fix(windows): complete concurrent auth consumption

tools/tht/internal/safeio/private_root_windows.go

@@ -955,14 +955,14 @@ func windowsRelativeClaimAbsentOrOrphan(directory *windowsPrivateDirectory, sour
 
 const windowsClaimSharingRetries = 100
 
-func openWindowsPrivateClaimSource(directory windows.Handle, source string) (*windowsPrivateRegularAt, error) {
+func openWindowsPrivateClaimRegular(
+	directory windows.Handle,
+	name string,
+	access uint32,
+	allowedLinks uint32,
+) (*windowsPrivateRegularAt, error) {
 	for attempt := 0; ; attempt++ {
-		value, err := openWindowsPrivateRegularAt(
-			directory,
-			source,
-			windows.FILE_GENERIC_READ|windows.FILE_GENERIC_WRITE|windows.DELETE,
-			1,
-		)
+		value, err := openWindowsPrivateRegularAt(directory, name, access, allowedLinks)
 		if !errors.Is(err, windows.ERROR_SHARING_VIOLATION) &&
 			!errors.Is(err, windows.STATUS_SHARING_VIOLATION) {
 			return value, err
@@ -981,7 +981,12 @@ func (directory *windowsPrivateDirectory) ClaimRegular(source, claim string) (bo
 	// A concurrent winner temporarily holds the source with DELETE access and deliberately
 	// without FILE_SHARE_DELETE. Wait only for that specific, bounded contention before
 	// observing the resulting pair or absence below. Persistent sharing remains unsafe.
-	value, err := openWindowsPrivateClaimSource(directory.handle, source)
+	value, err := openWindowsPrivateClaimRegular(
+		directory.handle,
+		source,
+		windows.FILE_GENERIC_READ|windows.FILE_GENERIC_WRITE|windows.DELETE,
+		1,
+	)
 	if err != nil {
 		pair, pairErr := windowsRelativeClaimPairExists(directory, source, claim)
 		if pairErr == nil && pair {
@@ -1058,7 +1063,14 @@ func (directory *windowsPrivateDirectory) RemoveClaim(source, claim string) (boo
 	if directory.Validate() != nil || !validPrivateLeafName(source) || !validPrivateLeafName(claim) {
 		return false, ErrUnsafeFile
 	}
-	value, err := openWindowsPrivateRegularAt(directory.handle, source, windows.FILE_GENERIC_READ|windows.DELETE, 2)
+	// A losing claimer can still be closing its no-delete source handle after observing the
+	// existing hard-link pair. Treat only that bounded sharing window as contention.
+	value, err := openWindowsPrivateClaimRegular(
+		directory.handle,
+		source,
+		windows.FILE_GENERIC_READ|windows.DELETE,
+		2,
+	)
 	if err != nil {
 		orphan, orphanErr := windowsRelativeClaimAbsentOrOrphan(directory, source, claim)
 		if orphanErr == nil && orphan {