docs: streamline LeetCode API discussion and merge post-processing summary into README

- Rewrite leetcode_api_discussion.md in concise English
  - Reduce content from extensive draft to a focused overview
  - Clarify API structure, field mapping, and URL generation logic
  - Retain only implementation-relevant details and usage notes

- Merge POST_PROCESSING_UPDATE_SUMMARY.md into tools/ai-markmap-agent/README.md
  - Add "Post-Processing Link Generation" section with standardized link formats
  - Document LeetCode API integration, data sources, and comparison file generation
  - Describe automatic URL normalization and GitHub solution link insertion

- Update README module responsibilities
  - Add post_processing.py for link normalization and generation
  - Add leetcode_api.py for LeetCode API data loading

- Remove temporary documentation file
  - Delete POST_PROCESSING_UPDATE_SUMMARY.md after consolidation

Author: lufftw

tools/ai-markmap-agent/README.md

@@ -161,8 +161,10 @@ Apply adopted improvements surgically to the baseline:
 ### Phase 5-6: Post-Processing
 
 - Translation (en → zh-TW)
-- Link validation
-- HTML generation
+- Link validation and normalization
+- Automatic LeetCode URL generation
+- GitHub solution link addition
+- Comparison file generation
 
 ---
 
@@ -902,6 +904,66 @@ The system automatically loads:
 
 ---
 
+## Post-Processing Link Generation
+
+### Link Format
+
+Post-processing automatically converts LeetCode problem references to standardized links:
+
+**Format:**
+```
+[LeetCode 11](leetcode_url) | [Solution](github_url)
+```
+
+**Features:**
+- Simple format: Only problem ID, no title
+- Handles multiple AI-generated formats
+- Auto-generates LeetCode URLs from API cache
+- Adds GitHub solution links when available
+
+### Data Sources
+
+1. **Local TOML files** (`meta/problems/`) - Primary source
+2. **LeetCode API cache** (`tools/.cache/leetcode_problems.json`) - Auto-supplement
+
+**Priority:** Local TOML > API cache
+
+### Comparison Files
+
+After each post-processing run, a comparison file is automatically generated:
+
+**Location:** `outputs/final/post_processing_comparison_{timestamp}.md`
+
+**Contents:**
+- Before: Original AI-generated content
+- After: Post-processed content with normalized links
+
+**Usage:**
+- Verify link generation correctness
+- Check format compliance
+- Identify improvements needed
+
+### LeetCode API Integration
+
+The system automatically syncs with LeetCode API:
+
+```bash
+# Sync LeetCode problem data (7-day cache)
+python tools/sync_leetcode_data.py
+
+# Check cache status
+python tools/sync_leetcode_data.py --check
+```
+
+**Integration:**
+- `PostProcessor` automatically loads and merges API cache data
+- Missing URLs are auto-generated from API data
+- No configuration required
+
+See [Post-Processing Links Documentation](docs/POST_PROCESSING_LINKS.md) for details.
+
+---
+
 ## Module Responsibilities
 
 | Module | Responsibility |
@@ -910,6 +972,8 @@ The system automatically loads:
 | `consensus.py` | Programmatic majority voting |
 | `writer.py` | Refinement-mode writer |
 | `graph.py` | LangGraph workflow orchestration |
+| `post_processing.py` | Link normalization and generation |
+| `leetcode_api.py` | LeetCode API data loading |
 | `config_loader.py` | Configuration management |
 
