docs(mwa): add quick-start, method reference, cache guide, and migration guide

.gitignore

@@ -39,9 +39,6 @@ LICENSE.meta
 README.md.meta
 package.json.meta
 
-docs/
-.claude/
-
 # Unity generated
 .utmp/
 **/[Ll]ibrary/
@@ -51,3 +48,4 @@ docs/
 **/[Ll]ogs/
 **/[Uu]ser[Ss]ettings/
 *.log
+

Runtime/codebase/SolanaMobileStack/AuthorizationRecord.cs

@@ -5,7 +5,7 @@ namespace Solana.Unity.SolanaMobileStack
     [Preserve]
     public sealed class AuthorizationRecord
     {
-        public int SchemaVersion { get; set; } = 1;
+        public int SchemaVersion { get; set; } = 2;
 
         public string AuthToken { get; set; }
 

Runtime/codebase/SolanaMobileStack/JsonRpc20Client.cs

@@ -39,7 +39,9 @@ protected Task<T> SendRequest<T>(JsonRequest jsonRequest)
         protected Task<JToken> SendRequestRaw(JsonRequest jsonRequest)
         {
             var message = JsonConvert.SerializeObject(jsonRequest);
+#if UNITY_EDITOR || MWA_VERBOSE_WIRE
             UnityEngine.Debug.Log($"[MWA Wire] → {message}");
+#endif
             var messageBytes = System.Text.Encoding.UTF8.GetBytes(message);
             _messageSender.Send(messageBytes);
             var rawTaskCompletionSource = new TaskCompletionSource<JToken>();

Runtime/codebase/SolanaMobileStack/JsonRpcClient/JsonRequest.cs

@@ -75,9 +75,6 @@ public class JsonRequestParams
             [JsonProperty("options", NullValueHandling = NullValueHandling.Ignore)]
             public JObject Options { get; set; }
 
-            [JsonProperty("sendOptions", NullValueHandling = NullValueHandling.Ignore)]
-            public JObject SendOptions { get; set; }
-
             [RequiredMember]
             public JsonRequestParams()
             {

Runtime/codebase/SolanaMobileStack/JsonRpcErrorCodes.cs

@@ -1,11 +1,12 @@
-// ReSharper disable once CheckNamespace
-
-public static class JsonRpcErrorCodes
+namespace Solana.Unity.SolanaMobileStack
 {
-    public const int AuthorizationFailed = -1;
-    public const int InvalidPayloads = -2;
-    public const int NotSigned = -3;
-    public const int NotSubmitted = -4;
-    public const int TooManyPayloads = -6;
-    public const int ChainNotSupported = -7;
+    public static class JsonRpcErrorCodes
+    {
+        public const int AuthorizationFailed = -1;
+        public const int InvalidPayloads = -2;
+        public const int NotSigned = -3;
+        public const int NotSubmitted = -4;
+        public const int TooManyPayloads = -6;
+        public const int ChainNotSupported = -7;
+    }
 }

Runtime/codebase/SolanaMobileStack/MobileWalletAdapterClient.cs

@@ -126,6 +126,8 @@ public async Task<JToken> SignAndSendTransactionsAsync(
     {
         if (base64Payloads == null || base64Payloads.Length == 0)
             throw new ArgumentException("At least one payload is required", nameof(base64Payloads));
+        if (base64Payloads.Any(p => string.IsNullOrEmpty(p)))
+            throw new ArgumentException("Payload entries must not be null or empty", nameof(base64Payloads));
         ct.ThrowIfCancellationRequested();
         UnityEngine.Debug.Log($"[MWA Client] sign_and_send_transactions: {base64Payloads.Length} payload(s)");
 
@@ -155,8 +157,7 @@ public async Task<JToken> SignAndSendTransactionsAsync(
             Params = new JsonRequest.JsonRequestParams
             {
                 Payloads = new List<string>(base64Payloads),
-                Options = wireOptions,
-                SendOptions = wireOptions
+                Options = wireOptions
             },
             Id = NextMessageId()
         };
@@ -226,7 +227,10 @@ public async Task<string> CloneAuthorizationAsync(string authToken, Cancellation
         };
 
         JToken raw = await SendRequestRaw(request);
-        return (string)raw?["auth_token"];
+        var token = (string)raw?["auth_token"];
+        if (string.IsNullOrEmpty(token))
+            throw new JsonRpcException(0, "clone_authorization response missing auth_token", raw);
+        return token;
     }
 
     private JsonRequest PrepareDeauthorizeRequest(string authToken)

Runtime/codebase/SolanaMobileStack/PlayerPrefsAuthorizationCache.cs

@@ -11,9 +11,7 @@ public sealed class PlayerPrefsAuthorizationCache : IAuthorizationCache
     {
         internal const string DefaultKey = "SolanaUnity.MWA.AuthorizationRecord.v1";
 
-        private const string LegacyPkKey = "pk";
-
-        private bool _warnedThisSession;
+        private static bool _warnedThisSession;
 
         private readonly string _key;