From e150802035530b4b7ec77949853125c7b71572e9 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Sun, 23 Nov 2025 21:00:33 -0500
Subject: [PATCH 01/32] [Firebase AI] Add `Generable` scaffolding

---
 .../ConvertibleFromGeneratedContent.swift     |  41 ++++
 .../ConvertibleToGeneratedContent.swift       |  42 ++++
 .../Types/Public/Generable/Generable.swift    | 196 +++++++++++++++++
 .../Public/Generable/GeneratedContent.swift   | 197 ++++++++++++++++++
 .../Public/Generable/GenerationGuide.swift    |  16 ++
 .../Public/Generable/GenerationSchema.swift   | 163 +++++++++++++++
 6 files changed, 655 insertions(+)
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/Generable.swift
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift
new file mode 100644
index 00000000000..4967c35963d
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift
@@ -0,0 +1,41 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// A type that can be initialized from generated content.
+public protocol ConvertibleFromGeneratedContent: SendableMetatype {
+  /// Creates an instance from content generated by a model.
+  ///
+  /// Conformance to this protocol is provided by the `@Generable` macro. A manual implementation
+  /// may be used to map values onto properties using different names. To manually initialize your
+  /// type from generated content, decode the values as shown below:
+  ///
+  /// ```swift
+  /// struct Person: ConvertibleFromGeneratedContent {
+  ///     var name: String
+  ///     var age: Int
+  ///
+  ///     init(_ content: GeneratedContent) {
+  ///         self.name = try content.value(forProperty: "firstName")
+  ///         self.age = try content.value(forProperty: "ageInYears")
+  ///     }
+  /// }
+  /// ```
+  ///
+  /// - Important: If your type also conforms to ``ConvertibleToGeneratedContent``, it is critical
+  /// that this implementation be symmetrical with
+  /// ``ConvertibleToGeneratedContent/generatedContent``.
+  ///
+  /// - SeeAlso: `@Generable` macro ``Generable(description:)``
+  init(_ content: GeneratedContent) throws
+}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift
new file mode 100644
index 00000000000..546c1b5c36a
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift
@@ -0,0 +1,42 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// A type that can be converted to generated content.
+public protocol ConvertibleToGeneratedContent {
+  /// This instance represented as generated content.
+  ///
+  /// Conformance to this protocol is provided by the `@Generable` macro. A manual implementation
+  /// may be used to map values onto properties using different names. Use the generated content
+  /// property as shown below, to manually return a new ``GeneratedContent`` with the properties
+  /// you specify.
+  ///
+  /// ```swift
+  /// struct Person: ConvertibleToGeneratedContent {
+  ///    var name: String
+  ///    var age: Int
+  ///
+  ///    var generatedContent: GeneratedContent {
+  ///        GeneratedContent(properties: [
+  ///            "firstName": name,
+  ///            "ageInYears": age
+  ///        ])
+  ///    }
+  /// }
+  /// ```
+  ///
+  /// - Important: If your type also conforms to ``ConvertibleFromGeneratedContent``, it is
+  /// critical that this implementation be symmetrical with
+  /// ``ConvertibleFromGeneratedContent/init(_:)``.
+  var generatedContent: GeneratedContent { get }
+}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
new file mode 100644
index 00000000000..f4e658039cf
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -0,0 +1,196 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+/// A type that the model uses when responding to prompts.
+///
+/// Annotate your Swift structure or enumeration with the `@Generable` macro to allow the model to
+/// respond to prompts by generating an instance of your type. Use the `@Guide` macro to provide
+/// natural language descriptions of your properties, and programmatically control the values that
+/// the model can generate.
+///
+/// ```swift
+/// @Generable
+/// struct SearchSuggestions {
+///     @Guide(description: "A list of suggested search terms", .count(4))
+///     var searchTerms: [SearchTerm]
+///
+///     @Generable
+///     struct SearchTerm {
+///         // Use a generation identifier for data structures the framework generates.
+///         var id: GenerationID
+///
+///         @Guide(description: "A 2 or 3 word search term, like 'Beautiful sunsets'")
+///         var searchTerm: String
+///     }
+/// }
+/// ```
+/// - SeeAlso: `@Generable` macro ``Generable(description:)`` and  `@Guide` macro
+/// ``Guide(description:)``.
+public protocol Generable: ConvertibleFromGeneratedContent, ConvertibleToGeneratedContent {
+  /// An instance of the generation schema.
+  static var generationSchema: GenerationSchema { get }
+}
+
+extension Optional where Wrapped: Generable {}
+
+extension Optional: ConvertibleToGeneratedContent where Wrapped: ConvertibleToGeneratedContent {
+  public var generatedContent: GeneratedContent {
+    guard let self else { return GeneratedContent(kind: .null) }
+
+    return GeneratedContent(self)
+  }
+}
+
+extension Bool: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .boolean, source: "Bool")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    guard case let .bool(value) = content.kind else {
+      // TODO: Determine the correct error to throw.
+      fatalError("Expected a boolean but found \(content.kind)")
+    }
+    self = value
+  }
+
+  public var generatedContent: GeneratedContent {
+    return GeneratedContent(kind: .bool(self))
+  }
+}
+
+extension String: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .string, source: "String")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    guard case let .string(value) = content.kind else {
+      // TODO: Determine the correct error to throw.
+      fatalError("Expected a string but found \(content.kind)")
+    }
+    self = value
+  }
+
+  public var generatedContent: GeneratedContent {
+    return GeneratedContent(kind: .string(self))
+  }
+}
+
+extension Int: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .integer, source: "Int")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    // TODO: Determine the correct errors to throw.
+    guard case let .number(value) = content.kind else {
+      fatalError("Expected a number but found \(content.kind)")
+    }
+    guard let integer = Int(exactly: value) else {
+      fatalError("Expected an integer but found \(value)")
+    }
+    self = integer
+  }
+
+  public var generatedContent: GeneratedContent {
+    return GeneratedContent(kind: .number(Double(self)))
+  }
+}
+
+extension Float: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .double, source: "Number")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    // TODO: Determine the correct error to throw.
+    guard case let .number(value) = content.kind else {
+      fatalError("Expected a number but found \(content.kind)")
+    }
+    guard let float = Float(exactly: value) else {
+      fatalError("Expected a float but found \(value)")
+    }
+    self = float
+  }
+
+  public var generatedContent: GeneratedContent {
+    return GeneratedContent(kind: .number(Double(self)))
+  }
+}
+
+extension Double: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .double, source: "Number")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    // TODO: Determine the correct error to throw.
+    guard case let .number(value) = content.kind else {
+      fatalError("Expected a number but found \(content.kind)")
+    }
+    guard let double = Double(exactly: value) else {
+      fatalError("Expected a double but found \(value)")
+    }
+    self = double
+  }
+
+  public var generatedContent: GeneratedContent {
+    return GeneratedContent(kind: .number(self))
+  }
+}
+
+extension Decimal: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .double, source: "Number")
+  }
+
+  public init(_ content: GeneratedContent) throws {
+    // TODO: Determine the correct error to throw.
+    guard case let .number(value) = content.kind else {
+      fatalError("Expected a number but found \(content.kind)")
+    }
+    self = Decimal(value)
+  }
+
+  public var generatedContent: GeneratedContent {
+    let doubleValue = (self as NSDecimalNumber).doubleValue
+    return GeneratedContent(kind: .number(doubleValue))
+  }
+}
+
+extension Array: Generable where Element: Generable {
+  public static var generationSchema: GenerationSchema {
+    GenerationSchema(kind: .array(item: Element.self), source: String(describing: self))
+  }
+}
+
+extension Array: ConvertibleToGeneratedContent where Element: ConvertibleToGeneratedContent {
+  public var generatedContent: GeneratedContent {
+    let values = map { $0.generatedContent }
+    return GeneratedContent(kind: .array(values))
+  }
+}
+
+extension Array: ConvertibleFromGeneratedContent where Element: ConvertibleFromGeneratedContent {
+  public init(_ content: GeneratedContent) throws {
+    // TODO: Determine the correct error to throw.
+    guard case let .array(values) = content.kind else {
+      fatalError("Expected an array but found \(content.kind)")
+    }
+    self = try values.map { try Element($0) }
+  }
+}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
new file mode 100644
index 00000000000..122d3b8d790
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
@@ -0,0 +1,197 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// A type that represents structured, generated content.
+///
+/// Generated content may contain a single value, an array, or key-value pairs with unique keys.
+public struct GeneratedContent: Sendable, Generable {
+  /// The kind representation of this generated content.
+  ///
+  /// This property provides access to the content in a strongly-typed enum representation,
+  /// preserving the hierarchical structure of the data and the  data's ``GenerationID`` ids.
+  public let kind: Kind
+
+  /// An instance of the generation schema.
+  public static var generationSchema: GenerationSchema {
+    // Return a schema equivalent to any legal JSON, i.e.:
+    // {
+    //   "anyOf" : [
+    //     {
+    //       "additionalProperties" : {
+    //         "$ref" : "#"
+    //       },
+    //       "type" : "object"
+    //     },
+    //     {
+    //       "items" : {
+    //         "$ref" : "#"
+    //       },
+    //       "type" : "array"
+    //     },
+    //     {
+    //       "type" : "boolean"
+    //     },
+    //     {
+    //       "type" : "number"
+    //     },
+    //     {
+    //       "type" : "string"
+    //     }
+    //   ],
+    //   "description" : "Any legal JSON",
+    //   "title" : "GeneratedContent"
+    // }
+    fatalError("`GeneratedContent.generationSchema` is not implemented.")
+  }
+
+  init(kind: Kind) {
+    self.kind = kind
+  }
+
+  /// Creates generated content from another value.
+  ///
+  /// This is used to satisfy `Generable.init(_:)`.
+  public init(_ content: GeneratedContent) throws {
+    self = content
+  }
+
+  /// A representation of this instance.
+  public var generatedContent: GeneratedContent { self }
+
+  /// Creates generated content representing a structure with the properties you specify.
+  ///
+  /// The order of properties is important. For ``Generable`` types, the order must match the order
+  /// properties in the types `schema`.
+  public init(properties: KeyValuePairs<String, any ConvertibleToGeneratedContent>) {
+    fatalError("`GeneratedContent.init(properties:)` is not implemented.")
+  }
+
+  /// Creates new generated content from the key-value pairs in the given sequence, using a
+  /// combining closure to determine the value for any duplicate keys.
+  ///
+  /// The order of properties is important. For ``Generable`` types, the order must match the order
+  /// properties in the types `schema`.
+  ///
+  /// You use this initializer to create generated content when you have a sequence of key-value
+  /// tuples that might have duplicate keys. As the content is built, the initializer calls the
+  /// `combine` closure with the current and new values for any duplicate keys. Pass a closure as
+  /// `combine` that returns the value to use in the resulting content: The closure can choose
+  /// between the two values, combine them to produce a new value, or even throw an error.
+  ///
+  /// The following example shows how to choose the first and last values for any duplicate keys:
+  ///
+  /// ```swift
+  ///     let content = GeneratedContent(
+  ///       properties: [("name", "John"), ("name", "Jane"), ("married", true)],
+  ///       uniquingKeysWith: { (first, _) in first }
+  ///     )
+  ///     // GeneratedContent(["name": "John", "married": true])
+  /// ```
+  ///
+  /// - Parameters:
+  ///   - properties: A sequence of key-value pairs to use for the new content.
+  ///   - id: A unique id associated with ``GeneratedContent``.
+  ///   - combine: A closure that is called with the values to resolve any duplicates
+  ///     keys that are encountered. The closure returns the desired value for the final content.
+  public init<S>(properties: S,
+                 uniquingKeysWith combine: (GeneratedContent, GeneratedContent) throws
+                   -> some ConvertibleToGeneratedContent) rethrows where S: Sequence, S.Element == (
+    String,
+    any ConvertibleToGeneratedContent
+  ) {
+    var propertyNames = [String]()
+    var propertyMap = [String: GeneratedContent]()
+    for (key, value) in properties {
+      if !propertyNames.contains(key) {
+        propertyNames.append(key)
+        propertyMap[key] = value.generatedContent
+      } else {
+        guard let existingProperty = propertyMap[key] else {
+          // TODO: Figure out an error to throw
+          fatalError()
+        }
+        let deduplicatedProperty = try combine(existingProperty, value.generatedContent)
+        propertyMap[key] = deduplicatedProperty.generatedContent
+      }
+    }
+
+    kind = .structure(properties: propertyMap, orderedKeys: propertyNames)
+  }
+
+  /// Creates content representing an array of elements you specify.
+  public init<S>(elements: S) where S: Sequence, S.Element == any ConvertibleToGeneratedContent {
+    fatalError("`GeneratedContent.init(elements:)` is not implemented.")
+  }
+
+  /// Creates content that contains a single value.
+  ///
+  /// - Parameters:
+  ///   - value: The underlying value.
+  public init(_ value: some ConvertibleToGeneratedContent) {
+    self = value.generatedContent
+  }
+
+  /// Reads a top level, concrete partially `Generable` type from a named property.
+  public func value<Value>(_ type: Value.Type = Value.self) throws -> Value
+    where Value: ConvertibleFromGeneratedContent {
+    fatalError("`GeneratedContent.value(_:)` is not implemented.")
+  }
+
+  /// Reads a concrete `Generable` type from named property.
+  public func value<Value>(_ type: Value.Type = Value.self,
+                           forProperty property: String) throws -> Value
+    where Value: ConvertibleFromGeneratedContent {
+    fatalError("`GeneratedContent.value(_:forProperty:)` is not implemented.")
+  }
+
+  /// Reads an optional, concrete generable type from named property.
+  public func value<Value>(_ type: Value?.Type = Value?.self,
+                           forProperty property: String) throws -> Value?
+    where Value: ConvertibleFromGeneratedContent {
+    fatalError("`GeneratedContent.value(_:forProperty:)` is not implemented.")
+  }
+}
+
+public extension GeneratedContent {
+  /// A representation of the different types of content that can be stored in `GeneratedContent`.
+  ///
+  /// `Kind` represents the various types of JSON-compatible data that can be held within a
+  /// ``GeneratedContent`` instance, including primitive types, arrays, and structured objects.
+  enum Kind: Sendable {
+    /// Represents a null value.
+    case null
+
+    /// Represents a boolean value.
+    /// - Parameter value: The boolean value.
+    case bool(Bool)
+
+    /// Represents a numeric value.
+    /// - Parameter value: The numeric value as a Double.
+    case number(Double)
+
+    /// Represents a string value.
+    /// - Parameter value: The string value.
+    case string(String)
+
+    /// Represents an array of `GeneratedContent` elements.
+    /// - Parameter elements: An array of ``GeneratedContent`` instances.
+    case array([GeneratedContent])
+
+    /// Represents a structured object with key-value pairs.
+    /// - Parameters:
+    ///   - properties: A dictionary mapping string keys to ``GeneratedContent`` values.
+    ///   - orderedKeys: An array of keys that specifies the order of properties.
+    case structure(properties: [String: GeneratedContent], orderedKeys: [String])
+  }
+}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
new file mode 100644
index 00000000000..2443af07ef8
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
@@ -0,0 +1,16 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// Guides that control how values are generated.
+public struct GenerationGuide<Value> {}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
new file mode 100644
index 00000000000..32862b9d779
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
@@ -0,0 +1,163 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+/// A type that describes the properties of an object and any guides on their values.
+///
+/// Generation  schemas guide the output of the model to deterministically ensure the output is in
+/// the desired format.
+public struct GenerationSchema: Sendable {
+  enum Kind {
+    case string
+    case integer
+    case double
+    case boolean
+    case array(item: Generable.Type)
+    case object(name: String, description: String?, properties: [Property])
+  }
+
+  let kind: Kind
+  let source: String
+
+  init(kind: Kind, source: String) {
+    self.kind = kind
+    self.source = source
+  }
+
+  /// A property that belongs to a generation schema.
+  ///
+  /// Fields are named members of object types. Fields are strongly typed and have optional
+  /// descriptions and guides.
+  public struct Property: Sendable {
+    let name: String
+    let description: String?
+    let isOptional: Bool
+    let type: Generable.Type
+    // TODO: Store `GenerationGuide` values.
+
+    /// Create a property that contains a generable type.
+    ///
+    /// - Parameters:
+    ///   - name: The property's name.
+    ///   - description: A natural language description of what content should be generated for this
+    ///     property.
+    ///   - type: The type this property represents.
+    ///   - guides: A list of guides to apply to this property.
+    public init<Value>(name: String, description: String? = nil, type: Value.Type,
+                       guides: [GenerationGuide<Value>] = []) where Value: Generable {
+      precondition(guides.isEmpty, "GenerationGuide support is not yet implemented.")
+      self.name = name
+      self.description = description
+      isOptional = false
+      self.type = Value.self
+    }
+
+    /// Create an optional property that contains a generable type.
+    ///
+    /// - Parameters:
+    ///   - name: The property's name.
+    ///   - description: A natural language description of what content should be generated for this
+    ///     property.
+    ///   - type: The type this property represents.
+    ///   - guides: A list of guides to apply to this property.
+    public init<Value>(name: String, description: String? = nil, type: Value?.Type,
+                       guides: [GenerationGuide<Value>] = []) where Value: Generable {
+      precondition(guides.isEmpty, "GenerationGuide support is not yet implemented.")
+      self.name = name
+      self.description = description
+      isOptional = true
+      self.type = Value.self
+    }
+  }
+
+  /// Creates a schema by providing an array of properties.
+  ///
+  /// - Parameters:
+  ///   - type: The type this schema represents.
+  ///   - description: A natural language description of this schema.
+  ///   - properties: An array of properties.
+  public init(type: any Generable.Type, description: String? = nil,
+              properties: [GenerationSchema.Property]) {
+    let name = String(describing: type)
+    kind = .object(name: name, description: description, properties: properties)
+    source = name
+  }
+
+  /// Creates a schema for a string enumeration.
+  ///
+  /// - Parameters:
+  ///   - type: The type this schema represents.
+  ///   - description: A natural language description of this schema.
+  ///   - anyOf: The allowed choices.
+  public init(type: any Generable.Type, description: String? = nil, anyOf choices: [String]) {
+    fatalError("`GenerationSchema.init(type:description:anyOf:)` is not implemented.")
+  }
+
+  /// Creates a schema as the union of several other types.
+  ///
+  /// - Parameters:
+  ///   - type: The type this schema represents.
+  ///   - description: A natural language description of this schema.
+  ///   - anyOf: The types this schema should be a union of.
+  public init(type: any Generable.Type, description: String? = nil,
+              anyOf types: [any Generable.Type]) {
+    fatalError("`GenerationSchema.init(type:description:anyOf:)` is not implemented.")
+  }
+
+  /// A error that occurs when there is a problem creating a generation schema.
+  public enum SchemaError: Error, LocalizedError {
+    /// The context in which the error occurred.
+    public struct Context: Sendable {
+      /// A string representation of the debug description.
+      ///
+      /// This string is not localized and is not appropriate for display to end users.
+      public let debugDescription: String
+
+      public init(debugDescription: String) {
+        self.debugDescription = debugDescription
+      }
+    }
+
+    /// An error that represents an attempt to construct a schema from dynamic schemas, and two or
+    /// more of the subschemas have the same type name.
+    case duplicateType(schema: String?, type: String, context: GenerationSchema.SchemaError.Context)
+
+    /// An error that represents an attempt to construct a dynamic schema with properties that have
+    /// conflicting names.
+    case duplicateProperty(
+      schema: String,
+      property: String,
+      context: GenerationSchema.SchemaError.Context
+    )
+
+    /// An error that represents an attempt to construct an anyOf schema with an empty array of type
+    /// choices.
+    case emptyTypeChoices(schema: String, context: GenerationSchema.SchemaError.Context)
+
+    /// An error that represents an attempt to construct a schema from dynamic schemas, and one of
+    /// those schemas references an undefined schema.
+    case undefinedReferences(
+      schema: String?,
+      references: [String],
+      context: GenerationSchema.SchemaError.Context
+    )
+
+    /// A string representation of the error description.
+    public var errorDescription: String? { nil }
+
+    /// A suggestion that indicates how to handle the error.
+    public var recoverySuggestion: String? { nil }
+  }
+}

