[gtokman]

Summary

Prevent synchronous Markdown rendering from aborting during helper teardown on older Swift runtimes, extending the lifetime fix in #16.

Problem

BlockProcessor, TextBuilder, and ReusableViewProvider still receive implicit isolated deinitializers under the package's default MainActor isolation. Releasing them synchronously outside a Swift task can enter swift_task_deinitOnExecutorMainActorBackDeploy → swift_task_deinitOnExecutorImpl → TaskLocal::StopLookupScope and abort with “pointer being freed was not allocated.” This matches Swift issue #88036.

The unmodified library reproduced this crash independently for all three classes on the iOS 26.2 simulator.

Solution

Add explicit empty nonisolated deinit implementations to those three classes, preserving MainActor isolation for their rendering operations. Extend the existing synchronous task-local lifetime tests to cover each helper and complete full/incremental renders, including release of the owned view provider.

Validation

• swift test --filter RenderingLifetimeTests: seven tests passed on macOS.
• SwiftPM build of the MarkdownView target for the iOS simulator passed.
• Linked a standalone synchronous harness against the actual iOS library, using the seven lifetime test bodies with precondition assertions: all seven passed on iOS 26.2, with 100 iterations per case.
• Original-source comparison harness reproduced SIGABRT independently in each of the three helper deinitializers; crash reports contained the same invalid-free / task-local / isolated-deinit stack.
• git diff --check passed. No xcodebuild or full app build was run.

The consuming app's dependency pin must be updated separately after this fix is available.

CI follow-up

The initial Swift workflow compiled successfully but failed two existing highlighting assertions: their Python/Swift grammars are optional and excluded from the default package traits. Use JavaScript fixtures for those tests and the highlight-cache test, and require a nonempty map before checking cache reuse. This preserves highlighting coverage under the default configuration.

Validation after the fixture correction: swift build and the full swift test suite pass locally (166 tests, zero failures).

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Project	Deployment	Actions	Updated
markdown-view	Ready	Preview, v0	Oct 19, 2026 4:54pm UTC