- Removed manifest link from index.html.

- Updated script and module preload links in index.html for optimized loading.
- Modified service worker (sw.js) to reflect new asset revisions and improve caching strategy.
- Updated configuration documentation in BT_RUN.md, docker-RUN.md, and manual_RUN.md to clarify currency rate settings.

src/config/config_test.go

@@ -1,11 +1,52 @@
 package config
 
 import (
+	"io"
+	"math"
+	"net/http"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
+	"time"
+
+	"github.com/GMWalletApp/epusdt/util/http_client"
+	"github.com/go-resty/resty/v2"
+	"github.com/spf13/viper"
 )
 
+func installSettingsGetter(t *testing.T, values map[string]string) {
+	t.Helper()
+
+	oldGetter := SettingsGetString
+	SettingsGetString = func(key string) string {
+		return values[key]
+	}
+	t.Cleanup(func() {
+		SettingsGetString = oldGetter
+	})
+}
+
+type roundTripFunc func(*http.Request) (*http.Response, error)
+
+func (f roundTripFunc) RoundTrip(req *http.Request) (*http.Response, error) {
+	return f(req)
+}
+
+func installMockHTTPClient(t *testing.T, handler roundTripFunc) {
+	t.Helper()
+
+	oldFactory := http_client.ClientFactory
+	http_client.ClientFactory = func() *resty.Client {
+		client := resty.NewWithClient(&http.Client{Transport: handler})
+		client.SetTimeout(10 * time.Second)
+		return client
+	}
+	t.Cleanup(func() {
+		http_client.ClientFactory = oldFactory
+	})
+}
+
 func TestNormalizeConfiguredPathUsesExplicitFile(t *testing.T) {
 	t.Helper()
 
@@ -135,3 +176,127 @@ func TestResolveConfigFilePathPrefersExplicitOverEnv(t *testing.T) {
 		t.Fatalf("config path = %s, want %s", got, flagPath)
 	}
 }
+
+func TestGetUsdtRatePrefersPositiveAdminOverride(t *testing.T) {
+	viper.Reset()
+	t.Cleanup(viper.Reset)
+	t.Setenv("API_RATE_URL", "")
+
+	apiCalled := false
+	installMockHTTPClient(t, func(r *http.Request) (*http.Response, error) {
+		apiCalled = true
+		return &http.Response{
+			StatusCode: http.StatusInternalServerError,
+			Status:     http.StatusText(http.StatusInternalServerError),
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader("")),
+			Request:    r,
+		}, nil
+	})
+
+	installSettingsGetter(t, map[string]string{
+		"rate.forced_usdt_rate": "7.25",
+		"rate.api_url":          "https://rate.example.test",
+	})
+
+	got := GetUsdtRate()
+	if got != 7.25 {
+		t.Fatalf("GetUsdtRate() = %v, want 7.25", got)
+	}
+	if apiCalled {
+		t.Fatalf("rate API should not be called when rate.forced_usdt_rate > 0")
+	}
+}
+
+func TestGetUsdtRateUsesAPIWhenAdminOverrideIsNotPositive(t *testing.T) {
+	viper.Reset()
+	t.Cleanup(viper.Reset)
+	t.Setenv("API_RATE_URL", "")
+
+	installMockHTTPClient(t, func(r *http.Request) (*http.Response, error) {
+		if r.URL.Path != "/cny.json" {
+			t.Fatalf("rate api path = %s, want /cny.json", r.URL.Path)
+		}
+		return &http.Response{
+			StatusCode: http.StatusOK,
+			Status:     "200 OK",
+			Header:     http.Header{"Content-Type": []string{"application/json"}},
+			Body:       io.NopCloser(strings.NewReader(`{"cny":{"usdt":0.14635}}`)),
+			Request:    r,
+		}, nil
+	})
+
+	installSettingsGetter(t, map[string]string{
+		"rate.forced_usdt_rate": "-1",
+		"rate.api_url":          "https://rate.example.test",
+	})
+
+	got := GetUsdtRate()
+	want := 1 / 0.14635
+	if math.Abs(got-want) > 1e-9 {
+		t.Fatalf("GetUsdtRate() = %v, want %v", got, want)
+	}
+
+	rate := GetRateForCoin("usdt", "cny")
+	if math.Abs(rate-0.14635) > 1e-9 {
+		t.Fatalf("GetRateForCoin(usdt, cny) = %v, want 0.14635", rate)
+	}
+}
+
+func TestGetUsdtRateReturnsZeroWhenAPIUnavailableWithoutAdminOverride(t *testing.T) {
+	viper.Reset()
+	t.Cleanup(viper.Reset)
+	t.Setenv("API_RATE_URL", "")
+
+	installMockHTTPClient(t, func(r *http.Request) (*http.Response, error) {
+		return &http.Response{
+			StatusCode: http.StatusBadGateway,
+			Status:     "502 Bad Gateway",
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader("")),
+			Request:    r,
+		}, nil
+	})
+
+	installSettingsGetter(t, map[string]string{
+		"rate.forced_usdt_rate": "0",
+		"rate.api_url":          "https://rate.example.test",
+	})
+
+	if got := GetUsdtRate(); got != 0 {
+		t.Fatalf("GetUsdtRate() = %v, want 0", got)
+	}
+	if got := GetRateForCoin("usdt", "cny"); got != 0 {
+		t.Fatalf("GetRateForCoin(usdt, cny) = %v, want 0", got)
+	}
+}
+
+func TestGetRateForCoinCallsRateAPIOnceForUsdtCnyFailure(t *testing.T) {
+	viper.Reset()
+	t.Cleanup(viper.Reset)
+	t.Setenv("API_RATE_URL", "")
+
+	callCount := 0
+	installMockHTTPClient(t, func(r *http.Request) (*http.Response, error) {
+		callCount++
+		return &http.Response{
+			StatusCode: http.StatusBadGateway,
+			Status:     "502 Bad Gateway",
+			Header:     make(http.Header),
+			Body:       io.NopCloser(strings.NewReader("")),
+			Request:    r,
+		}, nil
+	})
+
+	installSettingsGetter(t, map[string]string{
+		"rate.forced_usdt_rate": "0",
+		"rate.api_url":          "https://rate.example.test",
+	})
+
+	if got := GetRateForCoin("usdt", "cny"); got != 0 {
+		t.Fatalf("GetRateForCoin(usdt, cny) = %v, want 0", got)
+	}
+	if callCount != 1 {
+		t.Fatalf("rate api call count = %d, want 1", callCount)
+	}
+}