use highlight.js in code_handlers where possible

src/services/llm/context/code_handlers.ts

@@ -2,6 +2,9 @@
  * Helper functions for processing code notes, including language detection and structure extraction
  */
 
+// Import highlight.js dynamically when needed
+let hljs: any = null;
+
 /**
  * Attempt to detect the programming language from code content or note attributes
  */
@@ -46,6 +49,51 @@ export function detectLanguage(content: string, mime: string): string {
         }
     }
 
+    // For performance, limit the amount of code we pass to highlight.js
+    // Use a maximum of ~10KB of code for detection
+    const MAX_SAMPLE_SIZE = 10240;
+    const codeSample = content.length > MAX_SAMPLE_SIZE
+        ? content.substring(0, MAX_SAMPLE_SIZE)
+        : content;
+
+    try {
+        // Browser environment
+        if (typeof window !== 'undefined' && window.hljs) {
+            const result = window.hljs.highlightAuto(codeSample);
+            if (result && result.language) {
+                return result.language;
+            }
+        }
+        // Node.js environment
+        else if (typeof process !== 'undefined' && process.versions && process.versions.node) {
+            // Only load highlight.js if we haven't already
+            if (!hljs) {
+                try {
+                    // We need to dynamically require highlight.js
+                    // Using a try/catch since it might not be available
+                    hljs = require('@highlightjs/cdn-assets/highlight.min.js');
+                } catch (e) {
+                    try {
+                        // Try alternative path
+                        hljs = require('highlight.js');
+                    } catch (e2) {
+                        console.debug("highlight.js not available in this environment, falling back to regex detection");
+                    }
+                }
+            }
+
+            if (hljs && typeof hljs.highlightAuto === 'function') {
+                const result = hljs.highlightAuto(codeSample);
+                if (result && result.language) {
+                    return result.language;
+                }
+            }
+        }
+    } catch (e) {
+        console.debug("Error using highlight.js for language detection:", e);
+    }
+
+    // Fallback to regex-based detection if highlight.js is not available or fails
     // Check for common language patterns in the first few lines
     const firstLines = content.split('\n').slice(0, 10).join('\n');