frontend/package-lock.json

@@ -8,8 +8,10 @@
       "name": "mindsift-frontend",
       "version": "1.0.0",
       "dependencies": {
+        "@types/prismjs": "^1.26.6",
         "framer-motion": "^11.15.0",
         "lucide-react": "^0.468.0",
+        "prismjs": "^1.30.0",
         "react": "^18.3.1",
         "react-dom": "^18.3.1"
       },
@@ -1224,6 +1226,12 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@types/prismjs": {
+      "version": "1.26.6",
+      "resolved": "https://registry.npmjs.org/@types/prismjs/-/prismjs-1.26.6.tgz",
+      "integrity": "sha512-vqlvI7qlMvcCBbVe0AKAb4f97//Hy0EBTaiW8AalRnG/xAN5zOiWWyrNqNXeq8+KAuvRewjCVY1+IPxk4RdNYw==",
+      "license": "MIT"
+    },
     "node_modules/@types/prop-types": {
       "version": "15.7.15",
       "resolved": "https://registry.npmjs.org/@types/prop-types/-/prop-types-15.7.15.tgz",
@@ -2242,6 +2250,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/prismjs": {
+      "version": "1.30.0",
+      "resolved": "https://registry.npmjs.org/prismjs/-/prismjs-1.30.0.tgz",
+      "integrity": "sha512-DEvV2ZF2r2/63V+tK8hQvrR2ZGn10srHbXviTlcv7Kpzw8jWiNTqbVgjO3IY8RxrrOUF8VPMQQFysYYYv0YZxw==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/queue-microtask": {
       "version": "1.2.3",
       "resolved": "https://registry.npmjs.org/queue-microtask/-/queue-microtask-1.2.3.tgz",

frontend/package.json

@@ -11,8 +11,10 @@
     "test:run": "echo 'Frontend checks passed'"
   },
   "dependencies": {
+    "@types/prismjs": "^1.26.6",
     "framer-motion": "^11.15.0",
     "lucide-react": "^0.468.0",
+    "prismjs": "^1.30.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1"
   },

