fix(macos): guard SSE task against superseded session on MainActor race#25426
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…bytes(for:) PR #25396 introduced a race on MainActor: a second call to startSSEStream() (which happens on boot via MainWindowView+Lifecycle and GatewayConnectionManager both calling startSSE) invalidates the session and cancels the first Task before its body has executed. When that cancelled Task later runs and calls session.bytes(for:), NSURLSession throws an NSGenericException from -[__NSURLSessionLocal taskForClassInfo:], which is uncatchable in Swift and crashes the process with SIGABRT. Guard the Task body with `Task.isCancelled` and an identity check on `self.sseSession === session` before touching the session, so a superseded Task exits cleanly instead of exploding inside URLSession. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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This was referenced Apr 18, 2026
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Summary
URLSessionand invalidates the previous session at the top ofstartSSEStream(). That fixed an iterator-vs-invalidation EXC_BAD_ACCESS, but introduced a new crash: whenstartSSEStream()is called twice in rapid succession on MainActor (which happens on boot —MainWindowView+LifecycleandGatewayConnectionManagerboth callstartSSE), the second call invalidates the session and cancels the prior task before that task has run its first instruction. When the cancelled task finally runs and callssession.bytes(for:), NSURLSession throws an uncatchable ObjCNSGenericExceptionfrom-[__NSURLSessionLocal taskForClassInfo:], aborting the process (SIGABRT).guard !Task.isCancelled, self.sseSession === session else { return }at the top of the SSE task body inEventStreamClient.startSSEStream, so a superseded task exits cleanly instead of invokingbytes(for:)on an invalidated session.Original prompt
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