📑 refactor: File Search Citations Dual-Format Unicode Handling (#10888)

* 🔖 refactor: citation handling with support for both literal and Unicode formats

* refactor: file search messages for edge cases in documents

* 🔧 refactor: Enhance citation handling with detailed regex patterns for literal and Unicode formats

* 🔧 refactor: Simplify file search query handling by removing unnecessary parameters and improving result formatting

* ✨ test: Add comprehensive integration tests for citation processing flow with support for literal and Unicode formats

* 🔧 refactor: Improve regex match handling and add performance tests for citation processing

api/app/clients/tools/util/fileSearch.js

@@ -86,7 +86,6 @@ const createFileSearchTool = async ({ userId, files, entity_id, fileCitations =
       }
 
       /**
-       *
        * @param {import('librechat-data-provider').TFile} file
        * @returns {{ file_id: string, query: string, k: number, entity_id?: string }}
        */
@@ -135,11 +134,16 @@ const createFileSearchTool = async ({ userId, files, entity_id, fileCitations =
             page: docInfo.metadata.page || null,
           })),
         )
-        // TODO: results should be sorted by relevance, not distance
         .sort((a, b) => a.distance - b.distance)
-        // TODO: make this configurable
         .slice(0, 10);
 
+      if (formattedResults.length === 0) {
+        return [
+          'No content found in the files. The files may not have been processed correctly or you may need to refine your query.',
+          undefined,
+        ];
+      }
+
       const formattedString = formattedResults
         .map(
           (result, index) =>
@@ -169,11 +173,12 @@ const createFileSearchTool = async ({ userId, files, entity_id, fileCitations =
           ? `
 
 **CITE FILE SEARCH RESULTS:**
-Use anchor markers immediately after statements derived from file content. Reference the filename in your text:
+Use the EXACT anchor markers shown below (copy them verbatim) immediately after statements derived from file content. Reference the filename in your text:
 - File citation: "The document.pdf states that... \\ue202turn0file0"  
 - Page reference: "According to report.docx... \\ue202turn0file1"
 - Multi-file: "Multiple sources confirm... \\ue200\\ue202turn0file0\\ue202turn0file1\\ue201"
 
+**CRITICAL:** Output these escape sequences EXACTLY as shown (e.g., \\ue202turn0file0). Do NOT substitute with other characters like † or similar symbols.
 **ALWAYS mention the filename in your text before the citation marker. NEVER use markdown links or footnotes.**`
           : ''
       }`,

api/app/clients/tools/util/handleTools.js

@@ -320,19 +320,19 @@ Current Date & Time: ${replaceSpecialVars({ text: '{{iso_datetime}}' })}
 
 **Execute immediately without preface.** After search, provide a brief summary addressing the query directly, then structure your response with clear Markdown formatting (## headers, lists, tables). Cite sources properly, tailor tone to query type, and provide comprehensive details.
 
-**CITATION FORMAT - INVISIBLE UNICODE ANCHORS ONLY:**
+**CITATION FORMAT - UNICODE ESCAPE SEQUENCES ONLY:**
-Use these Unicode characters: \\ue202 (before each anchor), \\ue200 (group start), \\ue201 (group end), \\ue203 (highlight start), \\ue204 (highlight end)
+Use these EXACT escape sequences (copy verbatim): \\ue202 (before each anchor), \\ue200 (group start), \\ue201 (group end), \\ue203 (highlight start), \\ue204 (highlight end)
 
-Anchor pattern: turn{N}{type}{index} where N=turn number, type=search|news|image|ref, index=0,1,2...
+Anchor pattern: \\ue202turn{N}{type}{index} where N=turn number, type=search|news|image|ref, index=0,1,2...
 
-**Examples:**
+**Examples (copy these exactly):**
 - Single: "Statement.\\ue202turn0search0"
 - Multiple: "Statement.\\ue202turn0search0\\ue202turn0news1"
 - Group: "Statement. \\ue200\\ue202turn0search0\\ue202turn0news1\\ue201"
 - Highlight: "\\ue203Cited text.\\ue204\\ue202turn0search0"
 - Image: "See photo\\ue202turn0image0."
 
