sdk(rust): Make AttributedDecision a struct-style variant

Hand-written Rust here has 157 enum variants: 89 unit, 35 tuple with
exactly one payload, and 33 struct-style. Every variant carrying two or
more values uses the struct form, so a two-payload tuple was the only
one of its kind.

Name the payloads instead. Construction and both read sites now say
which value they mean rather than relying on position.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 79152db2-4cc7-4777-983a-655fae5b68c9

Author: aymenfurter

rust/src/handler.rs

@@ -49,7 +49,12 @@ pub enum PermissionResult {
     ///
     /// The context is informational only — it never changes permission
     /// behavior.
-    AttributedDecision(PermissionDecision, PermissionDecisionContext),
+    AttributedDecision {
+        /// The decision to send on the wire.
+        decision: PermissionDecision,
+        /// Context describing how and where the decision was reached.
+        context: PermissionDecisionContext,
+    },
     /// Decline to respond to this request, allowing another connected
     /// client to answer instead. The SDK suppresses the response.
     NoResult,
@@ -105,8 +110,8 @@ impl PermissionResult {
     /// ```
     pub fn with_context(self, context: PermissionDecisionContext) -> Self {
         match self {
-            Self::Decision(decision) | Self::AttributedDecision(decision, _) => {
-                Self::AttributedDecision(decision, context)
+            Self::Decision(decision) | Self::AttributedDecision { decision, .. } => {
+                Self::AttributedDecision { decision, context }
             }
             Self::NoResult => Self::NoResult,
         }

rust/src/session.rs

@@ -1581,7 +1581,7 @@ fn notification_permission_payload(result: &PermissionResult) -> Option<Value> {
     match result {
         PermissionResult::NoResult => None,
         PermissionResult::Decision(decision)
-        | PermissionResult::AttributedDecision(decision, _) => Some(
+        | PermissionResult::AttributedDecision { decision, .. } => Some(
             serde_json::to_value(decision).expect("serializing permission decision should succeed"),
         ),
     }
@@ -1605,7 +1605,7 @@ fn permission_response_params(
         "requestId": request_id,
         "result": result_value,
     });
-    if let PermissionResult::AttributedDecision(_, context) = result {
+    if let PermissionResult::AttributedDecision { context, .. } = result {
         params["decisionContext"] =
             serde_json::to_value(context).expect("serializing decision context should succeed");
     }