[gtokman]

Summary

Avoid the isolated-deinitializer back-deployment path when synchronous Markdown rendering releases ListProcessor and its owned InlineAttributeCache.

Problem

Production SIGABRT stacks during assistant-message and plan-preview rendering show nested destruction of these classes through swift_task_deinitOnExecutorMainActorBackDeploy, ending in swift::TaskLocal::StopLookupScope and an invalid free. Both classes inherit the target's default MainActor isolation and have implicit destructors.

Solution

Add explicit empty nonisolated deinit implementations to both classes. Their rendering APIs retain MainActor isolation; the destructors contain no actor-dependent cleanup. Add synchronous lifetime tests for direct cache release and processor/owned-cache release inside a task-local scope.

Validation

• Swift 6.4 optimized iOS and macOS code generation in a reduced harness: executor-deinit calls are present in both original destructors and absent with this change.
• Reduced macOS harness passes 100 synchronous nested releases and task-local restoration checks. The original also passes on this runtime, so this is not a reproduction of the production crash.
• Full changed MarkdownView source and new tests type-check using direct Swift 6.3.3 compiler and existing dependency modules, with a matching Litext module emitted from source.
• Parsing and diff checks pass. Full package tests and affected-device verification remain outstanding.

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Project	Deployment	Actions	Updated
markdown-view	Ready	Preview, v0	Oct 16, 2026 5:29pm UTC