feat(error-tracking): standardize exception event metadata

[hpouillot]

💡 Motivation and Context

Standardize Android, JVM, server, and native crash exception events with the cross-SDK metadata contract. This makes severity, capture source, mechanism semantics, deterministic linkage, and reserved metadata ownership consistent.

Canonical contract: https://github.com/PostHog/sdk-specs/blob/main/openspec/specs/exception-event-metadata/spec.md

💚 How did you test it?

• Focused Gradle tests for core exception capture, native crash coercion, and the server SDK
• Spotless checks

📝 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 with pi from the shared OpenSpec contract. Nested causes and suppressed exceptions receive deterministic relationship metadata while callers retain control of custom fingerprints.

[github-actions]

posthog-android Compliance Report

Date: 2026-08-26 08:30:37 UTC
Duration: 118858ms

✅ All Tests Passed!

46/46 tests passed

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Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	418ms
Format Validation.Event Has Uuid	✅	39ms
Format Validation.Event Has Lib Properties	✅	38ms
Format Validation.Distinct Id Is String	✅	33ms
Format Validation.Token Is Present	✅	32ms
Format Validation.Custom Properties Preserved	✅	36ms
Format Validation.Event Has Timestamp	✅	31ms
Retry Behavior.Retries On 503	✅	7037ms
Retry Behavior.Does Not Retry On 400	✅	4043ms
Retry Behavior.Does Not Retry On 401	✅	4029ms
Retry Behavior.Respects Retry After Header	✅	7033ms
Retry Behavior.Implements Backoff	✅	17043ms
Retry Behavior.Retries On 500	✅	7022ms
Retry Behavior.Retries On 502	✅	7023ms
Retry Behavior.Retries On 504	✅	7024ms
Retry Behavior.Max Retries Respected	✅	17042ms
Deduplication.Generates Unique Uuids	✅	48ms
Deduplication.Preserves Uuid On Retry	✅	7017ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	12037ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	7023ms
Deduplication.No Duplicate Events In Batch	✅	52ms
Deduplication.Different Events Have Different Uuids	✅	30ms
Compression.Sends Gzip When Enabled	✅	28ms
Batch Format.Uses Proper Batch Structure	✅	28ms
Batch Format.Flush With No Events Sends Nothing	✅	20ms
Batch Format.Multiple Events Batched Together	✅	49ms
Error Handling.Does Not Retry On 403	✅	4024ms
Error Handling.Does Not Retry On 413	✅	4047ms
Error Handling.Retries On 408	✅	5036ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	44ms
Request Payload.Flags Request Uses V2 Query Param	✅	37ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	27ms
Request Payload.Flags Request Omits Authorization Header	✅	31ms
Request Payload.Token In Flags Body Matches Init	✅	29ms
Request Payload.Groups Round Trip	✅	34ms
Request Payload.Groups Default To Empty Object	✅	35ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	33ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	32ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	26ms
Request Lifecycle.No Flags Request On Init Alone	✅	13ms
Request Lifecycle.No Flags Request On Normal Capture	✅	31ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	60ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	27ms
Retry Behavior.Retries Flags On 502	✅	332ms
Retry Behavior.Retries Flags On 504	✅	332ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	30ms