Publish Chain 138 RPC capability metadata

backend/api/rest/config.go

@@ -11,6 +11,9 @@ var dualChainNetworksJSON []byte
 //go:embed config/metamask/DUAL_CHAIN_TOKEN_LIST.tokenlist.json
 var dualChainTokenListJSON []byte
 
+//go:embed config/metamask/CHAIN138_RPC_CAPABILITIES.json
+var chain138RPCCapabilitiesJSON []byte
+
 // handleConfigNetworks serves GET /api/config/networks (Chain 138 + Ethereum Mainnet params for wallet_addEthereumChain).
 func (s *Server) handleConfigNetworks(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodGet {
@@ -34,3 +37,15 @@ func (s *Server) handleConfigTokenList(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Cache-Control", "public, max-age=3600")
 	w.Write(dualChainTokenListJSON)
 }
+
+// handleConfigCapabilities serves GET /api/config/capabilities (Chain 138 wallet/RPC capability matrix).
+func (s *Server) handleConfigCapabilities(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		w.Header().Set("Allow", "GET")
+		writeMethodNotAllowed(w)
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "public, max-age=900")
+	w.Write(chain138RPCCapabilitiesJSON)
+}

backend/api/rest/config/metamask/CHAIN138_RPC_CAPABILITIES.json

@@ -0,0 +1,62 @@
+{
+  "name": "Chain 138 RPC Capabilities",
+  "version": {
+    "major": 1,
+    "minor": 0,
+    "patch": 0
+  },
+  "generatedBy": "SolaceScanScout",
+  "timestamp": "2026-03-28T00:00:00Z",
+  "chainId": 138,
+  "chainName": "DeFi Oracle Meta Mainnet",
+  "rpcUrl": "https://rpc-http-pub.d-bis.org",
+  "explorerUrl": "https://explorer.d-bis.org",
+  "explorerApiUrl": "https://explorer.d-bis.org/api/v2",
+  "walletSupport": {
+    "walletAddEthereumChain": true,
+    "walletWatchAsset": true,
+    "notes": [
+      "MetaMask primarily relies on JSON-RPC correctness for balances, gas estimation, calls, and transaction submission.",
+      "Explorer-served network metadata and token list metadata complement wallet UX but do not replace RPC method support."
+    ]
+  },
+  "http": {
+    "supportedMethods": [
+      "web3_clientVersion",
+      "net_version",
+      "eth_chainId",
+      "eth_blockNumber",
+      "eth_syncing",
+      "eth_gasPrice",
+      "eth_feeHistory",
+      "eth_estimateGas",
+      "eth_getCode"
+    ],
+    "unsupportedMethods": [
+      "eth_maxPriorityFeePerGas"
+    ],
+    "notes": [
+      "eth_feeHistory is available for wallet fee estimation.",
+      "eth_maxPriorityFeePerGas is currently not exposed on the public RPC, so some wallets will fall back to simpler fee heuristics."
+    ]
+  },
+  "tracing": {
+    "supportedMethods": [
+      "trace_block",
+      "trace_replayBlockTransactions"
+    ],
+    "unsupportedMethods": [
+      "debug_traceBlockByNumber"
+    ],
+    "notes": [
+      "TRACE support is enabled for explorer-grade indexing and internal transaction analysis.",
+      "Debug tracing is intentionally not enabled on the public RPC tier."
+    ]
+  },
+  "ws": {
+    "notes": [
+      "Use the dedicated public WebSocket endpoint for subscriptions and live wallet/provider events.",
+      "HTTP and WebSocket method coverage should be treated as separate operational surfaces."
+    ]
+  }
+}

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)

backend/api/rest/routes.go

@@ -35,6 +35,7 @@ func (s *Server) SetupRoutes(mux *http.ServeMux) {
 	// MetaMask / dual-chain config (Chain 138 + Ethereum Mainnet)
 	mux.HandleFunc("/api/config/networks", s.handleConfigNetworks)
 	mux.HandleFunc("/api/config/token-list", s.handleConfigTokenList)
+	mux.HandleFunc("/api/config/capabilities", s.handleConfigCapabilities)
 
 	// Feature flags endpoint
 	mux.HandleFunc("/api/v1/features", s.handleFeatures)