Publish Chain 138 RPC capability metadata

backend/api/rest/config_test.go

@@ -46,6 +46,29 @@ type testTokenList struct {
 	} `json:"tokens"`
 }
 
+type testCapabilitiesCatalog struct {
+	Name        string `json:"name"`
+	GeneratedBy string `json:"generatedBy"`
+	ChainID     int    `json:"chainId"`
+	ChainName   string `json:"chainName"`
+	RPCURL      string `json:"rpcUrl"`
+	HTTP        struct {
+		SupportedMethods   []string `json:"supportedMethods"`
+		UnsupportedMethods []string `json:"unsupportedMethods"`
+		Notes              []string `json:"notes"`
+	} `json:"http"`
+	Tracing struct {
+		SupportedMethods   []string `json:"supportedMethods"`
+		UnsupportedMethods []string `json:"unsupportedMethods"`
+		Notes              []string `json:"notes"`
+	} `json:"tracing"`
+	WalletSupport struct {
+		WalletAddEthereumChain bool     `json:"walletAddEthereumChain"`
+		WalletWatchAsset       bool     `json:"walletWatchAsset"`
+		Notes                  []string `json:"notes"`
+	} `json:"walletSupport"`
+}
+
 func setupConfigHandler() http.Handler {
 	server := NewServer(nil, 138)
 	mux := http.NewServeMux()
@@ -53,6 +76,15 @@ func setupConfigHandler() http.Handler {
 	return server.addMiddleware(mux)
 }
 
+func containsString(items []string, want string) bool {
+	for _, item := range items {
+		if item == want {
+			return true
+		}
+	}
+	return false
+}
+
 func TestConfigNetworksEndpointProvidesWalletMetadata(t *testing.T) {
 	handler := setupConfigHandler()
 	req := httptest.NewRequest(http.MethodGet, "/api/config/networks", nil)
@@ -148,6 +180,38 @@ func TestConfigTokenListEndpointProvidesOptionalMetadata(t *testing.T) {
 	}
 }
 
+func TestConfigCapabilitiesEndpointProvidesRPCCapabilityMatrix(t *testing.T) {
+	handler := setupConfigHandler()
+	req := httptest.NewRequest(http.MethodGet, "/api/config/capabilities", nil)
+	w := httptest.NewRecorder()
+	handler.ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d", w.Code)
+	}
+
+	var payload testCapabilitiesCatalog
+	if err := json.Unmarshal(w.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("failed to parse capabilities payload: %v", err)
+	}
+
+	if payload.ChainID != 138 || payload.ChainName == "" || payload.RPCURL == "" || payload.GeneratedBy == "" {
+		t.Fatal("expected populated chain-level capability metadata")
+	}
+	if !payload.WalletSupport.WalletAddEthereumChain || !payload.WalletSupport.WalletWatchAsset {
+		t.Fatal("expected wallet support flags to be true")
+	}
+	if !containsString(payload.HTTP.SupportedMethods, "eth_feeHistory") {
+		t.Fatal("expected eth_feeHistory support to be documented")
+	}
+	if !containsString(payload.HTTP.UnsupportedMethods, "eth_maxPriorityFeePerGas") {
+		t.Fatal("expected missing eth_maxPriorityFeePerGas support to be documented")
+	}
+	if !containsString(payload.Tracing.SupportedMethods, "trace_block") {
+		t.Fatal("expected trace_block support to be documented")
+	}
+}
+
 func TestConfigEndpointsSupportOptionsPreflight(t *testing.T) {
 	handler := setupConfigHandler()
 	req := httptest.NewRequest(http.MethodOptions, "/api/config/token-list", nil)