[dborgards]

What does this change?

The IsoTpChannel constructor catch detached the BackgroundExceptionOccurred handler before disposing an owned actor. It now disposes the owned actor first and unsubscribes afterwards, the order the J1939/J1939-TP constructors use since #446, so a shutdown-timeout report from a failing constructor is not dropped.

No regression test, deliberately, and the reasoning of #446 holds here: a throwing constructor never returns the channel, so nothing can subscribe to its BackgroundExceptionOccurred, and OnActorBackgroundException forwards to that empty subscriber list (RaiseBackgroundException). IProtocolActor can be injected, but an injected actor is not disposed here (_ownsActor), and the owned ProtocolActor is sealed with a plain event, so the order is observable only by reflecting on its delegate field from inside its Dispose -- an invasive seam. No mutation was run for that reason.

Not changed, noticed: IsoTpChannel.Dispose still unsubscribes before disposing the owned actor (with a comment giving its reason), unlike the J1939 Dispose paths. That is outside #447 and left alone.

Type of change

• feat - new behaviour (minor release)
• fix / perf - bug or performance fix (patch release)
• docs / test / refactor / chore / ci - no release
• Breaking change

Checklist

• Build with -p:CI=true (0 warnings, 0 errors), IsoTp tests (286, net10.0) and dotnet format --verify-no-changes pass locally. Pack not run (no csproj/props change).
• Public API changes are documented with XML comments (none)
• New behaviour is covered by a test (not deterministically possible without an invasive seam, see above)
• Related: J1939/J1939-TP: constructor failure paths unsubscribe before disposing the owned actor #442, fix(j1939): unsubscribe after the owned actor's Dispose in constructor failure paths #446

Closes #447

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Generated by Claude Code

[cursor]

PR Summary

Low Risk
Narrow change to the constructor error path only; aligns with an existing J1939 cleanup pattern and does not alter normal channel lifetime or Dispose behavior.

Overview
Constructor failure cleanup in IsoTpChannel now matches the J1939/J1939-TP pattern (#446): on Subscribe failure, an owned ProtocolActor is disposed before detaching BackgroundExceptionOccurred, so shutdown-timeout reports from actor teardown are not dropped because the handler was removed too early.

IsoTpChannel.Dispose is unchanged (still unsubscribes before disposing the owned actor); that ordering was intentionally left out of this fix.

^{Reviewed by Cursor Bugbot for commit e7bbd6d. Bugbot is set up for automated code reviews on this repo. Configure here.}

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-25T09:19:21.726120Z	e7bbd6d	PR opened

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