From 4f7b30af92713cac5a0de1f0320502faa2a54f9e Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 15:02:21 -0500
Subject: [PATCH 02/32] Add `asOpenAPISchema()` to `GenerationSchema`

---
 .../Public/Generable/GenerationSchema.swift   | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
index 32862b9d779..4a6e469a619 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
@@ -160,4 +160,36 @@ public struct GenerationSchema: Sendable {
     /// A suggestion that indicates how to handle the error.
     public var recoverySuggestion: String? { nil }
   }
+
+  /// Returns an OpenAPI ``Schema`` equivalent of this JSON schema for testing.
+  public func asOpenAPISchema() -> Schema {
+    // TODO: Make this method internal or remove it when JSON Schema serialization is implemented.
+    switch kind {
+    case .string:
+      return .string()
+    case .integer:
+      return .integer()
+    case .double:
+      return .double()
+    case .boolean:
+      return .boolean()
+    case let .array(item: item):
+      return .array(items: item.generationSchema.asOpenAPISchema())
+    case let .object(name: name, description: description, properties: properties):
+      var objectProperties = [String: Schema]()
+      for property in properties {
+        objectProperties[property.name] = property.type.generationSchema.asOpenAPISchema()
+      }
+      return .object(
+        properties: objectProperties,
+        optionalProperties: properties.compactMap { property in
+          guard property.isOptional else { return nil }
+          return property.name
+        },
+        propertyOrdering: properties.map { $0.name },
+        description: description,
+        title: name
+      )
+    }
+  }
 }

From 97cee24ac880de5451b9ea2c4d9c74acddd0fa79 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 15:10:22 -0500
Subject: [PATCH 03/32] Rename `GenerationSchema` to `JSONSchema`

---
 .../Types/Public/Generable/Generable.swift    | 32 +++++++++----------
 .../Public/Generable/GeneratedContent.swift   |  4 +--
 ...enerationSchema.swift => JSONSchema.swift} | 20 ++++++------
 3 files changed, 28 insertions(+), 28 deletions(-)
 rename FirebaseAI/Sources/Types/Public/Generable/{GenerationSchema.swift => JSONSchema.swift} (90%)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index f4e658039cf..4149052ebbb 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -40,8 +40,8 @@ import Foundation
 /// - SeeAlso: `@Generable` macro ``Generable(description:)`` and  `@Guide` macro
 /// ``Guide(description:)``.
 public protocol Generable: ConvertibleFromGeneratedContent, ConvertibleToGeneratedContent {
-  /// An instance of the generation schema.
-  static var generationSchema: GenerationSchema { get }
+  /// An instance of the JSON schema.
+  static var jsonSchema: JSONSchema { get }
 }
 
 extension Optional where Wrapped: Generable {}
@@ -55,8 +55,8 @@ extension Optional: ConvertibleToGeneratedContent where Wrapped: ConvertibleToGe
 }
 
 extension Bool: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .boolean, source: "Bool")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .boolean, source: "Bool")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -73,8 +73,8 @@ extension Bool: Generable {
 }
 
 extension String: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .string, source: "String")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .string, source: "String")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -91,8 +91,8 @@ extension String: Generable {
 }
 
 extension Int: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .integer, source: "Int")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .integer, source: "Int")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -112,8 +112,8 @@ extension Int: Generable {
 }
 
 extension Float: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .double, source: "Number")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .double, source: "Number")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -133,8 +133,8 @@ extension Float: Generable {
 }
 
 extension Double: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .double, source: "Number")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .double, source: "Number")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -154,8 +154,8 @@ extension Double: Generable {
 }
 
 extension Decimal: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .double, source: "Number")
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .double, source: "Number")
   }
 
   public init(_ content: GeneratedContent) throws {
@@ -173,8 +173,8 @@ extension Decimal: Generable {
 }
 
 extension Array: Generable where Element: Generable {
-  public static var generationSchema: GenerationSchema {
-    GenerationSchema(kind: .array(item: Element.self), source: String(describing: self))
+  public static var jsonSchema: JSONSchema {
+    JSONSchema(kind: .array(item: Element.self), source: String(describing: self))
   }
 }
 
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
index 122d3b8d790..b5eff276449 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
@@ -22,8 +22,8 @@ public struct GeneratedContent: Sendable, Generable {
   /// preserving the hierarchical structure of the data and the  data's ``GenerationID`` ids.
   public let kind: Kind
 
-  /// An instance of the generation schema.
-  public static var generationSchema: GenerationSchema {
+  /// An instance of the JSON schema.
+  public static var jsonSchema: JSONSchema {
     // Return a schema equivalent to any legal JSON, i.e.:
     // {
     //   "anyOf" : [
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
similarity index 90%
rename from FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
rename to FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
index 4a6e469a619..58a4330bfe0 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GenerationSchema.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
@@ -18,7 +18,7 @@ import Foundation
 ///
 /// Generation  schemas guide the output of the model to deterministically ensure the output is in
 /// the desired format.
-public struct GenerationSchema: Sendable {
+public struct JSONSchema: Sendable {
   enum Kind {
     case string
     case integer
@@ -36,7 +36,7 @@ public struct GenerationSchema: Sendable {
     self.source = source
   }
 
-  /// A property that belongs to a generation schema.
+  /// A property that belongs to a JSON schema.
   ///
   /// Fields are named members of object types. Fields are strongly typed and have optional
   /// descriptions and guides.
@@ -89,7 +89,7 @@ public struct GenerationSchema: Sendable {
   ///   - description: A natural language description of this schema.
   ///   - properties: An array of properties.
   public init(type: any Generable.Type, description: String? = nil,
-              properties: [GenerationSchema.Property]) {
+              properties: [JSONSchema.Property]) {
     let name = String(describing: type)
     kind = .object(name: name, description: description, properties: properties)
     source = name
@@ -116,7 +116,7 @@ public struct GenerationSchema: Sendable {
     fatalError("`GenerationSchema.init(type:description:anyOf:)` is not implemented.")
   }
 
-  /// A error that occurs when there is a problem creating a generation schema.
+  /// A error that occurs when there is a problem creating a JSON schema.
   public enum SchemaError: Error, LocalizedError {
     /// The context in which the error occurred.
     public struct Context: Sendable {
@@ -132,26 +132,26 @@ public struct GenerationSchema: Sendable {
 
     /// An error that represents an attempt to construct a schema from dynamic schemas, and two or
     /// more of the subschemas have the same type name.
-    case duplicateType(schema: String?, type: String, context: GenerationSchema.SchemaError.Context)
+    case duplicateType(schema: String?, type: String, context: JSONSchema.SchemaError.Context)
 
     /// An error that represents an attempt to construct a dynamic schema with properties that have
     /// conflicting names.
     case duplicateProperty(
       schema: String,
       property: String,
-      context: GenerationSchema.SchemaError.Context
+      context: JSONSchema.SchemaError.Context
     )
 
     /// An error that represents an attempt to construct an anyOf schema with an empty array of type
     /// choices.
-    case emptyTypeChoices(schema: String, context: GenerationSchema.SchemaError.Context)
+    case emptyTypeChoices(schema: String, context: JSONSchema.SchemaError.Context)
 
     /// An error that represents an attempt to construct a schema from dynamic schemas, and one of
     /// those schemas references an undefined schema.
     case undefinedReferences(
       schema: String?,
       references: [String],
-      context: GenerationSchema.SchemaError.Context
+      context: JSONSchema.SchemaError.Context
     )
 
     /// A string representation of the error description.
@@ -174,11 +174,11 @@ public struct GenerationSchema: Sendable {
     case .boolean:
       return .boolean()
     case let .array(item: item):
-      return .array(items: item.generationSchema.asOpenAPISchema())
+      return .array(items: item.jsonSchema.asOpenAPISchema())
     case let .object(name: name, description: description, properties: properties):
       var objectProperties = [String: Schema]()
       for property in properties {
-        objectProperties[property.name] = property.type.generationSchema.asOpenAPISchema()
+        objectProperties[property.name] = property.type.jsonSchema.asOpenAPISchema()
       }
       return .object(
         properties: objectProperties,

From d8d983fedfed1e09730ebbbae7f1195bd0a1517d Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 15:24:11 -0500
Subject: [PATCH 04/32] Rename `GeneratedContent` to `ModelOutput`

---
 ...swift => ConvertibleFromModelOutput.swift} | 16 ++--
 ...t.swift => ConvertibleToModelOutput.swift} | 22 ++---
 .../Types/Public/Generable/Generable.swift    | 58 ++++++-------
 ...neratedContent.swift => ModelOutput.swift} | 84 +++++++++----------
 4 files changed, 90 insertions(+), 90 deletions(-)
 rename FirebaseAI/Sources/Types/Public/Generable/{ConvertibleFromGeneratedContent.swift => ConvertibleFromModelOutput.swift} (74%)
 rename FirebaseAI/Sources/Types/Public/Generable/{ConvertibleToGeneratedContent.swift => ConvertibleToModelOutput.swift} (66%)
 rename FirebaseAI/Sources/Types/Public/Generable/{GeneratedContent.swift => ModelOutput.swift} (66%)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
similarity index 74%
rename from FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift
rename to FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
index 4967c35963d..c8d55889973 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromGeneratedContent.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
@@ -12,30 +12,30 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/// A type that can be initialized from generated content.
-public protocol ConvertibleFromGeneratedContent: SendableMetatype {
+/// A type that can be initialized from model output.
+public protocol ConvertibleFromModelOutput: SendableMetatype {
   /// Creates an instance from content generated by a model.
   ///
   /// Conformance to this protocol is provided by the `@Generable` macro. A manual implementation
   /// may be used to map values onto properties using different names. To manually initialize your
-  /// type from generated content, decode the values as shown below:
+  /// type from model output, decode the values as shown below:
   ///
   /// ```swift
-  /// struct Person: ConvertibleFromGeneratedContent {
+  /// struct Person: ConvertibleFromModelOutput {
   ///     var name: String
   ///     var age: Int
   ///
-  ///     init(_ content: GeneratedContent) {
+  ///     init(_ content: ModelOutput) {
   ///         self.name = try content.value(forProperty: "firstName")
   ///         self.age = try content.value(forProperty: "ageInYears")
   ///     }
   /// }
   /// ```
   ///
-  /// - Important: If your type also conforms to ``ConvertibleToGeneratedContent``, it is critical
+  /// - Important: If your type also conforms to ``ConvertibleToModelOutput``, it is critical
   /// that this implementation be symmetrical with
-  /// ``ConvertibleToGeneratedContent/generatedContent``.
+  /// ``ConvertibleToModelOutput/modelOutput``.
   ///
   /// - SeeAlso: `@Generable` macro ``Generable(description:)``
-  init(_ content: GeneratedContent) throws
+  init(_ content: ModelOutput) throws
 }
diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
similarity index 66%
rename from FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift
rename to FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
index 546c1b5c36a..af0648a8b77 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToGeneratedContent.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
@@ -12,22 +12,22 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/// A type that can be converted to generated content.
-public protocol ConvertibleToGeneratedContent {
-  /// This instance represented as generated content.
+/// A type that can be converted to model output.
+public protocol ConvertibleToModelOutput {
+  /// This instance represented as model output.
   ///
   /// Conformance to this protocol is provided by the `@Generable` macro. A manual implementation
-  /// may be used to map values onto properties using different names. Use the generated content
-  /// property as shown below, to manually return a new ``GeneratedContent`` with the properties
+  /// may be used to map values onto properties using different names. Use the `modelOutput`
+  /// property as shown below, to manually return a new ``ModelOutput`` with the properties
   /// you specify.
   ///
   /// ```swift
-  /// struct Person: ConvertibleToGeneratedContent {
+  /// struct Person: ConvertibleToModelOutput {
   ///    var name: String
   ///    var age: Int
   ///
-  ///    var generatedContent: GeneratedContent {
-  ///        GeneratedContent(properties: [
+  ///    var modelOutput: ModelOutput {
+  ///        ModelOutput(properties: [
   ///            "firstName": name,
   ///            "ageInYears": age
   ///        ])
@@ -35,8 +35,8 @@ public protocol ConvertibleToGeneratedContent {
   /// }
   /// ```
   ///
-  /// - Important: If your type also conforms to ``ConvertibleFromGeneratedContent``, it is
+  /// - Important: If your type also conforms to ``ConvertibleFromModelOutput``, it is
   /// critical that this implementation be symmetrical with
-  /// ``ConvertibleFromGeneratedContent/init(_:)``.
-  var generatedContent: GeneratedContent { get }
+  /// ``ConvertibleFromModelOutput/init(_:)``.
+  var modelOutput: ModelOutput { get }
 }
diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index 4149052ebbb..9cb2336fc5a 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -39,18 +39,18 @@ import Foundation
 /// ```
 /// - SeeAlso: `@Generable` macro ``Generable(description:)`` and  `@Guide` macro
 /// ``Guide(description:)``.
-public protocol Generable: ConvertibleFromGeneratedContent, ConvertibleToGeneratedContent {
+public protocol Generable: ConvertibleFromModelOutput, ConvertibleToModelOutput {
   /// An instance of the JSON schema.
   static var jsonSchema: JSONSchema { get }
 }
 
 extension Optional where Wrapped: Generable {}
 
-extension Optional: ConvertibleToGeneratedContent where Wrapped: ConvertibleToGeneratedContent {
-  public var generatedContent: GeneratedContent {
-    guard let self else { return GeneratedContent(kind: .null) }
+extension Optional: ConvertibleToModelOutput where Wrapped: ConvertibleToModelOutput {
+  public var modelOutput: ModelOutput {
+    guard let self else { return ModelOutput(kind: .null) }
 
-    return GeneratedContent(self)
+    return ModelOutput(self)
   }
 }
 
@@ -59,7 +59,7 @@ extension Bool: Generable {
     JSONSchema(kind: .boolean, source: "Bool")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     guard case let .bool(value) = content.kind else {
       // TODO: Determine the correct error to throw.
       fatalError("Expected a boolean but found \(content.kind)")
@@ -67,8 +67,8 @@ extension Bool: Generable {
     self = value
   }
 
-  public var generatedContent: GeneratedContent {
-    return GeneratedContent(kind: .bool(self))
+  public var modelOutput: ModelOutput {
+    return ModelOutput(kind: .bool(self))
   }
 }
 
@@ -77,7 +77,7 @@ extension String: Generable {
     JSONSchema(kind: .string, source: "String")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     guard case let .string(value) = content.kind else {
       // TODO: Determine the correct error to throw.
       fatalError("Expected a string but found \(content.kind)")
@@ -85,8 +85,8 @@ extension String: Generable {
     self = value
   }
 
-  public var generatedContent: GeneratedContent {
-    return GeneratedContent(kind: .string(self))
+  public var modelOutput: ModelOutput {
+    return ModelOutput(kind: .string(self))
   }
 }
 
@@ -95,7 +95,7 @@ extension Int: Generable {
     JSONSchema(kind: .integer, source: "Int")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct errors to throw.
     guard case let .number(value) = content.kind else {
       fatalError("Expected a number but found \(content.kind)")
@@ -106,8 +106,8 @@ extension Int: Generable {
     self = integer
   }
 
-  public var generatedContent: GeneratedContent {
-    return GeneratedContent(kind: .number(Double(self)))
+  public var modelOutput: ModelOutput {
+    return ModelOutput(kind: .number(Double(self)))
   }
 }
 
