Roadmap: 1.0 (Foundation Models 26) and 2.0 (Foundation Models 27)

[mattt]

Now that @pcuenca and I are back on this, here's the plan:

1.0 — a stable release against the current Foundation Models API in iOS/macOS 26. Before tagging it, I want to tidy up the places where AnyLanguageModel grew beyond what Apple's framework offers, mostly to compensate for early limitations:

• Remove the APIs that are already marked deprecated (Llama passthrough properties, the legacy Gemini Thinking / ServerTool types).
• Fix respond(to:schema:), which currently ignores its schema argument.
• Make Instructions Sendable, and close a few other small parity gaps.
• Clearly mark our extensions (tool execution delegate, image inputs, [custom:] options) as extensions.

2.0 — track the Foundation Models changes in iOS/macOS 27. I expect source-breaking changes around session construction, image inputs, and generation options, so that'll be a major version. Availability-gated additions (like #206) can land before then.

If there's something you need in 1.0, please say so here.

[mergesort]

Hey @mattt and @pcuenca, want to start by saying thank you for the great library — I really appreciate it!

Will 2.0 support deployments back to OS 26 as well, or will it be considered a source breaking change that only works with 27+. I'd really appreciate being able to use 2.0 to support my users on both iOS 26/27, while providing access to the new PCC models on iOS 27.