fix(citations): keep copied markdown references valid (#7743)

* fix(citations): keep copied markdown references valid

formatCitationMarkdownReference pasted the source title and URL into
"[title](url)" verbatim. A title with a stray "[" or "]" ends the link text
early, and a URL with an unbalanced parenthesis ends the destination, so a
copied reference no longer rendered as a link. Escape brackets in the title and
wrap a parenthesized URL in the angle-bracket form.

* fix(citations): only angle-bracket a parenthesized URL

normalizeUrl already percent-encodes "<", ">" and whitespace, so including
them in the trigger could wrap such a URL in an angle-bracket destination that
CommonMark forbids, which is worse than the bare form. Parentheses are the only
reachable delimiter that breaks the bare destination.

README.md

@@ -1708,7 +1708,10 @@ provider, document title, and retrieved excerpt in chat, including after reload
 and when a subagent performed the retrieval. Missing page numbers and public
 URLs remain absent; sources without a URL are readable as local evidence.
 Inline citations remain readable after Markdown sanitization, and supplied page
-numbers use the selected interface language. New providers use the shared
+numbers use the selected interface language.
+Copying a source reference produces a Markdown link that escapes brackets in the
+visible title and wraps a URL containing parentheses in angle brackets, so the
+copied reference stays a valid link. New providers use the shared
 envelope; existing RAGFlow citation histories remain supported.
 Expand a completed subtask card to inspect its report's forwarded knowledge
 sources, including when reopening a saved conversation.

frontend/src/core/citations/sources.ts

@@ -206,7 +206,13 @@ export function extractCitationSources(
 export function formatCitationMarkdownReference(
   source: CitationSource,
 ): string {
-  return `[${source.title}](${source.url})`;
+  // Link text may contain balanced brackets, but a stray "[" or "]" would end
+  // it early; escape both so a copied reference keeps the visible title.
+  const title = source.title.replace(/([\\[\]])/g, "\\$1");
+  // A bare link destination stops at an unbalanced parenthesis. The
+  // angle-bracket form keeps URLs with parentheses valid.
+  const url = /[()]/.test(source.url) ? `<${source.url}>` : source.url;
+  return `[${title}](${url})`;
 }
 
 function normalizeTitle(title: string, domain: string): string {

frontend/tests/unit/core/citations/sources.test.ts

@@ -1042,4 +1042,30 @@ describe("formatCitationMarkdownReference", () => {
       "[Paper A](https://example.com/a)",
     );
   });
+
+  it("escapes brackets in the title so the copied link keeps its label", () => {
+    const [source] = extractCitationSources(
+      "Evidence [citation:Paper A](https://example.com/a).",
+    );
+
+    expect(
+      formatCitationMarkdownReference({
+        ...source!,
+        title: "Why ] matters [draft",
+      }),
+    ).toBe("[Why \\] matters \\[draft](https://example.com/a)");
+  });
+
+  it("wraps a URL with parentheses so the destination stays intact", () => {
+    const [source] = extractCitationSources(
+      "Evidence [citation:Paper A](https://example.com/a).",
+    );
+
+    expect(
+      formatCitationMarkdownReference({
+        ...source!,
+        url: "https://example.com/a)b(c",
+      }),
+    ).toBe("[Paper A](<https://example.com/a)b(c>)");
+  });
 });