@@ -116,7 +116,7 @@ extension Float: Generable {
     JSONSchema(kind: .double, source: "Number")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
       fatalError("Expected a number but found \(content.kind)")
@@ -127,8 +127,8 @@ extension Float: Generable {
     self = float
   }
 
-  public var generatedContent: GeneratedContent {
-    return GeneratedContent(kind: .number(Double(self)))
+  public var modelOutput: ModelOutput {
+    return ModelOutput(kind: .number(Double(self)))
   }
 }
 
@@ -137,7 +137,7 @@ extension Double: Generable {
     JSONSchema(kind: .double, source: "Number")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
       fatalError("Expected a number but found \(content.kind)")
@@ -148,8 +148,8 @@ extension Double: Generable {
     self = double
   }
 
-  public var generatedContent: GeneratedContent {
-    return GeneratedContent(kind: .number(self))
+  public var modelOutput: ModelOutput {
+    return ModelOutput(kind: .number(self))
   }
 }
 
@@ -158,7 +158,7 @@ extension Decimal: Generable {
     JSONSchema(kind: .double, source: "Number")
   }
 
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
       fatalError("Expected a number but found \(content.kind)")
@@ -166,9 +166,9 @@ extension Decimal: Generable {
     self = Decimal(value)
   }
 
-  public var generatedContent: GeneratedContent {
+  public var modelOutput: ModelOutput {
     let doubleValue = (self as NSDecimalNumber).doubleValue
-    return GeneratedContent(kind: .number(doubleValue))
+    return ModelOutput(kind: .number(doubleValue))
   }
 }
 
@@ -178,15 +178,15 @@ extension Array: Generable where Element: Generable {
   }
 }
 
-extension Array: ConvertibleToGeneratedContent where Element: ConvertibleToGeneratedContent {
-  public var generatedContent: GeneratedContent {
-    let values = map { $0.generatedContent }
-    return GeneratedContent(kind: .array(values))
+extension Array: ConvertibleToModelOutput where Element: ConvertibleToModelOutput {
+  public var modelOutput: ModelOutput {
+    let values = map { $0.modelOutput }
+    return ModelOutput(kind: .array(values))
   }
 }
 
-extension Array: ConvertibleFromGeneratedContent where Element: ConvertibleFromGeneratedContent {
-  public init(_ content: GeneratedContent) throws {
+extension Array: ConvertibleFromModelOutput where Element: ConvertibleFromModelOutput {
+  public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct error to throw.
     guard case let .array(values) = content.kind else {
       fatalError("Expected an array but found \(content.kind)")
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
similarity index 66%
rename from FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
rename to FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index b5eff276449..8ba8ebe8da9 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GeneratedContent.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -12,11 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-/// A type that represents structured, generated content.
+/// A type that represents structured model output.
 ///
-/// Generated content may contain a single value, an array, or key-value pairs with unique keys.
-public struct GeneratedContent: Sendable, Generable {
-  /// The kind representation of this generated content.
+/// Model output may contain a single value, an array, or key-value pairs with unique keys.
+public struct ModelOutput: Sendable, Generable {
+  /// The kind representation of this model output.
   ///
   /// This property provides access to the content in a strongly-typed enum representation,
   /// preserving the hierarchical structure of the data and the  data's ``GenerationID`` ids.
@@ -50,40 +50,40 @@ public struct GeneratedContent: Sendable, Generable {
     //     }
     //   ],
     //   "description" : "Any legal JSON",
-    //   "title" : "GeneratedContent"
+    //   "title" : "ModelOutput"
     // }
-    fatalError("`GeneratedContent.generationSchema` is not implemented.")
+    fatalError("`ModelOutput.generationSchema` is not implemented.")
   }
 
   init(kind: Kind) {
     self.kind = kind
   }
 
-  /// Creates generated content from another value.
+  /// Creates model output from another value.
   ///
   /// This is used to satisfy `Generable.init(_:)`.
-  public init(_ content: GeneratedContent) throws {
+  public init(_ content: ModelOutput) throws {
     self = content
   }
 
   /// A representation of this instance.
-  public var generatedContent: GeneratedContent { self }
+  public var modelOutput: ModelOutput { self }
 
-  /// Creates generated content representing a structure with the properties you specify.
+  /// Creates model output representing a structure with the properties you specify.
   ///
   /// The order of properties is important. For ``Generable`` types, the order must match the order
   /// properties in the types `schema`.
-  public init(properties: KeyValuePairs<String, any ConvertibleToGeneratedContent>) {
-    fatalError("`GeneratedContent.init(properties:)` is not implemented.")
+  public init(properties: KeyValuePairs<String, any ConvertibleToModelOutput>) {
+    fatalError("`ModelOutput.init(properties:)` is not implemented.")
   }
 
-  /// Creates new generated content from the key-value pairs in the given sequence, using a
+  /// Creates new model output from the key-value pairs in the given sequence, using a
   /// combining closure to determine the value for any duplicate keys.
   ///
   /// The order of properties is important. For ``Generable`` types, the order must match the order
   /// properties in the types `schema`.
   ///
-  /// You use this initializer to create generated content when you have a sequence of key-value
+  /// You use this initializer to create model output when you have a sequence of key-value
   /// tuples that might have duplicate keys. As the content is built, the initializer calls the
   /// `combine` closure with the current and new values for any duplicate keys. Pass a closure as
   /// `combine` that returns the value to use in the resulting content: The closure can choose
@@ -92,37 +92,37 @@ public struct GeneratedContent: Sendable, Generable {
   /// The following example shows how to choose the first and last values for any duplicate keys:
   ///
   /// ```swift
-  ///     let content = GeneratedContent(
+  ///     let content = ModelOutput(
   ///       properties: [("name", "John"), ("name", "Jane"), ("married", true)],
   ///       uniquingKeysWith: { (first, _) in first }
   ///     )
-  ///     // GeneratedContent(["name": "John", "married": true])
+  ///     // ModelOutput(["name": "John", "married": true])
   /// ```
   ///
   /// - Parameters:
   ///   - properties: A sequence of key-value pairs to use for the new content.
-  ///   - id: A unique id associated with ``GeneratedContent``.
+  ///   - id: A unique id associated with ``ModelOutput``.
   ///   - combine: A closure that is called with the values to resolve any duplicates
   ///     keys that are encountered. The closure returns the desired value for the final content.
   public init<S>(properties: S,
-                 uniquingKeysWith combine: (GeneratedContent, GeneratedContent) throws
-                   -> some ConvertibleToGeneratedContent) rethrows where S: Sequence, S.Element == (
+                 uniquingKeysWith combine: (ModelOutput, ModelOutput) throws
+                   -> some ConvertibleToModelOutput) rethrows where S: Sequence, S.Element == (
     String,
-    any ConvertibleToGeneratedContent
+    any ConvertibleToModelOutput
   ) {
     var propertyNames = [String]()
-    var propertyMap = [String: GeneratedContent]()
+    var propertyMap = [String: ModelOutput]()
     for (key, value) in properties {
       if !propertyNames.contains(key) {
         propertyNames.append(key)
-        propertyMap[key] = value.generatedContent
+        propertyMap[key] = value.modelOutput
       } else {
         guard let existingProperty = propertyMap[key] else {
           // TODO: Figure out an error to throw
           fatalError()
         }
-        let deduplicatedProperty = try combine(existingProperty, value.generatedContent)
-        propertyMap[key] = deduplicatedProperty.generatedContent
+        let deduplicatedProperty = try combine(existingProperty, value.modelOutput)
+        propertyMap[key] = deduplicatedProperty.modelOutput
       }
     }
 
@@ -130,44 +130,44 @@ public struct GeneratedContent: Sendable, Generable {
   }
 
   /// Creates content representing an array of elements you specify.
-  public init<S>(elements: S) where S: Sequence, S.Element == any ConvertibleToGeneratedContent {
-    fatalError("`GeneratedContent.init(elements:)` is not implemented.")
+  public init<S>(elements: S) where S: Sequence, S.Element == any ConvertibleToModelOutput {
+    fatalError("`ModelOutput.init(elements:)` is not implemented.")
   }
 
   /// Creates content that contains a single value.
   ///
   /// - Parameters:
   ///   - value: The underlying value.
-  public init(_ value: some ConvertibleToGeneratedContent) {
-    self = value.generatedContent
+  public init(_ value: some ConvertibleToModelOutput) {
+    self = value.modelOutput
   }
 
   /// Reads a top level, concrete partially `Generable` type from a named property.
   public func value<Value>(_ type: Value.Type = Value.self) throws -> Value
-    where Value: ConvertibleFromGeneratedContent {
-    fatalError("`GeneratedContent.value(_:)` is not implemented.")
+    where Value: ConvertibleFromModelOutput {
+    fatalError("`ModelOutput.value(_:)` is not implemented.")
   }
 
   /// Reads a concrete `Generable` type from named property.
   public func value<Value>(_ type: Value.Type = Value.self,
                            forProperty property: String) throws -> Value
-    where Value: ConvertibleFromGeneratedContent {
-    fatalError("`GeneratedContent.value(_:forProperty:)` is not implemented.")
+    where Value: ConvertibleFromModelOutput {
+    fatalError("`ModelOutput.value(_:forProperty:)` is not implemented.")
   }
 
   /// Reads an optional, concrete generable type from named property.
   public func value<Value>(_ type: Value?.Type = Value?.self,
                            forProperty property: String) throws -> Value?
-    where Value: ConvertibleFromGeneratedContent {
-    fatalError("`GeneratedContent.value(_:forProperty:)` is not implemented.")
+    where Value: ConvertibleFromModelOutput {
+    fatalError("`ModelOutput.value(_:forProperty:)` is not implemented.")
   }
 }
 
-public extension GeneratedContent {
-  /// A representation of the different types of content that can be stored in `GeneratedContent`.
+public extension ModelOutput {
+  /// A representation of the different types of content that can be stored in `ModelOutput`.
   ///
   /// `Kind` represents the various types of JSON-compatible data that can be held within a
-  /// ``GeneratedContent`` instance, including primitive types, arrays, and structured objects.
+  /// ``ModelOutput`` instance, including primitive types, arrays, and structured objects.
   enum Kind: Sendable {
     /// Represents a null value.
     case null
@@ -184,14 +184,14 @@ public extension GeneratedContent {
     /// - Parameter value: The string value.
     case string(String)
 
-    /// Represents an array of `GeneratedContent` elements.
-    /// - Parameter elements: An array of ``GeneratedContent`` instances.
-    case array([GeneratedContent])
+    /// Represents an array of `ModelOutput` elements.
+    /// - Parameter elements: An array of ``ModelOutput`` instances.
+    case array([ModelOutput])
 
     /// Represents a structured object with key-value pairs.
     /// - Parameters:
-    ///   - properties: A dictionary mapping string keys to ``GeneratedContent`` values.
+    ///   - properties: A dictionary mapping string keys to ``ModelOutput`` values.
     ///   - orderedKeys: An array of keys that specifies the order of properties.
-    case structure(properties: [String: GeneratedContent], orderedKeys: [String])
+    case structure(properties: [String: ModelOutput], orderedKeys: [String])
   }
 }

From 7184df472ecc79e97d6cde9fd5fee826d28b1b4a Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 16:01:08 -0500
Subject: [PATCH 05/32] Add `available(iOS 15.0, macOS 12.0, ..., *)`
 annotations

---
 .../Generable/ConvertibleFromModelOutput.swift       |  1 +
 .../Public/Generable/ConvertibleToModelOutput.swift  |  1 +
 .../Sources/Types/Public/Generable/Generable.swift   | 12 ++++++++++++
 .../Types/Public/Generable/GenerationGuide.swift     |  1 +
 .../Sources/Types/Public/Generable/JSONSchema.swift  |  1 +
 .../Sources/Types/Public/Generable/ModelOutput.swift |  1 +
 6 files changed, 17 insertions(+)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
index c8d55889973..eb8cf938009 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 /// A type that can be initialized from model output.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public protocol ConvertibleFromModelOutput: SendableMetatype {
   /// Creates an instance from content generated by a model.
   ///
diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
index af0648a8b77..93367388510 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleToModelOutput.swift
@@ -13,6 +13,7 @@
 // limitations under the License.
 
 /// A type that can be converted to model output.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public protocol ConvertibleToModelOutput {
   /// This instance represented as model output.
   ///
diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index 9cb2336fc5a..8769295f4da 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -39,13 +39,16 @@ import Foundation
 /// ```
 /// - SeeAlso: `@Generable` macro ``Generable(description:)`` and  `@Guide` macro
 /// ``Guide(description:)``.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public protocol Generable: ConvertibleFromModelOutput, ConvertibleToModelOutput {
   /// An instance of the JSON schema.
   static var jsonSchema: JSONSchema { get }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Optional where Wrapped: Generable {}
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Optional: ConvertibleToModelOutput where Wrapped: ConvertibleToModelOutput {
   public var modelOutput: ModelOutput {
     guard let self else { return ModelOutput(kind: .null) }
@@ -54,6 +57,7 @@ extension Optional: ConvertibleToModelOutput where Wrapped: ConvertibleToModelOu
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Bool: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .boolean, source: "Bool")
@@ -72,6 +76,7 @@ extension Bool: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension String: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .string, source: "String")
@@ -90,6 +95,7 @@ extension String: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Int: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .integer, source: "Int")
@@ -111,6 +117,7 @@ extension Int: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Float: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .double, source: "Number")
@@ -132,6 +139,7 @@ extension Float: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Double: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .double, source: "Number")
@@ -153,6 +161,7 @@ extension Double: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Decimal: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .double, source: "Number")
@@ -172,12 +181,14 @@ extension Decimal: Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Array: Generable where Element: Generable {
   public static var jsonSchema: JSONSchema {
     JSONSchema(kind: .array(item: Element.self), source: String(describing: self))
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Array: ConvertibleToModelOutput where Element: ConvertibleToModelOutput {
   public var modelOutput: ModelOutput {
     let values = map { $0.modelOutput }
@@ -185,6 +196,7 @@ extension Array: ConvertibleToModelOutput where Element: ConvertibleToModelOutpu
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Array: ConvertibleFromModelOutput where Element: ConvertibleFromModelOutput {
   public init(_ content: ModelOutput) throws {
     // TODO: Determine the correct error to throw.
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
index 2443af07ef8..1ab6c9b3c50 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerationGuide.swift
@@ -13,4 +13,5 @@
 // limitations under the License.
 
 /// Guides that control how values are generated.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct GenerationGuide<Value> {}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
index 58a4330bfe0..f48ca185ee1 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
@@ -18,6 +18,7 @@ import Foundation
 ///
 /// Generation  schemas guide the output of the model to deterministically ensure the output is in
 /// the desired format.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct JSONSchema: Sendable {
   enum Kind {
     case string
diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index 8ba8ebe8da9..c2b67db01c0 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -15,6 +15,7 @@
 /// A type that represents structured model output.
 ///
 /// Model output may contain a single value, an array, or key-value pairs with unique keys.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct ModelOutput: Sendable, Generable {
   /// The kind representation of this model output.
   ///

From d555f0cd4d2413cb10e087311a2a1587611a91fc Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 17:36:06 -0500
Subject: [PATCH 06/32] Add example output for the `Generable` macro

---
 .../Unit/Types/Generable/GenerableTests.swift | 66 +++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
new file mode 100644
index 00000000000..700955b6074
--- /dev/null
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -0,0 +1,66 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// An example of the expected output from the `@FirebaseAILogic.Generable` macro.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+struct Person: Equatable {
+  let firstName: String
+  let middleName: String?
+  let lastName: String
+  let age: Int
+
+  nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
+    FirebaseAILogic.JSONSchema(
+      type: Self.self,
+      properties: [
+        FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
+        FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
+      ]
+    )
+  }
+
+  nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
+    var properties = [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)]()
+    addProperty(name: "firstName", value: firstName)
+    addProperty(name: "middleName", value: middleName)
+    addProperty(name: "lastName", value: lastName)
+    addProperty(name: "age", value: age)
+    return ModelOutput(
+      properties: properties,
+      uniquingKeysWith: { _, second in
+        second
+      }
+    )
+    func addProperty(name: String, value: some FirebaseAILogic.Generable) {
+      properties.append((name, value))
+    }
+    func addProperty(name: String, value: (some FirebaseAILogic.Generable)?) {
+      if let value {
+        properties.append((name, value))
+      }
+    }
+  }
+}
+
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+extension Person: nonisolated FirebaseAILogic.Generable {
+  nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
+    firstName = try content.value(forProperty: "firstName")
+    middleName = try content.value(forProperty: "middleName")
+    lastName = try content.value(forProperty: "lastName")
+    age = try content.value(forProperty: "age")
+  }
+}

From c435c920cd37777d1d588b00a37c450cec36546d Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Mon, 24 Nov 2025 17:36:42 -0500
Subject: [PATCH 07/32] Implement `ModelOutput.value(_:forProperty:)` and add
 tests

---
 .../Types/Public/Generable/ModelOutput.swift  | 21 ++++++-
 .../Unit/Types/Generable/GenerableTests.swift | 63 +++++++++++++++++++
 2 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index c2b67db01c0..30f35ec3d40 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -153,14 +153,31 @@ public struct ModelOutput: Sendable, Generable {
   public func value<Value>(_ type: Value.Type = Value.self,
                            forProperty property: String) throws -> Value
     where Value: ConvertibleFromModelOutput {
-    fatalError("`ModelOutput.value(_:forProperty:)` is not implemented.")
+    guard case let .structure(properties, _) = kind else {
+      // TODO: Throw an error instead
+      fatalError("Attempting to access a property on a non-object ModelOutput.")
+    }
+    guard let value = properties[property] else {
+      // TODO: Throw an error instead
+      fatalError("Property '\(property)' not found in model output.")
+    }
+
+    return try Value(value)
   }
 