-**CRITICAL:** Place anchors AFTER punctuation. Cite every non-obvious fact/quote. NEVER use markdown links, [1], footnotes, or HTML tags.`.trim();
+**CRITICAL:** Output escape sequences EXACTLY as shown. Do NOT substitute with † or other symbols. Place anchors AFTER punctuation. Cite every non-obvious fact/quote. NEVER use markdown links, [1], footnotes, or HTML tags.`.trim();
         return createSearchTool({
           ...result.authResult,
           onSearchResults,

client/src/components/Web/plugin.ts

@@ -4,13 +4,29 @@ import type { Citation, CitationNode } from './types';
 import { SPAN_REGEX, STANDALONE_PATTERN, CLEANUP_REGEX, COMPOSITE_REGEX } from '~/utils/citations';
 
 /**
- * Checks if a standalone marker is truly standalone (not inside a composite block)
+ * Checks if a standalone marker is truly standalone (not inside a composite block).
+ * A marker is inside a composite if there's an opening \ue200 without a closing \ue201 after it.
+ *
+ * Handles both literal text format ("\ue200") and actual Unicode (U+E200) by checking
+ * for both and using the rightmost occurrence. This correctly handles:
+ * - Pure literal format: "\ue200...\ue201"
+ * - Pure Unicode format: "..."
+ * - Mixed formats: "\ue200..." (different formats for open/close)
  */
 function isStandaloneMarker(text: string, position: number): boolean {
   const beforeText = text.substring(0, position);
-  const lastUe200 = beforeText.lastIndexOf('\\ue200');
-  const lastUe201 = beforeText.lastIndexOf('\\ue201');
 
+  // Find rightmost composite block start (either format)
+  const lastUe200Literal = beforeText.lastIndexOf('\\ue200');
+  const lastUe200Char = beforeText.lastIndexOf('\ue200');
+  const lastUe200 = Math.max(lastUe200Literal, lastUe200Char);
+
+  // Find rightmost composite block end (either format)
+  const lastUe201Literal = beforeText.lastIndexOf('\\ue201');
+  const lastUe201Char = beforeText.lastIndexOf('\ue201');
+  const lastUe201 = Math.max(lastUe201Literal, lastUe201Char);
+
+  // Standalone if: no opening marker OR closing marker appears after opening
   return lastUe200 === -1 || (lastUe201 !== -1 && lastUe201 > lastUe200);
 }
 

client/src/hooks/Messages/useCopyToClipboard.ts

@@ -129,7 +129,7 @@ function processCitations(text: string, searchResults: { [key: string]: SearchRe
 
   // Step 1: Process highlighted text first (simplify by just making it bold in markdown)
   formattedText = formattedText.replace(SPAN_REGEX, (match) => {
-    const text = match.replace(/\\ue203|\\ue204/g, '');
+    const text = match.replace(/\\ue203|\\ue204|\ue203|\ue204/g, '');
     return `**${text}**`;
   });
 