frontend/src/features/workspace/CodeBlockItem.tsx

@@ -0,0 +1,282 @@
+import React, { useState, useMemo, useRef, useEffect } from 'react';
+import Prism from 'prismjs';
+import 'prismjs/components/prism-python';
+import 'prismjs/components/prism-typescript';
+import 'prismjs/components/prism-bash';
+import 'prismjs/components/prism-json';
+import 'prismjs/components/prism-go';
+import 'prismjs/components/prism-sql';
+import 'prismjs/components/prism-yaml';
+import 'prismjs/components/prism-rust';
+import 'prismjs/components/prism-c';
+import 'prismjs/components/prism-cpp';
+import 'prismjs/components/prism-java';
+import 'prismjs/components/prism-php';
+import 'prismjs/components/prism-docker';
+import 'prismjs/components/prism-markdown';
+import { Code, Copy, Check, Eye, Edit3 } from 'lucide-react';
+import { DocumentBlock } from '../../lib/types';
+
+export interface CodeBlockItemProps {
+  block: DocumentBlock;
+  isReadOnly: boolean;
+  onChangeContent: (content: string) => void;
+  onChangeLang: (lang: string) => void;
+  onFocus?: () => void;
+  onBlur?: () => void;
+  inputRef?: (el: HTMLTextAreaElement | null) => void;
+}
+
+export const CODE_LANGUAGES = [
+  { id: 'javascript', label: 'JavaScript' },
+  { id: 'typescript', label: 'TypeScript' },
+  { id: 'python', label: 'Python' },
+  { id: 'go', label: 'Go' },
+  { id: 'bash', label: 'Bash / Shell' },
+  { id: 'json', label: 'JSON' },
+  { id: 'html', label: 'HTML / XML', alias: 'markup' },
+  { id: 'css', label: 'CSS' },
+  { id: 'sql', label: 'SQL' },
+  { id: 'rust', label: 'Rust' },
+  { id: 'cpp', label: 'C++' },
+  { id: 'c', label: 'C' },
+  { id: 'java', label: 'Java' },
+  { id: 'php', label: 'PHP' },
+  { id: 'yaml', label: 'YAML' },
+  { id: 'docker', label: 'Dockerfile' },
+  { id: 'markdown', label: 'Markdown' },
+  { id: 'text', label: 'Plain Text' },
+];
+
+export const CodeBlockItem: React.FC<CodeBlockItemProps> = ({
+  block,
+  isReadOnly,
+  onChangeContent,
+  onChangeLang,
+  onFocus,
+  onBlur,
+  inputRef,
+}) => {
+  const [isEditing, setIsEditing] = useState(false);
+  const [copied, setCopied] = useState(false);
+  const localTextareaRef = useRef<HTMLTextAreaElement | null>(null);
+
+  const currentLang = block.lang || 'javascript';
+
+  // Highlighted HTML generated by Prism
+  const highlightedCode = useMemo(() => {
+    const code = block.content || '';
+    if (!code) return '';
+
+    const prismLang = currentLang === 'html' ? 'markup' : currentLang;
+    const grammar = Prism.languages[prismLang] || Prism.languages.javascript;
+    if (!grammar) {
+      return code
+        .replace(/&/g, '&amp;')
+        .replace(/</g, '&lt;')
+        .replace(/>/g, '&gt;');
+    }
+    try {
+      return Prism.highlight(code, grammar, prismLang);
+    } catch {
+      return code
+        .replace(/&/g, '&amp;')
+        .replace(/</g, '&lt;')
+        .replace(/>/g, '&gt;');
+    }
+  }, [block.content, currentLang]);
+
+  // Code lines for line numbers
+  const lines = useMemo(() => {
+    return (block.content || '').split('\n');
+  }, [block.content]);
+
+  const handleCopy = async (e: React.MouseEvent) => {
+    e.stopPropagation();
+    try {
+      await navigator.clipboard.writeText(block.content || '');
+      setCopied(true);
+      setTimeout(() => setCopied(false), 2000);
+    } catch {
+      // Fallback
+    }
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
+    if (e.key === 'Escape') {
+      setIsEditing(false);
+      return;
+    }
+    // Tab key indent/outdent
+    if (e.key === 'Tab') {
+      e.preventDefault();
+      const textarea = e.currentTarget;
+      const start = textarea.selectionStart;
+      const end = textarea.selectionEnd;
+      const val = textarea.value;
+
+      if (e.shiftKey) {
+        if (val.substring(start - 2, start) === '  ') {
+          const newVal = val.substring(0, start - 2) + val.substring(start);
+          onChangeContent(newVal);
+          setTimeout(() => {
+            textarea.selectionStart = textarea.selectionEnd = Math.max(0, start - 2);
+          }, 0);
+        }
+      } else {
+        const newVal = val.substring(0, start) + '  ' + val.substring(end);
+        onChangeContent(newVal);
+        setTimeout(() => {
+          textarea.selectionStart = textarea.selectionEnd = start + 2;
+        }, 0);
+      }
+    }
+  };
+
+  const switchToEdit = () => {
+    if (isReadOnly) return;
+    setIsEditing(true);
+    setTimeout(() => {
+      localTextareaRef.current?.focus();
+    }, 20);
+  };
+
+  return (
+    <div className="rounded-card border border-border bg-panel overflow-hidden shadow-xs my-1 group/code">
+      {/* Code Block Header Toolbar */}
+      <div className="flex items-center justify-between px-3 py-1.5 bg-canvas border-b border-border text-xs">
+        {/* Left: Language Selection */}
+        <div className="flex items-center gap-2">
+          <Code className="w-3.5 h-3.5 text-accent flex-shrink-0" />
+          <select
+            value={currentLang}
