fix(graphstore): give users actionable paths when the ladybug provider is a stub

Before this, cloning the repo and running `go run ./cmd/umodel-server`
without `-tags ladybug` gave:

  local.ladybug provider is disabled in this build

with no hint about what to do next. The stub's Health, OpenWorkspace,
EnsureSchema, and every other operation now all report:

  build with -tags ladybug to enable local.ladybug,
  or run with --graphstore file.memory for local development

Two clear paths, one line — no need to dig through source or ask around.

DefaultProviderType stays local.ladybug. file.memory is not the new default.
The real ladybug provider (built with -tags ladybug) is completely unaffected.
Zero changes to REST, CLI, MCP schema, SDK, Query, Web UI, or runtime storage.

Author: Chloride233

cmd/README.en.md

@@ -14,6 +14,8 @@ Entry Layer: process entry points.
 
 `umodel-server` and `umodel-mcp` both support `--graphstore`:
 
+When `--graphstore` is omitted, Go entrypoints use `local.ladybug`. Builds without `-tags ladybug` report clear startup guidance: build with the Ladybug tag, or pass `--graphstore file.memory` for local development.
+
 | Provider | Description |
 |---|---|
 | `memory` | In-memory provider for fast local verification; data is lost on process exit. |

cmd/README.md

@@ -12,6 +12,8 @@ Entry Layer — 二进制入口点。
 
 `umodel-server` 和 `umodel-mcp` 都支持 `--graphstore`：
 
+未显式传入 `--graphstore` 时，Go 入口默认使用 `local.ladybug`。如果构建时没有 `-tags ladybug`，启动错误会提示两条路径：使用 Ladybug tag 构建，或在本地开发时传入 `--graphstore file.memory`。
+
 | Provider | 说明 |
 |---|---|
 | `memory` | 纯内存，适合本地快速验证，进程退出后数据丢失；通过纯 Go 引擎支持 Ladybug 兼容只读 Cypher。 |

cmd/umodel-mcp/main_test.go

@@ -30,6 +30,21 @@ func TestRunQuickStartPreloadsMCPWorkspace(t *testing.T) {
 	}
 }
 
+func TestRunDefaultLadybugUnavailableGuidesLocalDevelopment(t *testing.T) {
+	var out bytes.Buffer
+	var errOut bytes.Buffer
+
+	err := run([]string{"--manifest", "--data", t.TempDir()}, strings.NewReader(""), &out, &errOut)
+	if err == nil {
+		t.Fatal("expected default local.ladybug stub to be unavailable in no-ladybug build")
+	}
+	for _, want := range []string{"local.ladybug", "-tags ladybug", "--graphstore file.memory"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Fatalf("expected %q in error %q", want, err.Error())
+		}
+	}
+}
+
 func TestEncodeTOONCoversObjectsAndTables(t *testing.T) {
 	got := encodeTOON(map[string]any{
 		"workspace": "demo",

docs/en/graphstore-providers.md

@@ -4,6 +4,8 @@
 
 UModel stores UModel elements, CMS 2.0 entities, and topology relations behind the `GraphStore` interface. Go entry binaries default to `local.ladybug` when `--graphstore` is omitted; select another provider with `--graphstore` on `umodel-server` or `umodel-mcp`.
 
+If a build omits the `ladybug` tag, the default `local.ladybug` provider reports an unavailable health status. Build with `-tags ladybug` to enable the real `local.ladybug` provider, or pass `--graphstore file.memory` for local development without Ladybug.
+
 ```bash
 go run ./cmd/umodel-server --addr :8080 --data data --graphstore file.memory
 ```

docs/zh/graphstore-providers.md

@@ -5,6 +5,8 @@ English: [GraphStore Providers](../en/graphstore-providers.md)
 UModel 通过 `GraphStore` 接口保存和查询 UModel elements、CMS 2.0 实体以及拓扑关系。运行时通过 `--graphstore` 选择 provider。
 
 
+未显式传入 `--graphstore` 时，Go 入口默认使用 `local.ladybug`。如果构建时没有 `-tags ladybug`，该 provider 会报告不可用状态。使用 `-tags ladybug` 构建即可启用真实的 `local.ladybug` provider；本地开发且不使用 Ladybug 时请显式传入 `--graphstore file.memory`。
+
 ## Providers
 
 | Provider | 持久化 | 典型用途 |

internal/graphstore/provider/ladybug/provider_stub.go

@@ -13,6 +13,8 @@ import (
 
 type Provider struct{}
 
+const noLadybugBuildGuidance = "build with -tags ladybug to enable local.ladybug, or run with --graphstore file.memory for local development"
+
 func NewProvider(config graphstore.ProviderConfig) (*Provider, error) {
 	return &Provider{}, nil
 }
@@ -64,11 +66,11 @@ func (p *Provider) Capabilities(ctx context.Context) (model.GraphStoreCapabiliti
 }
 
 func (p *Provider) Health(ctx context.Context) (model.GraphStoreHealth, error) {
-	return model.GraphStoreHealth{Provider: graphstore.ProviderTypeLadybug, Status: "unavailable", Message: "build with -tags ladybug to enable local.ladybug"}, nil
+	return model.GraphStoreHealth{Provider: graphstore.ProviderTypeLadybug, Status: "unavailable", Message: noLadybugBuildGuidance}, nil
 }
 
 func unavailable() error {
-	return apperrors.New(apperrors.CodeProviderUnavailable, "local.ladybug provider is disabled in this build")
+	return apperrors.New(apperrors.CodeProviderUnavailable, "local.ladybug provider is disabled in this build; "+noLadybugBuildGuidance)
 }
 
 func ladybugCapabilities() model.GraphStoreCapabilities {

internal/graphstore/provider/ladybug/provider_stub_test.go

@@ -4,6 +4,7 @@ package ladybug
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	"github.com/alibaba/UnifiedModel/internal/graphstore"
@@ -20,9 +21,13 @@ func TestStubProviderReportsUnavailable(t *testing.T) {
 	ctx := context.Background()
 	if health, err := provider.Health(ctx); err != nil || health.Status != "unavailable" || health.Provider != graphstore.ProviderTypeLadybug {
 		t.Fatalf("health: %+v err=%v", health, err)
+	} else {
+		requireLadybugGuidance(t, health.Message)
 	}
 	if err := provider.OpenWorkspace(ctx, model.WorkspaceMetadata{ID: "demo"}); !apperrors.IsCode(err, apperrors.CodeProviderUnavailable) {
 		t.Fatalf("expected provider unavailable, got %v", err)
+	} else {
+		requireLadybugGuidance(t, err.Error())
 	}
 	if capabilities, err := provider.Capabilities(ctx); err != nil || !capabilities.ControlledCypher || capabilities.MaxLimit == 0 {
 		t.Fatalf("stub should expose intended local.ladybug capabilities for planning, got %+v err=%v", capabilities, err)
@@ -36,5 +41,16 @@ func TestStubProviderIsRegisteredButUnavailable(t *testing.T) {
 	}
 	if err := provider.EnsureSchema(context.Background(), "demo"); !apperrors.IsCode(err, apperrors.CodeProviderUnavailable) {
 		t.Fatalf("expected registered stub provider to be unavailable, got %v", err)
+	} else {
+		requireLadybugGuidance(t, err.Error())
+	}
+}
+
+func requireLadybugGuidance(t *testing.T, message string) {
+	t.Helper()
+	for _, want := range []string{"-tags ladybug", "--graphstore file.memory"} {
+		if !strings.Contains(message, want) {
+			t.Fatalf("expected %q guidance in %q", want, message)
+		}
 	}
 }