client/src/utils/__tests__/citations.test.ts

@@ -0,0 +1,558 @@
+import {
+  SPAN_REGEX,
+  COMPOSITE_REGEX,
+  STANDALONE_PATTERN,
+  CLEANUP_REGEX,
+  INVALID_CITATION_REGEX,
+} from '../citations';
+
+describe('Citation Regex Patterns', () => {
+  beforeEach(() => {
+    // Reset regex lastIndex for global patterns
+    SPAN_REGEX.lastIndex = 0;
+    COMPOSITE_REGEX.lastIndex = 0;
+    STANDALONE_PATTERN.lastIndex = 0;
+    CLEANUP_REGEX.lastIndex = 0;
+    INVALID_CITATION_REGEX.lastIndex = 0;
+  });
+
+  describe('STANDALONE_PATTERN', () => {
+    describe('literal text format (\\ue202)', () => {
+      it('should match literal text search citation', () => {
+        const text = 'Some fact \\ue202turn0search0 here';
+        STANDALONE_PATTERN.lastIndex = 0;
+        const match = STANDALONE_PATTERN.exec(text);
+        expect(match).not.toBeNull();
+        expect(match?.[1]).toBe('0'); // turn number
+        expect(match?.[2]).toBe('search'); // type
+        expect(match?.[3]).toBe('0'); // index
+      });
+
+      it('should match literal text file citation', () => {
+        const text = 'Document says \\ue202turn0file0 (doc.pdf)';
+        STANDALONE_PATTERN.lastIndex = 0;
+        const match = STANDALONE_PATTERN.exec(text);
+        expect(match).not.toBeNull();
+        expect(match?.[1]).toBe('0');
+        expect(match?.[2]).toBe('file');
+        expect(match?.[3]).toBe('0');
+      });
+
+      it('should match literal text news citation', () => {
+        const text = 'Breaking news \\ue202turn0news1';
+        STANDALONE_PATTERN.lastIndex = 0;
+        const match = STANDALONE_PATTERN.exec(text);
+        expect(match).not.toBeNull();
+        expect(match?.[1]).toBe('0');
+        expect(match?.[2]).toBe('news');
+        expect(match?.[3]).toBe('1');
+      });
+
+      it('should match multiple literal text citations', () => {
+        const text = 'Fact one \\ue202turn0search0 and fact two \\ue202turn0file1';
+        const matches: RegExpExecArray[] = [];
+        let match: RegExpExecArray | null;
+        STANDALONE_PATTERN.lastIndex = 0;
+        while ((match = STANDALONE_PATTERN.exec(text)) !== null) {
+          matches.push(match);
+        }
+        expect(matches).toHaveLength(2);
+        expect(matches[0][2]).toBe('search');
+        expect(matches[1][2]).toBe('file');
+      });
+
+      it('should match all supported types in literal text format', () => {
+        const types = ['search', 'image', 'news', 'video', 'ref', 'file'];
+        for (const type of types) {
+          const text = `Test \\ue202turn0${type}0`;
+          STANDALONE_PATTERN.lastIndex = 0;
+          const match = STANDALONE_PATTERN.exec(text);
+          expect(match).not.toBeNull();
+          expect(match?.[2]).toBe(type);
+        }
+      });
+    });
+
+    describe('actual Unicode character format (U+E202)', () => {
+      it('should match actual Unicode search citation', () => {
+        const text = 'Some fact \ue202turn0search0 here';
+        STANDALONE_PATTERN.lastIndex = 0;
+        const match = STANDALONE_PATTERN.exec(text);
+        expect(match).not.toBeNull();
+        expect(match?.[1]).toBe('0');
+        expect(match?.[2]).toBe('search');
+        expect(match?.[3]).toBe('0');
+      });
+
+      it('should match actual Unicode file citation', () => {
+        const text = 'Document says \ue202turn0file0 (doc.pdf)';
+        STANDALONE_PATTERN.lastIndex = 0;
+        const match = STANDALONE_PATTERN.exec(text);
+        expect(match).not.toBeNull();
+        expect(match?.[1]).toBe('0');
+        expect(match?.[2]).toBe('file');
+        expect(match?.[3]).toBe('0');
+      });
+
+      it('should match all supported types in actual Unicode format', () => {
+        const types = ['search', 'image', 'news', 'video', 'ref', 'file'];
+        for (const type of types) {
+          const text = `Test \ue202turn0${type}0`;
+          STANDALONE_PATTERN.lastIndex = 0;
+          const match = STANDALONE_PATTERN.exec(text);
+          expect(match).not.toBeNull();
+          expect(match?.[2]).toBe(type);
+        }
+      });
+    });
+
+    describe('mixed format handling', () => {
+      it('should match both formats in the same text', () => {
