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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
/// We need these compile time checks so the app can be built with pre‑iOS 26 SDKs.
/// Once our BR workflow switches to 26, we can remove them,
/// as the runtime @available checks will be enough.
#if canImport(FoundationModels)
import FoundationModels
import Foundation
/// Adapter bridging Apple's `LanguageModelSession` to `LanguageModelSessionProtocol`.
/// This is needed because `LanguageModelSession.respond()` returns a concrete type `LanguageModelSession.Response`
/// whereas `LanguageModelSessionProtocol.respond() returns `any ResponseProtocol`.
/// Eventhough `LanguageModelSession.Response` conforms to `ResponseProtocol`, the compiler treats them as different types.
/// In tests, `MockLanguageModelSession` will be used instead of this.
@available(iOS 26, *)
final class LanguageModelSessionAdapter: LanguageModelSessionProtocol {
private let realSession: LanguageModelSession
init(instructions: String) {
self.realSession = LanguageModelSession(instructions: instructions)
}
func respond(
to prompt: Prompt,
options: GenerationOptions,
isolation: isolated (any Actor)?
) async throws -> any LanguageModelResponseProtocol {
let realResponse: LanguageModelSession.Response<String> =
try await realSession.respond(to: prompt, options: options)
return realResponse
}
func streamResponse(
to prompt: Prompt,
options: GenerationOptions
) -> any LanguageModelResponseStreamProtocol {
// TODO(FXIOS-13088): The API changed between beta 4 and 5, so this now breaks when building.
// To avoid any future issues, this is commented out until we get the stable API.
// This is unused in the current implementation. We only use non-streaming responses.
// realSession.streamResponse(to: prompt, options: options)
assertionFailure(
"""
streaming is disabled until we get a stable API for
`LanguageModelSession.ResponseStream`.
"""
)
return AsyncThrowingStream<String, Error> { $0.finish() }
}
}
#endif