+            disabled={isReadOnly}
+            onChange={(e) => onChangeLang(e.target.value)}
+            className="bg-transparent text-main font-mono text-[11px] font-medium border border-transparent hover:border-border focus:border-accent rounded px-1.5 py-0.5 outline-none cursor-pointer"
+          >
+            {CODE_LANGUAGES.map((lang) => (
+              <option key={lang.id} value={lang.id} className="bg-panel text-main">
+                {lang.label}
+              </option>
+            ))}
+          </select>
+        </div>
+
+        {/* Right: Mode Toggle & Copy */}
+        <div className="flex items-center gap-1.5">
+          {!isReadOnly && (
+            <button
+              type="button"
+              onClick={() => {
+                if (isEditing) {
+                  setIsEditing(false);
+                } else {
+                  switchToEdit();
+                }
+              }}
+              className="px-2 py-0.5 rounded text-[11px] font-medium text-muted hover:text-main hover:bg-panel-elevated transition-colors flex items-center gap-1 cursor-pointer"
+              title={isEditing ? 'Zur farbigen Vorschau wechseln (Esc)' : 'Code bearbeiten'}
+            >
+              {isEditing ? (
+                <>
+                  <Eye className="w-3 h-3 text-accent" />
+                  <span>Vorschau</span>
+                </>
+              ) : (
+                <>
+                  <Edit3 className="w-3 h-3 text-muted" />
+                  <span>Bearbeiten</span>
+                </>
+              )}
+            </button>
+          )}
+
+          <button
+            type="button"
+            onClick={handleCopy}
+            className={`px-2 py-0.5 rounded text-[11px] font-medium transition-colors flex items-center gap-1 cursor-pointer ${
+              copied
+                ? 'text-emerald-500 bg-emerald-500/10'
+                : 'text-muted hover:text-main hover:bg-panel-elevated'
+            }`}
+            title="Code in Zwischenablage kopieren"
+          >
+            {copied ? (
+              <>
+                <Check className="w-3 h-3 text-emerald-500" />
+                <span>Kopiert!</span>
+              </>
+            ) : (
+              <>
+                <Copy className="w-3 h-3 opacity-70" />
+                <span>Kopieren</span>
+              </>
+            )}
+          </button>
+        </div>
+      </div>
+
+      {/* Code Block Content */}
+      {isEditing && !isReadOnly ? (
+        <div className="relative">
+          <textarea
+            ref={(el) => {
+              localTextareaRef.current = el;
+              if (inputRef) inputRef(el);
+            }}
+            rows={Math.max(3, lines.length)}
+            value={block.content || ''}
+            onFocus={() => onFocus && onFocus()}
+            onBlur={() => {
+              if (onBlur) onBlur();
+            }}
+            onChange={(e) => onChangeContent(e.target.value)}
+            onKeyDown={handleKeyDown}
+            placeholder="// Code hier eingeben..."
+            className="w-full p-3 bg-panel-elevated/40 font-mono text-xs text-main leading-relaxed focus:outline-none resize-none placeholder:text-faint"
+          />
+          <div className="px-3 py-1 bg-canvas/40 border-t border-border/50 text-[10px] text-faint flex items-center justify-between">
+            <span>Tab: Einrücken (2 Leerzeichen) • Shift+Tab: Ausrücken</span>
+            <button
+              type="button"
+              onClick={() => setIsEditing(false)}
+              className="hover:text-accent cursor-pointer"
+            >
+              Vorschau anzeigen (Esc)
+            </button>
+          </div>
+        </div>
+      ) : (
+        <div
+          onClick={switchToEdit}
+          className={`relative p-3 font-mono text-xs overflow-x-auto ${
+            isReadOnly ? '' : 'cursor-pointer hover:bg-panel-elevated/20 transition-colors'
+          }`}
+          title={isReadOnly ? undefined : 'Klicken zum Bearbeiten'}
+        >
+          {block.content ? (
+            <div className="flex gap-3">
+              {/* Line numbers */}
+              <div className="select-none text-right text-faint opacity-50 font-mono text-xs leading-relaxed flex-shrink-0">
+                {lines.map((_, idx) => (
+                  <div key={idx}>{idx + 1}</div>
+                ))}
+              </div>
+              {/* Syntax highlighted code */}
+              <pre className="m-0 p-0 font-mono text-xs leading-relaxed whitespace-pre overflow-x-auto flex-1">
+                <code
+                  dangerouslySetInnerHTML={{ __html: highlightedCode }}
+                  className={`language-${currentLang}`}
+                />
+              </pre>
+            </div>
+          ) : (
+            <div className="text-faint italic py-2">
+              {isReadOnly ? '(Kein Code hinterlegt)' : '(Klicken, um Code einzugeben...)'}
+            </div>
+          )}
+        </div>
+      )}
+    </div>
+  );
+};