+        const text = 'Literal \\ue202turn0search0 and Unicode \ue202turn0file1';
+        const matches: RegExpExecArray[] = [];
+        let match: RegExpExecArray | null;
+        STANDALONE_PATTERN.lastIndex = 0;
+        while ((match = STANDALONE_PATTERN.exec(text)) !== null) {
+          matches.push(match);
+        }
+        expect(matches).toHaveLength(2);
+        expect(matches[0][2]).toBe('search');
+        expect(matches[1][2]).toBe('file');
+      });
+    });
+  });
+
+  describe('SPAN_REGEX', () => {
+    it('should match literal text span markers', () => {
+      const text = 'Before \\ue203highlighted text\\ue204 after';
+      SPAN_REGEX.lastIndex = 0;
+      const match = SPAN_REGEX.exec(text);
+      expect(match).not.toBeNull();
+      expect(match?.[0]).toContain('highlighted text');
+    });
+
+    it('should match actual Unicode span markers', () => {
+      const text = 'Before \ue203highlighted text\ue204 after';
+      SPAN_REGEX.lastIndex = 0;
+      const match = SPAN_REGEX.exec(text);
+      expect(match).not.toBeNull();
+      expect(match?.[0]).toContain('highlighted text');
+    });
+  });
+
+  describe('COMPOSITE_REGEX', () => {
+    it('should match literal text composite markers', () => {
+      const text = 'Statement \\ue200\\ue202turn0search0\\ue202turn0news0\\ue201';
+      COMPOSITE_REGEX.lastIndex = 0;
+      const match = COMPOSITE_REGEX.exec(text);
+      expect(match).not.toBeNull();
+    });
+
+    it('should match actual Unicode composite markers', () => {
+      const text = 'Statement \ue200\ue202turn0search0\ue202turn0news0\ue201';
+      COMPOSITE_REGEX.lastIndex = 0;
+      const match = COMPOSITE_REGEX.exec(text);
+      expect(match).not.toBeNull();
+    });
+  });
+
+  describe('CLEANUP_REGEX', () => {
+    it('should clean up literal text markers', () => {
+      const text = '\\ue200\\ue201\\ue202\\ue203\\ue204\\ue206';
+      const cleaned = text.replace(CLEANUP_REGEX, '');
+      expect(cleaned).toBe('');
+    });
+
+    it('should clean up actual Unicode markers', () => {
+      const text = '\ue200\ue201\ue202\ue203\ue204\ue206';
+      const cleaned = text.replace(CLEANUP_REGEX, '');
+      expect(cleaned).toBe('');
+    });
+
+    it('should preserve normal text while cleaning markers', () => {
+      const text = 'Hello \\ue202turn0search0 world';
+      const cleaned = text.replace(CLEANUP_REGEX, '');
+      expect(cleaned).toBe('Hello turn0search0 world');
+    });
+  });
+
+  describe('INVALID_CITATION_REGEX', () => {
+    it('should match invalid literal text citations with leading whitespace', () => {
+      const text = 'Text  \\ue202turn0search5';
+      INVALID_CITATION_REGEX.lastIndex = 0;
+      const match = INVALID_CITATION_REGEX.exec(text);
+      expect(match).not.toBeNull();
+    });
+
+    it('should match invalid actual Unicode citations with leading whitespace', () => {
+      const text = 'Text  \ue202turn0search5';
+      INVALID_CITATION_REGEX.lastIndex = 0;
+      const match = INVALID_CITATION_REGEX.exec(text);
+      expect(match).not.toBeNull();
+    });
+  });
+
+  describe('Integration: Full Citation Processing Flow', () => {
+    /**
+     * Simulates the citation processing flow used in the markdown plugin and copy-to-clipboard
+     */
+    const processFullCitationFlow = (text: string) => {
+      // Step 1: Extract highlighted spans
+      const spans: Array<{ content: string; position: number }> = [];
+      let spanMatch;
+      const spanRegex = new RegExp(SPAN_REGEX.source, 'g');
+      while ((spanMatch = spanRegex.exec(text)) !== null) {
+        const content = spanMatch[0].replace(/\\ue203|\\ue204|\ue203|\ue204/g, '');
+        spans.push({ content, position: spanMatch.index });
+      }
+
+      // Step 2: Extract composite blocks
+      const composites: Array<{ citations: string[]; position: number }> = [];
+      let compMatch;
+      const compRegex = new RegExp(COMPOSITE_REGEX.source, 'g');
+      while ((compMatch = compRegex.exec(text)) !== null) {
+        const block = compMatch[0];
+        const citations: string[] = [];
+        let citMatch;
+        const citRegex = new RegExp(STANDALONE_PATTERN.source, 'g');
