Fix image signed URLs ignoring updated public base URL.

Resolve public_base_url at SignURL time so admin settings apply without restart.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/prediction/service.go

@@ -24,20 +24,19 @@ type Service struct {
 	db        *gorm.DB
 	cache     *cache.Store
 	images    *imagestore.Store
-	hub       *Hub
-	publicURL string
-	waitSec   int64
+	hub     *Hub
+	waitSec int64
 	mu        sync.Mutex
 	running   map[string]context.CancelFunc
 }
 
-func NewService(db *gorm.DB, c *cache.Store, images *imagestore.Store, publicURL string, waitSec int64) *Service {
+func NewService(db *gorm.DB, c *cache.Store, images *imagestore.Store, waitSec int64) *Service {
 	if waitSec <= 0 {
 		waitSec = 60
 	}
 	return &Service{
 		db: db, cache: c, images: images, hub: NewHub(),
-		publicURL: strings.TrimRight(publicURL, "/"), waitSec: waitSec,
+		waitSec: waitSec,
 		running: make(map[string]context.CancelFunc),
 	}
 }

internal/storage/imagestore/store.go

@@ -17,15 +17,22 @@ import (
 )
 
 type Store struct {
-	db       *gorm.DB
-	baseDir  string
-	signKey  string
-	publicURL string
-	ttl      time.Duration
+	db        *gorm.DB
+	baseDir   string
+	signKey   string
+	publicURL func() string
+	ttl       time.Duration
 }
 
-func New(db *gorm.DB, baseDir, publicURL, signKey string, ttl time.Duration) *Store {
-	return &Store{db: db, baseDir: baseDir, publicURL: strings.TrimRight(publicURL, "/"), signKey: signKey, ttl: ttl}
+func New(db *gorm.DB, baseDir string, publicURL func() string, signKey string, ttl time.Duration) *Store {
+	return &Store{db: db, baseDir: baseDir, publicURL: publicURL, signKey: signKey, ttl: ttl}
+}
+
+func (s *Store) baseURL() string {
+	if s.publicURL == nil {
+		return ""
+	}
+	return strings.TrimRight(s.publicURL(), "/")
 }
 
 func (s *Store) EnsureDir() error {
@@ -76,7 +83,7 @@ func (s *Store) ListByPrediction(predictionID string) ([]model.StoredImage, erro
 func (s *Store) SignURL(imageID string) string {
 	exp := time.Now().Add(s.ttl).Unix()
 	sig := s.sign(imageID, exp)
-	return fmt.Sprintf("%s/files/%s?exp=%d&sig=%s", s.publicURL, imageID, exp, sig)
+	return fmt.Sprintf("%s/files/%s?exp=%d&sig=%s", s.baseURL(), imageID, exp, sig)
 }
 
 func (s *Store) Verify(imageID string, exp int64, sig string) bool {

internal/storage/imagestore/store_test.go

@@ -0,0 +1,24 @@
+package imagestore
+
+import (
+	"testing"
+	"time"
+)
+
+func TestSignURLUsesDynamicPublicBase(t *testing.T) {
+	current := "http://localhost:8293"
+	store := New(nil, t.TempDir(), func() string { return current }, "test-key", time.Hour)
+
+	if got := store.SignURL("img-1"); !hasPrefix(got, "http://localhost:8293/files/img-1") {
+		t.Fatalf("unexpected url: %s", got)
+	}
+
+	current = "https://gateway.example.com"
+	if got := store.SignURL("img-2"); !hasPrefix(got, "https://gateway.example.com/files/img-2") {
+		t.Fatalf("expected updated base url, got: %s", got)
+	}
+}
+
+func hasPrefix(s, prefix string) bool {
+	return len(s) >= len(prefix) && s[:len(prefix)] == prefix
+}