feat: allow production provider bootstrap

backend/internal/jobs/job.go

@@ -92,9 +92,10 @@ func (scope Scope) Owns(job Job) bool {
 type ErrorKind string
 
 const (
-	ErrorInvalid  ErrorKind = "invalid"
-	ErrorNotFound ErrorKind = "not_found"
-	ErrorConflict ErrorKind = "conflict"
+	ErrorInvalid     ErrorKind = "invalid"
+	ErrorNotFound    ErrorKind = "not_found"
+	ErrorConflict    ErrorKind = "conflict"
+	ErrorUnavailable ErrorKind = "unavailable"
 )
 
 type Error struct {

backend/internal/jobs/provider.go

@@ -121,6 +121,7 @@ type ProviderJobBuilder struct {
 	ImageEngine, VideoEngine     string
 	ImageEngines                 map[string]ProviderTarget
 	VideoEngines                 map[string]ProviderTarget
+	UnavailableProviders         map[string]string
 	NewID                        func() string
 }
 
@@ -141,6 +142,9 @@ func (b ProviderJobBuilder) Build(_ context.Context, owner, client, capability,
 	if err != nil {
 		return CreateCommand{}, err
 	}
+	if message := strings.TrimSpace(b.UnavailableProviders[target.Provider]); message != "" {
+		return CreateCommand{}, &Error{Kind: ErrorUnavailable, Status: 503, Message: message}
+	}
 	if target.Provider == "" || target.Model == "" || b.NewID == nil {
 		return CreateCommand{}, errors.New("provider job builder is not configured")
 	}

backend/internal/jobs/provider_test.go

@@ -40,6 +40,23 @@ func TestProviderJobBuilderPreparesImageRequestAndEngineOverride(t *testing.T) {
 	}
 }
 
+func TestProviderJobBuilderRejectsUnconfiguredProviderBeforeCreation(t *testing.T) {
+	b := testProviderBuilder()
+	b.UnavailableProviders = map[string]string{
+		"evolink": "EvoLink 服务商未配置，请先配置 EVOLINK_API_KEY。",
+	}
+	_, err := b.Build(context.Background(), "owner", "client", "image.generate", "idem", map[string]any{
+		"engine": "evolink", "prompt": "hello",
+	})
+	if err == nil || err.Error() != "EvoLink 服务商未配置，请先配置 EVOLINK_API_KEY。" {
+		t.Fatalf("error = %v", err)
+	}
+	var unavailable *Error
+	if !errors.As(err, &unavailable) || unavailable.Kind != ErrorUnavailable || unavailable.Status != 503 {
+		t.Fatalf("error = %#v, want unavailable 503", err)
+	}
+}
+
 func TestProviderJobBuilderUsesPublicInputURLsForImageMaterialCoverage(t *testing.T) {
 	b := testProviderBuilder()
 	cmd, err := b.Build(context.Background(), "owner", "client", "image.generate", "", map[string]any{