+        while ((citMatch = citRegex.exec(block)) !== null) {
+          citations.push(`turn${citMatch[1]}${citMatch[2]}${citMatch[3]}`);
+        }
+        composites.push({ citations, position: compMatch.index });
+      }
+
+      // Step 3: Extract standalone citations (not in composites)
+      const standalones: Array<{ citation: string; position: number }> = [];
+      let standMatch;
+      const standRegex = new RegExp(STANDALONE_PATTERN.source, 'g');
+      while ((standMatch = standRegex.exec(text)) !== null) {
+        // Check if this position is inside a composite
+        const isInComposite = composites.some(
+          (c) => standMatch && standMatch.index >= c.position && standMatch.index < c.position + 50,
+        );
+        if (!isInComposite) {
+          standalones.push({
+            citation: `turn${standMatch[1]}${standMatch[2]}${standMatch[3]}`,
+            position: standMatch.index,
+          });
+        }
+      }
+
+      // Step 4: Clean up text
+      const cleanedText = text.replace(INVALID_CITATION_REGEX, '').replace(CLEANUP_REGEX, '');
+
+      return { spans, composites, standalones, cleanedText };
+    };
+
+    describe('literal text format integration', () => {
+      it('should process complex LLM response with multiple citation types', () => {
+        const llmResponse = `Here's what I found about the topic.
+
+\\ue203This is an important quote from the source.\\ue204 \\ue202turn0search0
+
+The data shows several key findings \\ue202turn0search1 including:
+- First finding \\ue202turn0news0
+- Second finding \\ue200\\ue202turn0search2\\ue202turn0file0\\ue201
+
+For more details, see the attached document \\ue202turn0file1.`;
+
+        const result = processFullCitationFlow(llmResponse);
+
+        expect(result.spans).toHaveLength(1);
+        expect(result.spans[0].content).toBe('This is an important quote from the source.');
+
+        expect(result.composites).toHaveLength(1);
+        expect(result.composites[0].citations).toEqual(['turn0search2', 'turn0file0']);
+
+        expect(result.standalones.length).toBeGreaterThanOrEqual(3);
+
+        expect(result.cleanedText).not.toContain('\\ue202');
+        expect(result.cleanedText).not.toContain('\\ue200');
+      });
+
+      it('should handle file citations from document search', () => {
+        const fileSearchResponse = `Based on the document medical-anthem-blue-cross.pdf:
+
+- **Annual deductible:** $3,300 per person \\ue202turn0file0
+- **Out-of-pocket maximum:** $4,000 per person \\ue202turn0file0
+- **Network:** Prudent Buyer PPO \\ue202turn0file1
+
+Multiple sources confirm these details. \\ue200\\ue202turn0file0\\ue202turn0file1\\ue202turn0file2\\ue201`;
+
+        const result = processFullCitationFlow(fileSearchResponse);
+
+        expect(result.composites).toHaveLength(1);
+        expect(result.composites[0].citations).toHaveLength(3);
+
+        // Should find standalone file citations
+        const fileCitations = result.standalones.filter((s) => s.citation.includes('file'));
+        expect(fileCitations.length).toBeGreaterThanOrEqual(2);
+      });
+    });
+
+    describe('actual Unicode format integration', () => {
+      it('should process response with actual Unicode characters', () => {
+        const llmResponse = `Research findings indicate the following:
+
+\ue203Key insight from the study.\ue204 \ue202turn0search0
+
+Additional context \ue202turn0news0 supports this conclusion \ue200\ue202turn0search1\ue202turn0ref0\ue201.`;
+
+        const result = processFullCitationFlow(llmResponse);
+
+        expect(result.spans).toHaveLength(1);
+        expect(result.composites).toHaveLength(1);
+        expect(result.standalones.length).toBeGreaterThanOrEqual(1);
+        expect(result.cleanedText).not.toContain('\ue202');
+      });
+    });
+
+    describe('mixed format integration', () => {
+      it('should handle mixed literal and Unicode formats in same response', () => {
+        const mixedResponse = `First citation uses literal \\ue202turn0search0 format.
+Second citation uses Unicode \ue202turn0search1 format.
+Composite with mixed: \\ue200\\ue202turn0file0\ue202turn0file1\\ue201`;
+
