fix(muya): remove the selected rest of a list or quote when a cut starts in it (#5385) - #5397

Closes #5385

Summary

Replacing a selection that starts inside a list or quote and ends in a block after it kept the selected rest of that list or quote. Backspace, typing, pasting over the selection and Cut are all affected. With Cut, those items were also on the clipboard, so Cut + Paste put them into the document twice.

A cross-block cut merges the text around the selection into the start block and calls removeBlocks(startBlock, endBlock) in packages/muya/src/clipboard/cut.ts. removeBlocks did two things:

• removed the siblings strictly between the start branch and the end branch, inside their lowest common container;
• pruned the end side with pruneAfterBranch.

Nothing handled the start side, so the blocks after the start leaf inside its own list item, list or quote stayed. The same gap kept a sub-list that a cut passes over inside a single list.

The new pruneBeforeBranch() is the start-side counterpart of pruneAfterBranch. Walking up from the start to the start branch, it removes the blocks that follow each node, as muyajs' removeBlocks did.

The walk starts at the whole block the start leaf belongs to (getAnchor()). That keeps two things intact:

• a code block's inner nodes, which share its json path, are never removed on their own (the Unexpected error with message Cannot insert into out of bounds index #4903 / Unexpected error with message Cannot pick up or remove undefined #5148 drift);
• a table's grid is never taken apart.

Steps to reproduce

Checked in the released MarkText 0.20.0-rc.2 (macOS), in a desktop build of develop @ e542262 and in a desktop build of this branch, with real mouse, keyboard and menu input.

1. Open a document with:

   - a
   - b
   - c
   
   tail

2. Click right after a and press Shift+↓ three times. The selection runs to the end of tail.
3. Press Backspace. For the Cut variant, choose Edit › Cut instead, then click after a, press Enter twice and choose Edit › Paste.

For the quote, use > a / > / > b / (blank line) / tail and press Shift+↓ twice.

Type of change

• Bug fix (non-breaking, fixes an issue)
• New feature (non-breaking, adds functionality)
• Breaking change (causes existing functionality to change)
• Documentation update

Test plan

• New unit tests in clipboard/__tests__/cutRestOfContainer5385.spec.ts (7 cases). Each checks the markdown and that the json state matches the block tree. All 7 fail on develop. The cases:
  • the rest of a bullet list;
  • the rest of a quote;
  • the rest of every list the start is nested in;
  • a paragraph and a code block after the start in its list item;
  • a sub-list passed over inside one list;
  • a cut ending in another list;
  • a cut from a nested language line (Code block no longer be input #918).
• New e2e spec editing/cut-rest-of-container-5385.spec.ts: Backspace over the list selection and typing over the quote selection, with the real keyboard. It fails on develop and passes with the fix (3/3 repeated).
• Related e2e specs pass (28 tests): the Unexpected error with message Cannot insert into out of bounds index #4903 / [Bug] Cutting from a nested code block's language box replaces the whole list or quote #5368 / [Bug] Cutting a selection that ends in a code block's language box duplicates text and removes the language box #5371 cut specs, clipboard, selection, table-rect-clipboard and undo-redo.
• Real desktop app (Playwright _electron): the table above, on the packaged 0.20.0-rc.2, a build:unpack of develop and a build:unpack of this branch.
• muya: vitest run 1682 tests; lint:types, eslint on the changed files and check-circular pass.
• Manually tested on: macOS

Notes for reviewers

• Out of scope: a cut that ends inside a table (removeBlocksIntoTable) or starts inside a table cell goes through separate code. Neither is changed here.
• Pasted - line: the empty - line in the pasted content comes from copying a selection that starts at the end of a. It is the same before and after this change.

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

🤖 Generated with Claude Code

https://claude.ai/code/session_01WEPLCvFTgbYf35z85XUJop