Fix crash: stale code-block token cache after a programmatic content swap

[secondstagehq]

Crash

updateCodeBlockSelection cuts each fenced block's code out of the current text with ranges from cachedCodeBlockTokens:

code: nsText.substring(with: token.contentRange)

That cache is only refreshed by the typing/caret delegate paths. A programmatic content swap — a document switch, or the SwiftUI text binding changing externally — goes through rebuildTextStorageAndStyle, which never touches the cache. The deferred refresh in updateNSView:

DispatchQueue.main.async {
    context.coordinator.updateCodeBlockSelection(textView: textView)
}

then runs with no parsed, indexes the new (shorter) string with the previous document's ranges, and -[NSString substringWithRange:] throws NSRangeException. Uncaught ObjC exception in a main-queue dispatch block → abort(). We hit this in production (macOS app embedding the engine, document with a fenced code block replaced by shorter content via sync) — crash report points exactly at NativeTextViewCoordinator.updateCodeBlockSelection ← closure #7 in NativeTextViewWrapper.updateNSView. Reproduced in a unit test (included); still present on 0.12.0 (the file is unchanged).

Fix (two layers)

1. Root cause — rebuildTextStorageAndStyle already computes a parse of the incoming text; hand its codeBlockTokensWithIndices to the cache there (and clear the cache in raw source mode), so the deferred refresh always reads ranges parsed from the text it is shown with.
2. Defence in depth — updateCodeBlockSelection skips any cached block whose range/contentRange no longer fits the current text instead of substringing it, so no caller racing a content mutation can abort the process. The next parse re-delivers the block.

Includes a regression test suite (CodeBlockSelectionStaleCacheTests) that reproduces the abort on unpatched code and verifies both layers. Full package suite passes (298 tests).

The branch is based on the 0.11.0 tag (the version we ship); happy to rebase onto main if you prefer.

🤖 Generated with Claude Code