   /// Reads an optional, concrete generable type from named property.
   public func value<Value>(_ type: Value?.Type = Value?.self,
                            forProperty property: String) throws -> Value?
     where Value: ConvertibleFromModelOutput {
-    fatalError("`ModelOutput.value(_:forProperty:)` is not implemented.")
+    guard case let .structure(properties, _) = kind else {
+      // TODO: Throw an error instead
+      fatalError("Attempting to access a property on a non-object ModelOutput.")
+    }
+    guard let value = properties[property] else {
+      return nil
+    }
+
+    return try Value(value)
   }
 }
 
diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index 700955b6074..2996f1d3ab7 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -12,6 +12,69 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import FirebaseAILogic
+import Testing
+
+struct GenerableTests {
+  @Test
+  func initializeGenerableTypeFromModelOutput() throws {
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [("firstName", "John"), ("lastName", "Doe"), ("age", 40)]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    let person = try Person(modelOutput)
+
+    #expect(person.firstName == "John")
+    #expect(person.lastName == "Doe")
+    #expect(person.age == 40)
+  }
+
+  @Test
+  func convertGenerableTypeToModelOutput() throws {
+    let person = Person(firstName: "Jane", middleName: "Marie", lastName: "Smith", age: 32)
+
+    let modelOutput = person.modelOutput
+
+    guard case let .structure(properties, orderedKeys) = modelOutput.kind else {
+      Issue.record("Model output is not a structure.")
+      return
+    }
+    let firstNameProperty = try #require(properties["firstName"])
+    guard case let .string(firstName) = firstNameProperty.kind else {
+      Issue.record("The 'firstName' property is not a string: \(firstNameProperty.kind)")
+      return
+    }
+    #expect(firstName == person.firstName)
+    #expect(try modelOutput.value(forProperty: "firstName") == person.firstName)
+    let middleNameProperty = try #require(properties["middleName"])
+    guard case let .string(middleName) = middleNameProperty.kind else {
+      Issue.record("The 'middleName' property is not a string: \(middleNameProperty.kind)")
+      return
+    }
+    #expect(middleName == person.middleName)
+    #expect(try modelOutput.value(forProperty: "middleName") == person.middleName)
+    let lastNameProperty = try #require(properties["lastName"])
+    guard case let .string(lastName) = lastNameProperty.kind else {
+      Issue.record("The 'lastName' property is not a string: \(lastNameProperty.kind)")
+      return
+    }
+    #expect(lastName == person.lastName)
+    #expect(try modelOutput.value(forProperty: "lastName") == person.lastName)
+    let ageProperty = try #require(properties["age"])
+    guard case let .number(age) = ageProperty.kind else {
+      Issue.record("The 'age' property is not a number: \(ageProperty.kind)")
+      return
+    }
+    #expect(Int(age) == person.age)
+    #expect(try modelOutput.value(forProperty: "age") == person.age)
+    // TODO: Implement `ModelOutput.value(_:)` and uncomment
+    // #expect(try modelOutput.value() == person)
+    #expect(orderedKeys == ["firstName", "middleName", "lastName", "age"])
+  }
+}
+
 // An example of the expected output from the `@FirebaseAILogic.Generable` macro.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 struct Person: Equatable {

From 61449924df4774aa6e906719d5cd0f74ac659d0d Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 12:22:48 -0500
Subject: [PATCH 08/32] Add `GenerativeModel.GenerationError` and throw
 `decodingFailure`

---
 .../Types/Public/Generable/Generable.swift    | 36 ++++++++++------
 .../GenerativeModel+GenerationError.swift     | 43 +++++++++++++++++++
 2 files changed, 65 insertions(+), 14 deletions(-)
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift

diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index 8769295f4da..325cd5c4794 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -65,8 +65,7 @@ extension Bool: Generable {
 
   public init(_ content: ModelOutput) throws {
     guard case let .bool(value) = content.kind else {
-      // TODO: Determine the correct error to throw.
-      fatalError("Expected a boolean but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
     self = value
   }
@@ -84,8 +83,7 @@ extension String: Generable {
 
   public init(_ content: ModelOutput) throws {
     guard case let .string(value) = content.kind else {
-      // TODO: Determine the correct error to throw.
-      fatalError("Expected a string but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
     self = value
   }
@@ -102,10 +100,10 @@ extension Int: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine the correct errors to throw.
     guard case let .number(value) = content.kind else {
-      fatalError("Expected a number but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
+    // TODO: Determine the correct error to throw.
     guard let integer = Int(exactly: value) else {
       fatalError("Expected an integer but found \(value)")
     }
@@ -124,10 +122,10 @@ extension Float: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
-      fatalError("Expected a number but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
+    // TODO: Determine the correct error to throw.
     guard let float = Float(exactly: value) else {
       fatalError("Expected a float but found \(value)")
     }
@@ -146,10 +144,10 @@ extension Double: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
-      fatalError("Expected a number but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
+    // TODO: Determine the correct error to throw.
     guard let double = Double(exactly: value) else {
       fatalError("Expected a double but found \(value)")
     }
@@ -168,9 +166,8 @@ extension Decimal: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine the correct error to throw.
     guard case let .number(value) = content.kind else {
-      fatalError("Expected a number but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
     self = Decimal(value)
   }
@@ -199,10 +196,21 @@ extension Array: ConvertibleToModelOutput where Element: ConvertibleToModelOutpu
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension Array: ConvertibleFromModelOutput where Element: ConvertibleFromModelOutput {
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine the correct error to throw.
     guard case let .array(values) = content.kind else {
-      fatalError("Expected an array but found \(content.kind)")
+      throw Self.decodingFailure(content)
     }
     self = try values.map { try Element($0) }
   }
 }
+
+private extension ConvertibleFromModelOutput {
+  /// Helper method to create ``GenerativeModel/GenerationError/decodingFailure(_:)`` instances.
+  static func decodingFailure(_ content: ModelOutput) -> GenerativeModel.GenerationError {
+    return GenerativeModel.GenerationError.decodingFailure(
+      GenerativeModel.GenerationError.Context(debugDescription: """
+      \(content.self) does not contain \(Self.self).
+      Content: \(content)
+      """)
+    )
+  }
+}
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift
new file mode 100644
index 00000000000..d505b46a2ef
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift
@@ -0,0 +1,43 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+public extension GenerativeModel {
+  /// An error that may occur while generating a response.
+  enum GenerationError: Error {
+    /// The context in which the error occurred.
+    public struct Context: Sendable {
+      /// A debug description to help developers diagnose issues during development.
+      ///
+      /// This string is not localized and is not appropriate for display to end users.
+      public let debugDescription: String
+
+      /// Creates a context.
+      ///
+      /// - Parameters:
+      ///   - debugDescription: The debug description to help developers diagnose issues during
+      /// development.
+      public init(debugDescription: String) {
+        self.debugDescription = debugDescription
+      }
+    }
+
+    /// An error that indicates the session failed to deserialize a valid generable type from model
+    /// output.
+    ///
+    /// This can happen if generation was terminated early.
+    case decodingFailure(GenerativeModel.GenerationError.Context)
+  }
+}

From 5541a002e31336bbf8d5b74712e03c2ce24c924f Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 12:37:05 -0500
Subject: [PATCH 09/32] Fix Xcode 16 build errors

---
 .../Types/Public/Generable/ConvertibleFromModelOutput.swift     | 2 ++
 FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift     | 1 +
 2 files changed, 3 insertions(+)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
index eb8cf938009..ad6cddf2a82 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ConvertibleFromModelOutput.swift
@@ -12,6 +12,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import Foundation
+
 /// A type that can be initialized from model output.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public protocol ConvertibleFromModelOutput: SendableMetatype {
diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index 30f35ec3d40..36d3626dde5 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -181,6 +181,7 @@ public struct ModelOutput: Sendable, Generable {
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public extension ModelOutput {
   /// A representation of the different types of content that can be stored in `ModelOutput`.
   ///

From 4cec2b30d30f2aa79c89789d023cd50f364bf036 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 15:01:34 -0500
Subject: [PATCH 10/32] More build fixes

---
 FirebaseAI/Sources/Types/Public/Generable/Generable.swift | 1 +
 .../Generable/GenerativeModel+GenerationError.swift       | 1 +
 .../Tests/Unit/Types/Generable/GenerableTests.swift       | 8 ++++----
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index 325cd5c4794..19ebf57fcbf 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -203,6 +203,7 @@ extension Array: ConvertibleFromModelOutput where Element: ConvertibleFromModelO
   }
 }
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 private extension ConvertibleFromModelOutput {
   /// Helper method to create ``GenerativeModel/GenerationError/decodingFailure(_:)`` instances.
   static func decodingFailure(_ content: ModelOutput) -> GenerativeModel.GenerationError {
diff --git a/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift b/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift
index d505b46a2ef..421378b0fca 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/GenerativeModel+GenerationError.swift
@@ -14,6 +14,7 @@
 
 import Foundation
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public extension GenerativeModel {
   /// An error that may occur while generating a response.
   enum GenerationError: Error {
diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index 2996f1d3ab7..e33d1d72526 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -16,8 +16,8 @@ import FirebaseAILogic
 import Testing
 
 struct GenerableTests {
-  @Test
-  func initializeGenerableTypeFromModelOutput() throws {
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  @Test func initializeGenerableTypeFromModelOutput() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("lastName", "Doe"), ("age", 40)]
     let modelOutput = ModelOutput(
@@ -31,8 +31,8 @@ struct GenerableTests {
     #expect(person.age == 40)
   }
 
-  @Test
-  func convertGenerableTypeToModelOutput() throws {
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  @Test func convertGenerableTypeToModelOutput() throws {
     let person = Person(firstName: "Jane", middleName: "Marie", lastName: "Smith", age: 32)
 
     let modelOutput = person.modelOutput

From a1aa0b054c3be294c00facf2bd77dcb95e51bc0a Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 15:17:39 -0500
Subject: [PATCH 11/32] Add `SendableMetatype` typealias for older Xcode
 versions

---
 .../Types/Public/Generable/JSONSchema.swift     |  2 +-
 .../Sources/Types/Public/SendableMetatype.swift | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 FirebaseAI/Sources/Types/Public/SendableMetatype.swift

diff --git a/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
index f48ca185ee1..15538214291 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/JSONSchema.swift
@@ -20,7 +20,7 @@ import Foundation
 /// the desired format.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public struct JSONSchema: Sendable {
-  enum Kind {
+  enum Kind: Sendable {
     case string
     case integer
     case double
diff --git a/FirebaseAI/Sources/Types/Public/SendableMetatype.swift b/FirebaseAI/Sources/Types/Public/SendableMetatype.swift
new file mode 100644
index 00000000000..46d8f4d1968
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/SendableMetatype.swift
@@ -0,0 +1,17 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#if compiler(<6.2)
+  public typealias SendableMetatype = Any
+#endif

From f687ab17a22df1113c5e39c1c8fad4547fd2f302 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 17:26:04 -0500
Subject: [PATCH 12/32] Another Xcode 16 workaround

---
 .../Unit/Types/Generable/GenerableTests.swift | 28 +++++++++++++------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index e33d1d72526..365403709ea 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -118,12 +118,24 @@ struct Person: Equatable {
   }
 }
 
-@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-extension Person: nonisolated FirebaseAILogic.Generable {
-  nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
-    firstName = try content.value(forProperty: "firstName")
-    middleName = try content.value(forProperty: "middleName")
-    lastName = try content.value(forProperty: "lastName")
-    age = try content.value(forProperty: "age")
+#if compiler(>=6.2)
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  extension Person: nonisolated FirebaseAILogic.Generable {
+    nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
+      firstName = try content.value(forProperty: "firstName")
+      middleName = try content.value(forProperty: "middleName")
+      lastName = try content.value(forProperty: "lastName")
+      age = try content.value(forProperty: "age")
+    }
   }
-}
+#else
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  extension Person: FirebaseAILogic.Generable {
+    nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
+      firstName = try content.value(forProperty: "firstName")
+      middleName = try content.value(forProperty: "middleName")
+      lastName = try content.value(forProperty: "lastName")
+      age = try content.value(forProperty: "age")
+    }
+  }
+#endif

From a219b40a4b4c2689ba3c176b8c18429f5e38f6bc Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Tue, 25 Nov 2025 18:32:52 -0500
Subject: [PATCH 13/32] Coalesce type conversion failures

---
 .../Types/Public/Generable/Generable.swift    | 20 +++++--------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index 19ebf57fcbf..cdd1fcc348f 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -100,13 +100,9 @@ extension Int: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    guard case let .number(value) = content.kind else {
+    guard case let .number(value) = content.kind, let integer = Int(exactly: value) else {
       throw Self.decodingFailure(content)
     }
-    // TODO: Determine the correct error to throw.
-    guard let integer = Int(exactly: value) else {
-      fatalError("Expected an integer but found \(value)")
-    }
     self = integer
   }
 
@@ -122,13 +118,10 @@ extension Float: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    guard case let .number(value) = content.kind else {
+    // TODO: Determine if we need to use `exactly: ` or be more lenient.
+    guard case let .number(value) = content.kind, let float = Float(exactly: value) else {
       throw Self.decodingFailure(content)
     }
-    // TODO: Determine the correct error to throw.
-    guard let float = Float(exactly: value) else {
-      fatalError("Expected a float but found \(value)")
-    }
     self = float
   }
 
@@ -144,13 +137,10 @@ extension Double: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    guard case let .number(value) = content.kind else {
+    // TODO: Determine if we need to use `exactly: ` or be more lenient.
+    guard case let .number(value) = content.kind, let double = Double(exactly: value) else {
       throw Self.decodingFailure(content)
     }
-    // TODO: Determine the correct error to throw.
-    guard let double = Double(exactly: value) else {
-      fatalError("Expected a double but found \(value)")
-    }
     self = double
   }
 

From 5cafb190a009288609bfd8993b631270b2dbc727 Mon Sep 17 00:00:00 2001
From: Paul Beusterien <paulbeusterien@google.com>
Date: Wed, 26 Nov 2025 11:16:13 -0800
Subject: [PATCH 14/32] Implement TODOs and add tests (#15535)

---
 .../Types/Public/Generable/ModelOutput.swift  |  65 ++-
 .../Unit/Types/Generable/GenerableTests.swift | 401 +++++++++++++++---
 2 files changed, 409 insertions(+), 57 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index 36d3626dde5..da3c09cc452 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -16,7 +16,7 @@
 ///
 /// Model output may contain a single value, an array, or key-value pairs with unique keys.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-public struct ModelOutput: Sendable, Generable {
+public struct ModelOutput: Sendable, Generable, CustomDebugStringConvertible {
   /// The kind representation of this model output.
   ///
   /// This property provides access to the content in a strongly-typed enum representation,
@@ -70,6 +70,10 @@ public struct ModelOutput: Sendable, Generable {
   /// A representation of this instance.
   public var modelOutput: ModelOutput { self }
 
+  public var debugDescription: String {
+    return kind.debugDescription
+  }
+
   /// Creates model output representing a structure with the properties you specify.
   ///
   /// The order of properties is important. For ``Generable`` types, the order must match the order
@@ -146,7 +150,7 @@ public struct ModelOutput: Sendable, Generable {
   /// Reads a top level, concrete partially `Generable` type from a named property.
   public func value<Value>(_ type: Value.Type = Value.self) throws -> Value
     where Value: ConvertibleFromModelOutput {
-    fatalError("`ModelOutput.value(_:)` is not implemented.")
+    return try Value(self)
   }
 
   /// Reads a concrete `Generable` type from named property.
@@ -154,12 +158,10 @@ public struct ModelOutput: Sendable, Generable {
                            forProperty property: String) throws -> Value
     where Value: ConvertibleFromModelOutput {
     guard case let .structure(properties, _) = kind else {
-      // TODO: Throw an error instead
-      fatalError("Attempting to access a property on a non-object ModelOutput.")
+      throw DecodingError.notAStructure
     }
     guard let value = properties[property] else {
-      // TODO: Throw an error instead
-      fatalError("Property '\(property)' not found in model output.")
+      throw DecodingError.missingProperty(name: property)
     }
 
     return try Value(value)
@@ -170,8 +172,7 @@ public struct ModelOutput: Sendable, Generable {
                            forProperty property: String) throws -> Value?
     where Value: ConvertibleFromModelOutput {
     guard case let .structure(properties, _) = kind else {
-      // TODO: Throw an error instead
-      fatalError("Attempting to access a property on a non-object ModelOutput.")
+      throw DecodingError.notAStructure
     }
     guard let value = properties[property] else {
       return nil
@@ -183,11 +184,35 @@ public struct ModelOutput: Sendable, Generable {
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public extension ModelOutput {
+  /// An error that occurs when decoding a value from `ModelOutput`.
+  enum DecodingError: Error, CustomDebugStringConvertible {
+    /// A required property was not found in the `ModelOutput`.
+    case missingProperty(name: String)
+
+    /// A property was accessed on a `ModelOutput` that is not a structure.
+    case notAStructure
+
+    /// The context for a decoding error.
+    public struct Context: Sendable {
+      /// A description of the error.
+      public let debugDescription: String
+    }
+
+    public var debugDescription: String {
+      switch self {
+      case let .missingProperty(name):
+        return "Missing property: \(name)"
+      case .notAStructure:
+        return "Not a structure"
+      }
+    }
+  }
+
   /// A representation of the different types of content that can be stored in `ModelOutput`.
   ///
   /// `Kind` represents the various types of JSON-compatible data that can be held within a
   /// ``ModelOutput`` instance, including primitive types, arrays, and structured objects.
-  enum Kind: Sendable {
+  enum Kind: Sendable, CustomDebugStringConvertible {
     /// Represents a null value.
     case null
 
