diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03a2bf2a..97548c74 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+## [5.4.2-dev.1](https://github.com/kaitranntt/ccs/compare/v5.4.1...v5.4.2-dev.1) (2025-12-03)
+
+
+### Bug Fixes
+
+* **merge:** resolve conflicts between dev and main ([8347ea6](https://github.com/kaitranntt/ccs/commit/8347ea64c6b919a79f5ab63c398b6c36f012ca2d))
+* **sync:** implement copy fallback for windows when symlinks unavailable ([6b3f93a](https://github.com/kaitranntt/ccs/commit/6b3f93a80a0232e8c964d73e51aa0afb0768b00f)), closes [#45](https://github.com/kaitranntt/ccs/issues/45)
+
 ## [5.4.1](https://github.com/kaitranntt/ccs/compare/v5.4.0...v5.4.1) (2025-12-03)
 
 
@@ -5,6 +13,7 @@
 
 * **cliproxy:** resolve windows auth browser not opening ([af4d6cf](https://github.com/kaitranntt/ccs/commit/af4d6cff89395a74e2eaf56551d3f56b95e0a6ce)), closes [#42](https://github.com/kaitranntt/ccs/issues/42)
 * **doctor:** resolve windows claude cli detection failure ([cfe9ba0](https://github.com/kaitranntt/ccs/commit/cfe9ba05a4351302fbb330ca00b6025cb65a8f20)), closes [#41](https://github.com/kaitranntt/ccs/issues/41)
+* **sync:** implement copy fallback for windows when symlinks unavailable ([6b3f93a](https://github.com/kaitranntt/ccs/commit/6b3f93a80a0232e8c964d73e51aa0afb0768b00f)), closes [#45](https://github.com/kaitranntt/ccs/issues/45)
 
 ## [5.4.1-dev.1](https://github.com/kaitranntt/ccs/compare/v5.4.0...v5.4.1-dev.1) (2025-12-03)
 
diff --git a/VERSION b/VERSION
index ade65226..ae273b6d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-5.4.1
+5.4.2-dev.1
diff --git a/installers/install.ps1 b/installers/install.ps1
index 9df8ae3a..8d09b784 100644
--- a/installers/install.ps1
+++ b/installers/install.ps1
@@ -83,7 +83,7 @@ $InstallMethod = if ($ScriptDir -and ((Test-Path "$ScriptDir\lib\ccs.ps1") -or (
 # IMPORTANT: Update this version when releasing new versions!
 # This hardcoded version is used for standalone installations (irm | iex)
 # For git installations, VERSION file is read if available
-$CcsVersion = "5.4.1"
+$CcsVersion = "5.4.2-dev.1"
 
 # Try to read VERSION file for git installations
 if ($ScriptDir) {
diff --git a/installers/install.sh b/installers/install.sh
index 0d7e874d..2e981f0a 100755
--- a/installers/install.sh
+++ b/installers/install.sh
@@ -84,7 +84,7 @@ fi
 # IMPORTANT: Update this version when releasing new versions!
 # This hardcoded version is used for standalone installations (curl | bash)
 # For git installations, VERSION file is read if available
-CCS_VERSION="5.4.1"
+CCS_VERSION="5.4.2-dev.1"
 
 # Try to read VERSION file for git installations
 if [[ -f "$SCRIPT_DIR/VERSION" ]]; then
diff --git a/package.json b/package.json
index dcca315f..0dff8516 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@kaitranntt/ccs",
-  "version": "5.4.1",
+  "version": "5.4.2-dev.1",
   "description": "Claude Code Switch - Instant profile switching between Claude Sonnet 4.5 and GLM 4.6",
   "keywords": [
     "cli",
diff --git a/src/utils/claude-symlink-manager.ts b/src/utils/claude-symlink-manager.ts
index 4011d007..29c98260 100644
--- a/src/utils/claude-symlink-manager.ts
+++ b/src/utils/claude-symlink-manager.ts
@@ -164,12 +164,9 @@ export class ClaudeSymlinkManager {
       if (!silent) console.log(`[OK] Symlinked ${item.target}`);
       return true;
     } catch (err) {
-      // Windows fallback: stub for now, full implementation in v4.2
+      // Windows fallback: copy instead of symlink when symlinks unavailable
       if (process.platform === 'win32') {
-        if (!silent) {
-          console.log(`[!] Symlink failed for ${item.target} (Windows fallback deferred to v4.2)`);
-          console.log(`[i] Enable Developer Mode or wait for next update`);
-        }
+        return this.copyFallback(sourcePath, targetPath, item, silent);
       } else {
         const error = err as Error;
         if (!silent) console.log(`[!] Failed to symlink ${item.target}: ${error.message}`);
@@ -178,6 +175,61 @@ export class ClaudeSymlinkManager {
     }
   }
 