 ---

tools/ai-markmap-agent/docs/POST_PROCESSING_LINKS.md

@@ -0,0 +1,184 @@
+# 後處理連結處理說明
+
+## 概述
+
+後處理模組 (`post_processing.py`) 負責將 AI 生成的 mindmap 內容中的 LeetCode 問題引用轉換為標準化的連結格式。
+
+## 連結格式
+
+### 目標格式
+
+```
+[LeetCode 11](leetcode_url) | [Solution](github_url)
+```
+
+**特點：**
+- 只使用題號，不包含標題
+- 格式簡潔統一
+- 自動添加 GitHub solution 連結（如果有）
+
+### 處理的輸入格式
+
+後處理會處理以下多種 AI 可能產生的格式：
+
+1. **純文字格式**
+   - `LeetCode 11`
+   - `LeetCode 11 - Container With Most Water`
+   - `LC 11`
+
+2. **Markdown 連結格式**
+   - `[LeetCode 11](url)`
+   - `[LeetCode 11 - Container With Most Water](url)`
+   - `[LC 11](url)`
+
+3. **錯誤的 URL**
+   - `[LeetCode 11](wrong_url)` → 自動修正為正確的 URL
+
+## 處理流程
+
+### 步驟 1: 文字替換
+
+- `LC 11` → `LeetCode 11`
+- `LC-11` → `LeetCode 11`
+- `LeetCode11` → `LeetCode 11`
+
+### 步驟 2: 連結轉換
+
+將純文字或現有連結轉換為標準格式：
+
+**輸入：**
+```
+LeetCode 11 - Container With Most Water
+```
+
+**輸出：**
+```
+[LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/)
+```
+
+### 步驟 3: URL 正規化
+
+確保所有 LeetCode URL 使用正確的格式：
+- 移除檔案名稱格式的 slug（如 `0011_container_with_most_water`）
+- 轉換為標準 slug（如 `container-with-most-water`）
+- 確保以 `/description/` 結尾
+
+### 步驟 4: 添加 GitHub Solution 連結
+
+如果問題有對應的 solution 檔案，自動添加 GitHub 連結：
+
+**輸入：**
+```
+[LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/)
+```
+
+**輸出：**
+```
+[LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+```
+
+## 資料來源
+
+### 本地 TOML 檔案
+
+從 `meta/problems/` 目錄載入問題元資料，包含：
+- 問題標題
+- Solution 檔案路徑
+- 其他元資料
+
+### LeetCode API 快取
+
+從 `tools/.cache/leetcode_problems.json` 載入：
+- LeetCode URL
+- Slug
+- 問題標題（作為補充）
+
+**優先順序：**
+1. 本地 TOML 資料（優先）
+2. API 快取資料（補充）
+
+## 對比檔案
+
+每次執行後處理後，會自動生成對比檔案：
+
+**位置：** `outputs/final/post_processing_comparison_{timestamp}.md`
+
+**內容：**
+- Before: 原始內容（AI 生成）
+- After: 後處理後的內容
+
+**用途：**
+- 檢查後處理效果
+- 驗證連結是否正確生成
+- 比較處理前後的差異
+
+## 範例
+
+### 範例 1: 純文字轉換
+
+**Before:**
+```markdown
+- LeetCode 11 - Container With Most Water
+- LeetCode 3 - Longest Substring
+```
+
+**After:**
+```markdown
+- [LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+- [LeetCode 3](https://leetcode.com/problems/longest-substring-without-repeating-characters/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0003_longest_substring_without_repeating_characters.py)
+```
+
+### 範例 2: 修正錯誤 URL
+
+**Before:**
+```markdown
+- [LeetCode 11](https://leetcode.com/problems/0011_container_with_most_water/)
+```
+
+**After:**
+```markdown
+- [LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+```
+
+### 範例 3: 處理多種格式
+
+**Before:**
+```markdown
+- LC 11
+- LeetCode 11 - Container With Most Water
+- [LeetCode 11](wrong_url)
+```
+
+**After:**
+```markdown
+- [LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+- [LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+- [LeetCode 11](https://leetcode.com/problems/container-with-most-water/description/) | [Solution](https://github.com/lufftw/neetcode/blob/main/solutions/0011_container_with_most_water.py)
+```
+
+## 配置
+
+後處理行為由 `config/config.yaml` 中的 `workflow.post_processing` 配置控制：
+
+```yaml
+workflow:
+  post_processing:
+    text_replacements:
+      - pattern: "\\bLC[-\\s]?(\\d+)"
+        replacement: "LeetCode \\1"
+```
+
+## 相關檔案
+
+- `src/post_processing.py` - 後處理主模組
+- `src/leetcode_api.py` - LeetCode API 資料載入
+- `src/graph.py` - 工作流程整合
+- `tools/sync_leetcode_data.py` - API 資料同步工具
+
+## 注意事項
+
+1. **格式簡化**：只使用題號，不包含標題，因為 AI 產生的格式很多元
+2. **自動補充**：如果本地資料缺少 URL，自動從 API 快取補充
+3. **對比檔案**：每次執行都會生成對比檔案，方便檢查效果
+4. **向後相容**：不影響現有功能，只做補充和標準化
+