frontend/src/features/workspace/WorkspaceView.tsx

@@ -51,6 +51,7 @@ import {
 } from 'lucide-react';
 import { BlockType, Document, DocumentBlock, DocLockInfo, DocShare, TagDetails, TagSummary, User } from '../../lib/types';
 import { api, getToken, triggerHaptic } from '../../lib/api';
+import { CodeBlockItem } from './CodeBlockItem';
 
 interface WorkspaceViewProps {
   currentUser?: User | null;
@@ -1377,7 +1378,12 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
         return;
       }
 
-      updateBlock(blockId, { type: cmd.type, content: cleanContent, checked: cmd.type === 'todo' ? false : undefined });
+      updateBlock(blockId, {
+        type: cmd.type,
+        content: cleanContent,
+        checked: cmd.type === 'todo' ? false : undefined,
+        lang: cmd.type === 'code' ? (block.lang || 'javascript') : block.lang,
+      });
       focusBlock(blockId);
     }
   };
@@ -2839,21 +2845,20 @@ export const WorkspaceView: React.FC<WorkspaceViewProps> = ({
 
                           {/* TYPE: CODE */}
                           {block.type === 'code' && (
-                            <div className="p-2 code-block">
-                              <textarea
-                                ref={(el) => (blockInputRefs.current[block.id] = el)}
-                                readOnly={isReadOnly}
-                                rows={Math.max(2, (block.content || '').split('\n').length)}
-                                value={block.content}
-                                onFocus={handleBlockFocus}
-                                onBlur={handleBlockBlur}
-                                onChange={(e) => handleContentChange(block, e.target.value)}
-                                onKeyDown={(e) => handleKeyDown(e, block, originalIndex)}
-                                className={`w-full bg-transparent text-xs font-mono text-main focus:outline-none resize-none ${
-                                  isReadOnly ? 'cursor-default' : ''
-                                }`}
-                              />
-                            </div>
+                            <CodeBlockItem
+                              block={block}
+                              isReadOnly={isReadOnly}
+                              inputRef={(el) => (blockInputRefs.current[block.id] = el)}
+                              onFocus={handleBlockFocus}
+                              onBlur={handleBlockBlur}
+                              onChangeContent={(content) => handleContentChange(block, content)}
+                              onChangeLang={(lang) => {
+                                if (!isReadOnly) {
+                                  ensureLock();
+                                  updateBlock(block.id, { lang });
+                                }
+                              }}
+                            />
                           )}
 
                           {/* TYPE: TABLE */}

frontend/src/index.css

@@ -358,4 +358,62 @@ body {
     border-left: 2px solid var(--accent-primary);
     color: var(--text-main);
   }
+
+  /* Prism Syntax Highlighting Tokens */
+  .token.comment,
+  .token.prolog,
+  .token.doctype,
+  .token.cdata {
+    color: #71717a;
+    font-style: italic;
+  }
+
+  .token.punctuation {
+    color: #94a3b8;
+  }
+
+  .token.property,
+  .token.tag,
+  .token.boolean,
+  .token.number,
+  .token.constant,
+  .token.symbol,
+  .token.deleted {
+    color: #f43f5e;
+  }
+
+  .token.selector,
+  .token.attr-name,
+  .token.string,
+  .token.char,
+  .token.builtin,
+  .token.inserted {
+    color: #10b981;
+  }
+
+  .token.operator,
+  .token.entity,
+  .token.url,
+  .language-css .token.string,
+  .style .token.string {
+    color: #38bdf8;
+  }
+
+  .token.atrule,
+  .token.attr-value,
+  .token.keyword {
+    color: #818cf8;
+    font-weight: 600;
+  }
+
+  .token.function,
+  .token.class-name {
+    color: #fbbf24;
+  }
+
+  .token.regex,
+  .token.important,
+  .token.variable {
+    color: #f97316;
+  }
 }