fix: sync Android default theme installs

internal/rpc/account_themes.go

@@ -220,6 +220,12 @@ func (r *Router) onAccountSaveTheme(ctx context.Context, req *tg.AccountSaveThem
 	if userID == 0 {
 		return false, authKeyUnregisteredErr()
 	}
+	if _, ok := tdesktop.LookupDefaultTheme(req.Theme); ok {
+		// Default catalog themes are always present in account.getThemes. Saving
+		// or unsaving one is therefore an idempotent signal and must not create a
+		// synthetic custom-theme row or user install.
+		return true, nil
+	}
 	if r.deps.Themes == nil {
 		return false, notImplementedErr()
 	}
@@ -252,14 +258,20 @@ func (r *Router) onAccountInstallTheme(ctx context.Context, req *tg.AccountInsta
 	if userID == 0 {
 		return false, authKeyUnregisteredErr()
 	}
-	if r.deps.Themes == nil {
-		return false, notImplementedErr()
-	}
 	dark := req.GetDark()
 	theme, ok := req.GetTheme()
 	if !ok {
 		return true, nil // 无 theme 引用:基础主题 no-op 安装
 	}
+	if _, ok := tdesktop.LookupDefaultTheme(theme); ok {
+		// The immutable defaults were issued by account.getThemes but do not
+		// live in the custom theme store. Applying one is a successful signal;
+		// the Android client owns the active day/night choice locally.
+		return true, nil
+	}
+	if r.deps.Themes == nil {
+		return false, notImplementedErr()
+	}
 	ref, ok := themeRefFromInput(theme)
 	if !ok {
 		return false, themeInvalidErr()
@@ -280,6 +292,9 @@ func (r *Router) onAccountGetTheme(ctx context.Context, req *tg.AccountGetThemeR
 	if err != nil {
 		return nil, internalErr()
 	}
+	if t, ok := tdesktop.LookupDefaultTheme(req.Theme); ok {
+		return projectThemeForClient(ctx, &t), nil
+	}
 	if r.deps.Themes == nil {
 		return nil, notImplementedErr()
 	}

internal/rpc/account_themes_compat_test.go

@@ -10,6 +10,7 @@ import (
 	"go.uber.org/zap"
 	"go.uber.org/zap/zaptest/observer"
 
+	"telesrv/internal/compat/tdesktop"
 	"telesrv/internal/domain"
 )
 
@@ -119,6 +120,26 @@ func TestLegacyThemeWireDispatch(t *testing.T) {
 		t.Fatalf("installTheme legacy wire id = %#x err=%v, want boolTrue", id, err)
 	}
 
+	// 同一 legacy overlay 必须接受 account.getThemes 下发的静态默认主题，
+	// 且不能要求该引用存在于自定义主题 store。
+	defaultTheme := tdesktop.DefaultThemeList()[0]
+	var defaultIB bin.Buffer
+	defaultIB.PutID(legacyInstallThemeID)
+	defaultIB.PutInt32((1 << 0) | (1 << 1))
+	defaultIB.PutString("android")
+	(&tg.InputTheme{ID: defaultTheme.ID, AccessHash: defaultTheme.AccessHash}).Encode(&defaultIB)
+	enc, err = r.Dispatch(ctx, authKeyID, sessionID, &defaultIB)
+	if err != nil {
+		t.Fatalf("installTheme legacy default dispatch: %v", err)
+	}
+	boolWire.Reset()
+	if err := enc.Encode(&boolWire); err != nil {
+		t.Fatalf("encode installTheme legacy default result: %v", err)
+	}
+	if id, err := boolWire.ID(); err != nil || id != tg.BoolTrueTypeID {
+		t.Fatalf("installTheme legacy default wire id = %#x err=%v, want boolTrue", id, err)
+	}
+
 	// 已声明 legacy 方法仍必须由静态 decoder 精确消费完整结构。
 	var malformed bin.Buffer
 	malformed.PutID(legacyCreateThemeID)

