fix: provide plain text and markdown clipboard formats

[Oguzhan-Ozpinar]

Summary

• expose clean visible text as text/plain for every WYSIWYG selection
• preserve rich formatting as text/html and provide serialized Markdown as text/markdown
• prefer explicit text/markdown when pasting back into Scratch so formatting survives round trips
• leave Markdown source mode copy behavior unchanged
• normalize non-breaking-space entities in copied Markdown, including table selections

Fixes #137

Rationale

WYSIWYG copy now adapts to the destination: terminals and plain-text apps receive clean visible text, while rich-text and Markdown-aware destinations can preserve document structure. The paste preference is included to keep Scratch-to-Scratch copying lossless when the explicit Markdown representation is available.

Testing

• npm run build
• verified code blocks, nested code blocks, inline code, headings, lists, emphasis, and mixed selections
• verified rich-text paste in Apple Notes, Obsidian, Mail, and TextEdit
• verified plain-text paste contains no Markdown wrappers

Summary by CodeRabbit

• New Features
  • Improved editor copy and paste behavior across supported clipboard formats.
  • Copy now preserves HTML, plain text, and Markdown when available.
  • Pasting prioritizes Markdown clipboard content and provides a more reliable plain-text fallback.

[coderabbitai]

📝 Walkthrough

Walkthrough

The editor now serializes selected ProseMirror slices into HTML, plain text, and optional Markdown during copy, then prefers explicit Markdown clipboard data during paste.

Changes

Editor clipboard handling

Layer / File(s)	Summary
Copy serialization flow src/components/editor/Editor.tsx	Adds slice-to-Markdown serialization and custom copy handling that writes HTML, plain text, and optional Markdown clipboard data.
Paste format selection src/components/editor/Editor.tsx	Paste handling prefers text/markdown, skips pattern gating for explicit Markdown, and parses it through the markdown manager when available.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant Editor
  participant ProseMirrorView
  participant MarkdownManager
  participant Clipboard
  Editor->>ProseMirrorView: serializeForClipboard(selection)
  ProseMirrorView-->>Editor: slice, plain text, HTML DOM
  Editor->>MarkdownManager: serialize slice content
  MarkdownManager-->>Editor: Markdown text
  Editor->>Clipboard: set HTML, plain text, and optional Markdown

Loading

Possibly related PRs

• erictli/scratch#33: Modifies plain-text clipboard copying in the same editor file.
• erictli/scratch#115: Introduces overlapping clipboard Markdown serialization in the same editor file.

Suggested reviewers: erictli

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Out of Scope Changes check	⚠️ Warning	The paste-handling changes go beyond the linked copy-only issue and add new markdown paste behavior.	Move the paste behavior into a separate PR or add it to the linked issue's acceptance criteria.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The copy handler now emits clean text/plain for WYSIWYG selections, addressing issue #137's markdown-in-clipboard problem.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: improving clipboard output with plain text and Markdown formats.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[Oguzhan-Ozpinar]

Follow-up after testing:

My first commit intentionally special-cased selections inside inline code and code blocks, since the example in #137 is code-oriented. After trying that behavior, however, it felt inconsistent: Markdown syntax can also leak from headings, lists, emphasis, and mixed selections, while users copying from the WYSIWYG view generally expect the visible content rather than the editor source.

I have therefore revised the implementation to publish multiple clipboard representations for every WYSIWYG selection:

• text/plain: clean visible text, without Markdown wrappers
• text/html: rich formatting for Mail, Notes, and other rich-text destinations
• text/markdown: Markdown for Markdown-aware destinations and format-preserving round trips

The Markdown source editor remains unchanged and continues to copy literal Markdown. Paste also prefers text/markdown when the destination is Scratch and that representation is available.

This seems like the least surprising compromise to me: plain-text destinations such as terminals get clean text, while rich-text and Markdown-aware destinations can preserve structure. I tested it with code blocks, mixed headings/lists/emphasis, Apple Notes, Obsidian, Mail, TextEdit, and plain-text paste.

I think this is the most natural behavior, but I am very open to adjusting it based on maintainer preference and feedback from other users.

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@src/components/editor/Editor.tsx`:
- Around line 121-124: Update the slice serialization in getMarkdown to
normalize TipTap non-breaking-space entities by removing or replacing both
  and &`#160`; before returning Markdown. Preserve the existing serialized
content and ensure copied table-cell selections produce normalized text/markdown
consistent with the full-document path.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 30ef8de5-6b63-4634-8d4f-cf4ac47c2333

📥 Commits

Reviewing files that changed from the base of the PR and between badf314 and bc6c971.

📒 Files selected for processing (1)

• src/components/editor/Editor.tsx