chore: import upstream snapshot with attribution

internal/server/serverid.go

@@ -0,0 +1,58 @@
+package server
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/google/uuid"
+
+	"github.com/zzet/gortex/internal/platform"
+)
+
+// DefaultServerIDPath returns the default persistence path for the
+// per-machine server id. Callers that want a process-local id (e.g.
+// tests, custom cache dirs) should pass their own dir to
+// LoadOrCreateServerID instead of calling this.
+//
+// An absolute $XDG_CACHE_HOME is honoured; otherwise the id stays under
+// os.UserCacheDir() — the historical location, kept so an existing
+// server id is not orphaned.
+func DefaultServerIDPath() (string, error) {
+	if v := os.Getenv("XDG_CACHE_HOME"); v == "" || !filepath.IsAbs(v) {
+		if _, err := os.UserCacheDir(); err != nil {
+			return "", fmt.Errorf("resolve user cache dir: %w", err)
+		}
+	}
+	return filepath.Join(platform.OSCacheDir(), "server.id"), nil
+}
+
+// LoadOrCreateServerID returns a stable UUID for this server
+// instance. If path already holds a valid UUID, it's returned as-is;
+// otherwise a fresh UUID is generated and persisted. Intermediate
+// directories are created as needed (0o755).
+//
+// A malformed existing file is replaced — the file is advisory
+// state, not authoritative, so there's no reason to fail loudly
+// when it gets corrupted.
+func LoadOrCreateServerID(path string) (string, error) {
+	if data, err := os.ReadFile(path); err == nil {
+		id := strings.TrimSpace(string(data))
+		if _, err := uuid.Parse(id); err == nil {
+			return id, nil
+		}
+		// Fall through — we'll regenerate below.
+	} else if !os.IsNotExist(err) {
+		return "", fmt.Errorf("read server id: %w", err)
+	}
+
+	id := uuid.NewString()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return "", fmt.Errorf("create server id dir: %w", err)
+	}
+	if err := os.WriteFile(path, []byte(id+"\n"), 0o600); err != nil {
+		return "", fmt.Errorf("write server id: %w", err)
+	}
+	return id, nil
+}