@@ -212,5 +237,27 @@ public extension ModelOutput {
     ///   - properties: A dictionary mapping string keys to ``ModelOutput`` values.
     ///   - orderedKeys: An array of keys that specifies the order of properties.
     case structure(properties: [String: ModelOutput], orderedKeys: [String])
+
+    public var debugDescription: String {
+      switch self {
+      case .null:
+        return "null"
+      case let .bool(value):
+        return String(describing: value)
+      case let .number(value):
+        return String(describing: value)
+      case let .string(value):
+        return #""\#(value)""#
+      case let .array(elements):
+        let descriptions = elements.map { $0.debugDescription }
+        return "[\(descriptions.joined(separator: ", "))]"
+      case let .structure(properties, orderedKeys):
+        let descriptions = orderedKeys.compactMap { key -> String? in
+          guard let value = properties[key] else { return nil }
+          return #""\#(key)": \#(value.debugDescription)"#
+        }
+        return "{\(descriptions.joined(separator: ", "))}"
+      }
+    }
   }
 }
diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index 365403709ea..a4f863b294c 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -12,14 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import FirebaseAILogic
+@testable import FirebaseAILogic
 import Testing
 
 struct GenerableTests {
-  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  @Test func initializeGenerableTypeFromModelOutput() throws {
+  @Test
+  func initializeGenerableTypeFromModelOutput() throws {
+    let addressProperties: [(String, any ConvertibleToModelOutput)] =
+      [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
+    let addressModelOutput = ModelOutput(
+      properties: addressProperties, uniquingKeysWith: { _, second in second }
+    )
     let properties: [(String, any ConvertibleToModelOutput)] =
-      [("firstName", "John"), ("lastName", "Doe"), ("age", 40)]
+      [("firstName", "John"), ("lastName", "Doe"), ("age", 40), ("address", addressModelOutput)]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
@@ -29,11 +34,142 @@ struct GenerableTests {
     #expect(person.firstName == "John")
     #expect(person.lastName == "Doe")
     #expect(person.age == 40)
+    #expect(person.address.street == "123 Main St")
+    #expect(person.address.city == "Anytown")
+    #expect(person.address.zipCode == "12345")
   }
 
-  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  @Test func convertGenerableTypeToModelOutput() throws {
-    let person = Person(firstName: "Jane", middleName: "Marie", lastName: "Smith", age: 32)
+  @Test
+  func initializeGenerableWithMissingProperty() throws {
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [("firstName", "John"), ("age", 40)]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let ModelOutput.DecodingError.missingProperty(name) {
+      #expect(name == "lastName")
+    } catch {
+      Issue.record("Threw an unexpected error: \(error)")
+    }
+  }
+
+  @Test
+  func initializeGenerableFromNonStructure() throws {
+    let modelOutput = ModelOutput("not a structure")
+
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch ModelOutput.DecodingError.notAStructure {
+      // Expected error
+    } catch {
+      Issue.record("Threw an unexpected error: \(error)")
+    }
+  }
+
+  @Test
+  func initializeGenerableWithTypeMismatch() throws {
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [("firstName", "John"), ("lastName", "Doe"), ("age", "forty")]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
+    } catch {
+      Issue.record("Threw an unexpected error: \(error)")
+    }
+  }
+
+  @Test
+  func initializeGenerableWithLossyNumericConversion() throws {
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [("firstName", "John"), ("lastName", "Doe"), ("age", 40.5)]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("40.5 does not contain Int."))
+    } catch {
+      Issue.record("Threw an unexpected error: \(error)")
+    }
+  }
+
+  @Test
+  func initializeGenerableWithExtraProperties() throws {
+    let addressProperties: [(String, any ConvertibleToModelOutput)] =
+      [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
+    let addressModelOutput = ModelOutput(
+      properties: addressProperties, uniquingKeysWith: { _, second in second }
+    )
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [
+        ("firstName", "John"),
+        ("lastName", "Doe"),
+        ("age", 40),
+        ("address", addressModelOutput),
+        ("country", "USA"),
+      ]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    let person = try Person(modelOutput)
+
+    #expect(person.firstName == "John")
+    #expect(person.lastName == "Doe")
+    #expect(person.age == 40)
+    #expect(person.address.street == "123 Main St")
+    #expect(person.address.city == "Anytown")
+    #expect(person.address.zipCode == "12345")
+  }
+
+  @Test
+  func initializeGenerableWithMissingOptionalProperty() throws {
+    let addressProperties: [(String, any ConvertibleToModelOutput)] =
+      [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
+    let addressModelOutput = ModelOutput(
+      properties: addressProperties, uniquingKeysWith: { _, second in second }
+    )
+    let properties: [(String, any ConvertibleToModelOutput)] =
+      [("firstName", "John"), ("lastName", "Doe"), ("age", 40), ("address", addressModelOutput)]
+    let modelOutput = ModelOutput(
+      properties: properties, uniquingKeysWith: { _, second in second }
+    )
+
+    let person = try Person(modelOutput)
+
+    #expect(person.firstName == "John")
+    #expect(person.lastName == "Doe")
+    #expect(person.age == 40)
+    #expect(person.middleName == nil)
+    #expect(person.address.street == "123 Main St")
+    #expect(person.address.city == "Anytown")
+    #expect(person.address.zipCode == "12345")
+  }
+
+  @Test
+  func convertGenerableTypeToModelOutput() throws {
+    let address = Address(street: "456 Oak Ave", city: "Someplace", zipCode: "54321")
+    let person = Person(
+      firstName: "Jane",
+      middleName: "Marie",
+      lastName: "Smith",
+      age: 32,
+      address: address
+    )
 
     let modelOutput = person.modelOutput
 
@@ -69,56 +205,106 @@ struct GenerableTests {
     }
     #expect(Int(age) == person.age)
     #expect(try modelOutput.value(forProperty: "age") == person.age)
-    // TODO: Implement `ModelOutput.value(_:)` and uncomment
-    // #expect(try modelOutput.value() == person)
-    #expect(orderedKeys == ["firstName", "middleName", "lastName", "age"])
+    let addressProperty: Address = try modelOutput.value(forProperty: "address")
+    #expect(addressProperty == person.address)
+    #expect(try modelOutput.value() == person)
+    #expect(orderedKeys == ["firstName", "middleName", "lastName", "age", "address"])
   }
-}
 
-// An example of the expected output from the `@FirebaseAILogic.Generable` macro.
-@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-struct Person: Equatable {
-  let firstName: String
-  let middleName: String?
-  let lastName: String
-  let age: Int
-
-  nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
-    FirebaseAILogic.JSONSchema(
-      type: Self.self,
-      properties: [
-        FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
-        FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
-        FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
-        FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
-      ]
+  @Test
+  func convertGenerableWithNilOptionalPropertyToModelOutput() throws {
+    let address = Address(street: "789 Pine Ln", city: "Nowhere", zipCode: "00000")
+    let person = Person(
+      firstName: "Jane",
+      middleName: nil,
+      lastName: "Smith",
+      age: 32,
+      address: address
     )
-  }
 
-  nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
-    var properties = [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)]()
-    addProperty(name: "firstName", value: firstName)
-    addProperty(name: "middleName", value: middleName)
-    addProperty(name: "lastName", value: lastName)
-    addProperty(name: "age", value: age)
-    return ModelOutput(
-      properties: properties,
-      uniquingKeysWith: { _, second in
-        second
-      }
-    )
-    func addProperty(name: String, value: some FirebaseAILogic.Generable) {
-      properties.append((name, value))
+    let modelOutput = person.modelOutput
+
+    guard case let .structure(properties, orderedKeys) = modelOutput.kind else {
+      Issue.record("Model output is not a structure.")
+      return
     }
-    func addProperty(name: String, value: (some FirebaseAILogic.Generable)?) {
-      if let value {
-        properties.append((name, value))
-      }
+
+    #expect(properties["middleName"] == nil)
+    #expect(orderedKeys == ["firstName", "lastName", "age", "address"])
+  }
+
+  @Test
+  func testPersonJSONSchema() throws {
+    let schema = Person.jsonSchema
+    guard case let .object(_, _, properties) = schema.kind else {
+      Issue.record("Schema kind is not an object.")
+      return
     }
+    #expect(properties.count == 5)
+
+    let firstName = try #require(properties.first { $0.name == "firstName" })
+    #expect(ObjectIdentifier(firstName.type) == ObjectIdentifier(String.self))
+    #expect(firstName.isOptional == false)
+
+    let middleName = try #require(properties.first { $0.name == "middleName" })
+    #expect(ObjectIdentifier(middleName.type) == ObjectIdentifier(String.self))
+    #expect(middleName.isOptional == true)
+
+    let lastName = try #require(properties.first { $0.name == "lastName" })
+    #expect(ObjectIdentifier(lastName.type) == ObjectIdentifier(String.self))
+    #expect(lastName.isOptional == false)
+
+    let age = try #require(properties.first { $0.name == "age" })
+    #expect(ObjectIdentifier(age.type) == ObjectIdentifier(Int.self))
+    #expect(age.isOptional == false)
+
+    let address = try #require(properties.first { $0.name == "address" })
+    #expect(ObjectIdentifier(address.type) == ObjectIdentifier(Address.self))
+    #expect(address.isOptional == false)
   }
 }
 
 #if compiler(>=6.2)
+  // An example of the expected output from the `@FirebaseAILogic.Generable` macro.
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  struct Person: Equatable {
+    let firstName: String
+    let middleName: String?
+    let lastName: String
+    let age: Int
+    let address: Address
+
+    nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
+      FirebaseAILogic.JSONSchema(
+        type: Self.self,
+        properties: [
+          FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
+          FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
+          FirebaseAILogic.JSONSchema.Property(name: "address", type: Address.self),
+        ]
+      )
+    }
+
+    nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
+      var properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = []
+      properties.append(("firstName", firstName))
+      if let middleName {
+        properties.append(("middleName", middleName))
+      }
+      properties.append(("lastName", lastName))
+      properties.append(("age", age))
+      properties.append(("address", address))
+      return ModelOutput(
+        properties: properties,
+        uniquingKeysWith: { _, second in
+          second
+        }
+      )
+    }
+  }
+
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Person: nonisolated FirebaseAILogic.Generable {
     nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
@@ -126,16 +312,135 @@ struct Person: Equatable {
       middleName = try content.value(forProperty: "middleName")
       lastName = try content.value(forProperty: "lastName")
       age = try content.value(forProperty: "age")
+      address = try content.value(forProperty: "address")
     }
   }
 #else
+  // An example of the expected output from the `@FirebaseAILogic.Generable` macro.
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  struct Person: Equatable {
+    let firstName: String
+    let middleName: String?
+    let lastName: String
+    let age: Int
+    let address: Address
+
+    static var jsonSchema: FirebaseAILogic.JSONSchema {
+      FirebaseAILogic.JSONSchema(
+        type: Self.self,
+        properties: [
+          FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
+          FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
+          FirebaseAILogic.JSONSchema.Property(name: "address", type: Address.self),
+        ]
+      )
+    }
+
+    var modelOutput: FirebaseAILogic.ModelOutput {
+      var properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = []
+      properties.append(("firstName", firstName))
+      if let middleName {
+        properties.append(("middleName", middleName))
+      }
+      properties.append(("lastName", lastName))
+      properties.append(("age", age))
+      properties.append(("address", address))
+      return ModelOutput(
+        properties: properties,
+        uniquingKeysWith: { _, second in
+          second
+        }
+      )
+    }
+  }
+
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Person: FirebaseAILogic.Generable {
-    nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
+    init(_ content: FirebaseAILogic.ModelOutput) throws {
       firstName = try content.value(forProperty: "firstName")
       middleName = try content.value(forProperty: "middleName")
       lastName = try content.value(forProperty: "lastName")
       age = try content.value(forProperty: "age")
+      address = try content.value(forProperty: "address")
+    }
+  }
+#endif
+
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+struct Address: Equatable {
+  let street: String
+  let city: String
+  let zipCode: String
+}
+
+#if compiler(>=6.2)
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  extension Address: nonisolated FirebaseAILogic.Generable {
+    nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
+      FirebaseAILogic.JSONSchema(
+        type: Self.self,
+        properties: [
+          FirebaseAILogic.JSONSchema.Property(name: "street", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "city", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "zipCode", type: String.self),
+        ]
+      )
+    }
+
+    nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
+      let properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = [
+        ("street", street),
+        ("city", city),
+        ("zipCode", zipCode),
+      ]
+      return ModelOutput(
+        properties: properties,
+        uniquingKeysWith: { _, second in
+          second
+        }
+      )
+    }
+
+    nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
+      street = try content.value(forProperty: "street")
+      city = try content.value(forProperty: "city")
+      zipCode = try content.value(forProperty: "zipCode")
+    }
+  }
+#else
+  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+  extension Address: FirebaseAILogic.Generable {
+    static var jsonSchema: FirebaseAILogic.JSONSchema {
+      FirebaseAILogic.JSONSchema(
+        type: Self.self,
+        properties: [
+          FirebaseAILogic.JSONSchema.Property(name: "street", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "city", type: String.self),
+          FirebaseAILogic.JSONSchema.Property(name: "zipCode", type: String.self),
+        ]
+      )
+    }
+
+    var modelOutput: FirebaseAILogic.ModelOutput {
+      let properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = [
+        ("street", street),
+        ("city", city),
+        ("zipCode", zipCode),
+      ]
+      return ModelOutput(
+        properties: properties,
+        uniquingKeysWith: { _, second in
+          second
+        }
+      )
+    }
+
+    init(_ content: FirebaseAILogic.ModelOutput) throws {
+      street = try content.value(forProperty: "street")
+      city = try content.value(forProperty: "city")
+      zipCode = try content.value(forProperty: "zipCode")
     }
   }
 #endif

From e0febcac249d19c96ab364c2ab12b7b39f027f68 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Wed, 26 Nov 2025 14:17:51 -0500
Subject: [PATCH 15/32] Decode `Float` and `Double` more leniently

---
 .../Sources/Types/Public/Generable/Generable.swift     | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
index cdd1fcc348f..5cd73a52dd8 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/Generable.swift
@@ -118,11 +118,10 @@ extension Float: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine if we need to use `exactly: ` or be more lenient.
-    guard case let .number(value) = content.kind, let float = Float(exactly: value) else {
+    guard case let .number(value) = content.kind else {
       throw Self.decodingFailure(content)
     }
-    self = float
+    self = Float(value)
   }
 
   public var modelOutput: ModelOutput {
@@ -137,11 +136,10 @@ extension Double: Generable {
   }
 
   public init(_ content: ModelOutput) throws {
-    // TODO: Determine if we need to use `exactly: ` or be more lenient.
-    guard case let .number(value) = content.kind, let double = Double(exactly: value) else {
+    guard case let .number(value) = content.kind else {
       throw Self.decodingFailure(content)
     }
-    self = double
+    self = value
   }
 
   public var modelOutput: ModelOutput {

From 52b4e17a4f43619a6de14420b1d349411ef41381 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Wed, 26 Nov 2025 14:18:55 -0500
Subject: [PATCH 16/32] Update error messages in `ModelOutput.value(...)`
 methods

# Conflicts:
#	FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
---
 .../Types/Public/Generable/ModelOutput.swift       | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index da3c09cc452..22a9d1f93de 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -158,10 +158,20 @@ public struct ModelOutput: Sendable, Generable, CustomDebugStringConvertible {
                            forProperty property: String) throws -> Value
     where Value: ConvertibleFromModelOutput {
     guard case let .structure(properties, _) = kind else {
-      throw DecodingError.notAStructure
+      throw GenerativeModel.GenerationError.decodingFailure(
+        GenerativeModel.GenerationError.Context(debugDescription: """
+        \(Self.self) does not contain an object.
+        Content: \(self.kind)
+        """)
+      )
     }
     guard let value = properties[property] else {
-      throw DecodingError.missingProperty(name: property)
+      throw GenerativeModel.GenerationError.decodingFailure(
+        GenerativeModel.GenerationError.Context(debugDescription: """
+        \(Self.self) does not contain a property '\(property)'.
+        Content: \(self)
+        """)
+      )
     }
 
     return try Value(value)

From 4c113d093e84ea04a9279525ddb2a958cd75abae Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Wed, 26 Nov 2025 15:07:17 -0500
Subject: [PATCH 17/32] Replace `ModelOutput.DecodingError` with
 `GenerativeModel.GenerationError`

---
 .../Types/Public/Generable/ModelOutput.swift  |  33 +--
 .../Unit/Types/Generable/GenerableTests.swift | 259 +++++++-----------
 2 files changed, 104 insertions(+), 188 deletions(-)

diff --git a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
index 22a9d1f93de..40be1ba638e 100644
--- a/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
+++ b/FirebaseAI/Sources/Types/Public/Generable/ModelOutput.swift
@@ -161,7 +161,7 @@ public struct ModelOutput: Sendable, Generable, CustomDebugStringConvertible {
       throw GenerativeModel.GenerationError.decodingFailure(
         GenerativeModel.GenerationError.Context(debugDescription: """
         \(Self.self) does not contain an object.
-        Content: \(self.kind)
+        Content: \(kind)
         """)
       )
     }
@@ -182,7 +182,12 @@ public struct ModelOutput: Sendable, Generable, CustomDebugStringConvertible {
                            forProperty property: String) throws -> Value?
     where Value: ConvertibleFromModelOutput {
     guard case let .structure(properties, _) = kind else {
-      throw DecodingError.notAStructure
+      throw GenerativeModel.GenerationError.decodingFailure(
+        GenerativeModel.GenerationError.Context(debugDescription: """
+        \(Self.self) does not contain an object.
+        Content: \(kind)
+        """)
+      )
     }
     guard let value = properties[property] else {
       return nil
@@ -194,30 +199,6 @@ public struct ModelOutput: Sendable, Generable, CustomDebugStringConvertible {
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 public extension ModelOutput {
-  /// An error that occurs when decoding a value from `ModelOutput`.
-  enum DecodingError: Error, CustomDebugStringConvertible {
-    /// A required property was not found in the `ModelOutput`.
-    case missingProperty(name: String)
-
-    /// A property was accessed on a `ModelOutput` that is not a structure.
-    case notAStructure
-
-    /// The context for a decoding error.
-    public struct Context: Sendable {
-      /// A description of the error.
-      public let debugDescription: String
-    }
-
-    public var debugDescription: String {
-      switch self {
-      case let .missingProperty(name):
-        return "Missing property: \(name)"
-      case .notAStructure:
-        return "Not a structure"
-      }
-    }
-  }
-
   /// A representation of the different types of content that can be stored in `ModelOutput`.
   ///
   /// `Kind` represents the various types of JSON-compatible data that can be held within a
diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index a4f863b294c..d8768ad7f25 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -40,53 +40,56 @@ struct GenerableTests {
   }
 
