apple-platform-targetslisted

# Apple Platform Deployment Targets ## When to invoke - Starting a new iOS / macOS App and setting the minimum deployment version. - Writing the `platforms:` block in `Package.swift`. - Deciding whether to adopt latest-OS-only APIs (Liquid Glass `.glassEffect()`, new Observation, new SwiftData behaviour, etc.). - User asks about minimum iOS / macOS version or whether to support the previous major version. ## Default decisions - **iOS 18 / macOS 15** as the default minimum. - Toolchain: **Xcode 16+** (the first version with formal Swift 6 language mode support). - Do not auto-bump with each Xcode major — bumping requires an explicit decision recorded in `foundations.md`. - Keep `Package.swift` `platforms:` **aligned** with the App target deployment target; no skew. ## Rationale - iOS 18 / macOS 15 aligns with the Swift 6 toolchain, unlocking Observation / SwiftData improvements and async sequence enhancements. - Locking out auto-bumps prevents blindly chasing each Xcode major and losing users who haven't upgraded. - For solo / small projects the user base is small, so the compatibility tax is low compared to the stability benefit. ## Deviation considerations ### Bump up to iOS 26 / macOS 26 (or newer) - **Trigger**: adopting Liquid Glass (`.glassEffect()` is iOS 26+) or other latest-OS-only APIs. - **Conditions**: the project has no backward-compat baggage (brand new App, no existing user base); or it's a personal / showcase project willing to cut off older versions.