fix: use uuid v7 for personless ids

[marandaneto]

💡 Motivation and Context

SDK-generated IDs should use UUID v7 where possible for time-ordered identifiers. A couple of personless distinct ID fallback paths still used random UUID v4 generation, and the event UUID documentation still referred to v4 even though event UUIDs are already v7.

💚 How did you test it?

./gradlew :posthog:test --tests com.posthog.PostHogStatelessTest --tests com.posthog.vendor.uuid.UUIDTest :posthog-server:test --tests com.posthog.server.PostHogRequestContextTest
pnpm changeset status --since origin/main

📝 Checklist

• 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)

Implemented the requested UUID v7 migration for the remaining runtime SDK-generated personless distinct IDs. Reused the existing TimeBasedEpochGenerator.generate() helper instead of adding a new dependency, and kept test-only arbitrary UUID.randomUUID() usages unchanged.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "fix: use uuid v7 for personless ids" | Re-trigger Greptile}

[github-actions]

posthog-android Compliance Report

Date: 2026-06-19 10:44:43 UTC
Duration: 119799ms

⚠️ Some Tests Failed

38/45 tests passed, 7 failed

---

Capture Tests

⚠️ 28/29 tests passed, 1 failed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	381ms
Format Validation.Event Has Uuid	✅	38ms
Format Validation.Event Has Lib Properties	✅	39ms
Format Validation.Distinct Id Is String	✅	29ms
Format Validation.Token Is Present	✅	29ms
Format Validation.Custom Properties Preserved	✅	28ms
Format Validation.Event Has Timestamp	✅	33ms
Retry Behavior.Retries On 503	✅	7027ms
Retry Behavior.Does Not Retry On 400	✅	4023ms
Retry Behavior.Does Not Retry On 401	✅	4025ms
Retry Behavior.Respects Retry After Header	✅	7026ms
Retry Behavior.Implements Backoff	✅	17035ms
Retry Behavior.Retries On 500	✅	7018ms
Retry Behavior.Retries On 502	✅	7023ms
Retry Behavior.Retries On 504	✅	7019ms
Retry Behavior.Max Retries Respected	✅	17036ms
Deduplication.Generates Unique Uuids	✅	44ms
Deduplication.Preserves Uuid On Retry	✅	7018ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	12022ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	7019ms
Deduplication.No Duplicate Events In Batch	✅	37ms
Deduplication.Different Events Have Different Uuids	✅	27ms
Compression.Sends Gzip When Enabled	✅	18ms
Batch Format.Uses Proper Batch Structure	✅	19ms
Batch Format.Flush With No Events Sends Nothing	✅	12ms
Batch Format.Multiple Events Batched Together	✅	32ms
Error Handling.Does Not Retry On 403	✅	4018ms
Error Handling.Does Not Retry On 413	❌	4016ms
Error Handling.Retries On 408	✅	5028ms

Failures

error_handling.does_not_retry_on_413

Expected 1 requests, got 2

Feature_Flags Tests

⚠️ 10/16 tests passed, 6 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	❌	31ms
Request Payload.Flags Request Uses V2 Query Param	✅	20ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	23ms
Request Payload.Flags Request Omits Authorization Header	✅	23ms
Request Payload.Token In Flags Body Matches Init	✅	19ms
Request Payload.Groups Round Trip	✅	19ms
Request Payload.Groups Default To Empty Object	❌	27ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	❌	29ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	❌	29ms
Request Payload.Disable Geoip Omitted Defaults To False	❌	26ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	❌	37ms
Request Lifecycle.No Flags Request On Init Alone	✅	13ms
Request Lifecycle.No Flags Request On Normal Capture	✅	41ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	2034ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	25ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	22ms

Failures

request_payload.request_with_person_properties_device_id

Expected distinct_id='test_user_123', got '019edf7b-9e34-7d06-af4d-9601e118635d'

request_payload.groups_default_to_empty_object

Field 'groups' not found in /flags request body at path 'groups'. Available keys: ['$anon_distinct_id', '$device_id', 'api_key', 'distinct_id', 'timezone', 'person_properties']

request_payload.person_properties_distinct_id_auto_populated_when_caller_omits_it

Field 'distinct_id' not found in /flags request body at path 'person_properties.distinct_id'. Available keys: ['$lib', '$lib_version', 'email']

request_payload.disable_geoip_false_propagates_as_geoip_disable_false

Field 'geoip_disable' not found in /flags request body at path 'geoip_disable'. Available keys: ['$anon_distinct_id', '$device_id', 'api_key', 'distinct_id', 'timezone', 'person_properties']

request_payload.disable_geoip_omitted_defaults_to_false

Field 'geoip_disable' not found in /flags request body at path 'geoip_disable'. Available keys: ['$anon_distinct_id', '$device_id', 'api_key', 'distinct_id', 'timezone', 'person_properties']

request_payload.flag_keys_to_evaluate_contains_only_requested_key

Field 'flag_keys_to_evaluate' not found in /flags request body at path 'flag_keys_to_evaluate'. Available keys: ['$anon_distinct_id', '$device_id', 'api_key', 'distinct_id', 'timezone', 'person_properties']