fix(ws): use uint64 for params.Subscription in incoming notifications (#427)

Solana validators emit subscription IDs as JSON unsigned 64-bit
integers; typing the decode target as `int` made decodeResponseFromMessage
fail for IDs above MaxInt32 (on 32-bit) or MaxInt64 (on 64-bit).
Switch to uint64 to match the wire format.
   
Closes #286.

Author: ozpool

rpc/ws/types.go

@@ -68,8 +68,15 @@ type response struct {
 }
 
 type params struct {
-	Result       *stdjson.RawMessage `json:"result"`
-	Subscription int                 `json:"subscription"`
+	Result *stdjson.RawMessage `json:"result"`
+	// Subscription is the validator-assigned subscription id. The validator
+	// emits these as JSON unsigned 64-bit integers, so the field must use
+	// uint64 to round-trip safely. Using int here failed JSON decoding on
+	// 32-bit builds and on any value above math.MaxInt64 (issue #286). The
+	// value is not consumed downstream — the routing key is parsed
+	// separately via getUint64WithOk in handleMessage — but the field is
+	// kept so encoding/json does not error on the incoming notification.
+	Subscription uint64 `json:"subscription"`
 }
 
 type Options struct {

rpc/ws/types_test.go

@@ -1,6 +1,7 @@
 package ws
 
 import (
+	stdjson "encoding/json"
 	"math"
 	"testing"
 
@@ -32,3 +33,24 @@ func TestGetUint64_AcceptsNumberAndString(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, uint64(3338220398172203928), id)
 }
+
+// TestResponseDecodesLargeSubscriptionID covers issue #286: validator
+// notifications carry the subscription id as a JSON uint64. Before the fix
+// params.Subscription was typed `int`, which fails encoding/json decode on
+// 32-bit builds and on any value above math.MaxInt64. The field must use
+// uint64 to round-trip safely.
+func TestResponseDecodesLargeSubscriptionID(t *testing.T) {
+	// Use the largest JSON-safe-but-still-uint64 value the server might emit.
+	// math.MaxUint64 itself stresses the regression most directly.
+	payload := []byte(`{
+		"jsonrpc": "2.0",
+		"params": {
+			"result": null,
+			"subscription": 18446744073709551615
+		}
+	}`)
+	var r response
+	require.NoError(t, stdjson.Unmarshal(payload, &r))
+	require.NotNil(t, r.Params)
+	require.Equal(t, uint64(math.MaxUint64), r.Params.Subscription)
+}