches Init	✅	21ms
Request Payload.Groups Round Trip	✅	22ms
Request Payload.Groups Default To Empty Object	✅	23ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	23ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	27ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	21ms
Request Lifecycle.No Flags Request On Init Alone	✅	11ms
Request Lifecycle.No Flags Request On Normal Capture	✅	20ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	36ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	23ms
Retry Behavior.Retries Flags On 502	✅	323ms
Retry Behavior.Retries Flags On 504	✅	321ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	21ms

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
posthog/src/main/java/com/posthog/PostHogIntegration.kt:39
**Breaks integration interface compatibility**

When a Java consumer upgrades with a custom `PostHogIntegration`, the new method is abstract in the generated JVM interface, causing source compilation failures; previously compiled implementations encounter `AbstractMethodError` when `optIn()` dispatches the method and therefore miss the lifecycle notification.

### Issue 2
posthog/src/main/java/com/posthog/PostHog.kt:1106
**Logger failure escapes dispatch**

When a custom integration and the configured logger both throw, this direct logging call lets the secondary exception escape `optIn()` and prevents later integrations from receiving the notification; use the existing non-throwing `safeLog` helper here.

```suggestion
                safeLog("Failed to notify integration of opt-in: $e.")
```

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "chore: record onOptIn in posthog-android..." | Re-trigger Greptile}

[posthog]

🦔 ReviewHog reviewed this pull request

Found 0 must fix, 2 should fix, 2 consider.

Published 4 findings (view the review).

[posthog]

ReviewHog Alpha 🦔 If you find any issues helpful - please reply "valid", "invalid", etc., for evaluation purposes 🙏

[posthog]

ReviewHog Report

Changes

Issues: 4 issues

Files (5)

• .changeset/push-optin-reregister.md
• posthog-android/src/main/java/com/posthog/android/internal/PostHogPushSubscriptionIntegration.kt
• posthog/api/posthog.api
• posthog/src/main/java/com/posthog/PostHog.kt
• posthog/src/main/java/com/posthog/PostHogOptInReceiver.kt