Keep launcher locale changes from mutating shared web-search routing (#2573)

The launcher wired UI language changes into a process-global backend
switch that changed auto web-search provider selection and the
reported current service for every handler in the same process.

This narrows the fix to the validated leak: remove backend sync from
frontend locale changes, drop the now-unused UI endpoint, and make
auto selection fall back to a stable default when the query itself
does not contain a script hint.

Constraint: Keep the patch small and mergeable without redesigning per-user preference storage
Rejected: Add per-user backend language state | larger scope than the validated bug and unclear maintainer preference
Rejected: Persist preferred language in config | still shares mutable state across clients of the same instance
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: If locale-aware provider routing is reintroduced later, scope it to explicit config or request context instead of package-global state
Tested: go test ./web/backend/api ./pkg/tools -count=1; pnpm lint; pnpm build
Not-tested: Full make check; live multi-browser manual launcher run after the backend endpoint removal

pkg/tools/integration/web.go

@@ -58,8 +58,6 @@ var (
 	reSogouRealURL = regexp.MustCompile(`url=([^&]+)`)
 )
 
-var preferredWebSearchLanguage atomic.Value
-
 type APIKeyPool struct {
 	keys    []string
 	current uint32
@@ -250,27 +248,6 @@ func mapBaiduRecencyFilter(rangeCode string) string {
 	}
 }
 
-func normalizePreferredWebSearchLanguage(lang string) string {
-	lang = strings.ToLower(strings.TrimSpace(lang))
-	switch {
-	case strings.HasPrefix(lang, "zh"), lang == "chinese":
-		return "zh"
-	case strings.HasPrefix(lang, "en"), lang == "english":
-		return "en"
-	default:
-		return ""
-	}
-}
-
-func SetPreferredWebSearchLanguage(lang string) {
-	preferredWebSearchLanguage.Store(normalizePreferredWebSearchLanguage(lang))
-}
-
-func GetPreferredWebSearchLanguage() string {
-	lang, _ := preferredWebSearchLanguage.Load().(string)
-	return lang
-}
-
 type BraveSearchProvider struct {
 	keyPool *APIKeyPool
 	proxy   string
@@ -1420,7 +1397,7 @@ func containsLatinLetter(text string) bool {
 func prefersDuckDuckGoQuery(text string) bool {
 	trimmed := strings.TrimSpace(text)
 	if trimmed == "" {
-		return GetPreferredWebSearchLanguage() == "en"
+		return false
 	}
 	if containsHan(trimmed) {
 		return false
@@ -1428,7 +1405,7 @@ func prefersDuckDuckGoQuery(text string) bool {
 	if containsLatinLetter(trimmed) {
 		return true
 	}
-	return GetPreferredWebSearchLanguage() == "en"
+	return false
 }
 
 func (opts WebSearchToolOptions) buildProviderResolver() (func(query string) (SearchProvider, int), error) {

pkg/tools/integration/web_test.go

@@ -1778,11 +1778,6 @@ func TestApplySogouRangeHint(t *testing.T) {
 }
 
 func TestPrefersDuckDuckGoQuery(t *testing.T) {
-	SetPreferredWebSearchLanguage("")
-	t.Cleanup(func() {
-		SetPreferredWebSearchLanguage("")
-	})
-
 	tests := []struct {
 		name  string
 		query string
@@ -1805,19 +1800,9 @@ func TestPrefersDuckDuckGoQuery(t *testing.T) {
 	}
 }
 
-func TestPrefersDuckDuckGoQuery_FallsBackToPreferredLanguage(t *testing.T) {
+func TestPrefersDuckDuckGoQuery_DoesNotUseGlobalLanguageFallback(t *testing.T) {
-	SetPreferredWebSearchLanguage("en")
-	t.Cleanup(func() {
-		SetPreferredWebSearchLanguage("")
-	})
-
-	if !prefersDuckDuckGoQuery("2026 04 15") {
-		t.Fatal("numeric query should prefer DuckDuckGo when preferred language is English")
-	}
-
-	SetPreferredWebSearchLanguage("zh")
 	if prefersDuckDuckGoQuery("2026 04 15") {
-		t.Fatal("numeric query should prefer Sogou when preferred language is Chinese")
+		t.Fatal("numeric query should default to Sogou when no script-specific hint is present")
 	}
 }
 

pkg/tools/integration_facade.go

@@ -65,14 +65,6 @@ func NewAPIKeyPool(keys []string) *APIKeyPool {
 	return integrationtools.NewAPIKeyPool(keys)
 }
 
-func SetPreferredWebSearchLanguage(lang string) {
-	integrationtools.SetPreferredWebSearchLanguage(lang)
-}
-
-func GetPreferredWebSearchLanguage() string {
-	return integrationtools.GetPreferredWebSearchLanguage()
-}
-
 func WebSearchToolOptionsFromConfig(cfg *config.Config) WebSearchToolOptions {
 	return integrationtools.WebSearchToolOptionsFromConfig(cfg)
 }

web/backend/api/router.go

@@ -89,7 +89,6 @@ func (h *Handler) RegisterRoutes(mux *http.ServeMux) {
 	// Skills and tools support/actions
 	h.registerSkillRoutes(mux)
 	h.registerToolRoutes(mux)
-	h.registerUIRoutes(mux)
 
 	// OS startup / launch-at-login
 	h.registerStartupRoutes(mux)

web/backend/api/tools_test.go

@@ -9,7 +9,6 @@ import (
 	"testing"
 
 	"github.com/sipeed/picoclaw/pkg/config"
-	picotools "github.com/sipeed/picoclaw/pkg/tools"
 )
 
 func TestHandleListTools(t *testing.T) {
@@ -517,22 +516,12 @@ func TestResolveCurrentWebSearchProvider_FallsBackWhenProviderIsUnknown(t *testi
 	}
 }
 
