feat(ios): HapiProtocol wire models, catalogs, session patching (A-M1a)

ios/Packages/HapiKit/Sources/HapiProtocol/Models/StrictDecoding.swift

@@ -0,0 +1,32 @@
+import Foundation
+
+/// A pass-through coding key used to enumerate whatever keys a JSON object
+/// actually carries (the synthesized `CodingKeys` enums cannot represent
+/// unknown keys).
+struct AnyCodingKey: CodingKey {
+    let stringValue: String
+    let intValue: Int?
+
+    init?(stringValue: String) {
+        self.stringValue = stringValue
+        self.intValue = nil
+    }
+
+    init?(intValue: Int) {
+        self.stringValue = String(intValue)
+        self.intValue = intValue
+    }
+}
+
+/// Mirror of zod's `.strict()`: throw when the payload carries a key outside
+/// `known`. Used by the patch types whose strictness discriminates the
+/// `Session | SessionPatch` and `Machine | MachinePatch | null` unions.
+func rejectUnknownKeys(in decoder: Decoder, known: Set<String>, payloadName: String) throws {
+    let container = try decoder.container(keyedBy: AnyCodingKey.self)
+    for key in container.allKeys where !known.contains(key.stringValue) {
+        throw DecodingError.dataCorrupted(DecodingError.Context(
+            codingPath: decoder.codingPath,
+            debugDescription: "Unknown key '\(key.stringValue)' in strict \(payloadName) payload"
+        ))
+    }
+}