fix: improve markdown parser robustness and update export snapshots

- Accept GFM tables with or without outer pipes
- Allow 0-3 leading spaces on fenced code blocks per CommonMark
- Strip optional titles from link URLs so they don't appear in href
- Use balanced bracket matching for image alt text
- Update 3 export snapshots for empty blocks after rebase

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: nperez0111

packages/core/src/api/parsers/markdown/markdownToHtml.ts

@@ -250,9 +250,10 @@ function parseImage(
   start: number
 ): { html: string; end: number } | null {
   // ![alt](url) or ![alt](url "title")
-  const altStart = start + 2; // after ![
-  const altEnd = text.indexOf("]", altStart);
+  // Use balanced bracket matching to handle nested/escaped brackets in alt text
+  const altEnd = findClosingBracket(text, start + 1);
   if (altEnd === -1) {return null;}
+  const altStart = start + 2; // after ![
 
   if (text[altEnd + 1] !== "(") {return null;}
 
@@ -303,7 +304,7 @@ function parseLink(
   if (parenEnd === -1) {return null;}
 
   const linkText = text.substring(textStart, textEnd);
-  const url = text.substring(urlStart, parenEnd).trim();
+  const url = extractDestination(text.substring(urlStart, parenEnd).trim());
 
   return {
     html: `<a href="${escapeHtml(url)}">${parseInline(linkText)}</a>`,
@@ -343,6 +344,35 @@ function findClosingParen(text: string, openPos: number): number {
   return -1;
 }
 
+/**
+ * Extract the destination URL from a link/image URL+title string.
+ * Handles angle-bracket destinations and strips optional titles.
+ * E.g., `<url>` → `url`, `url "title"` → `url`
+ */
+function extractDestination(raw: string): string {
+  // Angle-bracket destination: <url>
+  if (raw.startsWith("<") && raw.endsWith(">")) {
+    return raw.substring(1, raw.length - 1);
+  }
+  if (raw.startsWith("<")) {
+    const close = raw.indexOf(">");
+    if (close !== -1) {
+      return raw.substring(1, close);
+    }
+  }
+  // Split at first unescaped whitespace to separate destination from title
+  for (let i = 0; i < raw.length; i++) {
+    if (raw[i] === "\\" && i + 1 < raw.length) {
+      i++; // skip escaped char
+      continue;
+    }
+    if (raw[i] === " " || raw[i] === "\t" || raw[i] === "\n") {
+      return raw.substring(0, i);
+    }
+  }
+  return raw;
+}
+
 function parseDelimited(
   text: string,
   start: number,
@@ -478,8 +508,8 @@ function tokenize(markdown: string): Token[] {
       continue;
     }
 
-    // Fenced code block
-    const fenceMatch = line.match(/^(`{3,}|~{3,})(.*)$/);
+    // Fenced code block (0-3 leading spaces allowed per CommonMark)
+    const fenceMatch = line.match(/^ {0,3}(`{3,}|~{3,})(.*)$/);
     if (fenceMatch) {
       const fence = fenceMatch[1];
       const fenceChar = fence[0];
@@ -489,7 +519,7 @@ function tokenize(markdown: string): Token[] {
       i++;
       while (i < lines.length) {
         const closingMatch = lines[i].match(
-          new RegExp(`^${fenceChar}{${fenceLen},}\\s*$`)
+          new RegExp(`^ {0,3}${fenceChar}{${fenceLen},}\\s*$`)
         );
         if (closingMatch) {
           i++;
@@ -750,11 +780,15 @@ function tryParseTable(
   const headerLine = lines[start];
   const separatorLine = lines[start + 1];
 
-  // Check separator line format: | --- | --- | or | :--- | ---: |
-  if (!/^\s*\|(\s*:?-+:?\s*\|)+\s*$/.test(separatorLine)) {return null;}
+  // Check separator line format: | --- | --- | or --- | --- (outer pipes optional)
+  // Must contain at least one pipe and only dashes, colons, pipes, and whitespace
+  if (
+    !separatorLine.includes("|") ||
+    !/^\s*\|?\s*:?-+:?\s*(\|\s*:?-+:?\s*)*\|?\s*$/.test(separatorLine)
+  ) {return null;}
 
-  // Check header line format: | ... | ... |
-  if (!/^\s*\|(.+\|)+\s*$/.test(headerLine)) {return null;}
+  // Check header line has at least one pipe (required to distinguish from plain text)
+  if (!headerLine.includes("|")) {return null;}
 
   const headers = parsePipeCells(headerLine);
   const alignments = parseAlignments(separatorLine);
@@ -763,7 +797,7 @@ function tryParseTable(
   let i = start + 2;
   while (i < lines.length) {
     const line = lines[i];
-    if (!/^\s*\|(.+\|)+\s*$/.test(line)) {break;}
+    if (!line.includes("|")) {break;}
     rows.push(parsePipeCells(line));
     i++;
   }

tests/src/unit/core/formatConversion/export/__snapshots__/markdown/hardbreak/only.md

