From b5924ffa993196b6df1d121519bc54917f973651 Mon Sep 17 00:00:00 2001
From: Naiyuan Qing <145280634+NevilleQingNY@users.noreply.github.com>
Date: Fri, 3 Apr 2026 11:17:03 +0800
Subject: [PATCH] fix(editor): reliable markdown paste and inline code line
 spacing
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Markdown paste: replace heuristic-based detection with a single
deterministic check — only use HTML clipboard path when source is
another ProseMirror editor (identified by data-pm-slice attribute).
All other pastes (VS Code, text editors, terminals, .md files) parse
text/plain as Markdown via @tiptap/markdown.

Inline code: add box-decoration-break: clone and line-height: 2 so
multi-line inline code renders with proper spacing between lines.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 apps/web/features/editor/content-editor.css   |  3 ++
 .../editor/extensions/markdown-paste.ts       | 34 +++++++++++++------
 2 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/apps/web/features/editor/content-editor.css b/apps/web/features/editor/content-editor.css
index b6e7ed16..697771a7 100644
--- a/apps/web/features/editor/content-editor.css
+++ b/apps/web/features/editor/content-editor.css
@@ -125,6 +125,9 @@
   color: color-mix(in srgb, var(--foreground) 75%, transparent);
   padding: 0.125rem 0.375rem;
   border-radius: var(--radius-sm);
+  box-decoration-break: clone;
+  -webkit-box-decoration-break: clone;
+  line-height: 2;
 }
 
 /* Code blocks */
diff --git a/apps/web/features/editor/extensions/markdown-paste.ts b/apps/web/features/editor/extensions/markdown-paste.ts
index fc549e8f..7dde1fb9 100644
--- a/apps/web/features/editor/extensions/markdown-paste.ts
+++ b/apps/web/features/editor/extensions/markdown-paste.ts
@@ -11,17 +11,29 @@ export function createMarkdownPasteExtension() {
         new Plugin({
           key: new PluginKey("markdownPaste"),
           props: {
-            clipboardTextParser(text, _context, plainText) {
-              if (!plainText && editor.markdown) {
-                const json = editor.markdown.parse(text);
-                const node = editor.schema.nodeFromJSON(json);
-                return Slice.maxOpen(node.content);
-              }
-              // Plain text fallback
-              const p = editor.schema.nodes.paragraph!;
-              const doc = editor.schema.nodes.doc!;
-              const paragraph = p.create(null, text ? editor.schema.text(text) : undefined);
-              return new Slice(doc.create(null, paragraph).content, 0, 0);
+            handlePaste(view, event) {
+              if (!editor.markdown) return false;
+              const clipboard = event.clipboardData;
+              if (!clipboard) return false;
+
+              const text = clipboard.getData("text/plain");
+              if (!text) return false;
+
+              const html = clipboard.getData("text/html");
+
+              // If HTML contains data-pm-slice, the source is another
+              // ProseMirror editor — let ProseMirror use its native HTML
+              // clipboard path to preserve exact node structure.
+              if (html && html.includes("data-pm-slice")) return false;
+
+              // Everything else (VS Code, text editors, .md files, terminals,
+              // web pages): parse text/plain as Markdown.
+              const json = editor.markdown.parse(text);
+              const node = editor.schema.nodeFromJSON(json);
+              const slice = Slice.maxOpen(node.content);
+              const tr = view.state.tr.replaceSelection(slice);
+              view.dispatch(tr);
+              return true;
             },
           },
         }),