Isolate Lens - a Flutter screen checked for work that freezes the main isolate

Check one Flutter screen, view model or service for work that blocks the main isolate, then correct it. Free in your browser: every piece of I/O and CPU work mapped to the isolate it runs on, and sleep() and synchronous file I/O on the main isolate, CPU work inside build, Isolate.run results not awaited, closures that capture context or setState, spawn entry points that are instance methods, workers with no SendPort handshake, ReceivePorts never closed, isolates never killed, builders missing the error or waiting state and futures created inside build flagged - plus the skill's decision matrix applied to each operation, a checklist and CSVs. Metered runs write the review (each finding confirmed or cleared, what a scan cannot see, the fixes in order) and the whole corrected file, which the page re-scans. Built on the SkillSafe skill @flutter/flutter-handling-concurrency, from flutter/skills (BSD-3-Clause), by the Flutter team.