Remove Codable conformance for request or response-only types

Sources/GoogleAI/CountTokensRequest.swift

@@ -33,6 +33,6 @@ extension CountTokensRequest: GenerativeAIRequest {
   }
 }
 
-public struct CountTokensResponse: Codable {
+public struct CountTokensResponse: Decodable {
   public let totalTokens: Int
 }

Sources/GoogleAI/Errors.swift

@@ -14,20 +14,22 @@
 
 import Foundation
 
-struct RPCError: Error, Decodable {
+struct RPCError: Error {
   let httpResponseCode: Int32
   let message: String
   let status: RPCStatus
 
-  enum CodingKeys: CodingKey {
-    case error
-  }
-
   init(httpResponseCode: Int32, message: String, status: RPCStatus) {
     self.httpResponseCode = httpResponseCode
     self.message = message
     self.status = status
   }
+}
+
+extension RPCError: Decodable {
+  enum CodingKeys: CodingKey {
+    case error
+  }
 
   init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -53,10 +55,18 @@ struct RPCError: Error, Decodable {
   }
 }
 
-struct ErrorStatus: Codable {
+struct ErrorStatus {
   let code: Int32?
   let message: String?
   let status: RPCStatus?
+}
+
+extension ErrorStatus: Decodable {
+  enum CodingKeys: CodingKey {
+    case code
+    case message
+    case status
+  }
 
   init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -70,7 +80,7 @@ struct ErrorStatus: Codable {
   }
 }
 
-enum RPCStatus: String, Codable {
+enum RPCStatus: String, Decodable {
   // Not an error; returned on success.
   case ok = "OK"
 

Sources/GoogleAI/GenerateContentRequest.swift

@@ -24,7 +24,7 @@ struct GenerateContentRequest {
 }
 
 extension GenerateContentRequest: Encodable {
-  private enum CodingKeys: String, CodingKey {
+  enum CodingKeys: String, CodingKey {
     case contents
     case generationConfig
     case safetySettings

Sources/GoogleAI/GenerateContentResponse.swift

@@ -14,7 +14,7 @@
 
 import Foundation
 
-public struct GenerateContentResponse: Codable {
+public struct GenerateContentResponse {
   public let candidates: [CandidateResponse]
 
   public let promptFeedback: PromptFeedback?
@@ -36,6 +36,13 @@ public struct GenerateContentResponse: Codable {
     self.candidates = candidates
     self.promptFeedback = promptFeedback
   }
+}
+
+extension GenerateContentResponse: Decodable {
+  enum CodingKeys: CodingKey {
+    case candidates
+    case promptFeedback
+  }
 
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -62,7 +69,7 @@ public struct GenerateContentResponse: Codable {
   }
 }
 
-public struct CandidateResponse: Codable {
+public struct CandidateResponse {
   public let content: ModelContent
   public let safetyRatings: [SafetyRating]
 
@@ -78,6 +85,16 @@ public struct CandidateResponse: Codable {
     self.finishReason = finishReason
     self.citationMetadata = citationMetadata
   }
+}
+
+extension CandidateResponse: Decodable {
+  enum CodingKeys: CodingKey {
+    case content
+    case safetyRatings
+    case finishReason
+    case finishMessage
+    case citationMetadata
+  }
 
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
@@ -117,18 +134,18 @@ public struct CandidateResponse: Codable {
 }
 
 /// A collection of source attributions for a piece of content.
-public struct CitationMetadata: Codable {
+public struct CitationMetadata: Decodable {
   public let citationSources: [Citation]
 }
 
-public struct Citation: Codable {
+public struct Citation: Decodable {
   public let startIndex: Int
   public let endIndex: Int
   public let uri: String
   public let license: String
 }
 
-public enum FinishReason: String, Codable {
+public enum FinishReason: String {
   case unknown = "FINISH_REASON_UNKNOWN"
 
   case unspecified = "FINISH_REASON_UNSPECIFIED"
@@ -145,7 +162,9 @@ public enum FinishReason: String, Codable {
   case safety = "SAFETY"
   case recitation = "RECITATION"
   case other = "OTHER"
+}
 
+extension FinishReason: Decodable {
   /// Do not explicitly use. Initializer required for Decodable conformance.
   public init(from decoder: Decoder) throws {
     let value = try decoder.singleValueContainer().decode(String.self)
@@ -160,8 +179,8 @@ public enum FinishReason: String, Codable {
   }
 }
 
-public struct PromptFeedback: Codable {
-  public enum BlockReason: String, Codable {
+public struct PromptFeedback {
+  public enum BlockReason: String, Decodable {
     case unknown = "UNKNOWN"
     case unspecified = "BLOCK_REASON_UNSPECIFIED"
     case safety = "SAFETY"
@@ -189,7 +208,15 @@ public struct PromptFeedback: Codable {
     self.blockReason = blockReason
     self.safetyRatings = safetyRatings
   }
+}
 
+extension PromptFeedback: Decodable {
+  enum CodingKeys: CodingKey {
+    case blockReason
+    case safetyRatings
+  }
+
+  /// Do not explicitly use. Initializer required for Decodable conformance.
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
     blockReason = try container.decodeIfPresent(

Sources/GoogleAI/GenerationConfig.swift

@@ -16,7 +16,7 @@ import Foundation
 
 /// A struct defining model parameters to be used when sending generative AI
 /// requests to the backend model.
-public struct GenerationConfig: Codable {
+public struct GenerationConfig: Encodable {
   /// A parameter controlling the degree of randomness in token selection. A
   /// temperature of zero is deterministic, always choosing the
   /// highest-probability response. Typical values are between 0 and 1

Sources/GoogleAI/Safety.swift

@@ -17,7 +17,7 @@ import Foundation
 /// A type defining potentially harmful media categories and their model-assigned ratings. A value
 /// of this type may be assigned to a category for every model-generated response, not just
 /// responses that exceed a certain threshold.
-public struct SafetyRating: Codable, Equatable {
+public struct SafetyRating: Decodable, Equatable {
   /// The category describing the potential harm a piece of content may pose. See
   /// ``SafetySetting.HarmCategory`` for a list of possible values.
   public let category: SafetySetting.HarmCategory
@@ -74,7 +74,7 @@ public struct SafetyRating: Codable, Equatable {
 }
 
 /// Safety feedback for an entire request.
-public struct SafetyFeedback: Codable {
+public struct SafetyFeedback: Decodable {
   /// Safety rating evaluated from content.
   public let rating: SafetyRating