foundation▌

见：references/dod_checklist.md

Foundation Models issues manifest as context window exceeded errors, guardrail violations, slow generation, availability failures, and unexpected output. Core principle 80% of Foundation Models problems stem from misunderstanding model capabilities (3B parameter device-scale model, not world knowledge), context limits (4096 tokens), or availability requirements—not framework bugs.

Use when:

On-device LLM integration for iOS 18+ using Apple's FoundationModels framework with privacy-first text generation and structured output. \n \n Covers text generation, structured output via @Generable macro, custom tool calling, and snapshot streaming—all running locally without cloud dependency \n Requires availability checks before session creation; supports single-turn and multi-turn conversations with optional system instructions \n Guided generation with @Guide constraints (numeric ranges, a

The Foundation Models framework provides access to Apple's on-device Large Language Model (3 billion parameters, 2-bit quantized) with a Swift API. This reference covers every API, all WWDC 2025 code examples, and comprehensive implementation patterns.