+        const result = processFullCitationFlow(mixedResponse);
+
+        // Should find citations from both formats
+        expect(result.standalones.length).toBeGreaterThanOrEqual(2);
+        expect(result.composites).toHaveLength(1);
+        expect(result.composites[0].citations).toHaveLength(2);
+      });
+    });
+  });
+
+  describe('Performance: Regex Benchmarks', () => {
+    /**
+     * Generates a realistic citation-heavy text with specified number of citations
+     */
+    const generateCitationHeavyText = (citationCount: number, format: 'literal' | 'unicode') => {
+      const marker = format === 'literal' ? '\\ue202' : '\ue202';
+      const spanStart = format === 'literal' ? '\\ue203' : '\ue203';
+      const spanEnd = format === 'literal' ? '\\ue204' : '\ue204';
+      const compStart = format === 'literal' ? '\\ue200' : '\ue200';
+      const compEnd = format === 'literal' ? '\\ue201' : '\ue201';
+
+      const types = ['search', 'news', 'file', 'ref', 'image', 'video'];
+      let text = '';
+
+      for (let i = 0; i < citationCount; i++) {
+        const type = types[i % types.length];
+        const turn = Math.floor(i / 10);
+        const index = i % 10;
+
+        if (i % 5 === 0) {
+          // Add highlighted text every 5th citation
+          text += `${spanStart}Important fact number ${i}.${spanEnd} ${marker}turn${turn}${type}${index} `;
+        } else if (i % 7 === 0) {
+          // Add composite every 7th citation
+          text += `Multiple sources ${compStart}${marker}turn${turn}${type}${index}${marker}turn${turn}${types[(i + 1) % types.length]}${(index + 1) % 10}${compEnd} confirm this. `;
+        } else {
+          text += `This is fact ${i} ${marker}turn${turn}${type}${index} from the research. `;
+        }
+      }
+
+      return text;
+    };
+
+    it('should process 100 literal citations in reasonable time (<100ms)', () => {
+      const text = generateCitationHeavyText(100, 'literal');
+
+      const start = performance.now();
+
+      // Run all regex operations
+      const results = { spans: 0, composites: 0, standalones: 0, cleaned: '' };
+
+      SPAN_REGEX.lastIndex = 0;
+      while (SPAN_REGEX.exec(text) !== null) {
+        results.spans++;
+      }
+
+      COMPOSITE_REGEX.lastIndex = 0;
+      while (COMPOSITE_REGEX.exec(text) !== null) {
+        results.composites++;
+      }
+
+      STANDALONE_PATTERN.lastIndex = 0;
+      while (STANDALONE_PATTERN.exec(text) !== null) {
+        results.standalones++;
+      }
+
+      results.cleaned = text.replace(CLEANUP_REGEX, '');
+
+      const duration = performance.now() - start;
+
+      expect(duration).toBeLessThan(100);
+      expect(results.standalones).toBeGreaterThan(80); // Most should be standalone
+      expect(results.spans).toBeGreaterThan(10); // Some highlighted
+      expect(results.composites).toBeGreaterThan(5); // Some composites
+    });
+
+    it('should process 100 Unicode citations in reasonable time (<100ms)', () => {
+      const text = generateCitationHeavyText(100, 'unicode');
+
+      const start = performance.now();
+
+      const results = { spans: 0, composites: 0, standalones: 0, cleaned: '' };
+
+      SPAN_REGEX.lastIndex = 0;
+      while (SPAN_REGEX.exec(text) !== null) {
+        results.spans++;
+      }
+
+      COMPOSITE_REGEX.lastIndex = 0;
+      while (COMPOSITE_REGEX.exec(text) !== null) {
+        results.composites++;
+      }
+
+      STANDALONE_PATTERN.lastIndex = 0;
+      while (STANDALONE_PATTERN.exec(text) !== null) {
+        results.standalones++;
+      }
+
+      results.cleaned = text.replace(CLEANUP_REGEX, '');
+
+      const duration = performance.now() - start;
+
+      expect(duration).toBeLessThan(100);
+      expect(results.standalones).toBeGreaterThan(80);
+    });
+
+    it('should process 500 citations without timeout (<500ms)', () => {
+      const text = generateCitationHeavyText(500, 'literal');
+
+      const start = performance.now();
+
+      let count = 0;
+
+      STANDALONE_PATTERN.lastIndex = 0;
+      while (STANDALONE_PATTERN.exec(text) !== null) {
+        count++;
+      }
+
+      const cleaned = text.replace(CLEANUP_REGEX, '');
+
+      const duration = performance.now() - start;
+