-func TestResolveCurrentWebSearchProvider_UsesPreferredLanguageForSogouAndDuckDuckGo(t *testing.T) {
+func TestResolveCurrentWebSearchProvider_PrefersStableDefaultForSogouAndDuckDuckGo(t *testing.T) {
 	cfg := config.DefaultConfig()
 	cfg.Tools.Web.Provider = "auto"
 	cfg.Tools.Web.Sogou.Enabled = true
 	cfg.Tools.Web.DuckDuckGo.Enabled = true
 
-	picotools.SetPreferredWebSearchLanguage("en")
-	t.Cleanup(func() {
-		picotools.SetPreferredWebSearchLanguage("")
-	})
-
-	if got := resolveCurrentWebSearchProvider(cfg); got != "duckduckgo" {
-		t.Fatalf("resolveCurrentWebSearchProvider() = %q, want duckduckgo", got)
-	}
-
-	picotools.SetPreferredWebSearchLanguage("zh")
 	if got := resolveCurrentWebSearchProvider(cfg); got != "sogou" {
 		t.Fatalf("resolveCurrentWebSearchProvider() = %q, want sogou", got)
 	}

web/backend/api/ui.go

@@ -1,27 +0,0 @@
-package api
-
-import (
-	"encoding/json"
-	"net/http"
-
-	"github.com/sipeed/picoclaw/pkg/tools"
-)
-
-type uiLanguageRequest struct {
-	Language string `json:"language"`
-}
-
-func (h *Handler) registerUIRoutes(mux *http.ServeMux) {
-	mux.HandleFunc("POST /api/ui/language", h.handleSetUILanguage)
-}
-
-func (h *Handler) handleSetUILanguage(w http.ResponseWriter, r *http.Request) {
-	var req uiLanguageRequest
-	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
-		http.Error(w, "invalid request body", http.StatusBadRequest)
-		return
-	}
-
-	tools.SetPreferredWebSearchLanguage(req.Language)
-	w.WriteHeader(http.StatusNoContent)
-}

web/backend/api/ui_test.go

@@ -1,48 +0,0 @@
-package api
-
-import (
-	"net/http"
-	"net/http/httptest"
-	"strings"
-	"testing"
-
-	"github.com/sipeed/picoclaw/pkg/tools"
-)
-
-func TestHandleSetUILanguage(t *testing.T) {
-	tools.SetPreferredWebSearchLanguage("")
-	t.Cleanup(func() {
-		tools.SetPreferredWebSearchLanguage("")
-	})
-
-	h := NewHandler("")
-	mux := http.NewServeMux()
-	h.RegisterRoutes(mux)
-
-	rec := httptest.NewRecorder()
-	req := httptest.NewRequest(http.MethodPost, "/api/ui/language", strings.NewReader(`{"language":"zh"}`))
-	req.Header.Set("Content-Type", "application/json")
-	mux.ServeHTTP(rec, req)
-
-	if rec.Code != http.StatusNoContent {
-		t.Fatalf("status = %d, want %d, body=%s", rec.Code, http.StatusNoContent, rec.Body.String())
-	}
-	if got := tools.GetPreferredWebSearchLanguage(); got != "zh" {
-		t.Fatalf("preferred web search language = %q, want zh", got)
-	}
-}
-
-func TestHandleSetUILanguage_RejectsInvalidJSON(t *testing.T) {
-	h := NewHandler("")
-	mux := http.NewServeMux()
-	h.RegisterRoutes(mux)
-
-	rec := httptest.NewRecorder()
-	req := httptest.NewRequest(http.MethodPost, "/api/ui/language", strings.NewReader(`{`))
-	req.Header.Set("Content-Type", "application/json")
-	mux.ServeHTTP(rec, req)
-
-	if rec.Code != http.StatusBadRequest {
-		t.Fatalf("status = %d, want %d", rec.Code, http.StatusBadRequest)
-	}
-}

web/backend/main.go

@@ -29,7 +29,6 @@ import (
 	"github.com/sipeed/picoclaw/pkg/config"
 	"github.com/sipeed/picoclaw/pkg/logger"
 	"github.com/sipeed/picoclaw/pkg/netbind"
-	"github.com/sipeed/picoclaw/pkg/tools"
 	"github.com/sipeed/picoclaw/web/backend/api"
 	"github.com/sipeed/picoclaw/web/backend/dashboardauth"
 	"github.com/sipeed/picoclaw/web/backend/launcherconfig"
@@ -409,7 +408,6 @@ func main() {
 	if *lang != "" {
 		SetLanguage(*lang)
 	}
-	tools.SetPreferredWebSearchLanguage(string(GetLanguage()))
 
 	// Resolve config path
 	configPath := utils.GetDefaultConfigPath()

web/frontend/src/i18n/index.ts

@@ -7,8 +7,6 @@ import i18n from "i18next"
 import LanguageDetector from "i18next-browser-languagedetector"
 import { initReactI18next } from "react-i18next"
 
-import { launcherFetch } from "@/api/http"
-
 import en from "./locales/en.json"
 import zh from "./locales/zh.json"
 
@@ -46,14 +44,6 @@ i18n.on("languageChanged", (lng) => {
   } else {
     dayjs.locale("en")
   }
-
-  void launcherFetch("/api/ui/language", {
-    method: "POST",
-    headers: { "Content-Type": "application/json" },
-    body: JSON.stringify({ language: lng }),
-  }).catch(() => {
-    // Keep UI language changes responsive even if backend sync fails.
-  })
 })
 
 export default i18n