Add symlink watcher support with tests

- syncCreate: remove existing file before creating symlink
- syncWrite: handle symlink target changes (remove + recreate)
- Added 4 new tests:
  - CreateSymlink: new symlink synced to /data
  - UpdateSymlinkTarget: symlink target change updates /data
  - RemoveSymlink: symlink removal synced
  - ModifySymlinkTargetFile: target file change preserves symlink
- 39 tests passing

1 files changed, 16 insertions, 0 deletions

diff --git a/watcher.go b/watcher.go
index 192b61b..d2a98e9 100644
--- a/watcher.go
+++ b/watcher.go
@@ -138,6 +138,7 @@ func syncCreate(srcPath, destPath, relPath string, manifest *Manifest, stack *Gi
 	}
 
 	os.MkdirAll(filepath.Dir(destPath), 0755)
+	os.Remove(destPath)
 
 	if linkTarget != "" {
 		if err := os.Symlink(linkTarget, destPath); err != nil {
@@ -166,10 +167,16 @@ func syncWrite(srcPath, destPath, relPath string, manifest *Manifest, dryRun, ve
 		return
 	}
 
+	linkTarget := ""
+	if info.Mode()&os.ModeSymlink != 0 {
+		linkTarget, _ = os.Readlink(srcPath)
+	}
+
 	manifest.Files[relPath] = FileMeta{
 		Size:    info.Size(),
 		Mode:    info.Mode(),
 		ModTime: info.ModTime(),
+		Symlink: linkTarget,
 	}
 
 	if dryRun {
@@ -177,6 +184,15 @@ func syncWrite(srcPath, destPath, relPath string, manifest *Manifest, dryRun, ve
 		return
 	}
 
+	os.Remove(destPath)
+
+	if linkTarget != "" {
+		if err := os.Symlink(linkTarget, destPath); err != nil {
+			log.Printf("error creating symlink %s: %v", relPath, err)
+		}
+		return
+	}
+
 	if err := copyFile(srcPath, destPath, info.Mode()); err != nil {
 		log.Printf("error copying %s: %v", relPath, err)
 	}