tools/ai-markmap-agent/src/graph.py

@@ -32,6 +32,7 @@
     ConsensusResult,
 )
 from .output.html_converter import save_all_markmaps, MarkMapHTMLConverter
+from datetime import datetime
 from .post_processing import clean_translated_content
 
 __all__ = [
@@ -98,6 +99,74 @@ class WorkflowState(TypedDict, total=False):
     _resume_config: dict[str, Any]
 
 
+def _save_post_processing_comparison(
+    comparison_data: dict[str, dict[str, str]],
+    config: dict[str, Any]
+) -> None:
+    """
+    Save post-processing before/after comparison to markdown file.
+    
+    Args:
+        comparison_data: Dict mapping output key to {"before": str, "after": str}
+        config: Configuration dictionary
+    """
+    if not comparison_data:
+        return
+    
+    # Get output directory from config
+    output_config = config.get("output", {})
+    final_dirs = output_config.get("final_dirs", {})
+    markdown_dir = final_dirs.get("markdown", "outputs/final")
+    
+    base_dir = Path(__file__).parent.parent.parent.parent
+    output_path = base_dir / markdown_dir
+    output_path.mkdir(parents=True, exist_ok=True)
+    
+    # Create comparison file
+    timestamp = datetime.now().strftime("%Y%m%d_%H%M%S")
+    comparison_file = output_path / f"post_processing_comparison_{timestamp}.md"
+    
+    content_parts = [
+        "# Post-Processing Link Comparison",
+        "",
+        f"Generated: {datetime.now().strftime('%Y-%m-%d %H:%M:%S')}",
+        "",
+        "This file shows the before/after comparison of post-processing link generation.",
+        "",
+        "---",
+        "",
+    ]
+    
+    for key, data in comparison_data.items():
+        before = data.get("before", "")
+        after = data.get("after", "")
+        
+        content_parts.extend([
+            f"## {key}",
+            "",
+            "### Before (原始內容)",
+            "",
+            "```markdown",
+            before[:5000] + ("..." if len(before) > 5000 else ""),  # Limit length
+            "```",
+            "",
+            "### After (後處理後)",
+            "",
+            "```markdown",
+            after[:5000] + ("..." if len(after) > 5000 else ""),  # Limit length
+            "```",
+            "",
+            "---",
+            "",
+        ])
+    
+    try:
+        comparison_file.write_text("\n".join(content_parts), encoding="utf-8")
+        print(f"  📄 Post-processing comparison saved: {comparison_file.name}")
+    except Exception as e:
+        print(f"  ⚠ Failed to save comparison: {e}")
+
+
 def load_baseline_markmap(config: dict[str, Any]) -> str:
     """
     Load the baseline Markmap from file.
@@ -873,17 +942,29 @@ def run_post_processing(state: WorkflowState) -> WorkflowState:
 
         # Apply post-processing
         final_outputs = {}
+        post_processing_comparison = {}  # Store before/after for comparison
+        
         for key, content in all_outputs.items():
             if debug.enabled:
                 debug.save_post_processing(content, key, is_before=True)
 
             processed = processor.process(content)
             final_outputs[key] = processed
+            
+            # Store comparison for later saving
+            post_processing_comparison[key] = {
+                "before": content,
+                "after": processed
+            }
+            
             print(f"  ✓ Processed: {key}")
 
             if debug.enabled:
                 debug.save_post_processing(processed, key, is_before=False)
 
+        # Save post-processing comparison to markdown file
+        _save_post_processing_comparison(post_processing_comparison, config)
+        
         state["final_outputs"] = final_outputs
         return state