🏄‍♂️ refactor: Optimize Reasoning UI & Token Streaming (#5546)

* ✨ feat: Implement Show Thinking feature; refactor: testing thinking render optimizations

* ✨ feat: Refactor Thinking component styles and enhance Markdown rendering

* chore: add back removed code, revert type changes

* chore: Add back resetCounter effect to Markdown component for improved code block indexing

* chore: bump @librechat/agents and google langchain packages

* WIP: reasoning type updates

* WIP: first pass, reasoning content blocks

* chore: revert code

* chore: bump @librechat/agents

* refactor: optimize reasoning tag handling

* style: ul indent padding

* feat: add Reasoning component to handle reasoning display

* feat: first pass, content reasoning part styling

* refactor: add content placeholder for endpoints using new stream handler

* refactor: only cache messages when requesting stream audio

* fix: circular dep.

* fix: add default param

* refactor: tts, only request after message stream, fix chrome autoplay

* style: update label for submitting state and add localization for 'Thinking...'

* fix: improve global audio pause logic and reset active run ID

* fix: handle artifact edge cases

* fix: remove unnecessary console log from artifact update test

* feat: add support for continued message handling with new streaming method

---------

Co-authored-by: Marco Beretta <81851188+berry-13@users.noreply.github.com>

api/server/services/Artifacts/update.spec.js

@@ -260,8 +260,61 @@ console.log(greeting);`;
       codeExample,
       'updated content',
     );
-    console.log(result);
     expect(result).toMatch(/id="2".*updated content/s);
     expect(result).toMatch(new RegExp(`${ARTIFACT_START}.*updated content.*${ARTIFACT_END}`, 's'));
   });
+
+  test('should handle empty content in artifact without code blocks', () => {
+    const artifactText = `${ARTIFACT_START}\n\n${ARTIFACT_END}`;
+    const artifact = {
+      start: 0,
+      end: artifactText.length,
+      text: artifactText,
+      source: 'text',
+    };
+
+    const result = replaceArtifactContent(artifactText, artifact, '', 'new content');
+    expect(result).toBe(`${ARTIFACT_START}\nnew content\n${ARTIFACT_END}`);
+  });
+
+  test('should handle empty content in artifact with code blocks', () => {
+    const artifactText = createArtifactText({ content: '' });
+    const artifact = {
+      start: 0,
+      end: artifactText.length,
+      text: artifactText,
+      source: 'text',
+    };
+
+    const result = replaceArtifactContent(artifactText, artifact, '', 'new content');
+    expect(result).toMatch(/```\nnew content\n```/);
+  });
+
+  test('should handle content with trailing newline in code blocks', () => {
+    const contentWithNewline = 'console.log("test")\n';
+    const message = {
+      text: `Some prefix text\n${createArtifactText({
+        content: contentWithNewline,
+      })}\nSome suffix text`,
+    };
+
+    const artifacts = findAllArtifacts(message);
+    expect(artifacts).toHaveLength(1);
+
+    const result = replaceArtifactContent(
+      message.text,
+      artifacts[0],
+      contentWithNewline,
+      'updated content',
+    );
+
+    // Should update the content and preserve artifact structure
+    expect(result).toContain('```\nupdated content\n```');
+    // Should preserve surrounding text
+    expect(result).toMatch(/^Some prefix text\n/);
+    expect(result).toMatch(/\nSome suffix text$/);
+    // Should not have extra newlines
+    expect(result).not.toContain('\n\n```');
+    expect(result).not.toContain('```\n\n');
+  });
 });