feat(v0.9.20): Auto-clear selection state on Focus Mode entry

- Modified handleDoubleClick() to automatically clear existing highlights before entering focus mode
- Added highlightManager.unhighlight({ force: true }) call for clean state transition
- Automatically hide statistics popup when entering focus mode to prevent visual conflicts
- Enhanced user experience with pristine focused context without residual artifacts
- Updated Interface Document.md, README.md, and TODO.md with v0.9.20 documentation
- Added bilingual comments (EN/中文) explaining the auto-clear logic

Author: Jacobinwwey

Interface Document.md

@@ -1,4 +1,4 @@
-# 2025-12-24 v0.9.19
+# 2025-12-24 v0.9.20
 
 # Interface Document
 
@@ -249,6 +249,13 @@ Renders the JSON data into an interactive DAG.
         *   **Behavior**: Double-clicking a related node while already in focus mode now properly refreshes the view to show the new node's context.
         *   **Fix**: Removes restriction that prevented switching focus between related nodes, enabling seamless exploration of connected concepts.
         *   **State Reset**: All node visibility flags are reset before entering new focus mode to prevent accumulation issues.
+    
+    *   **Selection State Auto-Clear (v0.9.20)**:
+        *   **Behavior**: When double-clicking a node to enter Focus Mode, any existing selection/highlight state is automatically cleared before entering the focused view.
+        *   **Implementation**: 
+            *   Calls `highlightManager.unhighlight({ force: true })` to clear highlight state.
+            *   Hides the statistics popup if visible (`#node-stats-popup`).
+        *   **User Experience**: Provides a clean transition into Focus Mode without residual visual artifacts from previous selections, ensuring the focused view is always clear and uncluttered.
 
     *   **Scalability Defaults (v0.8.8)**:
         *   **Orphans**: Hidden by default.
@@ -484,7 +491,6 @@ Manages node highlighting interactions for both PC and mobile interfaces.
     *   **Focus Mode**: Highlighting disabled, focus mode handles visualization.
 
 
-```
 
 
 
@@ -833,4 +839,3 @@ Manages node highlighting interactions for both PC and mobile interfaces.
     2.  **资源编译**: `npm run build` -> 填充 `dist/frontend`。
     3.  **同步**: `npx cap sync android` -> 将 `dist/frontend` 复制到 `android/app/src/main/assets/public`。
     4.  **原生构建**: `gradlew assembleDebug` -> 编译 APK。
-

README.md

@@ -119,6 +119,11 @@ NoteConnection uses **Capacitor** to build native mobile apps.
 
 ## 📅 Changelog
 
+### v0.9.20 - Selection State Auto-Clear on Focus Entry (2025-12-24)
+- [x] **Clean Focus Transition**: When double-clicking a node to enter Focus Mode, any existing selection or highlight state is now automatically cleared, providing a clean and uncluttered focused view.
+- [x] **Auto-Hide Popup**: The statistics popup is automatically hidden when entering Focus Mode, preventing visual conflicts.
+- [x] **Enhanced UX**: Ensures users always start with a pristine focused context without residual artifacts from previous node selections.
+
 ### v0.9.19 - Focus Mode & Popup Enhancements (2025-12-24)
 - [x] **Focus Mode Re-entry**: Fixed issue where double-clicking a related node while in focus mode wouldn't refresh properly. Now seamlessly switches focus between connected nodes.
 - [x] **Draggable Popup**: Node statistics popup can now be dragged by its header to any screen position for better workspace organization.

TODO.md

@@ -1,11 +1,33 @@
-# 2025-12-24 v0.9.19
+# 2025-12-24 v0.9.20
 
 # Project Build Plan: Progressive Hierarchical Knowledge Graph
 
 This document outlines the roadmap for building `NoteConnection`, a system capable of visualizing tens of thousands of knowledge points as a Directed Acyclic Graph (DAG), highlighting hierarchical relationships and learning paths.
 
 ---
 
+# 2025-12-24 v0.9.20 - Selection State Auto-Clear on Focus Entry
+
+**Goal**: Automatically clear any existing selection or highlight state when entering Focus Mode via double-click for a clean transition.
+
+- [x] **Auto-Clear Implementation**
+    - [x] **Highlight Clearing**: Modified `handleDoubleClick()` to call `highlightManager.unhighlight({ force: true })` before entering focus mode.
+    - [x] **Popup Hiding**: Automatically hide the statistics popup (`#node-stats-popup`) when entering focus mode.
+    - [x] **State Management**: Ensures clean state transition without residual visual artifacts.
+
+- [x] **User Experience Enhancement**
+    - [x] **Clean Transition**: Users always start with a pristine focused context.
+    - [x] **Visual Clarity**: Prevents confusion from overlapping highlights between normal and focus modes.
+    - [x] **Consistent Behavior**: Standardized focus mode entry behavior across all scenarios.
+
+- [x] **Documentation**
+    - [x] **Interface Document**: Updated with v0.9.20 selection auto-clear specifications.
+    - [x] **README**: Added v0.9.20 changelog entries in both English and Chinese.
+    - [x] **Code Comments**: Bilingual comments explaining the auto-clear logic.
+    - [x] **TODO**: Documented completed feature implementation.
+
+---
+
 # 2025-12-24 v0.9.19 - Focus Mode & Popup Enhancements
 
 **Goal**: Fix focus mode refresh issues and add drag/zoom functionality to the statistics popup for better user experience.

src/frontend/app.js

@@ -785,12 +785,27 @@ function handleDoubleClick(event, d) {
     // 要求：双击进入专注模式
     // v0.9.19 Fix: Allow re-entering focus mode for different nodes
     // v0.9.19 修复：允许为不同节点重新进入专注模式
+    // v0.9.20 Enhancement: Auto-clear selection state when entering focus mode
+    // v0.9.20 增强：进入专注模式时自动清除选择状态
 
     if (focusNode && focusNode.id === d.id) {
         // Already focused on same node -> Open Reader
         // 已经专注于同一节点 -> 打开阅读器
         if (window.reader) window.reader.open(d);
     } else {
+        // Clear any existing selection/highlight state before entering focus mode
+        // 在进入专注模式前清除任何现有的选择/高亮状态
+        if (window.highlightManager) {
+            window.highlightManager.unhighlight({ force: true });
+        }
+        
+        // Hide statistics popup if visible
+        // 如果统计弹窗可见则隐藏
+        const popup = document.getElementById('node-stats-popup');
+        if (popup && popup.style.display !== 'none') {
+            popup.style.display = 'none';
+        }
+        
         // Enter or Re-enter Focus Mode for new node
         // 为新节点进入或重新进入专注模式
         // This properly handles the case when double-clicking a related node while in focus mode