Dedupe installs resolving to the same directory (os.SameFile)

backend/installfinders/common/helpers.go

@@ -2,12 +2,22 @@ package common
 
 import (
 	"log/slog"
+	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
 )
 
 func OsPathEqual(path1, path2 string) bool {
+	// Same file on disk (inode) means same install, regardless of path
+	// spelling. This catches duplicates from case-only differences on
+	// case-insensitive filesystems (e.g. macOS default APFS), where string
+	// comparison alone sees two different installs.
+	if info1, err1 := os.Stat(path1); err1 == nil {
+		if info2, err2 := os.Stat(path2); err2 == nil && os.SameFile(info1, info2) {
+			return true
+		}
+	}
 	path1 = realPath(path1)
 	path2 = realPath(path2)
 	if runtime.GOOS == "windows" {

backend/installfinders/common/helpers_test.go

@@ -0,0 +1,31 @@
+package common
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestOsPathEqualSameFile(t *testing.T) {
+	dir := t.TempDir()
+
+	// Same path is trivially equal.
+	if !OsPathEqual(dir, dir) {
+		t.Error("identical paths should be equal")
+	}
+
+	// Same directory reached through a symlink must be equal.
+	link := filepath.Join(t.TempDir(), "link")
+	if err := os.Symlink(dir, link); err != nil {
+		t.Skipf("cannot create symlink: %v", err)
+	}
+	if !OsPathEqual(dir, link) {
+		t.Error("symlinked paths to the same directory should be equal")
+	}
+
+	// Different directories must not be equal.
+	other := t.TempDir()
+	if OsPathEqual(dir, other) {
+		t.Error("different directories should not be equal")
+	}
+}