fix(editor): preserve inline boundary typing sessions

[murongg]

Summary

• retain explicit inside/outside affinity when desktop WebViews overwrite the ProseMirror boundary selection
• preserve inside affinity across consecutive characters while remapping and revalidating live Markdown ranges
• restore the captured selection and stored marks before native IME composition starts
• leave intermediate IME composition text under native ProseMirror/WebView control and apply only the final commit
• clear stale affinity when arrows cross delimiters or live syntax becomes invalid
• take over only cancelable, non-composing insertText events and keep native RTL/bidi navigation
• cover finalized and live **, ***, ~~, inline-code, and IME boundary cases with English synthetic tests

Why

This is a follow-up to #419 and #510. Real macOS WebKit and Windows WebView2 can restore a DOM selection after ProseMirror has assigned mark affinity, causing boundary input to intermittently move outside the wrapper, change sides after the first character, or start native IME composition on the wrong side. Handling intermediate composition text directly can also duplicate phonetic input and lose the caret.

Validation

• pnpm --filter @markra/app test — 116 files and 1807 tests passed
• pnpm --filter @markra/editor build — passed
• pnpm --filter @markra/app build — passed
• pnpm --filter @markra/desktop build — passed, including vendor chunk verification
• git diff --check — passed

Risk

• Only composition that starts with a captured formatted-boundary intent receives the corrected selection and marks; intermediate IME text remains native.
• Non-cancelable input and RTL/bidi arrow navigation intentionally fall back to native ProseMirror/WebView behavior.
• Manual macOS and Windows WebView QA is still required because jsdom cannot reproduce native candidate UI, DOM mutation timing, caret restoration, or every selection event ordering.

Refs #419

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Project	Deployment	Actions	Updated (UTC)
markra-web	Ready	Preview, Comment	Jul 11, 2026 12:09pm

[murongg]

Closing this follow-up because native macOS and Windows WebView testing still reproduces the boundary and Chinese IME failures. The merged #510 changes are being reverted in #518.

[murongg]

Reopened per clarification: keep this PR available for continued investigation. Only the previously merged #510 changes were reverted from main by #518; this PR and its branch remain intact.