   @Test
-  func initializeGenerableWithMissingProperty() throws {
+  func initializeGenerableWithMissingPropertyThrows() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("age", 40)]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let ModelOutput.DecodingError.missingProperty(name) {
-      #expect(name == "lastName")
-    } catch {
+    let error = try #require(throws: GenerativeModel.GenerationError.self) {
+      try Person(modelOutput)
+    }
+
+    guard case let .decodingFailure(context) = error else {
       Issue.record("Threw an unexpected error: \(error)")
+      return
     }
+    #expect(context.debugDescription.contains("lastName"))
   }
 
   @Test
-  func initializeGenerableFromNonStructure() throws {
+  func initializeGenerableFromNonStructureThrows() throws {
     let modelOutput = ModelOutput("not a structure")
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch ModelOutput.DecodingError.notAStructure {
-      // Expected error
-    } catch {
+    let error = try #require(throws: GenerativeModel.GenerationError.self) {
+      try Person(modelOutput)
+    }
+
+    guard case let .decodingFailure(context) = error else {
       Issue.record("Threw an unexpected error: \(error)")
+      return
     }
+    #expect(context.debugDescription.contains("does not contain an object"))
   }
 
   @Test
-  func initializeGenerableWithTypeMismatch() throws {
+  func initializeGenerableWithTypeMismatchThrows() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("lastName", "Doe"), ("age", "forty")]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
-    } catch {
+    let error = try #require(throws: GenerativeModel.GenerationError.self) {
+      try Person(modelOutput)
+    }
+
+    guard case let .decodingFailure(context) = error else {
       Issue.record("Threw an unexpected error: \(error)")
+      return
     }
+    #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
   }
 
   @Test
@@ -97,14 +100,15 @@ struct GenerableTests {
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("40.5 does not contain Int."))
-    } catch {
+    let error = try #require(throws: GenerativeModel.GenerationError.self) {
+      try Person(modelOutput)
+    }
+
+    guard case let .decodingFailure(context) = error else {
       Issue.record("Threw an unexpected error: \(error)")
+      return
     }
+    #expect(context.debugDescription.contains("40.5 does not contain Int."))
   }
 
   @Test
@@ -228,7 +232,6 @@ struct GenerableTests {
       Issue.record("Model output is not a structure.")
       return
     }
-
     #expect(properties["middleName"] == nil)
     #expect(orderedKeys == ["firstName", "lastName", "age", "address"])
   }
@@ -236,75 +239,72 @@ struct GenerableTests {
   @Test
   func testPersonJSONSchema() throws {
     let schema = Person.jsonSchema
+
     guard case let .object(_, _, properties) = schema.kind else {
       Issue.record("Schema kind is not an object.")
       return
     }
-    #expect(properties.count == 5)
 
+    #expect(properties.count == 5)
     let firstName = try #require(properties.first { $0.name == "firstName" })
     #expect(ObjectIdentifier(firstName.type) == ObjectIdentifier(String.self))
     #expect(firstName.isOptional == false)
-
     let middleName = try #require(properties.first { $0.name == "middleName" })
     #expect(ObjectIdentifier(middleName.type) == ObjectIdentifier(String.self))
     #expect(middleName.isOptional == true)
-
     let lastName = try #require(properties.first { $0.name == "lastName" })
     #expect(ObjectIdentifier(lastName.type) == ObjectIdentifier(String.self))
     #expect(lastName.isOptional == false)
-
     let age = try #require(properties.first { $0.name == "age" })
     #expect(ObjectIdentifier(age.type) == ObjectIdentifier(Int.self))
     #expect(age.isOptional == false)
-
     let address = try #require(properties.first { $0.name == "address" })
     #expect(ObjectIdentifier(address.type) == ObjectIdentifier(Address.self))
     #expect(address.isOptional == false)
   }
 }
 
-#if compiler(>=6.2)
-  // An example of the expected output from the `@FirebaseAILogic.Generable` macro.
-  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  struct Person: Equatable {
-    let firstName: String
-    let middleName: String?
-    let lastName: String
-    let age: Int
-    let address: Address
-
-    nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
-      FirebaseAILogic.JSONSchema(
-        type: Self.self,
-        properties: [
-          FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
-          FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
-          FirebaseAILogic.JSONSchema.Property(name: "address", type: Address.self),
-        ]
-      )
-    }
+// An example of the expected output from the `@FirebaseAILogic.Generable` macro.
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+struct Person: Equatable {
+  let firstName: String
+  let middleName: String?
+  let lastName: String
+  let age: Int
+  let address: Address
+
+  nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
+    FirebaseAILogic.JSONSchema(
+      type: Self.self,
+      properties: [
+        FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
+        FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
+        FirebaseAILogic.JSONSchema.Property(name: "address", type: Address.self),
+      ]
+    )
+  }
 
-    nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
-      var properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = []
-      properties.append(("firstName", firstName))
-      if let middleName {
-        properties.append(("middleName", middleName))
-      }
-      properties.append(("lastName", lastName))
-      properties.append(("age", age))
-      properties.append(("address", address))
-      return ModelOutput(
-        properties: properties,
-        uniquingKeysWith: { _, second in
-          second
-        }
-      )
+  nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
+    var properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = []
+    properties.append(("firstName", firstName))
+    if let middleName {
+      properties.append(("middleName", middleName))
     }
+    properties.append(("lastName", lastName))
+    properties.append(("age", age))
+    properties.append(("address", address))
+    return ModelOutput(
+      properties: properties,
+      uniquingKeysWith: { _, second in
+        second
+      }
+    )
   }
+}
 
+#if compiler(>=6.2)
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Person: nonisolated FirebaseAILogic.Generable {
     nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
@@ -316,46 +316,6 @@ struct GenerableTests {
     }
   }
 #else
-  // An example of the expected output from the `@FirebaseAILogic.Generable` macro.
-  @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
-  struct Person: Equatable {
-    let firstName: String
-    let middleName: String?
-    let lastName: String
-    let age: Int
-    let address: Address
-
-    static var jsonSchema: FirebaseAILogic.JSONSchema {
-      FirebaseAILogic.JSONSchema(
-        type: Self.self,
-        properties: [
-          FirebaseAILogic.JSONSchema.Property(name: "firstName", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "middleName", type: String?.self),
-          FirebaseAILogic.JSONSchema.Property(name: "lastName", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "age", type: Int.self),
-          FirebaseAILogic.JSONSchema.Property(name: "address", type: Address.self),
-        ]
-      )
-    }
-
-    var modelOutput: FirebaseAILogic.ModelOutput {
-      var properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = []
-      properties.append(("firstName", firstName))
-      if let middleName {
-        properties.append(("middleName", middleName))
-      }
-      properties.append(("lastName", lastName))
-      properties.append(("age", age))
-      properties.append(("address", address))
-      return ModelOutput(
-        properties: properties,
-        uniquingKeysWith: { _, second in
-          second
-        }
-      )
-    }
-  }
-
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Person: FirebaseAILogic.Generable {
     init(_ content: FirebaseAILogic.ModelOutput) throws {
@@ -366,43 +326,43 @@ struct GenerableTests {
       address = try content.value(forProperty: "address")
     }
   }
-#endif
+#endif // compiler(>=6.2)
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 struct Address: Equatable {
   let street: String
   let city: String
   let zipCode: String
+
+  nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
+    FirebaseAILogic.JSONSchema(
+      type: Self.self,
+      properties: [
+        FirebaseAILogic.JSONSchema.Property(name: "street", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "city", type: String.self),
+        FirebaseAILogic.JSONSchema.Property(name: "zipCode", type: String.self),
+      ]
+    )
+  }
+
+  nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
+    let properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = [
+      ("street", street),
+      ("city", city),
+      ("zipCode", zipCode),
+    ]
+    return ModelOutput(
+      properties: properties,
+      uniquingKeysWith: { _, second in
+        second
+      }
+    )
+  }
 }
 
 #if compiler(>=6.2)
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Address: nonisolated FirebaseAILogic.Generable {
-    nonisolated static var jsonSchema: FirebaseAILogic.JSONSchema {
-      FirebaseAILogic.JSONSchema(
-        type: Self.self,
-        properties: [
-          FirebaseAILogic.JSONSchema.Property(name: "street", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "city", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "zipCode", type: String.self),
-        ]
-      )
-    }
-
-    nonisolated var modelOutput: FirebaseAILogic.ModelOutput {
-      let properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = [
-        ("street", street),
-        ("city", city),
-        ("zipCode", zipCode),
-      ]
-      return ModelOutput(
-        properties: properties,
-        uniquingKeysWith: { _, second in
-          second
-        }
-      )
-    }
-
     nonisolated init(_ content: FirebaseAILogic.ModelOutput) throws {
       street = try content.value(forProperty: "street")
       city = try content.value(forProperty: "city")
@@ -412,35 +372,10 @@ struct Address: Equatable {
 #else
   @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
   extension Address: FirebaseAILogic.Generable {
-    static var jsonSchema: FirebaseAILogic.JSONSchema {
-      FirebaseAILogic.JSONSchema(
-        type: Self.self,
-        properties: [
-          FirebaseAILogic.JSONSchema.Property(name: "street", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "city", type: String.self),
-          FirebaseAILogic.JSONSchema.Property(name: "zipCode", type: String.self),
-        ]
-      )
-    }
-
-    var modelOutput: FirebaseAILogic.ModelOutput {
-      let properties: [(name: String, value: any FirebaseAILogic.ConvertibleToModelOutput)] = [
-        ("street", street),
-        ("city", city),
-        ("zipCode", zipCode),
-      ]
-      return ModelOutput(
-        properties: properties,
-        uniquingKeysWith: { _, second in
-          second
-        }
-      )
-    }
-
     init(_ content: FirebaseAILogic.ModelOutput) throws {
       street = try content.value(forProperty: "street")
       city = try content.value(forProperty: "city")
       zipCode = try content.value(forProperty: "zipCode")
     }
   }
-#endif
+#endif // compiler(>=6.2)

From 65d786004cd1bd0d4350a927505a6aeebac50a09 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 10:45:17 -0500
Subject: [PATCH 18/32] Fix `GenerableTests` on Xcode 16.2

---
 .../Unit/Types/Generable/GenerableTests.swift | 52 +++++++++----------
 1 file changed, 24 insertions(+), 28 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index d8768ad7f25..aa2a3188fd3 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -47,30 +47,28 @@ struct GenerableTests {
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    let error = try #require(throws: GenerativeModel.GenerationError.self) {
-      try Person(modelOutput)
-    }
-
-    guard case let .decodingFailure(context) = error else {
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("lastName"))
+    } catch {
       Issue.record("Threw an unexpected error: \(error)")
-      return
     }
-    #expect(context.debugDescription.contains("lastName"))
   }
 
   @Test
   func initializeGenerableFromNonStructureThrows() throws {
     let modelOutput = ModelOutput("not a structure")
 
-    let error = try #require(throws: GenerativeModel.GenerationError.self) {
-      try Person(modelOutput)
-    }
-
-    guard case let .decodingFailure(context) = error else {
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("does not contain an object"))
+    } catch {
       Issue.record("Threw an unexpected error: \(error)")
-      return
     }
-    #expect(context.debugDescription.contains("does not contain an object"))
   }
 
   @Test
@@ -81,15 +79,14 @@ struct GenerableTests {
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    let error = try #require(throws: GenerativeModel.GenerationError.self) {
-      try Person(modelOutput)
-    }
-
-    guard case let .decodingFailure(context) = error else {
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
+    } catch {
       Issue.record("Threw an unexpected error: \(error)")
-      return
     }
-    #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
   }
 
   @Test
@@ -100,15 +97,14 @@ struct GenerableTests {
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    let error = try #require(throws: GenerativeModel.GenerationError.self) {
-      try Person(modelOutput)
-    }
-
-    guard case let .decodingFailure(context) = error else {
+    do {
+      _ = try Person(modelOutput)
+      Issue.record("Did not throw an error.")
+    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
+      #expect(context.debugDescription.contains("40.5 does not contain Int."))
+    } catch {
       Issue.record("Threw an unexpected error: \(error)")
-      return
     }
-    #expect(context.debugDescription.contains("40.5 does not contain Int."))
   }
 
   @Test

From 33c2a1e289b658d0ba399ee08b1e989abb3fd645 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 11:00:44 -0500
Subject: [PATCH 19/32] Add `available(iOS 15.0, macOS 12.0, ..., *)` to
 `GenerableTests`

---
 FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift | 1 +
 1 file changed, 1 insertion(+)

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index aa2a3188fd3..6ee0f90f26f 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -15,6 +15,7 @@
 @testable import FirebaseAILogic
 import Testing
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 struct GenerableTests {
   @Test
   func initializeGenerableTypeFromModelOutput() throws {

From ad396d5feb4edc9dbccf03cf3fa69a15e4c6eb0d Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 11:24:49 -0500
Subject: [PATCH 20/32] Try forcing Swift 6 mode on macOS 14 / Xcode 16.2

---
 .github/workflows/firebaseai.yml                           | 4 +++-
 FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift | 1 -
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/firebaseai.yml b/.github/workflows/firebaseai.yml
index 1f3cde4a26a..6aa1adc666f 100644
--- a/.github/workflows/firebaseai.yml
+++ b/.github/workflows/firebaseai.yml
@@ -78,7 +78,9 @@ jobs:
     with:
       product: ${{  matrix.product }}
       supports_swift6: true
-      setup_command: scripts/update_vertexai_responses.sh
+      setup_command: |
+        scripts/update_vertexai_responses.sh; \
+        sed -i "" "s/s.swift_version[[:space:]]*=[[:space:]]*'5.9'/s.swift_version = '6.0'/" ${{  matrix.product }}.podspec
 
   quickstart:
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'
diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index 6ee0f90f26f..aa2a3188fd3 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -15,7 +15,6 @@
 @testable import FirebaseAILogic
 import Testing
 
-@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 struct GenerableTests {
   @Test
   func initializeGenerableTypeFromModelOutput() throws {

From 99229572fae29957ac87dd40ddf24cd80882e98c Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 17:02:26 -0500
Subject: [PATCH 21/32] Rewrite `GenerableTests` from Swift Testing to XCTest

---
 .../Unit/Types/Generable/GenerableTests.swift | 206 +++++++++---------
 1 file changed, 98 insertions(+), 108 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index aa2a3188fd3..97a38c20937 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -13,11 +13,10 @@
 // limitations under the License.
 