@@ -0,0 +1 @@
+

tests/src/unit/core/formatConversion/export/__snapshots__/markdown/pageBreak/basic.md

@@ -0,0 +1 @@
+

tests/src/unit/core/formatConversion/export/__snapshots__/markdown/paragraph/empty.md

@@ -0,0 +1 @@
+

tests/src/unit/core/formatConversion/parse/__snapshots__/markdown/codeBlockIndented.json

@@ -0,0 +1,17 @@
+[
+  {
+    "children": [],
+    "content": [
+      {
+        "styles": {},
+        "text": "const x = 1;",
+        "type": "text",
+      },
+    ],
+    "id": "1",
+    "props": {
+      "language": "ts",
+    },
+    "type": "codeBlock",
+  },
+]

tests/src/unit/core/formatConversion/parse/__snapshots__/markdown/imageNestedBracketsAlt.json

@@ -0,0 +1,16 @@
+[
+  {
+    "children": [],
+    "content": undefined,
+    "id": "1",
+    "props": {
+      "backgroundColor": "default",
+      "caption": "",
+      "name": "alt [with] brackets",
+      "showPreview": true,
+      "textAlignment": "left",
+      "url": "https://example.com/image.png",
+    },
+    "type": "image",
+  },
+]

tests/src/unit/core/formatConversion/parse/__snapshots__/markdown/linkWithTitle.json

@@ -0,0 +1,25 @@
+[
+  {
+    "children": [],
+    "content": [
+      {
+        "content": [
+          {
+            "styles": {},
+            "text": "example",
+            "type": "text",
+          },
+        ],
+        "href": "https://example.com",
+        "type": "link",
+      },
+    ],
+    "id": "1",
+    "props": {
+      "backgroundColor": "default",
+      "textAlignment": "left",
+      "textColor": "default",
+    },
+    "type": "paragraph",
+  },
+]

tests/src/unit/core/formatConversion/parse/__snapshots__/markdown/tablePipeless.json

@@ -0,0 +1,97 @@
+[
+  {
+    "children": [],
+    "content": {
+      "columnWidths": [
+        undefined,
+        undefined,
+      ],
+      "headerCols": undefined,
+      "headerRows": 1,
+      "rows": [
+        {
+          "cells": [
+            {
+              "content": [
+                {
+                  "styles": {},
+                  "text": "Col 1",
+                  "type": "text",
+                },
+              ],
+              "props": {
+                "backgroundColor": "default",
+                "colspan": 1,
+                "rowspan": 1,
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "type": "tableCell",
+            },
+            {
+              "content": [
+                {
+                  "styles": {},
+                  "text": "Col 2",
+                  "type": "text",
+                },
+              ],
+              "props": {
+                "backgroundColor": "default",
+                "colspan": 1,
+                "rowspan": 1,
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "type": "tableCell",
+            },
+          ],
+        },
+        {
+          "cells": [
+            {
+              "content": [
+                {
+                  "styles": {},
+                  "text": "A",
+                  "type": "text",
+                },
+              ],
+              "props": {
+                "backgroundColor": "default",
+                "colspan": 1,
+                "rowspan": 1,
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "type": "tableCell",
+            },
+            {
+              "content": [
+                {
+                  "styles": {},
+                  "text": "B",
+                  "type": "text",
+                },
+              ],
+              "props": {
+                "backgroundColor": "default",
+                "colspan": 1,
+                "rowspan": 1,
+                "textAlignment": "left",
+                "textColor": "default",
+              },
+              "type": "tableCell",
+            },
+          ],
+        },
+      ],
+      "type": "tableContent",
+    },
+    "id": "1",
+    "props": {
+      "textColor": "default",
+    },
+    "type": "table",
+  },
+]

tests/src/unit/core/formatConversion/parse/parseTestInstances.ts

@@ -1880,4 +1880,40 @@ Paragraph after table`,
     },
     executeTest: testParseMarkdown,
   },
+  // Table without outer pipes (GFM allows optional outer pipes)
+  {
+    testCase: {
+      name: "tablePipeless",
+      content: `Col 1 | Col 2
+----- | -----
+A     | B`,
+    },
+    executeTest: testParseMarkdown,
+  },
+  // Indented fenced code block (up to 3 leading spaces per CommonMark)
+  {
+    testCase: {
+      name: "codeBlockIndented",
+      content: `   \`\`\`ts
+const x = 1;
+   \`\`\``,
+    },
+    executeTest: testParseMarkdown,
+  },
+  // Link with title (title should not appear in href)
+  {
+    testCase: {
+      name: "linkWithTitle",
+      content: `[example](https://example.com "Example Site")`,
+    },
+    executeTest: testParseMarkdown,
+  },
+  // Image with nested brackets in alt text
+  {
+    testCase: {
+      name: "imageNestedBracketsAlt",
+      content: `![alt [with] brackets](https://example.com/image.png)`,
+    },
+    executeTest: testParseMarkdown,
+  },
 ];