feat: cross-SDK testing

Author: CarsonRoscoe

examples/go/clients/batch-settlement-concurrent/.env.example

@@ -3,6 +3,9 @@ EVM_PRIVATE_KEY=0x...
 # Optional: dedicated voucher-signing EOA (faster verification, recommended for smart wallets)
 EVM_VOUCHER_SIGNER_PRIVATE_KEY=
 
+# RPC endpoint used to read channel state when local storage is empty.
+EVM_RPC_URL=https://sepolia.base.org
+
 RESOURCE_SERVER_URL=http://localhost:4021
 ENDPOINT_PATH=/api/generate
 

examples/go/clients/batch-settlement-concurrent/main.go

@@ -13,6 +13,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/joho/godotenv"
 	x402 "github.com/x402-foundation/x402/go"
 	x402http "github.com/x402-foundation/x402/go/http"
@@ -38,12 +39,21 @@ func main() {
 	endpointPath := envOr("ENDPOINT_PATH", "/api/generate")
 	url := baseURL + endpointPath
 
+	rpcURL := envOr("EVM_RPC_URL", "https://sepolia.base.org")
 	baseSalt := envOr("CHANNEL_SALT", batchedclient.DefaultSalt)
 	storageDir := os.Getenv("STORAGE_DIR")
 	concurrency := atoiOr("CONCURRENCY", 3)
 	numberOfChannels := atoiOr("NUMBER_OF_CHANNELS", 3)
 
-	signer, err := evmsigners.NewClientSignerFromPrivateKey(evmPrivateKey)
+	// RPC required so the signer can recover channel state when local storage is empty.
+	ethClient, err := ethclient.Dial(rpcURL)
+	if err != nil {
+		fmt.Printf("Failed to dial EVM RPC %s: %v\n", rpcURL, err)
+		os.Exit(1)
+	}
+	defer ethClient.Close()
+
+	signer, err := evmsigners.NewClientSignerFromPrivateKeyWithClient(evmPrivateKey, ethClient)
 	if err != nil {
 		fmt.Printf("Failed to create signer: %v\n", err)
 		os.Exit(1)

examples/go/clients/batch-settlement-streaming/.env.example

@@ -3,6 +3,9 @@ EVM_PRIVATE_KEY=0x...
 # Optional: dedicated voucher-signing EOA (faster verification, recommended for smart wallets)
 EVM_VOUCHER_SIGNER_PRIVATE_KEY=
 
+# RPC endpoint used to read channel state when local storage is empty.
+EVM_RPC_URL=https://sepolia.base.org
+
 RESOURCE_SERVER_URL=http://localhost:4021
 
 # 32-byte hex channel salt

examples/go/clients/batch-settlement-streaming/main.go

@@ -14,6 +14,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/joho/godotenv"
 	x402 "github.com/x402-foundation/x402/go"
 	x402http "github.com/x402-foundation/x402/go/http"
@@ -50,10 +51,19 @@ func main() {
 		os.Exit(1)
 	}
 	baseURL := envOr("RESOURCE_SERVER_URL", "http://localhost:4021")
+	rpcURL := envOr("EVM_RPC_URL", "https://sepolia.base.org")
 	channelSalt := envOr("CHANNEL_SALT", batchedclient.DefaultSalt)
 	storageDir := os.Getenv("STORAGE_DIR")
 
-	signer, err := evmsigners.NewClientSignerFromPrivateKey(evmPrivateKey)
+	// RPC required so the signer can recover channel state when local storage is empty.
+	ethClient, err := ethclient.Dial(rpcURL)
+	if err != nil {
+		fmt.Printf("Failed to dial EVM RPC %s: %v\n", rpcURL, err)
+		os.Exit(1)
+	}
+	defer ethClient.Close()
+
+	signer, err := evmsigners.NewClientSignerFromPrivateKeyWithClient(evmPrivateKey, ethClient)
 	if err != nil {
 		fmt.Printf("Failed to create signer: %v\n", err)
 		os.Exit(1)

examples/go/clients/batch-settlement/.env-example

@@ -0,0 +1,25 @@
+EVM_PRIVATE_KEY=0x...
+
+# Optional: dedicated voucher-signing EOA (faster verification, recommended for smart wallets)
+EVM_VOUCHER_SIGNER_PRIVATE_KEY=
+
+# RPC endpoint used to read channel state when local storage is empty (cold-start
+# recovery so the client picks up an existing channel's totalClaimed instead of
+# signing a fresh voucher that the facilitator would reject).
+EVM_RPC_URL=https://sepolia.base.org
+
+RESOURCE_SERVER_URL=http://localhost:4021
+ENDPOINT_PATH=/api/generate
+
+# 32-byte hex; differentiates channels with the same payer/payee/token tuple
+CHANNEL_SALT=0x0000000000000000000000000000000000000000000000000000000000000000
+
+# Optional: persist session state across runs
+STORAGE_DIR=
+
+NUMBER_OF_REQUESTS=3
+
+# After the request loop completes, request a cooperative refund.
+REFUND_AFTER_REQUESTS=false
+# Optional partial refund amount (base units). Empty drains the remaining channel balance.
+REFUND_AMOUNT=

examples/go/clients/batch-settlement/README.md

@@ -8,14 +8,18 @@ that update cumulative claimable amount.
 
 ```bash
 cp .env.example .env
-# fill in EVM_PRIVATE_KEY and (optional) FILE_STORAGE_DIR
+# fill in EVM_PRIVATE_KEY and optional STORAGE_DIR
 
 go run .
 ```
 
 The companion server is in `examples/go/servers/batch-settlement` and the
 facilitator is in `examples/go/facilitator/batch-settlement`.
 