 @testable import FirebaseAILogic
-import Testing
+import XCTest
 
-struct GenerableTests {
-  @Test
-  func initializeGenerableTypeFromModelOutput() throws {
+final class GenerableTests: XCTestCase {
+  func testInitializeGenerableTypeFromModelOutput() throws {
     let addressProperties: [(String, any ConvertibleToModelOutput)] =
       [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
     let addressModelOutput = ModelOutput(
@@ -31,84 +30,79 @@ struct GenerableTests {
 
     let person = try Person(modelOutput)
 
-    #expect(person.firstName == "John")
-    #expect(person.lastName == "Doe")
-    #expect(person.age == 40)
-    #expect(person.address.street == "123 Main St")
-    #expect(person.address.city == "Anytown")
-    #expect(person.address.zipCode == "12345")
+    XCTAssertEqual(person.firstName, "John")
+    XCTAssertEqual(person.lastName, "Doe")
+    XCTAssertEqual(person.age, 40)
+    XCTAssertEqual(person.address.street, "123 Main St")
+    XCTAssertEqual(person.address.city, "Anytown")
+    XCTAssertEqual(person.address.zipCode, "12345")
   }
 
-  @Test
-  func initializeGenerableWithMissingPropertyThrows() throws {
+  func testInitializeGenerableWithMissingPropertyThrows() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("age", 40)]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("lastName"))
-    } catch {
-      Issue.record("Threw an unexpected error: \(error)")
+    XCTAssertThrowsError(try Person(modelOutput)) { error in
+      guard let error = error as? GenerativeModel.GenerationError,
+            case let .decodingFailure(context) = error else {
+        XCTFail("Threw an unexpected error: \(error)")
+        return
+      }
+      XCTAssertContains(context.debugDescription, "lastName")
     }
   }
 
-  @Test
-  func initializeGenerableFromNonStructureThrows() throws {
+  func testInitializeGenerableFromNonStructureThrows() throws {
     let modelOutput = ModelOutput("not a structure")
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("does not contain an object"))
-    } catch {
-      Issue.record("Threw an unexpected error: \(error)")
+    XCTAssertThrowsError(try Person(modelOutput)) { error in
+      guard let error = error as? GenerativeModel.GenerationError,
+            case let .decodingFailure(context) = error else {
+        XCTFail("Threw an unexpected error: \(error)")
+        return
+      }
+      XCTAssertContains(context.debugDescription, "does not contain an object")
     }
   }
 
-  @Test
-  func initializeGenerableWithTypeMismatchThrows() throws {
+  func testInitializeGenerableWithTypeMismatchThrows() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("lastName", "Doe"), ("age", "forty")]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("\"forty\" does not contain Int"))
-    } catch {
-      Issue.record("Threw an unexpected error: \(error)")
+    XCTAssertThrowsError(try Person(modelOutput)) { error in
+      guard let error = error as? GenerativeModel.GenerationError,
+            case let .decodingFailure(context) = error else {
+        XCTFail("Threw an unexpected error: \(error)")
+        return
+      }
+      XCTAssertContains(context.debugDescription, "\"forty\" does not contain Int")
     }
   }
 
-  @Test
-  func initializeGenerableWithLossyNumericConversion() throws {
+  func testInitializeGenerableWithLossyNumericConversion() throws {
     let properties: [(String, any ConvertibleToModelOutput)] =
       [("firstName", "John"), ("lastName", "Doe"), ("age", 40.5)]
     let modelOutput = ModelOutput(
       properties: properties, uniquingKeysWith: { _, second in second }
     )
 
-    do {
-      _ = try Person(modelOutput)
-      Issue.record("Did not throw an error.")
-    } catch let GenerativeModel.GenerationError.decodingFailure(context) {
-      #expect(context.debugDescription.contains("40.5 does not contain Int."))
-    } catch {
-      Issue.record("Threw an unexpected error: \(error)")
+    XCTAssertThrowsError(try Person(modelOutput)) { error in
+      guard let error = error as? GenerativeModel.GenerationError,
+            case let .decodingFailure(context) = error else {
+        XCTFail("Threw an unexpected error: \(error)")
+        return
+      }
+      XCTAssertContains(context.debugDescription, "40.5 does not contain Int.")
     }
   }
 
-  @Test
-  func initializeGenerableWithExtraProperties() throws {
+  func testInitializeGenerableWithExtraProperties() throws {
     let addressProperties: [(String, any ConvertibleToModelOutput)] =
       [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
     let addressModelOutput = ModelOutput(
@@ -128,16 +122,15 @@ struct GenerableTests {
 
     let person = try Person(modelOutput)
 
-    #expect(person.firstName == "John")
-    #expect(person.lastName == "Doe")
-    #expect(person.age == 40)
-    #expect(person.address.street == "123 Main St")
-    #expect(person.address.city == "Anytown")
-    #expect(person.address.zipCode == "12345")
+    XCTAssertEqual(person.firstName, "John")
+    XCTAssertEqual(person.lastName, "Doe")
+    XCTAssertEqual(person.age, 40)
+    XCTAssertEqual(person.address.street, "123 Main St")
+    XCTAssertEqual(person.address.city, "Anytown")
+    XCTAssertEqual(person.address.zipCode, "12345")
   }
 
-  @Test
-  func initializeGenerableWithMissingOptionalProperty() throws {
+  func testInitializeGenerableWithMissingOptionalProperty() throws {
     let addressProperties: [(String, any ConvertibleToModelOutput)] =
       [("street", "123 Main St"), ("city", "Anytown"), ("zipCode", "12345")]
     let addressModelOutput = ModelOutput(
@@ -151,17 +144,16 @@ struct GenerableTests {
 
     let person = try Person(modelOutput)
 
-    #expect(person.firstName == "John")
-    #expect(person.lastName == "Doe")
-    #expect(person.age == 40)
-    #expect(person.middleName == nil)
-    #expect(person.address.street == "123 Main St")
-    #expect(person.address.city == "Anytown")
-    #expect(person.address.zipCode == "12345")
+    XCTAssertEqual(person.firstName, "John")
+    XCTAssertEqual(person.lastName, "Doe")
+    XCTAssertEqual(person.age, 40)
+    XCTAssertNil(person.middleName)
+    XCTAssertEqual(person.address.street, "123 Main St")
+    XCTAssertEqual(person.address.city, "Anytown")
+    XCTAssertEqual(person.address.zipCode, "12345")
   }
 
-  @Test
-  func convertGenerableTypeToModelOutput() throws {
+  func testConvertGenerableTypeToModelOutput() throws {
     let address = Address(street: "456 Oak Ave", city: "Someplace", zipCode: "54321")
     let person = Person(
       firstName: "Jane",
@@ -174,45 +166,44 @@ struct GenerableTests {
     let modelOutput = person.modelOutput
 
     guard case let .structure(properties, orderedKeys) = modelOutput.kind else {
-      Issue.record("Model output is not a structure.")
+      XCTFail("Model output is not a structure.")
       return
     }
-    let firstNameProperty = try #require(properties["firstName"])
+    let firstNameProperty = try XCTUnwrap(properties["firstName"])
     guard case let .string(firstName) = firstNameProperty.kind else {
-      Issue.record("The 'firstName' property is not a string: \(firstNameProperty.kind)")
+      XCTFail("The 'firstName' property is not a string: \(firstNameProperty.kind)")
       return
     }
-    #expect(firstName == person.firstName)
-    #expect(try modelOutput.value(forProperty: "firstName") == person.firstName)
-    let middleNameProperty = try #require(properties["middleName"])
+    XCTAssertEqual(firstName, person.firstName)
+    XCTAssertEqual(try modelOutput.value(forProperty: "firstName"), person.firstName)
+    let middleNameProperty = try XCTUnwrap(properties["middleName"])
     guard case let .string(middleName) = middleNameProperty.kind else {
-      Issue.record("The 'middleName' property is not a string: \(middleNameProperty.kind)")
+      XCTFail("The 'middleName' property is not a string: \(middleNameProperty.kind)")
       return
     }
-    #expect(middleName == person.middleName)
-    #expect(try modelOutput.value(forProperty: "middleName") == person.middleName)
-    let lastNameProperty = try #require(properties["lastName"])
+    XCTAssertEqual(middleName, person.middleName)
+    XCTAssertEqual(try modelOutput.value(forProperty: "middleName"), person.middleName)
+    let lastNameProperty = try XCTUnwrap(properties["lastName"])
     guard case let .string(lastName) = lastNameProperty.kind else {
-      Issue.record("The 'lastName' property is not a string: \(lastNameProperty.kind)")
+      XCTFail("The 'lastName' property is not a string: \(lastNameProperty.kind)")
       return
     }
-    #expect(lastName == person.lastName)
-    #expect(try modelOutput.value(forProperty: "lastName") == person.lastName)
-    let ageProperty = try #require(properties["age"])
+    XCTAssertEqual(lastName, person.lastName)
+    XCTAssertEqual(try modelOutput.value(forProperty: "lastName"), person.lastName)
+    let ageProperty = try XCTUnwrap(properties["age"])
     guard case let .number(age) = ageProperty.kind else {
-      Issue.record("The 'age' property is not a number: \(ageProperty.kind)")
+      XCTFail("The 'age' property is not a number: \(ageProperty.kind)")
       return
     }
-    #expect(Int(age) == person.age)
-    #expect(try modelOutput.value(forProperty: "age") == person.age)
+    XCTAssertEqual(Int(age), person.age)
+    XCTAssertEqual(try modelOutput.value(forProperty: "age"), person.age)
     let addressProperty: Address = try modelOutput.value(forProperty: "address")
-    #expect(addressProperty == person.address)
-    #expect(try modelOutput.value() == person)
-    #expect(orderedKeys == ["firstName", "middleName", "lastName", "age", "address"])
+    XCTAssertEqual(addressProperty, person.address)
+    XCTAssertEqual(try modelOutput.value(), person)
+    XCTAssertEqual(orderedKeys, ["firstName", "middleName", "lastName", "age", "address"])
   }
 
-  @Test
-  func convertGenerableWithNilOptionalPropertyToModelOutput() throws {
+  func testConvertGenerableWithNilOptionalPropertyToModelOutput() throws {
     let address = Address(street: "789 Pine Ln", city: "Nowhere", zipCode: "00000")
     let person = Person(
       firstName: "Jane",
@@ -225,38 +216,37 @@ struct GenerableTests {
     let modelOutput = person.modelOutput
 
     guard case let .structure(properties, orderedKeys) = modelOutput.kind else {
-      Issue.record("Model output is not a structure.")
+      XCTFail("Model output is not a structure.")
       return
     }
-    #expect(properties["middleName"] == nil)
-    #expect(orderedKeys == ["firstName", "lastName", "age", "address"])
+    XCTAssertNil(properties["middleName"])
+    XCTAssertEqual(orderedKeys, ["firstName", "lastName", "age", "address"])
   }
 
-  @Test
   func testPersonJSONSchema() throws {
     let schema = Person.jsonSchema
 
     guard case let .object(_, _, properties) = schema.kind else {
-      Issue.record("Schema kind is not an object.")
+      XCTFail("Schema kind is not an object.")
       return
     }
 
-    #expect(properties.count == 5)
-    let firstName = try #require(properties.first { $0.name == "firstName" })
-    #expect(ObjectIdentifier(firstName.type) == ObjectIdentifier(String.self))
-    #expect(firstName.isOptional == false)
-    let middleName = try #require(properties.first { $0.name == "middleName" })
-    #expect(ObjectIdentifier(middleName.type) == ObjectIdentifier(String.self))
-    #expect(middleName.isOptional == true)
-    let lastName = try #require(properties.first { $0.name == "lastName" })
-    #expect(ObjectIdentifier(lastName.type) == ObjectIdentifier(String.self))
-    #expect(lastName.isOptional == false)
-    let age = try #require(properties.first { $0.name == "age" })
-    #expect(ObjectIdentifier(age.type) == ObjectIdentifier(Int.self))
-    #expect(age.isOptional == false)
-    let address = try #require(properties.first { $0.name == "address" })
-    #expect(ObjectIdentifier(address.type) == ObjectIdentifier(Address.self))
-    #expect(address.isOptional == false)
+    XCTAssertEqual(properties.count, 5)
+    let firstName = try XCTUnwrap(properties.first { $0.name == "firstName" })
+    XCTAssert(firstName.type == String.self)
+    XCTAssertFalse(firstName.isOptional)
+    let middleName = try XCTUnwrap(properties.first { $0.name == "middleName" })
+    XCTAssert(middleName.type == String.self)
+    XCTAssertTrue(middleName.isOptional)
+    let lastName = try XCTUnwrap(properties.first { $0.name == "lastName" })
+    XCTAssert(lastName.type == String.self)
+    XCTAssertFalse(lastName.isOptional)
+    let age = try XCTUnwrap(properties.first { $0.name == "age" })
+    XCTAssert(age.type == Int.self)
+    XCTAssertFalse(age.isOptional)
+    let address = try XCTUnwrap(properties.first { $0.name == "address" })
+    XCTAssert(address.type == Address.self)
+    XCTAssertFalse(address.isOptional)
   }
 }
 

From bfb5bf43ab2436937366bee74ca4a188f7d545c2 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 17:03:42 -0500
Subject: [PATCH 22/32] Add `available(iOS 15.0, macOS 12.0, ..., *)`
 annotation

---
 FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift | 1 +
 1 file changed, 1 insertion(+)

diff --git a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
index 97a38c20937..dd9ffb9cf99 100644
--- a/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
+++ b/FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
@@ -15,6 +15,7 @@
 @testable import FirebaseAILogic
 import XCTest
 
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 final class GenerableTests: XCTestCase {
   func testInitializeGenerableTypeFromModelOutput() throws {
     let addressProperties: [(String, any ConvertibleToModelOutput)] =

From b81c1549ed8be87a99c338ef34cf2ec165a01bdf Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 17:31:03 -0500
Subject: [PATCH 23/32] Add `FirebaseAILogicMacros` SPM target with placeholder
 macro

---
 .../Macros/FirebaseAILogicPlugin.swift        | 23 +++++++
 .../Sources/Macros/StringifyMacro.swift       | 37 +++++++++++
 .../Unit/Macros/GenerableMacroTests.swift     | 63 +++++++++++++++++++
 FirebaseAILogic.podspec                       |  4 ++
 Package.swift                                 | 18 +++++-
 5 files changed, 144 insertions(+), 1 deletion(-)
 create mode 100644 FirebaseAI/Sources/Macros/FirebaseAILogicPlugin.swift
 create mode 100644 FirebaseAI/Sources/Macros/StringifyMacro.swift
 create mode 100644 FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift

diff --git a/FirebaseAI/Sources/Macros/FirebaseAILogicPlugin.swift b/FirebaseAI/Sources/Macros/FirebaseAILogicPlugin.swift
new file mode 100644
index 00000000000..104736c6fd2
--- /dev/null
+++ b/FirebaseAI/Sources/Macros/FirebaseAILogicPlugin.swift
@@ -0,0 +1,23 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import SwiftCompilerPlugin
+import SwiftSyntaxMacros
+
+@main
+struct FirebaseAILogicPlugin: CompilerPlugin {
+  let providingMacros: [Macro.Type] = [
+    StringifyMacro.self,
+  ]
+}
diff --git a/FirebaseAI/Sources/Macros/StringifyMacro.swift b/FirebaseAI/Sources/Macros/StringifyMacro.swift
new file mode 100644
index 00000000000..2f18067b6ae
--- /dev/null
+++ b/FirebaseAI/Sources/Macros/StringifyMacro.swift
@@ -0,0 +1,37 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import SwiftSyntax
+import SwiftSyntaxBuilder
+import SwiftSyntaxMacros
+
+/// Implementation of the `stringify` macro, which takes an expression
+/// of any type and produces a tuple containing the value of that expression
+/// and the source code that produced the value. For example
+///
+///     #stringify(x + y)
+///
+///  will expand to
+///
+///     (x + y, "x + y")
+public struct StringifyMacro: ExpressionMacro {
+  public static func expansion(of node: some FreestandingMacroExpansionSyntax,
+                               in context: some MacroExpansionContext) -> ExprSyntax {
+    guard let argument = node.arguments.first?.expression else {
+      fatalError("compiler bug: the macro does not have any arguments")
+    }
+
+    return "(\(argument), \(literal: argument.description))"
+  }
+}
diff --git a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
new file mode 100644
index 00000000000..55aa4ce4591
--- /dev/null
+++ b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
@@ -0,0 +1,63 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import SwiftSyntax
+import SwiftSyntaxBuilder
+import SwiftSyntaxMacros
+import SwiftSyntaxMacrosTestSupport
+import XCTest
+
+// Macro implementations build for the host, so the corresponding module is not available when
+// cross-compiling. Cross-compiled tests may still make use of the macro itself in end-to-end tests.
+#if canImport(FirebaseAILogicMacros)
+  import FirebaseAILogicMacros
+#endif
+
+final class GenerableMacroTests: XCTestCase {
+  #if canImport(FirebaseAILogicMacros)
+    let testMacros: [String: Macro.Type] = [
+      "stringify": StringifyMacro.self,
+    ]
+  #else
+    let testMacros = [String: Macro.Type]()
+
+    override func setUpWithError() throws {
+      throw XCTSkip("Macros are only supported when running tests for the host platform.")
+    }
+  #endif // canImport(FirebaseAILogicMacros)
+
+  func testMacro() throws {
+    assertMacroExpansion(
+      """
+      #stringify(a + b)
+      """,
+      expandedSource: """
+      (a + b, "a + b")
+      """,
+      macros: testMacros
+    )
+  }
+
+  func testMacroWithStringLiteral() throws {
+    assertMacroExpansion(
+      #"""
+      #stringify("Hello, \(name)")
+      """#,
+      expandedSource: #"""
+      ("Hello, \(name)", #""Hello, \(name)""#)
+      """#,
+      macros: testMacros
+    )
+  }
+}
diff --git a/FirebaseAILogic.podspec b/FirebaseAILogic.podspec
index 58638c2737f..c9f535ae4b3 100644
--- a/FirebaseAILogic.podspec
+++ b/FirebaseAILogic.podspec
@@ -34,6 +34,9 @@ Build AI-powered apps and features with the Gemini API using the Firebase AI Log
   s.source_files = [
     'FirebaseAI/Sources/**/*.swift',
   ]
+  s.exclude_files = [
+    'FirebaseAI/Sources/Macros',
+  ]
 
   s.swift_version = '6.0'
 
@@ -60,6 +63,7 @@ Build AI-powered apps and features with the Gemini API using the Firebase AI Log
       unit_tests_dir + '**/*.swift',
     ]
     unit_tests.exclude_files = [
+      unit_tests_dir + 'Macros/**/*.swift',
       unit_tests_dir + 'Snippets/**/*.swift',
     ]
     unit_tests.resources = [
diff --git a/Package.swift b/Package.swift
index 41afc02d1b4..11f04b728de 100644
--- a/Package.swift
+++ b/Package.swift
@@ -16,6 +16,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+import CompilerPluginSupport
 import PackageDescription
 
 let firebaseVersion = "12.7.0"
@@ -176,6 +177,7 @@ let package = Package(
     ),
     .package(url: "https://github.com/google/app-check.git",
              "11.0.1" ..< "12.0.0"),
+    .package(url: "https://github.com/swiftlang/swift-syntax.git", "600.0.1" ..< "601.0.0"),
   ],
   targets: [
     .target(
@@ -189,18 +191,32 @@ let package = Package(
     .target(
       name: "FirebaseAILogic",
       dependencies: [
+        "FirebaseAILogicMacros",
         "FirebaseAppCheckInterop",
         "FirebaseAuthInterop",
         "FirebaseCore",
         "FirebaseCoreExtension",
       ],
-      path: "FirebaseAI/Sources"
+      path: "FirebaseAI/Sources",
+      exclude: ["Macros"]
+    ),
+    .macro(
+      name: "FirebaseAILogicMacros",
+      dependencies: [
+        .product(name: "SwiftSyntax", package: "swift-syntax"),
+        .product(name: "SwiftSyntaxMacroExpansion", package: "swift-syntax"),
+        .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
+        .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
+      ],
+      path: "FirebaseAI/Sources/Macros"
     ),
     .testTarget(
       name: "FirebaseAILogicUnit",
       dependencies: [
         "FirebaseAILogic",
+        "FirebaseAILogicMacros",
         "FirebaseStorage",
+        .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax"),
       ],
       path: "FirebaseAI/Tests/Unit",
       resources: [