internal/rpc/account_themes_rpc_test.go

@@ -126,6 +126,95 @@ func TestAccountCreateThemeFullFlow(t *testing.T) {
 	}
 }
 
+func TestAccountDefaultThemeReferencesResolveWithoutCustomPersistence(t *testing.T) {
+	const userID = 1000012
+	ctx := WithClientInfo(
+		WithUserID(context.Background(), userID),
+		ClientInfo{Type: ClientTypeAndroid, AppVersion: "12.9.0 (69669)"},
+	)
+	r := newThemeRouter(t, &fakeFiles{})
+	defaults := tdesktop.DefaultThemeList()
+	if len(defaults) == 0 {
+		t.Fatal("default theme catalog is empty")
+	}
+
+	for i, theme := range defaults {
+		t.Run(theme.Slug, func(t *testing.T) {
+			input := &tg.InputTheme{ID: theme.ID, AccessHash: theme.AccessHash}
+			install := &tg.AccountInstallThemeRequest{}
+			install.SetDark(i%2 == 0)
+			install.SetTheme(input)
+			install.SetFormat("android")
+			if ok, err := r.onAccountInstallTheme(ctx, install); err != nil || !ok {
+				t.Fatalf("install default theme %d = %v/%v, want true/nil", theme.ID, ok, err)
+			}
+
+			for _, unsave := range []bool{false, true} {
+				if ok, err := r.onAccountSaveTheme(ctx, &tg.AccountSaveThemeRequest{
+					Theme:  input,
+					Unsave: unsave,
+				}); err != nil || !ok {
+					t.Fatalf("save default theme %d unsave=%v = %v/%v, want true/nil", theme.ID, unsave, ok, err)
+				}
+			}
+
+			got, err := r.onAccountGetTheme(ctx, &tg.AccountGetThemeRequest{
+				Format: "android",
+				Theme:  &tg.InputThemeSlug{Slug: theme.Slug},
+			})
+			if err != nil || got.ID != theme.ID || got.AccessHash != theme.AccessHash {
+				t.Fatalf("get default theme %d = %#v/%v", theme.ID, got, err)
+			}
+
+			if ok, err := r.onAccountSaveTheme(ctx, &tg.AccountSaveThemeRequest{
+				Theme: &tg.InputThemeSlug{Slug: theme.Slug},
+			}); err != nil || !ok {
+				t.Fatalf("save default theme slug %q = %v/%v, want true/nil", theme.Slug, ok, err)
+			}
+		})
+	}
+
+	// Reproduce issue #29 through the canonical Layer 228 wire constructor,
+	// not only by invoking the typed handler directly.
+	canonical := &tg.AccountInstallThemeRequest{}
+	canonical.SetDark(true)
+	canonical.SetTheme(&tg.InputTheme{ID: defaults[0].ID, AccessHash: defaults[0].AccessHash})
+	canonical.SetFormat("android")
+	var body bin.Buffer
+	if err := canonical.Encode(&body); err != nil {
+		t.Fatalf("encode canonical installTheme: %v", err)
+	}
+	var authKeyID [8]byte
+	authKeyID[0] = 2
+	encoded, err := r.Dispatch(ctx, authKeyID, 1001, &body)
+	if err != nil {
+		t.Fatalf("canonical installTheme dispatch: %v", err)
+	}
+	var result bin.Buffer
+	if err := encoded.Encode(&result); err != nil {
+		t.Fatalf("encode canonical installTheme result: %v", err)
+	}
+	if id, err := result.ID(); err != nil || id != tg.BoolTrueTypeID {
+		t.Fatalf("canonical installTheme result id = %#x err=%v, want boolTrue", id, err)
+	}
+
+	installed, err := r.deps.Themes.ListInstalled(ctx, userID)
+	if err != nil {
+		t.Fatalf("list custom installs after default signals: %v", err)
+	}
+	if len(installed) != 0 {
+		t.Fatalf("default signals created %d custom installs, want 0", len(installed))
+	}
+
+	forged := defaults[0]
+	badInstall := &tg.AccountInstallThemeRequest{}
+	badInstall.SetTheme(&tg.InputTheme{ID: forged.ID, AccessHash: forged.AccessHash + 1})
+	badInstall.SetFormat("android")
+	if _, err := r.onAccountInstallTheme(ctx, badInstall); !tgerr.Is(err, "THEME_INVALID") {
+		t.Fatalf("install forged default reference err = %v, want THEME_INVALID", err)
+	}
+}
+
 // TestAccountGetThemesIncludesUserThemes 验证 getThemes 跨设备同步:返回内置默认主题
 // (is_default=true,emoji 预览条用)+ 当前用户创建的自定义主题(is_default=false,creator=true);
 // hash 稳定→NotModified,集合变化→重取。