fix: Strip breadcrumb metadata on OOM to prevent silent event loss

[spawnia]

Fixes getsentry/sentry-laravel#909

When an out-of-memory error occurs with large breadcrumbs (e.g. 100 SQL queries with ~100KB bindings each), the event is silently lost. Serialization needs ~15MB of working memory but only 5MB headroom is available after ErrorHandler raises the limit. The secondary OOM during json_encode is caught by invokeListeners() and discarded.

This fix detects OOM in FatalErrorListenerIntegration and strips breadcrumb metadata before capture — freeing the bulk of the memory while preserving the full breadcrumb trail (type, category, timestamp, message) for debugging.

Design decisions

Why strip metadata instead of clearing all breadcrumbs? The breadcrumb timeline (which queries ran, in what order) is valuable for diagnosing OOM. The metadata (SQL bindings, HTTP bodies) is what carries the bulk (~99% of size) and is rarely needed for OOM diagnosis.

Why in the integration, not ErrorHandler or PayloadSerializer? The integration already has access to the exception message for OOM detection. Putting it in ErrorHandler would couple the low-level handler to Hub/Scope. Catching OOM in the serializer is unreliable since PHP's nested try/catch behavior during OOM is fragile.

Why modify the scope directly instead of using an event processor? The scope's breadcrumb objects hold references to the large metadata strings. These must be freed from PHP's heap before serialization to make room. An event processor runs after applyToEvent copies breadcrumbs to the event — by then the scope still holds the originals in memory and the headroom is already consumed.

Why add Scope::getBreadcrumbs()? We need to read the breadcrumbs to build stripped copies before clearing. The scope had no getter — addBreadcrumb and clearBreadcrumbs existed but you couldn't iterate the collection.

🤖 Generated with Claude Code

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[stayallive]

We might in the future want to take a look at modifying or walking breadcrumbs to make this a bit more efficient but with our current API constraints this is a pretty good idea actually. Much appreciate you taking the time to figure this out and create a cool solution!