3rd-party test and monitor result ingestion into Dynatrace Grail via the platform events ingest API (platform/ingest/custom/events/). Use when sending external synthetic test outcomes, CI monitor data, or third-party check results to Dynatrace. Covers token scope, full event schema for external_test_run and external_test_step (including dt.security_context, ci.*, trace correlation, and pipeline-added fields), curl and Java DTO examples, and DQL verification. Triggers: "ingest test results", "send monitor results", "third party monitor", "external test ingestion", "send synthetic results to Grail", "external test run event schema". Not for Dynatrace-native Synthetic Monitoring browser/HTTP checks, or RUM (use dt-obs-frontends). For migrating from the deprecated POST /api/v1/synthetic/ext/tests API, load dt-upgrade instead.