Default to VALIDATED function calling mode in GeminiLanguageModel and
switch guided generation to responseJsonSchema.
Previously, tool-calling requests mapped the default or allowed mode to
AUTO, which does not strictly enforce parameter schemas. Because Swift
decodes tool arguments strictly, schema malformation results in failed
turns. Additionally, guided generation used responseFormat, which the
Gemini backend ignores when VALIDATED mode is active during tool-calling
sessions, dropping response schemas and causing structured decoding
failures in respond(to:generating:).
* Default unset and explicit .allowed toolCallingMode to VALIDATED mode
to strictly enforce schema adherence via constrained decoding.
* Throw LanguageModelError.unsupportedCapability on unrecognized future
tool calling modes instead of silently falling back to allowed.
* Omit functionCallingConfig entirely when requests declare no functions
to avoid contradictory constrained decoding states.
* Send responseJsonSchema with application/json MIME type for guided
generation, which constrained decoding honors alongside VALIDATED.
* Remove unused _responseJsonSchema property from GenerationConfig.
* End SSE response streams and cancel tasks upon receiving terminal
finish reasons or prompt feedback block reasons.
* Add integration test for combined tool calling and guided generation.
* Refresh cached App Check debug tokens proactively within TTL window.
Remove the GEMINI_LANGUAGE_MODEL environment variable check in
Package.swift to unconditionally include GeminiLanguageModel targets
and dependencies on supported Swift 6.4+ toolchains.
Add DocC documentation comments for the GeminiLanguageModel integration
with Apple's Foundation Models framework.
Provide usage guidance, public preview warnings, and links to Apple's
LanguageModel protocol, LanguageModelSession, and DynamicProfile. In
addition, document FirebaseAI.geminiLanguageModel(name:) and include
a code example showing how to instantiate and use the model.
Implemented `GeminiLanguageModel`, providing an adapter for Google's
Gemini models conforming to Apple's `FoundationModels.LanguageModel`
protocol. This PR includes text to text generation capabilities; other
modalities and Gemini features will be handled in follow-up PRs.
**Note:** The `GeminiLanguageModel` implementation is guarded by the
environment variable `GEMINI_LANGUAGE_MODEL`. By default none of the
`GeminiLanguageModel` implementation is included.
Key additions:
- `GeminiLanguageModel`: Implements `LanguageModel` protocol with
reasoning capabilities, configuring execution via `ModelResource`
and `EndpointConfiguration`.
- `GeminiLanguageModelExecutor`: Converts prompt instructions and
history into Gemini streaming requests, yielding responses as
`LanguageModelSession.ResponseStream`.
- `GeminiTranscriptTranslator`: Translates Apple `Transcript` entries
and segments into Gemini `Content` structures while preserving thought
signatures and validating supported transcript features.
- `GeminiLanguageModel.Error` and `GeminiErrorMapper`: Translates Gemini
API, HTTP, and network errors into standard `LanguageModelError` cases
(`rateLimited`, `timeout`, `guardrailViolation`, `refusal`, and
`unsupportedLanguageOrLocale`) or `GeminiLanguageModel.Error` cases
(`serviceUnavailable`, `networkFailure`, `modelNotFound`, `apiError`).
The `APIError` payload is designed for seamless forward compatibility
with both GenerateContent and the upcoming Interactions API.
- Testing infrastructure: Adds `ConditionTrait.requireFoundationModels`
to conditionally run Foundation Models tests only on supported
platforms (macOS 27+, iOS 27+, watchOS 27+, visionOS 27+), along with
shared test constants, mock fixtures, and comprehensive unit and
integration test suites.
Andrew Heard