feat(rpc): SubmitBlock endpoint

Co-Authored-By: Charon <charon@lethean.io>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

rpc/mining.go

@@ -0,0 +1,26 @@
+// Copyright (c) 2017-2026 Lethean (https://lt.hn)
+//
+// Licensed under the European Union Public Licence (EUPL) version 1.2.
+// SPDX-License-Identifier: EUPL-1.2
+
+package rpc
+
+import "fmt"
+
+// SubmitBlock submits a mined block to the daemon.
+// The hexBlob is the hex-encoded serialised block.
+// Note: submitblock takes a JSON array as params, not an object.
+func (c *Client) SubmitBlock(hexBlob string) error {
+	// submitblock expects params as an array: ["hexblob"]
+	params := []string{hexBlob}
+	var resp struct {
+		Status string `json:"status"`
+	}
+	if err := c.call("submitblock", params, &resp); err != nil {
+		return err
+	}
+	if resp.Status != "OK" {
+		return fmt.Errorf("submitblock: status %q", resp.Status)
+	}
+	return nil
+}

rpc/mining_test.go

@@ -0,0 +1,69 @@
+// Copyright (c) 2017-2026 Lethean (https://lt.hn)
+//
+// Licensed under the European Union Public Licence (EUPL) version 1.2.
+// SPDX-License-Identifier: EUPL-1.2
+
+package rpc
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+func TestSubmitBlock_Good(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		var req jsonRPCRequest
+		json.Unmarshal(body, &req)
+		if req.Method != "submitblock" {
+			t.Errorf("method: got %q, want %q", req.Method, "submitblock")
+		}
+		// Verify params is an array.
+		raw, _ := json.Marshal(req.Params)
+		if raw[0] != '[' {
+			t.Errorf("params should be array, got: %s", raw)
+		}
+
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(jsonRPCResponse{
+			JSONRPC: "2.0",
+			ID:      json.RawMessage(`"0"`),
+			Result:  json.RawMessage(`{"status":"OK"}`),
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient(srv.URL)
+	err := c.SubmitBlock("0300000001020304")
+	if err != nil {
+		t.Fatalf("SubmitBlock: %v", err)
+	}
+}
+
+func TestSubmitBlock_Bad_Rejected(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(jsonRPCResponse{
+			JSONRPC: "2.0",
+			ID:      json.RawMessage(`"0"`),
+			Error:   &jsonRPCError{Code: -7, Message: "BLOCK_NOT_ACCEPTED"},
+		})
+	}))
+	defer srv.Close()
+
+	c := NewClient(srv.URL)
+	err := c.SubmitBlock("invalid")
+	if err == nil {
+		t.Fatal("expected error")
+	}
+	rpcErr, ok := err.(*RPCError)
+	if !ok {
+		t.Fatalf("expected *RPCError, got %T", err)
+	}
+	if rpcErr.Code != -7 {
+		t.Errorf("code: got %d, want -7", rpcErr.Code)
+	}
+}