+      expect(duration).toBeLessThan(500);
+      expect(count).toBeGreaterThan(400);
+      expect(cleaned.length).toBeLessThan(text.length);
+    });
+
+    it('should handle mixed formats efficiently (<100ms for 100 citations)', () => {
+      // Generate text with alternating formats
+      const literalText = generateCitationHeavyText(50, 'literal');
+      const unicodeText = generateCitationHeavyText(50, 'unicode');
+      const mixedText = literalText + '\n\n' + unicodeText;
+
+      const start = performance.now();
+
+      let count = 0;
+
+      STANDALONE_PATTERN.lastIndex = 0;
+      while (STANDALONE_PATTERN.exec(mixedText) !== null) {
+        count++;
+      }
+
+      const duration = performance.now() - start;
+
+      expect(duration).toBeLessThan(100);
+      expect(count).toBeGreaterThan(80); // Should find citations from both halves
+    });
+
+    it('should handle repeated execution during streaming simulation (<1000ms cumulative)', () => {
+      /**
+       * Simulates the markdown plugin running repeatedly during LLM streaming.
+       * Each "token" adds ~10 characters, plugin runs on every update.
+       */
+      const fullText = generateCitationHeavyText(50, 'literal');
+      const tokens: string[] = [];
+
+      // Simulate streaming: break text into ~100 incremental chunks
+      const chunkSize = Math.ceil(fullText.length / 100);
+      for (let i = 0; i < fullText.length; i += chunkSize) {
+        tokens.push(fullText.slice(0, i + chunkSize));
+      }
+
+      const start = performance.now();
+      let totalMatches = 0;
+      let spanCount = 0;
+      let compositeCount = 0;
+
+      // Simulate plugin running on each streaming update
+      for (const partialText of tokens) {
+        // Run all regex operations (simulating unicodeCitation plugin)
+        SPAN_REGEX.lastIndex = 0;
+        while (SPAN_REGEX.exec(partialText) !== null) {
+          spanCount++;
+        }
+
+        COMPOSITE_REGEX.lastIndex = 0;
+        while (COMPOSITE_REGEX.exec(partialText) !== null) {
+          compositeCount++;
+        }
+
+        STANDALONE_PATTERN.lastIndex = 0;
+        while (STANDALONE_PATTERN.exec(partialText) !== null) {
+          totalMatches++;
+        }
+
+        // Cleanup would also run
+        void partialText.replace(CLEANUP_REGEX, '');
+      }
+
+      const duration = performance.now() - start;
+
+      // 100 streaming updates processing up to 50 citations each
+      // Should complete in under 1 second cumulative
+      expect(duration).toBeLessThan(1000);
+      expect(totalMatches).toBeGreaterThan(1000); // Many matches across all iterations
+      expect(spanCount).toBeGreaterThan(0);
+      expect(compositeCount).toBeGreaterThan(0);
+    });
+
+    it('should handle rapid repeated execution (300 renders with 20 citations)', () => {
+      /**
+       * Realistic streaming scenario: 300 token updates, final text has ~20 citations
+       */
+      const fullText = generateCitationHeavyText(20, 'literal');
+      const renderCount = 300;
+
+      const start = performance.now();
+      let totalOps = 0;
+
+      // Simulate 300 renders, each processing progressively more text
+      for (let i = 0; i < renderCount; i++) {
+        const progress = Math.min(1, (i + 1) / renderCount);
+        const partialText = fullText.slice(0, Math.floor(fullText.length * progress));
+
+        SPAN_REGEX.lastIndex = 0;
+        while (SPAN_REGEX.exec(partialText) !== null) {
+          totalOps++;
+        }
+
+        COMPOSITE_REGEX.lastIndex = 0;
+        while (COMPOSITE_REGEX.exec(partialText) !== null) {
+          totalOps++;
+        }
+
+        STANDALONE_PATTERN.lastIndex = 0;
+        while (STANDALONE_PATTERN.exec(partialText) !== null) {
+          totalOps++;
+        }
+
+        void partialText.replace(CLEANUP_REGEX, '');
+      }
+
+      const duration = performance.now() - start;
+      const avgPerRender = duration / renderCount;
+
+      // Should complete all 300 renders in under 500ms total
+      // Average per render should be under 2ms
+      expect(duration).toBeLessThan(500);
+      expect(avgPerRender).toBeLessThan(2);
+      expect(totalOps).toBeGreaterThan(0);
+    });
+  });
+});

