diff --git a/internal/infra/llm/registry.go b/internal/infra/llm/registry.go
new file mode 100644
index 0000000..27cabc7
--- /dev/null
+++ b/internal/infra/llm/registry.go
@@ -0,0 +1,84 @@
+package llm
+
+import (
+	"context"
+	"fmt"
+	"sync"
+
+	"github.com/google/uuid"
+)
+
+// Endpoint 是 Registry 从外部 loader 拿到的端点描述（已解密 api_key）。
+type Endpoint struct {
+	ID       uuid.UUID
+	Provider string
+	BaseURL  string
+	APIKey   string
+}
+
+// EndpointLoader 由 chat repository / endpointService 实现，按 id 拉取端点
+// 并完成 AES-GCM 解密。Registry 只看到明文 Endpoint。
+type EndpointLoader interface {
+	Load(ctx context.Context, id uuid.UUID) (Endpoint, error)
+}
+
+// Registry 缓存 endpoint_id → LLMClient。endpoint mutation 后由 service 层调
+// Invalidate 强制下次 GetClient 重新构造（带新 base_url / api_key）。
+type Registry struct {
+	loader EndpointLoader
+	mu     sync.Mutex
+	cache  map[uuid.UUID]LLMClient
+}
+
+// NewRegistry 构造一个空缓存的 Registry。
+func NewRegistry(loader EndpointLoader) *Registry {
+	return &Registry{loader: loader, cache: map[uuid.UUID]LLMClient{}}
+}
+
+// GetClient 返回该 endpoint 对应的 LLMClient。命中缓存直接返回，否则 Load + buildClient
+// 后写入缓存。多 goroutine 并发触发 miss 时，仅一个写入生效（double-checked under lock）。
+func (r *Registry) GetClient(ctx context.Context, id uuid.UUID) (LLMClient, error) {
+	r.mu.Lock()
+	if c, ok := r.cache[id]; ok {
+		r.mu.Unlock()
+		return c, nil
+	}
+	r.mu.Unlock()
+
+	ep, err := r.loader.Load(ctx, id)
+	if err != nil {
+		return nil, err
+	}
+	c, err := buildClient(ep)
+	if err != nil {
+		return nil, err
+	}
+
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if existing, ok := r.cache[id]; ok {
+		return existing, nil
+	}
+	r.cache[id] = c
+	return c, nil
+}
+
+// Invalidate 删除该 endpoint 的缓存条目。endpoint CRUD 后由 service 层调用。
+func (r *Registry) Invalidate(id uuid.UUID) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	delete(r.cache, id)
+}
+
+func buildClient(ep Endpoint) (LLMClient, error) {
+	switch ep.Provider {
+	case "anthropic":
+		return NewAnthropic(ep.APIKey, ep.BaseURL)
+	case "openai":
+		return NewOpenAI(ep.APIKey, ep.BaseURL)
+	case "gemini":
+		return NewGemini(ep.APIKey, ep.BaseURL)
+	default:
+		return nil, fmt.Errorf("llm registry: unknown provider %q", ep.Provider)
+	}
+}
diff --git a/internal/infra/llm/registry_test.go b/internal/infra/llm/registry_test.go
new file mode 100644
index 0000000..405c5ae
--- /dev/null
+++ b/internal/infra/llm/registry_test.go
@@ -0,0 +1,78 @@
+package llm
+
+import (
+	"context"
+	"errors"
+	"sync/atomic"
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+)
+
+type fakeEndpoint struct {
+	ID       uuid.UUID
+	Provider string
+	BaseURL  string
+	APIKey   string
+}
+
+type fakeLoader struct {
+	endpoints map[uuid.UUID]fakeEndpoint
+	calls     int32
+}
+
+func (l *fakeLoader) Load(ctx context.Context, id uuid.UUID) (Endpoint, error) {
+	atomic.AddInt32(&l.calls, 1)
+	ep, ok := l.endpoints[id]
+	if !ok {
+		return Endpoint{}, errors.New("not found")
+	}
+	return Endpoint{ID: ep.ID, Provider: ep.Provider, BaseURL: ep.BaseURL, APIKey: ep.APIKey}, nil
+}
+
+func TestRegistry_CachesByEndpointID(t *testing.T) {
+	id := uuid.New()
+	loader := &fakeLoader{endpoints: map[uuid.UUID]fakeEndpoint{
+		id: {ID: id, Provider: "anthropic", BaseURL: "http://localhost", APIKey: "k"},
+	}}
+	r := NewRegistry(loader)
+
+	c1, err := r.GetClient(context.Background(), id)
+	require.NoError(t, err)
+	c2, err := r.GetClient(context.Background(), id)
+	require.NoError(t, err)
+	require.Same(t, c1, c2)
+	require.Equal(t, int32(1), atomic.LoadInt32(&loader.calls))
+}
+
+func TestRegistry_InvalidateForcesReload(t *testing.T) {
+	id := uuid.New()
+	loader := &fakeLoader{endpoints: map[uuid.UUID]fakeEndpoint{
+		id: {ID: id, Provider: "anthropic", BaseURL: "http://localhost", APIKey: "k"},
+	}}
+	r := NewRegistry(loader)
+	_, err := r.GetClient(context.Background(), id)
+	require.NoError(t, err)
+	r.Invalidate(id)
+	_, err = r.GetClient(context.Background(), id)
+	require.NoError(t, err)
+	require.Equal(t, int32(2), atomic.LoadInt32(&loader.calls))
+}
+
+func TestRegistry_UnknownProviderReturnsError(t *testing.T) {
+	id := uuid.New()
+	loader := &fakeLoader{endpoints: map[uuid.UUID]fakeEndpoint{
+		id: {ID: id, Provider: "claude-3-but-typoed"},
+	}}
+	r := NewRegistry(loader)
+	_, err := r.GetClient(context.Background(), id)
+	require.Error(t, err)
+}
+
+func TestRegistry_LoaderErrorPropagates(t *testing.T) {
+	loader := &fakeLoader{endpoints: map[uuid.UUID]fakeEndpoint{}}
+	r := NewRegistry(loader)
+	_, err := r.GetClient(context.Background(), uuid.New())
+	require.Error(t, err)
+}