Agent! Now Runs on macOS 14.6 and Intel Macs: How We Got Off macOS 26

Until today, Agent! required macOS 26. As of today's pre-release it runs on macOS 14.6 or later, on Apple Silicon and Intel. That covers a lot of perfectly good Macs that were locked out, many of which can't run Apple Intelligence at all.

Here's what it took, commit by commit, in one day.

The blocker: FoundationModels

Agent! uses Apple's on-device model through the FoundationModels framework, which only exists on macOS 26. It isn't the main brain, since your chosen provider handles that. But it does several jobs: fast summaries during context compaction, on-device token counting, a prewarmed session at launch, and some triage.

Code that names a macOS 26 type won't build for an older deployment target. So step one (ea5ce624) was to put every use of FoundationModels behind #available(macOS 26, *). That covered FoundationModelService, AppleIntelligenceMediator, the prewarm in AgentApp, compaction summaries and token counting in Compression.swift, and AboutSelf.

The trick: type-erase the stored property

#available works for code paths, but not for a stored property. A class can't hold a LanguageModelSession? when the type doesn't exist on the running OS. The fix is to store it as AnyObject? and cast it back where it's used, inside gated code:

/// Type-erased `LanguageModelSession` so the stored property compiles below macOS 26.
private(set) var session: AnyObject?

@available(macOS 26.0, *)
var transcript: Transcript? {
    (session as? LanguageModelSession)?.transcript
}

As the commit message puts it, the stored properties no longer "drag the framework type into the class layout."

Availability checks also got an honest answer for older systems:

static var unavailabilityReason: String {
    guard #available(macOS 26.0, *) else { return "Apple Intelligence requires macOS 26 or later." }
    ...
}

So on macOS 14 or 15, Apple Intelligence just shows as unavailable with a clear reason, and everything else works. On macOS 26, nothing changes.

The long tail: ten packages

Agent! is built from its own Swift packages, and each one declared its own minimum OS. Commit 4d7fca86 bumped all ten to releases that declare .macOS(.v14):

Owning every dependency pays off on days like this. There was no waiting on an upstream maintainer, just ten tags.

The surprise: 26.4

One API needed more than a 26.0 gate. SystemLanguageModel.tokenCount(for:) only exists from macOS 26.4, so its availability check moved from 26.0 to 26.4. Without that, a Mac on 26.0 through 26.3 would have tried to call a method that doesn't exist yet. It's a good reminder that "the framework is available" and "this method is available" aren't the same question.

What you get on older Macs

On macOS 14.6 and 15, on Apple Silicon or Intel, Agent! works the same way:

• all 23 cloud and local LLM providers
• the full tool loop: coding, Xcode builds, git, shell as you or as root, Accessibility, AppleScript, JXA, AgentScript, Safari automation and MCP
• context compaction, which uses the model's own summaries and the provider's token counts, just without the Apple Intelligence tier

Only the on-device Apple Intelligence features need macOS 26.

Get it

Every release and pre-release ships a signed, notarized and stapled binary. You never need to build from source:

brew update && brew install --cask agentiloop-agent

Or download the .dmg from GitHub Releases. If you've been waiting on an older MacBook or an Intel Mac mini, today's the day.