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Add a persistent $device_id that survives identify() and reset() calls, enabling stable device-level feature flag bucketing across identity changes. The device ID is seeded from the anonymous ID on first init and sent in /flags request payloads.
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posthog-android Compliance ReportDate: 2026-04-09 18:05:12 UTC ✅ All Tests Passed!0/0 tests passed |
marandaneto
reviewed
Apr 9, 2026
| getPreferences().setValue(DISTINCT_ID, value) | ||
| } | ||
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| private fun initDeviceId() { |
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doing the same as getDeviceId
should we just call getDeviceId instead?
marandaneto
reviewed
Apr 9, 2026
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| val deviceId = getPreferences().getValue(DEVICE_ID) as? String | ||
| if (deviceId.isNullOrBlank()) { | ||
| // Lazy init for upgrades: existing installs won't have a device_id yet | ||
| val anonId = anonymousId | ||
| if (anonId.isNotBlank()) { | ||
| getPreferences().setValue(DEVICE_ID, anonId) | ||
| return anonId | ||
| } | ||
| return "" | ||
| } |
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we should use a lock here similar to anonymousLock
- Remove initDeviceId() and call getDeviceId() during setup instead, since they do the same thing - Add deviceIdLock to synchronize getDeviceId() for thread safety, matching the pattern used by anonymousLock
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Summary
$device_idto the Android SDK for stable device-level feature flag bucketing across identity changesidentify()andreset()calls, and is sent in/flagsrequest payloadsProblem
Users running experiments targeting anonymous users see variant assignments flip when
identify()orreset()changes thedistinct_id. The hash changes, causing a different bucket and different variant for the same physical device.Changes
PostHogPreferences: AddDEVICE_IDconstant and include inALL_INTERNAL_KEYSPostHogFlagsRequest: Add optionaldeviceIdparameter, serialized as$device_idPostHogApi.flags(): ThreaddeviceIdparameter toPostHogFlagsRequestPostHogRemoteConfig: ReaddeviceIdfromcachePreferencesinexecuteFeatureFlags()and pass to APIPostHog.kt:initDeviceId()— seeds device_id from anonymous ID on first setupreset()— preservesDEVICE_IDacross resets (alongsideVERSIONandBUILD)getDeviceId()— public method with lazy-init fallback for SDK upgradesPostHogInterface: AddgetDeviceId()to public API surfaceTest plan
PostHogFlagsRequestTesttests (includes/excludes device_id)PostHogTesttests (init, persistence, identify/reset preservation, flags payload, lazy-init upgrades)