fix: read the add-on's persisted system_id when no flag is given [on hold: ownership]

client/VERSION

@@ -1 +1 @@
-1.12.2
+1.12.3

client/docs/API.md

@@ -2,7 +2,7 @@
 
 > Generated from `internal/apispec` by `cmd/apidocgen`. Do not edit by hand.
 
-**Client version:** `1.12.2`
+**Client version:** `1.12.3`
 
 The Client is a local HTTP server (default port **62485**) that bridges Blendkit DCC add-ons (Blender, Godot, and embedders such as Maya and Rhino) with the Blendkit web service.
 

client/docs/openapi.json

@@ -5,7 +5,7 @@
       "name": "GPL-2.0-or-later"
     },
     "title": "Blendkit-Client API",
-    "version": "1.12.2"
+    "version": "1.12.3"
   },
   "openapi": "3.1.0",
   "paths": {

client/main.go

@@ -273,12 +273,17 @@ func main() {
 	systemIDOverride := flag.String("system_id", "", "stable machine ID (15 digits) persisted by the add-on; overrides the MAC-derived ID so telemetry survives MAC randomization")
 	flag.Parse()
 
+	// Machine ID precedence: --system_id from the spawning add-on, then the ID the
+	// add-on persisted (a standalone Client gets no flag but must report the same
+	// machine), and only then the MAC-derived fallback set in init().
 	if *systemIDOverride != "" {
 		if validSystemID(*systemIDOverride) {
 			SystemID = systemIDOverride
 		} else {
 			BKLog.Printf("Ignoring invalid --system_id %q, keeping MAC-derived ID", *systemIDOverride)
 		}
+	} else if persisted := persistedSystemID(); persisted != "" {
+		SystemID = &persisted
 	}
 
 	// A standalone Client is one a user started directly — no add-on passed its

client/utils.go

@@ -75,6 +75,42 @@ func validSystemID(s string) bool {
 	return true
 }
 
+// systemIDFilePath mirrors the add-on's paths.get_system_id_filepath().
+func systemIDFilePath() string {
+	home := os.Getenv("XDG_DATA_HOME")
+	if home == "" {
+		var err error
+		home, err = os.UserHomeDir()
+		if err != nil {
+			return ""
+		}
+	}
+	return filepath.Join(home, "blenderkit_data", "system_id")
+}
+
+// persistedSystemID returns the machine ID the add-on stored, or "" when absent.
+//
+// The add-on passes the same value via --system_id when it spawns the Client, but
+// a Client started standalone (or by another software's add-on) gets no flag, and
+// must not fall back to a MAC-derived ID the add-on no longer uses: the two would
+// then report different machines for the same user. The file is the shared source
+// of truth; the Client only ever reads it.
+func persistedSystemID() string {
+	path := systemIDFilePath()
+	if path == "" {
+		return ""
+	}
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return ""
+	}
+	id := strings.TrimSpace(string(content))
+	if !validSystemID(id) {
+		return ""
+	}
+	return id
+}
+
 func StringToAddonVersion(s string) (*AddonVersionStruct, error) {
 	adVer := &AddonVersionStruct{}
 	if s == "" {

client/utils_test.go

@@ -20,6 +20,8 @@ package main
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 	"reflect"
 	"regexp"
 	"strings"
@@ -205,3 +207,30 @@ func TestValidSystemID(t *testing.T) {
 		}
 	}
 }
+
+func TestPersistedSystemID(t *testing.T) {
+	dir := t.TempDir()
+	t.Setenv("XDG_DATA_HOME", dir)
+	if err := os.MkdirAll(filepath.Join(dir, "blenderkit_data"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	path := filepath.Join(dir, "blenderkit_data", "system_id")
+
+	if got := persistedSystemID(); got != "" {
+		t.Errorf("missing file: got %q; want empty", got)
+	}
+
+	if err := os.WriteFile(path, []byte("000000000000123\n"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if got := persistedSystemID(); got != "000000000000123" {
+		t.Errorf("valid file: got %q; want 000000000000123", got)
+	}
+
+	if err := os.WriteFile(path, []byte("not-an-id"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if got := persistedSystemID(); got != "" {
+		t.Errorf("garbage file: got %q; want empty (falls back to MAC)", got)
+	}
+}