From 551cfd73be86345a72fc2f0d28a18bd7e044a5be Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 18:11:25 -0500
Subject: [PATCH 24/32] Workaround transient SPM build issues due to prebuilt
 swift-syntax

---
 .../Unit/Macros/GenerableMacroTests.swift     | 65 ++++++++-----------
 Package.swift                                 | 11 +++-
 2 files changed, 37 insertions(+), 39 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
index 55aa4ce4591..bf04d14ca0f 100644
--- a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
+++ b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
@@ -12,52 +12,43 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-import SwiftSyntax
-import SwiftSyntaxBuilder
-import SwiftSyntaxMacros
-import SwiftSyntaxMacrosTestSupport
-import XCTest
-
 // Macro implementations build for the host, so the corresponding module is not available when
 // cross-compiling. Cross-compiled tests may still make use of the macro itself in end-to-end tests.
 #if canImport(FirebaseAILogicMacros)
   import FirebaseAILogicMacros
-#endif
+  import SwiftSyntax
+  import SwiftSyntaxBuilder
+  import SwiftSyntaxMacros
+  import SwiftSyntaxMacrosTestSupport
+  import XCTest
 
-final class GenerableMacroTests: XCTestCase {
-  #if canImport(FirebaseAILogicMacros)
+  final class GenerableMacroTests: XCTestCase {
     let testMacros: [String: Macro.Type] = [
       "stringify": StringifyMacro.self,
     ]
-  #else
-    let testMacros = [String: Macro.Type]()
 
-    override func setUpWithError() throws {
-      throw XCTSkip("Macros are only supported when running tests for the host platform.")
+    func testMacro() throws {
+      assertMacroExpansion(
+        """
+        #stringify(a + b)
+        """,
+        expandedSource: """
+        (a + b, "a + b")
+        """,
+        macros: testMacros
+      )
     }
-  #endif // canImport(FirebaseAILogicMacros)
-
-  func testMacro() throws {
-    assertMacroExpansion(
-      """
-      #stringify(a + b)
-      """,
-      expandedSource: """
-      (a + b, "a + b")
-      """,
-      macros: testMacros
-    )
-  }
 
-  func testMacroWithStringLiteral() throws {
-    assertMacroExpansion(
-      #"""
-      #stringify("Hello, \(name)")
-      """#,
-      expandedSource: #"""
-      ("Hello, \(name)", #""Hello, \(name)""#)
-      """#,
-      macros: testMacros
-    )
+    func testMacroWithStringLiteral() throws {
+      assertMacroExpansion(
+        #"""
+        #stringify("Hello, \(name)")
+        """#,
+        expandedSource: #"""
+        ("Hello, \(name)", #""Hello, \(name)""#)
+        """#,
+        macros: testMacros
+      )
+    }
   }
-}
+#endif // canImport(FirebaseAILogicMacros)
diff --git a/Package.swift b/Package.swift
index 11f04b728de..23f228cc80a 100644
--- a/Package.swift
+++ b/Package.swift
@@ -214,9 +214,16 @@ let package = Package(
       name: "FirebaseAILogicUnit",
       dependencies: [
         "FirebaseAILogic",
-        "FirebaseAILogicMacros",
         "FirebaseStorage",
-        .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax"),
+        .target(
+          name: "FirebaseAILogicMacros",
+          condition: .when(platforms: [.macOS])
+        ),
+        .product(
+          name: "SwiftSyntaxMacrosTestSupport",
+          package: "swift-syntax",
+          condition: .when(platforms: [.macOS])
+        ),
       ],
       path: "FirebaseAI/Tests/Unit",
       resources: [

From 94f989f2e4687c935bb0e3f0433bf42763fb4fdd Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 18:13:17 -0500
Subject: [PATCH 25/32] Revert "Try forcing Swift 6 mode on macOS 14 / Xcode
 16.2"

This reverts commit ad396d5feb4edc9dbccf03cf3fa69a15e4c6eb0d.

# Conflicts:
#	FirebaseAI/Tests/Unit/Types/Generable/GenerableTests.swift
---
 .github/workflows/firebaseai.yml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/.github/workflows/firebaseai.yml b/.github/workflows/firebaseai.yml
index 6aa1adc666f..1f3cde4a26a 100644
--- a/.github/workflows/firebaseai.yml
+++ b/.github/workflows/firebaseai.yml
@@ -78,9 +78,7 @@ jobs:
     with:
       product: ${{  matrix.product }}
       supports_swift6: true
-      setup_command: |
-        scripts/update_vertexai_responses.sh; \
-        sed -i "" "s/s.swift_version[[:space:]]*=[[:space:]]*'5.9'/s.swift_version = '6.0'/" ${{  matrix.product }}.podspec
+      setup_command: scripts/update_vertexai_responses.sh
 
   quickstart:
     if: (github.repository == 'Firebase/firebase-ios-sdk' && github.event_name == 'schedule') || github.event_name == 'pull_request'

From 21816b0720bf456f2c61ecb215f2f0aec45b3a02 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 19:13:00 -0500
Subject: [PATCH 26/32] Try removing `spm-package-resolved` job

---
 .github/workflows/common.yml | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index 4af29b0f68b..1611900e7e4 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -85,7 +85,6 @@ jobs:
   spm:
     # Run on the main repo's scheduled jobs or pull requests and manual workflow invocations.
     if: (github.repository == 'firebase/firebase-ios-sdk' && github.event_name == 'schedule') || contains(fromJSON('["pull_request", "workflow_dispatch"]'), github.event_name)
-    needs: [spm-package-resolved]
     strategy:
       matrix:
         os: [macos-15]
@@ -101,10 +100,6 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
-    - uses: actions/cache/restore@v4
-      with:
-        path: .build
-        key: ${{needs.spm-package-resolved.outputs.cache_key}}
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: Run setup command, if needed.

From fb5f2e2f2ca7716acc49c962ddbad1902e317265 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 19:39:52 -0500
Subject: [PATCH 27/32] Revert "Try removing `spm-package-resolved` job"

This reverts commit 21816b0720bf456f2c61ecb215f2f0aec45b3a02.
---
 .github/workflows/common.yml | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index 1611900e7e4..4af29b0f68b 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -85,6 +85,7 @@ jobs:
   spm:
     # Run on the main repo's scheduled jobs or pull requests and manual workflow invocations.
     if: (github.repository == 'firebase/firebase-ios-sdk' && github.event_name == 'schedule') || contains(fromJSON('["pull_request", "workflow_dispatch"]'), github.event_name)
+    needs: [spm-package-resolved]
     strategy:
       matrix:
         os: [macos-15]
@@ -100,6 +101,10 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
     - uses: actions/checkout@v4
+    - uses: actions/cache/restore@v4
+      with:
+        path: .build
+        key: ${{needs.spm-package-resolved.outputs.cache_key}}
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: Run setup command, if needed.

From fdb4dbf030347c642f370c179e404a66980ca317 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 19:44:47 -0500
Subject: [PATCH 28/32] Set `IDEPackageEnablePrebuilts NO`

---
 .github/workflows/common.yml | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index 4af29b0f68b..e02a4a2713e 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -68,6 +68,8 @@ jobs:
       - uses: actions/checkout@v4
       - name: Xcode
         run: sudo xcode-select -s /Applications/Xcode_16.4.app/Contents/Developer
+      - name: Disable SPM Prebuilts
+        run: defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts NO
       - name: Generate Swift Package.resolved
         id: swift_package_resolve
         run: swift package resolve
@@ -112,11 +114,13 @@ jobs:
       run: ${{ inputs.setup_command }}
     - name: Initialize xcodebuild
       run: scripts/setup_spm_tests.sh
+    - name: Disable SPM Prebuilts
+      run: defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts NO
     - uses: nick-fields/retry@ce71cc2ab81d554ebbe88c79ab5975992d79ba08 # v3
       if: contains(join(inputs.platforms), matrix.platform) || matrix.os == 'macos-14'
       with:
         timeout_minutes: 15
-        max_attempts: 3
+        max_attempts: 1 # TODO: Change back to 3 after testing
         retry_wait_seconds: 120
         command: |
           ./scripts/build.sh \

From 2395e13ce634dc75df875fc41aca21a862e6b62a Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Thu, 27 Nov 2025 20:03:35 -0500
Subject: [PATCH 29/32] Revert "Set `IDEPackageEnablePrebuilts NO`"

This reverts commit fdb4dbf030347c642f370c179e404a66980ca317.
---
 .github/workflows/common.yml | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index e02a4a2713e..4af29b0f68b 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -68,8 +68,6 @@ jobs:
       - uses: actions/checkout@v4
       - name: Xcode
         run: sudo xcode-select -s /Applications/Xcode_16.4.app/Contents/Developer
-      - name: Disable SPM Prebuilts
-        run: defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts NO
       - name: Generate Swift Package.resolved
         id: swift_package_resolve
         run: swift package resolve
@@ -114,13 +112,11 @@ jobs:
       run: ${{ inputs.setup_command }}
     - name: Initialize xcodebuild
       run: scripts/setup_spm_tests.sh
-    - name: Disable SPM Prebuilts
-      run: defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts NO
     - uses: nick-fields/retry@ce71cc2ab81d554ebbe88c79ab5975992d79ba08 # v3
       if: contains(join(inputs.platforms), matrix.platform) || matrix.os == 'macos-14'
       with:
         timeout_minutes: 15
-        max_attempts: 1 # TODO: Change back to 3 after testing
+        max_attempts: 3
         retry_wait_seconds: 120
         command: |
           ./scripts/build.sh \

From 33bda287864964eda417e8536b07a1eb7cd8e59f Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Fri, 28 Nov 2025 11:51:24 -0500
Subject: [PATCH 30/32] Refactor to more closely match starter project from
 Xcode 16.2

---
 .../Public/Generable/MacroDeclarations.swift  | 23 +++++++++++++++++++
 .../Unit/Macros/GenerableMacroTests.swift     | 16 +++++++++----
 Package.swift                                 | 18 +++------------
 3 files changed, 37 insertions(+), 20 deletions(-)
 create mode 100644 FirebaseAI/Sources/Types/Public/Generable/MacroDeclarations.swift

diff --git a/FirebaseAI/Sources/Types/Public/Generable/MacroDeclarations.swift b/FirebaseAI/Sources/Types/Public/Generable/MacroDeclarations.swift
new file mode 100644
index 00000000000..ddee87d671b
--- /dev/null
+++ b/FirebaseAI/Sources/Types/Public/Generable/MacroDeclarations.swift
@@ -0,0 +1,23 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// A macro that produces both a value and a string containing the
+/// source code that generated the value. For example,
+///
+///     #stringify(x + y)
+///
+/// produces a tuple `(x + y, "x + y")`.
+@freestanding(expression)
+public macro stringify<T>(_ value: T) -> (T, String) =
+  #externalMacro(module: "FirebaseAILogicMacros", type: "StringifyMacro")
diff --git a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
index bf04d14ca0f..8f0978214ad 100644
--- a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
+++ b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
@@ -23,9 +23,15 @@
   import XCTest
 
   final class GenerableMacroTests: XCTestCase {
-    let testMacros: [String: Macro.Type] = [
-      "stringify": StringifyMacro.self,
-    ]
+    #if swift(>=6.2)
+      nonisolated(unsafe) static let testMacros: [String: Macro.Type] = [
+        "stringify": StringifyMacro.self,
+      ]
+    #else
+      static let testMacros: [String: Macro.Type] = [
+        "stringify": StringifyMacro.self,
+      ]
+    #endif // swift(>=6.2)
 
     func testMacro() throws {
       assertMacroExpansion(
@@ -35,7 +41,7 @@
         expandedSource: """
         (a + b, "a + b")
         """,
-        macros: testMacros
+        macros: GenerableMacroTests.testMacros
       )
     }
 
@@ -47,7 +53,7 @@
         expandedSource: #"""
         ("Hello, \(name)", #""Hello, \(name)""#)
         """#,
-        macros: testMacros
+        macros: GenerableMacroTests.testMacros
       )
     }
   }
diff --git a/Package.swift b/Package.swift
index 23f228cc80a..528c340da21 100644
--- a/Package.swift
+++ b/Package.swift
@@ -177,7 +177,7 @@ let package = Package(
     ),
     .package(url: "https://github.com/google/app-check.git",
              "11.0.1" ..< "12.0.0"),
-    .package(url: "https://github.com/swiftlang/swift-syntax.git", "600.0.1" ..< "601.0.0"),
+    .package(url: "https://github.com/swiftlang/swift-syntax.git", from: "600.0.0-latest"),
   ],
   targets: [
     .target(
@@ -203,8 +203,6 @@ let package = Package(
     .macro(
       name: "FirebaseAILogicMacros",
       dependencies: [
-        .product(name: "SwiftSyntax", package: "swift-syntax"),
-        .product(name: "SwiftSyntaxMacroExpansion", package: "swift-syntax"),
         .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),
         .product(name: "SwiftCompilerPlugin", package: "swift-syntax"),
       ],
@@ -215,23 +213,13 @@ let package = Package(
       dependencies: [
         "FirebaseAILogic",
         "FirebaseStorage",
-        .target(
-          name: "FirebaseAILogicMacros",
-          condition: .when(platforms: [.macOS])
-        ),
-        .product(
-          name: "SwiftSyntaxMacrosTestSupport",
-          package: "swift-syntax",
-          condition: .when(platforms: [.macOS])
-        ),
+        "FirebaseAILogicMacros",
+        .product(name: "SwiftSyntaxMacrosTestSupport", package: "swift-syntax"),
       ],
       path: "FirebaseAI/Tests/Unit",
       resources: [
         .copy("vertexai-sdk-test-data/mock-responses"),
         .process("Resources"),
-      ],
-      cSettings: [
-        .headerSearchPath("../../../"),
       ]
     ),
     .target(

From 45c4300244ab16c4ecf45061e176e75f702b6538 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Fri, 28 Nov 2025 12:38:19 -0500
Subject: [PATCH 31/32] Switch `swift-syntax` dependency version based on Swift
 version

---
 .../Tests/Unit/Macros/GenerableMacroTests.swift     | 12 +++---------
 Package.swift                                       | 13 ++++++++++++-
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
index 8f0978214ad..207254ed144 100644
--- a/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
+++ b/FirebaseAI/Tests/Unit/Macros/GenerableMacroTests.swift
@@ -23,15 +23,9 @@
   import XCTest
 
   final class GenerableMacroTests: XCTestCase {
-    #if swift(>=6.2)
-      nonisolated(unsafe) static let testMacros: [String: Macro.Type] = [
-        "stringify": StringifyMacro.self,
-      ]
-    #else
-      static let testMacros: [String: Macro.Type] = [
-        "stringify": StringifyMacro.self,
-      ]
-    #endif // swift(>=6.2)
+    static let testMacros: [String: Macro.Type] = [
+      "stringify": StringifyMacro.self,
+    ]
 
     func testMacro() throws {
       assertMacroExpansion(
diff --git a/Package.swift b/Package.swift
index 528c340da21..5884573b241 100644
--- a/Package.swift
+++ b/Package.swift
@@ -177,7 +177,7 @@ let package = Package(
     ),
     .package(url: "https://github.com/google/app-check.git",
              "11.0.1" ..< "12.0.0"),
-    .package(url: "https://github.com/swiftlang/swift-syntax.git", from: "600.0.0-latest"),
+    swiftSyntaxDependency(),
   ],
   targets: [
     .target(
@@ -1459,6 +1459,17 @@ func grpcDependency() -> Package.Dependency {
   return .package(url: packageInfo.url, packageInfo.range)
 }
 
+func swiftSyntaxDependency() -> Package.Dependency {
+  let url = "https://github.com/swiftlang/swift-syntax.git"
+  #if swift(>=6.2)
+    return .package(url: url, from: "602.0.0-latest")
+  #elseif swift(>=6.1)
+    return .package(url: url, from: "601.0.0-latest")
+  #else
+    return .package(url: url, from: "600.0.0-latest")
+  #endif
+}
+
 func firestoreWrapperTarget() -> Target {
   if Context.environment["FIREBASE_SOURCE_FIRESTORE"] != nil {
     return .target(

From e817d78d67ac97d7c24037d026d4587f855d1879 Mon Sep 17 00:00:00 2001
From: Andrew Heard <andrewheard@google.com>
Date: Fri, 28 Nov 2025 13:40:30 -0500
Subject: [PATCH 32/32] Try disabling Swift prebuilts again

---
 .github/workflows/common.yml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/.github/workflows/common.yml b/.github/workflows/common.yml
index 4af29b0f68b..486f07d1995 100644
--- a/.github/workflows/common.yml
+++ b/.github/workflows/common.yml
@@ -105,6 +105,12 @@ jobs:
       with:
         path: .build
         key: ${{needs.spm-package-resolved.outputs.cache_key}}
+    - name: Disable SwiftPM prebuilts in Xcode
+      run: |
+        defaults write com.apple.dt.Xcode IDEPackageEnablePrebuilts -bool NO
+        defaults read com.apple.dt.Xcode IDEPackageEnablePrebuilts
+    - name: Clear SwiftPM caches
+      run: rm -rf ~/.swiftpm/artifacts ~/.swiftpm/cache
     - name: Xcode
       run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app/Contents/Developer
     - name: Run setup command, if needed.