client/src/utils/citations.ts

@@ -1,5 +1,46 @@
-export const SPAN_REGEX = /(\\ue203.*?\\ue204)/g;
+/**
-export const COMPOSITE_REGEX = /(\\ue200.*?\\ue201)/g;
+ * Citation Regex Patterns
-export const STANDALONE_PATTERN = /\\ue202turn(\d+)(search|image|news|video|ref|file)(\d+)/g;
+ *
-export const CLEANUP_REGEX = /\\ue200|\\ue201|\\ue202|\\ue203|\\ue204|\\ue206/g;
+ * These patterns handle two formats that LLMs may output:
-export const INVALID_CITATION_REGEX = /\s*\\ue202turn\d+(search|news|image|video|ref|file)\d+/g;
+ * 1. Literal escape sequences: "\ue202turn0search0" (backslash + "ue202" = 6 chars)
+ * 2. Actual Unicode characters: "turn0search0" (U+E202 = 1 char, private use area)
+ *
+ * The system instructs LLMs to output literal escape sequences, but some models
+ * may convert them to actual Unicode characters during text generation. These
+ * dual-format patterns ensure robust citation handling regardless of output format.
+ *
+ * Citation Format:
+ * - \ue202 / U+E202: Standalone citation marker (before each anchor)
+ * - \ue200 / U+E200: Composite group start
+ * - \ue201 / U+E201: Composite group end
+ * - \ue203 / U+E203: Highlight span start
+ * - \ue204 / U+E204: Highlight span end
+ *
+ * Anchor Pattern: turn{N}{type}{index}
+ * - N: Turn number (0-based)
+ * - type: search|image|news|video|ref|file
+ * - index: Result index within that type (0-based)
+ *
+ * Examples:
+ * - Standalone: "Statement.\ue202turn0search0"
+ * - Composite: "\ue200\ue202turn0search0\ue202turn0news1\ue201"
+ * - Highlighted: "\ue203Cited text.\ue204\ue202turn0search0"
+ */
+
+/** Matches highlighted text spans in both literal and Unicode formats */
+export const SPAN_REGEX = /((?:\\ue203|\ue203).*?(?:\\ue204|\ue204))/g;
+
+/** Matches composite citation blocks (multiple citations grouped together) */
+export const COMPOSITE_REGEX = /((?:\\ue200|\ue200).*?(?:\\ue201|\ue201))/g;
+
+/** Matches standalone citation anchors with turn, type, and index capture groups */
+export const STANDALONE_PATTERN =
+  /(?:\\ue202|\ue202)turn(\d+)(search|image|news|video|ref|file)(\d+)/g;
+
+/** Removes all citation marker characters from text for clean display */
+export const CLEANUP_REGEX =
+  /\\ue200|\\ue201|\\ue202|\\ue203|\\ue204|\\ue206|\ue200|\ue201|\ue202|\ue203|\ue204|\ue206/g;
+
+/** Matches invalid/orphaned citations (with leading whitespace) for removal */
+export const INVALID_CITATION_REGEX =
+  /\s*(?:\\ue202|\ue202)turn\d+(search|news|image|video|ref|file)\d+/g;