Accept stringified primitives in Generable conversions

Sources/AnyLanguageModel/Generable.swift

@@ -113,10 +113,17 @@ extension Bool: Generable {
 
     /// Creates an instance with the content.
     public init(_ content: GeneratedContent) throws {
-        guard case .bool(let value) = content.kind else {
+        switch content.kind {
+        case .bool(let value):
+            self = value
+        case .string(let text):
+            guard let value = Bool(coercing: text) else {
+                throw GeneratedContentConversionError.typeMismatch
+            }
+            self = value
+        default:
             throw GeneratedContentConversionError.typeMismatch
         }
-        self = value
     }
 
     /// An instance that represents the generated content.
@@ -163,10 +170,17 @@ extension Int: Generable {
 
     /// Creates an instance with the content.
     public init(_ content: GeneratedContent) throws {
-        guard case .number(let value) = content.kind else {
+        switch content.kind {
+        case .number(let value):
+            self = Int(value)
+        case .string(let text):
+            guard let value = Double(coercing: text), value == value.rounded() else {
+                throw GeneratedContentConversionError.typeMismatch
+            }
+            self = Int(value)
+        default:
             throw GeneratedContentConversionError.typeMismatch
         }
-        self = Int(value)
     }
 
     /// An instance that represents the generated content.
@@ -188,10 +202,17 @@ extension Float: Generable {
 
     /// Creates an instance with the content.
     public init(_ content: GeneratedContent) throws {
-        guard case .number(let value) = content.kind else {
+        switch content.kind {
+        case .number(let value):
+            self = Float(value)
+        case .string(let text):
+            guard let value = Double(coercing: text) else {
+                throw GeneratedContentConversionError.typeMismatch
+            }
+            self = Float(value)
+        default:
             throw GeneratedContentConversionError.typeMismatch
         }
-        self = Float(value)
     }
 
     /// An instance that represents the generated content.
@@ -213,10 +234,17 @@ extension Double: Generable {
 
     /// Creates an instance with the content.
     public init(_ content: GeneratedContent) throws {
-        guard case .number(let value) = content.kind else {
+        switch content.kind {
+        case .number(let value):
+            self = value
+        case .string(let text):
+            guard let value = Double(coercing: text) else {
+                throw GeneratedContentConversionError.typeMismatch
+            }
+            self = value
+        default:
             throw GeneratedContentConversionError.typeMismatch
         }
-        self = value
     }
 
     /// An instance that represents the generated content.
@@ -238,10 +266,17 @@ extension Decimal: Generable {
 
     /// Creates an instance with the content.
     public init(_ content: GeneratedContent) throws {
-        guard case .number(let value) = content.kind else {
+        switch content.kind {
+        case .number(let value):
+            self = Decimal(value)
+        case .string(let text):
+            guard let value = Double(coercing: text) else {
+                throw GeneratedContentConversionError.typeMismatch
+            }
+            self = Decimal(value)
+        default:
             throw GeneratedContentConversionError.typeMismatch
         }
-        self = Decimal(value)
     }
 
     /// An instance that represents the generated content.
@@ -251,6 +286,31 @@ extension Decimal: Generable {
     }
 }
 
+// MARK: String Coercion
+
+/// Language models sometimes emit primitive values as JSON strings, most commonly in
+/// tool-call arguments where a chat template stringifies every argument value. The
+/// primitive initializers above accept such strings when they parse unambiguously as
+/// the target type, and throw ``GeneratedContentConversionError/typeMismatch`` otherwise.
+extension Bool {
+    fileprivate init?(coercing text: String) {
+        switch text.trimmingCharacters(in: .whitespacesAndNewlines).lowercased() {
+        case "true":
+            self = true
+        case "false":
+            self = false
+        default:
+            return nil
+        }
+    }
+}
+
+extension Double {
+    fileprivate init?(coercing text: String) {
+        self.init(text.trimmingCharacters(in: .whitespacesAndNewlines))
+    }
+}
+
 // MARK: Array
 
 extension Array: Generable where Element: Generable {

Tests/AnyLanguageModelTests/PrimitiveStringCoercionTests.swift

@@ -0,0 +1,56 @@
+import Foundation
+import Testing
+
+@testable import AnyLanguageModel
+
+@Generable
+private struct StringifiedToolArguments {
+    var count: Int?
+    var enabled: Bool?
+    var ratio: Double?
+}
+
+@Suite("Primitive string coercion")
+struct PrimitiveStringCoercionTests {
+    @Test func decodesStringifiedNumbersAndBools() throws {
+        #expect(try Int(GeneratedContent(kind: .string("5"))) == 5)
+        #expect(try Int(GeneratedContent(kind: .string(" -12 "))) == -12)
+        #expect(try Int(GeneratedContent(kind: .string("5.0"))) == 5)
+        #expect(try Bool(GeneratedContent(kind: .string("true"))) == true)
+        #expect(try Bool(GeneratedContent(kind: .string("False"))) == false)
+        #expect(try Double(GeneratedContent(kind: .string("3.25"))) == 3.25)
+        #expect(try Float(GeneratedContent(kind: .string("0.5"))) == 0.5)
+        #expect(try Decimal(GeneratedContent(kind: .string("2.5"))) == Decimal(2.5))
+    }
+
+    @Test func rejectsUnparseableStrings() {
+        #expect(throws: GeneratedContentConversionError.self) {
+            try Int(GeneratedContent(kind: .string("five")))
+        }
+        #expect(throws: GeneratedContentConversionError.self) {
+            try Int(GeneratedContent(kind: .string("5.5")))
+        }
+        #expect(throws: GeneratedContentConversionError.self) {
+            try Bool(GeneratedContent(kind: .string("yes")))
+        }
+        #expect(throws: GeneratedContentConversionError.self) {
+            try Double(GeneratedContent(kind: .string("")))
+        }
+    }
+
+    @Test func nativeKindsStillDecode() throws {
+        #expect(try Int(GeneratedContent(kind: .number(7))) == 7)
+        #expect(try Bool(GeneratedContent(kind: .bool(true))) == true)
+        #expect(try Double(GeneratedContent(kind: .number(1.5))) == 1.5)
+        #expect(try String(GeneratedContent(kind: .string("text"))) == "text")
+    }
+
+    @Test func decodesGenerableArgumentsWithStringifiedValues() throws {
+        let json = #"{"count": "3", "enabled": "true", "ratio": "0.75"}"#
+        let arguments = try StringifiedToolArguments(GeneratedContent(json: json))
+
+        #expect(arguments.count == 3)
+        #expect(arguments.enabled == true)
+        #expect(arguments.ratio == 0.75)
+    }
+}