fix(rich-markdown-editor): isolate verbatim block nodes from boundary joins

footnoteDef and rawHtmlBlock hold exact source text but were neither isolating nor
atom, so a single Backspace/Delete at their boundary let ProseMirror's default join
merge their raw markdown into an adjacent paragraph as HTML-escaped prose — silently
destroying the node and corrupting saved markdown. Mark the block variants isolating
so boundary keys can't cross their edge. Round-trip and in-place editing are unchanged.

Author: waleedlatif1

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/keymap.test.ts

@@ -228,3 +228,32 @@ describe('empty list-item Enter', () => {
     editor.destroy()
   })
 })
+
+describe('verbatim block boundary (isolating)', () => {
+  beforeEach(() => {
+    Element.prototype.scrollIntoView = vi.fn()
+  })
+
+  function caretIntoNode(editor: Editor, nodeType: string): void {
+    editor.state.doc.descendants((node, pos) => {
+      if (node.type.name === nodeType) editor.commands.setTextSelection(pos + 1)
+    })
+  }
+
+  it.each([
+    ['footnote definition', 'body text[^x]\n\n[^x]: the note', 'footnoteDef'],
+    ['raw HTML block', 'body\n\n<div>\nhello\n</div>', 'rawHtmlBlock'],
+  ])(
+    'Backspace at the start of a %s does not merge across its boundary and destroy it',
+    (_label, markdown, nodeType) => {
+      const editor = editorWith('')
+      editor.commands.setContent(markdown, { contentType: 'markdown' })
+      editor.commands.focus()
+      expect(blockShape(editor)).toContain(nodeType)
+      caretIntoNode(editor, nodeType)
+      pressBackspace(editor)
+      expect(blockShape(editor)).toContain(nodeType)
+      editor.destroy()
+    }
+  )
+})

apps/sim/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/raw-markdown-snippet.tsx

@@ -167,6 +167,10 @@ function verbatimNodeConfig({ name, inline, badgeLabel }: VerbatimNodeOptions) {
     marks: '',
     code: true,
     defining: !inline,
+    // Block verbatim nodes hold exact source text; `isolating` stops a boundary Backspace/Delete from
+    // joining across their edge, which would otherwise merge their raw markdown into an adjacent
+    // paragraph as HTML-escaped prose and destroy the node (silent data loss on save).
+    isolating: !inline,
     selectable: true,
     atom: false,
     parseHTML() {