fix: backslash newlines when copying from a code block (#2709)

* fix: backslash newlines when copying from a code block

When copying inline content from inside a code block, the text/plain
clipboard payload had a backslash before every newline (markdown's
hard-break syntax) and the text/html had `<br>` separators inside the
code instead of literal newlines.

Two changes fix this:

- copyExtension routes selections inside a code block through the
  block-export path so the code block's own toExternalHTML produces
  the proper `<pre><code>` wrapper.
- serializeInlineContentExternalHTML now plumbs blockType through to
  inlineContentToNodes (mirroring the internal HTML serializer) so
  `\n` in code-block content stays as literal text instead of being
  split into hardBreak nodes that render as `<br>`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* fix: drop `as const` from PRETTIFY_OPTIONS to satisfy htmlfy types

`as const` typed `ignore` as a readonly tuple, which doesn't match
`UserConfig.ignore: string[]`, breaking CI typecheck.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* test: integrate code-block copy regression into existing copy test suite

Address PR review:
- Drop standalone codeBlockMarkdown.test.ts; add `codeBlockFullContent` and
  `codeBlockPartialSelection` cases to copyTestInstances.ts and snapshot
  text/plain markdown for all copy test instances via a new
  `Copy tests (Markdown)` describe block (mirrors the export test pattern).
- Trim verbose comments in copyExtension and serializeBlocksExternalHTML.
- copyPasteEquality executor now passes the actual markdown payload as the
  text/plain MIME instead of a literal "text" placeholder, so paste handlers
  that prefer text/plain (e.g. inside code blocks) round-trip correctly.
- Update mixedInParagraph snapshots: prettify's `ignore: ["code"]` preserves
  trailing whitespace inside `<code>` spans, which is the actual HTML output.

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nperez0111

packages/core/src/api/clipboard/toClipboard/copyExtension.ts

@@ -140,7 +140,18 @@ export function selectedFragmentToHTML<
     editor,
   );
 
-  const markdown = cleanHTMLToMarkdown(externalHTML);
+  // Code blocks are treated differently for copying: text/plain is the raw
+  // selected text instead of markdown.
+  const { $from, $to } = view.state.selection;
+  const parentBlockType = $from.parent.type.name;
+  const parentBlockSpec = editor.blockImplementations[parentBlockType as any];
+  const isPurelyInsideCodeBlock =
+    $from.sameParent($to) &&
+    parentBlockSpec?.implementation.meta?.code === true;
+
+  const markdown = isPurelyInsideCodeBlock
+    ? view.state.doc.textBetween($from.pos, $to.pos)
+    : cleanHTMLToMarkdown(externalHTML);
 
   return { clipboardHTML, externalHTML, markdown };
 }

packages/core/src/api/exporters/html/util/serializeBlocksExternalHTML.ts

@@ -37,17 +37,25 @@ export function serializeInlineContentExternalHTML<
   editor: BlockNoteEditor<any, I, S>,
   blockContent: PartialBlock<BSchema, I, S>["content"],
   serializer: DOMSerializer,
-  options?: { document?: Document },
+  options?: { document?: Document; blockType?: string },
 ) {
   let nodes: Node[];
 
   // TODO: reuse function from nodeconversions?
   if (!blockContent) {
     throw new Error("blockContent is required");
   } else if (typeof blockContent === "string") {
-    nodes = inlineContentToNodes([blockContent], editor.pmSchema);
+    nodes = inlineContentToNodes(
+      [blockContent],
+      editor.pmSchema,
+      options?.blockType,
+    );
   } else if (Array.isArray(blockContent)) {
-    nodes = inlineContentToNodes(blockContent, editor.pmSchema);
+    nodes = inlineContentToNodes(
+      blockContent,
+      editor.pmSchema,
+      options?.blockType,
+    );
   } else if (blockContent.type === "tableContent") {
     nodes = tableContentToNodes(blockContent, editor.pmSchema);
   } else {
@@ -262,7 +270,7 @@ function serializeBlock<
       editor,
       block.content as any, // TODO
       serializer,
-      options,
+      { ...options, blockType: block.type },
     );
 
     ret.contentDOM.appendChild(ic);

tests/src/unit/core/clipboard/copy/__snapshots__/text/html/codeBlockFullContent.html

@@ -0,0 +1,3 @@
+const a = 1;
+<br />
+const b = 2;

tests/src/unit/core/clipboard/copy/__snapshots__/text/html/codeBlockPartialSelection.html

@@ -0,0 +1,3 @@
+onst a = 1;
+<br />
+const b = 2

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/basicBlocks.md

@@ -0,0 +1,24 @@
+Paragraph 1
+
+# Heading 1
+
+1. Numbered List Item 1
+
+* Bullet List Item 1
+* [ ] Check List Item 1
+* Toggle List Item 1
+
+```text
+console.log("Hello World");
+```
+
+|              |              |
+| ------------ | ------------ |
+| Table Cell 1 | Table Cell 2 |
+| Table Cell 3 | Table Cell 4 |
+
+
+
+***
+
+Paragraph 2

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/basicBlocksWithProps.md

@@ -0,0 +1,24 @@
+Paragraph 1
+
+## Heading 1
+
+2. Numbered List Item 1
+
+* Bullet List Item 1
+* [x] Check List Item 1
+* Toggle List Item 1
+
+```typescript
+console.log("Hello World");
+```
+
+|              |              |
+| ------------ | ------------ |
+| Table Cell 1 | Table Cell 2 |
+| Table Cell 3 | Table Cell 4 |
+
+<figure><img alt="1280px-Placeholder_view_vector.svg.png" src="https://upload.wikimedia.org/wikipedia/commons/thumb/3/3f/Placeholder_view_vector.svg/1280px-Placeholder_view_vector.svg.png"><figcaption>Placeholder</figcaption></figure>
+
+***
+
+Paragraph 2

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/childToParent.md

@@ -0,0 +1,3 @@
+Paragraph 1
+
+Nested Paragraph 1

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/childrenToNextParent.md

@@ -0,0 +1,7 @@
+Nested Paragraph 1
+
+Nested Paragraph 2
+
+Nested Paragraph 3
+
+Paragraph 2

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/childrenToNextParentsChildren.md

@@ -0,0 +1,13 @@
+Nested Paragraph 1
+
+Nested Paragraph 2
+
+Nested Paragraph 3
+
+Paragraph 2
+
+Nested Paragraph 4
+
+Nested Paragraph 5
+
+Nested Paragraph 6

tests/src/unit/core/clipboard/copy/__snapshots__/text/plain/codeBlockFullContent.md

@@ -0,0 +1,2 @@
+const a = 1;
+const b = 2;