feat(session-replay): embed crash event breadcrumbs into replay recordings#1875
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`sentry__value_from_msgpack` decodes a buffer holding a single value to that bare value, so consumers of append-only files like the breadcrumb ring files had to wrap single objects manually. Add `sentry__value_from_msgpack_stream` which always returns a list and use it in the crash daemon's breadcrumb ring reader.
Convert the breadcrumbs carried by the crash event that fall inside the replay window into rrweb `breadcrumb` custom events and append them to the `replay_recording` payload, matching how the Cocoa and Android SDKs surface breadcrumbs on the replay timeline. The breakpad and inproc backends already pass a crash event with scope breadcrumbs applied, so they pick this up without further changes.
The crashpad handler applies the scope to the crash event without breadcrumbs since those are streamed to the `__sentry-breadcrumb1/2` ring files on the hot path. Read and merge the ring files onto the in-memory crash event before flushing the staged session replay, so the replay recording can embed them. The on-disk `__sentry-event` and the regular crash delivery path are unaffected.
The crash event the daemon re-reads from `__sentry-event` for the session replay flush is scope-applied without breadcrumbs; those only get merged from the `__sentry-breadcrumb1/2` ring files into the in-memory event used for the crash envelope. Apply the same merge to the replay flush copy so the replay recording can embed the breadcrumbs.
The example already adds three breadcrumbs in its default setup before crashing, so extend the shared replay envelope assertion to verify they are embedded in the recording as rrweb `breadcrumb` custom events with correct payload fields, ms/s timestamp duality, replay window bounds, and chronological ordering. Covers the crashpad, breakpad, inproc and native daemon backends via the existing replay tests.
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tustanivsky
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to getsentry/sentry-unreal
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Jul 16, 2026
Temporary pin to getsentry/sentry-native#1875 so CI builds binaries that embed breadcrumbs into crash replay recordings; revert to a tagged release once it ships.
jpnurmi
reviewed
Jul 16, 2026
mujacica
approved these changes
Jul 17, 2026
Now that stream consumers use sentry__value_from_msgpack_stream, the implicit wrap-multiple-values-in-a-list behavior only obscures misuse. Require a single value spanning the whole buffer and decode the breadcrumb ring files in report_to_envelope with the stream variant, which also stops dropping breadcrumbs when a ring file holds a single entry.
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jpnurmi
reviewed
Jul 17, 2026
The handler runs in-process, so the scope ring buffer is available directly - no need to read the ring files back; those remain for the out-of-process daemon and next-launch report processing. This also matches how breakpad and inproc get breadcrumbs onto crash events.
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This PR adds breadcrumbs to session replay recordings: breadcrumbs carried by the crash event that fall inside the replay window are converted into rrweb
breadcrumbcustom events and embedded into thereplay_recordingpayload, matching how the Cocoa and Android SDKs surface breadcrumbs on the replay timeline.Key changes
sentry__value_from_msgpack_streamdecodes append-only msgpack streams (like the breadcrumb ring files) into a list even when the buffer holds a single value; the crash daemon's ring-file reader andreport_to_envelopenow use it.sentry__value_from_msgpackrejects buffers holding concatenated values instead of implicitly wrapping them in a list, so each call site declares its intent. This also fixesreport_to_envelopedropping breadcrumbs when a ring file holds exactly one entry.sentry__session_replay_flush_pendingembeds the crash event's in-window breadcrumbs into the rrweb recording as type-5 custom events withtag: "breadcrumb"(outer timestamps in ms, payload timestamps in seconds, chronological order). The breakpad and inproc backends pick this up without further changes since their crash event already carries the scope breadcrumbs.__sentry-breadcrumb1/2ring files onto the in-memory crash event before flushing the staged replay; the on-disk__sentry-eventand the regular crash delivery path are unaffected.__sentry-eventsnapshot is scope-applied without breadcrumbs).Testing
value_from_msgpack_streamunit test.