+For **cross-SDK** runs (Go server + TypeScript client, etc.), use the same
+variable names as `examples/typescript/clients/batch-settlement/.env-example`
+— they are aligned with this file so one `.env` can drive either stack.
+
 ## Environment
 
 | Variable                          | Description |

examples/go/clients/batch-settlement/main.go

@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/joho/godotenv"
 	x402 "github.com/x402-foundation/x402/go"
 	x402http "github.com/x402-foundation/x402/go/http"
@@ -34,13 +35,25 @@ func main() {
 	endpointPath := envOr("ENDPOINT_PATH", "/api/generate")
 	url := baseURL + endpointPath
 
+	rpcURL := envOr("EVM_RPC_URL", "https://sepolia.base.org")
 	channelSalt := envOr("CHANNEL_SALT", batchedclient.DefaultSalt)
 	storageDir := os.Getenv("STORAGE_DIR")
 	numberOfRequests := atoiOr("NUMBER_OF_REQUESTS", 3)
 	refundAfterRequests := os.Getenv("REFUND_AFTER_REQUESTS") == "true"
 	refundAmount := os.Getenv("REFUND_AMOUNT")
 
-	signer, err := evmsigners.NewClientSignerFromPrivateKey(evmPrivateKey)
+	// Dial an RPC client so the signer can read on-chain channel state when
+	// local storage is cold. Without this, a fresh client run against a channel
+	// that already has on-chain totalClaimed would sign vouchers with a stale
+	// cumulative base and the facilitator would reject them.
+	ethClient, err := ethclient.Dial(rpcURL)
+	if err != nil {
+		fmt.Printf("Failed to dial EVM RPC %s: %v\n", rpcURL, err)
+		os.Exit(1)
+	}
+	defer ethClient.Close()
+
+	signer, err := evmsigners.NewClientSignerFromPrivateKeyWithClient(evmPrivateKey, ethClient)
 	if err != nil {
 		fmt.Printf("Failed to create signer: %v\n", err)
 		os.Exit(1)
@@ -95,11 +108,18 @@ func main() {
 			os.Exit(1)
 		}
 
-		body, _ := readJSON(resp)
-		fmt.Printf("Request %d — RESPONSE\n%s\n", i+1, indent(body))
+		fmt.Printf("Request %d — %s\n", i+1, resp.Status)
+		body, errBody := readJSON(resp)
+		if errBody != nil {
+			fmt.Printf("  body: <not JSON: %v>\n", errBody)
+		} else {
+			fmt.Printf("Request %d — RESPONSE\n%s\n", i+1, indent(body))
+		}
 
 		if settle, _ := extractSettleResponse(resp); settle != nil {
 			fmt.Println(indent(settle))
+		} else if resp.StatusCode != http.StatusOK {
+			fmt.Printf("  no PAYMENT-RESPONSE (%s) — payment did not settle\n", resp.Status)
 		}
 
 		_ = resp.Body.Close()

examples/go/facilitator/batch-settlement/.env-example

@@ -0,0 +1,8 @@
+EVM_PRIVATE_KEY=0x...
+EVM_RPC_URL=https://sepolia.base.org
+
+# Optional dedicated authorizer key (defaults to EVM_PRIVATE_KEY)
+EVM_RECEIVER_AUTHORIZER_PRIVATE_KEY=
+
+# Optional (default 4022). Same as examples/typescript/facilitator/batch-settlement.
+PORT=

examples/go/facilitator/batch-settlement/README.md

@@ -23,7 +23,8 @@ cp .env.example .env
 go run .
 ```
 
-Listens on `http://localhost:4022` by default.
+Listens on `http://localhost:4022` by default (`PORT` overrides; same as the
+TypeScript facilitator example).
 
 ## Environment
 
@@ -32,3 +33,4 @@ Listens on `http://localhost:4022` by default.
 | `EVM_PRIVATE_KEY` (required)              | Facilitator wallet — signs and submits on-chain transactions |
 | `EVM_RECEIVER_AUTHORIZER_PRIVATE_KEY`     | Optional dedicated authorizer key. Defaults to `EVM_PRIVATE_KEY`. |
 | `EVM_RPC_URL`                             | Default `https://sepolia.base.org` |
+| `PORT`                                    | Listen port (default `4022`) |

examples/go/facilitator/batch-settlement/main.go

@@ -18,6 +18,8 @@ const defaultPort = "4022"
 func main() {
 	_ = godotenv.Load()
 
+	port := envOr("PORT", defaultPort)
+
 	evmPrivateKey := os.Getenv("EVM_PRIVATE_KEY")
 	if evmPrivateKey == "" {
 		fmt.Println("EVM_PRIVATE_KEY environment variable is required")
@@ -100,8 +102,8 @@ func main() {
 		writeJSON(w, http.StatusOK, result)
 	})
 
-	fmt.Printf("Facilitator listening on http://localhost:%s\n", defaultPort)
-	if err := http.ListenAndServe(":"+defaultPort, mux); err != nil {
+	fmt.Printf("Facilitator listening on http://localhost:%s\n", port)
+	if err := http.ListenAndServe(":"+port, mux); err != nil {
 		fmt.Printf("Server error: %v\n", err)
 		os.Exit(1)
 	}