+  /**
+   * Windows fallback: copy files/directories when symlinks unavailable
+   * Note: Changes won't auto-sync; user must run 'ccs sync' after updates
+   */
+  private copyFallback(
+    sourcePath: string,
+    targetPath: string,
+    item: CcsItem,
+    silent = false
+  ): boolean {
+    try {
+      if (item.type === 'directory') {
+        // Copy directory recursively
+        this.copyDirRecursive(sourcePath, targetPath);
+      } else {
+        // Copy single file
+        fs.copyFileSync(sourcePath, targetPath);
+      }
+      if (!silent) {
+        console.log(`[OK] Copied ${item.target} (symlink unavailable)`);
+        console.log(`[i] Run 'ccs sync' after CCS updates to refresh`);
+      }
+      return true;
+    } catch (copyErr) {
+      const error = copyErr as Error;
+      if (!silent) {
+        console.log(`[!] Failed to copy ${item.target}: ${error.message}`);
+        console.log(`[i] Enable Developer Mode for symlinks, or check permissions`);
+      }
+      return false;
+    }
+  }
+
+  /**
+   * Recursively copy directory (for Windows fallback)
+   */
+  private copyDirRecursive(src: string, dest: string): void {
+    if (!fs.existsSync(dest)) {
+      fs.mkdirSync(dest, { recursive: true });
+    }
+
+    const entries = fs.readdirSync(src, { withFileTypes: true });
+
+    for (const entry of entries) {
+      const srcPath = path.join(src, entry.name);
+      const destPath = path.join(dest, entry.name);
+
+      if (entry.isDirectory()) {
+        this.copyDirRecursive(srcPath, destPath);
+      } else {
+        fs.copyFileSync(srcPath, destPath);
+      }
+    }
+  }
+
   /**
    * Check if target is already the correct symlink pointing to source
    */
@@ -224,8 +276,8 @@ export class ClaudeSymlinkManager {
   }
 
   /**
-   * Uninstall CCS items from ~/.claude/ (remove symlinks only)
-   * Safe: only removes items that are CCS symlinks
+   * Uninstall CCS items from ~/.claude/ (remove symlinks or copied files)
+   * Safe: only removes items that are CCS symlinks or valid copies
    */
   uninstall(): void {
     let removed = 0;
@@ -234,10 +286,20 @@ export class ClaudeSymlinkManager {
       const targetPath = path.join(this.userClaudeDir, item.target);
       const sourcePath = path.join(this.ccsClaudeDir, item.source);
 
-      // Only remove if it's our symlink
-      if (fs.existsSync(targetPath) && this.isOurSymlink(targetPath, sourcePath)) {
+      // Check if it's our symlink or a valid copy (Windows fallback)
+      const isSymlink = this.isOurSymlink(targetPath, sourcePath);
+      const isCopy =
+        process.platform === 'win32' && this.isCopiedItem(targetPath, sourcePath, item.type);
+
+      if (fs.existsSync(targetPath) && (isSymlink || isCopy)) {
         try {
-          fs.unlinkSync(targetPath);
+          if (item.type === 'directory' && !isSymlink) {
+            // Remove copied directory recursively
+            fs.rmSync(targetPath, { recursive: true, force: true });
+          } else {
+            // Remove symlink or file
+            fs.unlinkSync(targetPath);
+          }
           console.log(`[OK] Removed ${item.target}`);
           removed++;
         } catch (err) {
@@ -286,14 +348,47 @@ export class ClaudeSymlinkManager {
         issues.push(`Not installed: ${item.target} (run 'ccs sync' to install)`);
         healthy = false;
       } else if (!this.isOurSymlink(targetPath, sourcePath)) {
-        issues.push(`Not a CCS symlink: ${item.target} (run 'ccs sync' to fix)`);
-        healthy = false;
+        // On Windows, copied files are valid (symlink fallback)
+        if (process.platform === 'win32' && this.isCopiedItem(targetPath, sourcePath, item.type)) {
+          // Copied file is valid on Windows, but note it's not a symlink
+          issues.push(`${item.target} is a copy (not symlink) - run 'ccs sync' after updates`);
+          // Still healthy, just a warning
+        } else {
+          issues.push(`Not a CCS symlink: ${item.target} (run 'ccs sync' to fix)`);
+          healthy = false;
+        }
       }
     }
 
     return { healthy, issues };
   }
 
+  /**
+   * Check if target is a valid copy of source (Windows fallback check)
+   */
+  private isCopiedItem(
+    targetPath: string,
+    sourcePath: string,
+    type: 'file' | 'directory'
+  ): boolean {
+    try {
+      const targetStats = fs.statSync(targetPath);
+      const sourceStats = fs.statSync(sourcePath);
+
+      if (type === 'directory') {
+        // For directories, just check both exist and are directories
+        return targetStats.isDirectory() && sourceStats.isDirectory();
+      } else {
+        // For files, compare size as basic validation
+        return (
+          targetStats.isFile() && sourceStats.isFile() && targetStats.size === sourceStats.size
+        );
+      }
+    } catch {
+      return false;
+    }
+  }
+
   /**
    * Sync delegation commands and skills to ~/.claude/ (used by 'ccs sync' command)
    * Same as install() but with explicit sync message