fix(collab-doc): match client markdown post-processing on server persist

Cursor review: yDocToFileMarkdown serialized the body with yDocToMarkdown only,
but the editor save path runs postProcessSerializedMarkdown before applyFrontmatter.
Server persist could therefore write markdown differing from a client save (empty
list markers, callout un-escaping) — spurious blob churn / round-trip drift despite
the byte-identical claim.

Apply postProcessSerializedMarkdown in yDocToFileMarkdown so a server persist is
byte-identical to a client save and the client's dirty-check baseline. Add a
regression test guarding the composition.

Author: waleedlatif1

apps/sim/lib/collab-doc/converter.test.ts

@@ -1,10 +1,20 @@
 /**
  * @vitest-environment jsdom
  */
+import { FILE_DOC_SEED } from '@sim/realtime-protocol/file-doc'
 import { describe, expect, it } from 'vitest'
 import * as Y from 'yjs'
+import {
+  applyFrontmatter,
+  postProcessSerializedMarkdown,
+} from '@/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/markdown-fidelity'
 import { serializeMarkdownBody } from '@/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/markdown-parse'
-import { applyMarkdownToYDoc, markdownToYDoc, yDocToMarkdown } from './converter'
+import {
+  applyMarkdownToYDoc,
+  markdownToYDoc,
+  yDocToFileMarkdown,
+  yDocToMarkdown,
+} from './converter'
 
 /** Representative markdown covering the custom-fidelity constructs (tables, code, lists, marks). */
 const SAMPLES = [
@@ -74,4 +84,25 @@ describe('collab-doc converter', () => {
     expect(merged).toContain('Alpha paragraph. EDITED')
     expect(merged).toContain('expanded by the agent')
   })
+
+  it('yDocToFileMarkdown matches the client save composition (frontmatter + postProcess body pass)', () => {
+    // A server-side persist must be byte-identical to the editor save — `applyFrontmatter(frontmatter,
+    // postProcessSerializedMarkdown(body))` — or it drifts from a client save / the dirty-check baseline
+    // and churns the blob. This guards against the postProcess pass being dropped from the server path.
+    const frontmatter = '---\ntitle: Doc\n---\n'
+    const doc = markdownToYDoc('- one\n- two\n\n> [!NOTE]\n> hi')
+    doc.getMap(FILE_DOC_SEED.configMap).set(FILE_DOC_SEED.frontmatterKey, frontmatter)
+    const expected = applyFrontmatter(
+      frontmatter,
+      postProcessSerializedMarkdown(yDocToMarkdown(doc))
+    )
+    expect(yDocToFileMarkdown(doc)).toBe(expected)
+    doc.destroy()
+  })
+
+  it('yDocToFileMarkdown re-attaches empty frontmatter when the config map has none', () => {
+    const doc = markdownToYDoc('plain body\n')
+    expect(yDocToFileMarkdown(doc)).toBe(postProcessSerializedMarkdown(yDocToMarkdown(doc)))
+    doc.destroy()
+  })
 })

apps/sim/lib/collab-doc/converter.ts

@@ -9,7 +9,10 @@ import {
 } from '@tiptap/y-tiptap'
 import type * as Y from 'yjs'
 import { createMarkdownContentExtensions } from '@/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/extensions'
-import { applyFrontmatter } from '@/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/markdown-fidelity'
+import {
+  applyFrontmatter,
+  postProcessSerializedMarkdown,
+} from '@/app/workspace/[workspaceId]/files/components/file-viewer/rich-markdown-editor/markdown-fidelity'
 import {
   parseMarkdownToDoc,
   serializeDocToMarkdown,
@@ -87,13 +90,18 @@ export function yDocToMarkdown(ydoc: Y.Doc): string {
 
 /**
  * Project a collaborative {@link Y.Doc} back to the file's FULL canonical markdown — the body from the
- * CRDT re-joined with the frontmatter carried in the config map. This is exactly what the editor
- * writes on save (`applyFrontmatter(resolveSaveFrontmatter(), body)`), so a server-side persist of the
- * live doc is byte-identical to a client save — no spurious churn on the round-trip.
+ * CRDT re-joined with the frontmatter carried in the config map. Mirrors the editor's save path EXACTLY
+ * (`applyFrontmatter(resolveSaveFrontmatter(), postProcessSerializedMarkdown(editor.getMarkdown()))`),
+ * INCLUDING the `postProcessSerializedMarkdown` body fidelity pass (empty list markers, callout
+ * un-escaping, trailing whitespace) — so a server-side persist is byte-identical to a client save and
+ * matches the client's dirty-check baseline, with no spurious blob churn on the round-trip.
  */
 export function yDocToFileMarkdown(ydoc: Y.Doc): string {
   const frontmatter = ydoc.getMap(FILE_DOC_SEED.configMap).get(FILE_DOC_SEED.frontmatterKey)
-  return applyFrontmatter(typeof frontmatter === 'string' ? frontmatter : '', yDocToMarkdown(ydoc))
+  return applyFrontmatter(
+    typeof frontmatter === 'string' ? frontmatter : '',
+    postProcessSerializedMarkdown(yDocToMarkdown(ydoc))
+  )
 }
 
 /**