# Platform Baseline The single source of truth for *which platform versions this kit is calibrated to*. The `Platform Currency` topic (in every role's `interview.html`) and a handful of version references scattered across the question banks and knowledge bases are pinned to this baseline. The `/maintain` skill diffs the live platform against this file once a year and refreshes what's drifted. **Do not let this file go stale silently.** If "Next review due" is in the past, run `/maintain`. --- ## Current baseline | Field | Value | |-------|-------| | **Last reviewed** | 2026-07-14 | | **Next review due** | 2027-07 (after WWDC 2027 betas settle) | | **iOS / iPadOS** | 26 generation shipping (iOS 26.5 SDK in the current shipping Xcode). iOS/iPadOS 27 are beta previews, not GA. | | **Swift** | 6.3 shipping; 6.4 in Xcode 27 beta. Swift 6 language mode and complete data-race checking remain independently adoptable per target. | | **Xcode** | 26.6 shipping; 27 beta (Apple-silicon-only) | | **Android** (Mobile track) | Android 16 / API 36 shipping; Android 17 / API 37 preview | | **Kotlin** (Mobile track) | 2.4 shipping | | **Cross-platform** (Mobile track) | Jetpack Compose, SwiftUI, Kotlin Multiplatform (formerly KMM), Compose Multiplatform | ### "Current new tech" the version-pinned questions reference These are the named technologies a candidate is expected to be aware of *right now*. This is the list `/maintain` re-evaluates each year — add what's newly GA, demote what's now ambient/old-hat. - **Established direction:** SwiftUI, Swift Concurrency/data-race safety, Observation and SwiftData. These remain adoption signals, but no longer count as newly announced technology by themselves. - **Shipping Swift/toolchain:** Swift 6.3 in Xcode 26.6; Xcode 26.3+ agentic coding integrations and MCP; Swift Testing as the modern unit-test framework alongside XCTest. - **Preview Swift/toolchain:** Swift 6.4 in Xcode 27 beta, including `anyAppleOS` availability syntax and asynchronous calls in `defer`; deeper agent workflows and Device Hub in Xcode 27 beta. - **Foundation Models:** on-device app-model access in the shipping generation; iOS 27 preview expands the framework toward Private Cloud Compute and conforming model providers. Model path and runtime availability must be stated rather than assuming every request is local. - **Core AI (iOS 27 / Xcode 27 beta preview):** Apple's bring-your-own-model LLM deployment framework, announced WWDC 2026 as a successor to Core ML for generative AI workloads (LLMs, diffusion models, large transformers). GA expected fall 2026 alongside iOS 27. **Distinct from Foundation Models**: Foundation Models = Apple's system model (managed path); Core AI = developer-owned model (custom path). The two serve different use cases and carry different privacy/availability/cost profiles — stating which path applies to a given feature is part of the adoption decision. - **Mobile track:** Android 16/API 36 and Kotlin 2.4 shipping; Android 17/API 37 preview; Jetpack Compose, coroutines/Flow, Kotlin Multiplatform and Compose Multiplatform. --- ## How the kit pins to this baseline 1. **`Platform Currency` topic** — every role's `interview.html` has a `platform-currency` topic (the last topic in `topics`). Within it: - **Evergreen questions** test *adoption judgment* and don't reference specific versions — they rarely change. - **Version-pinned questions** are tagged with an inline `// ANNUAL: version-pinned` comment and name specific current versions/frameworks. **These are the ones `/maintain` rewrites.** There are 2–3 per role. 2. **Scattered version references** — strings like `Swift 6`, `iOS 26`, `SwiftData`, `Observation`, `@Observable` appear in other topics' `reveals`/`hints` and in `knowledge-base/**`. `/maintain` greps for these and refreshes any that read as stale. 3. **Academy Unit 8 ("Keeping Current")** — `academy/content/u8-l*.js` are version-pinned Academy lessons (headed `// ANNUAL: version-pinned`). They teach the last ~3 years as a status-aware arc: macro era 5.9 → Swift 6 data-race safety → 6.2 approachable-concurrency settings → shipping Swift 6.3/Xcode 26.6 versus preview Swift 6.4/Xcode 27; Swift Testing, Foundation Models and a reversible adoption-decision lab. `/maintain` slides the window forward each July, labels shipping versus preview, and demotes what's become ambient. Units 1–7 are evergreen by rule — never touch them. 4. **Academy Unit 9 ("The AI-Native Engineer")** — `academy/content/u9-l*.js` are also version-pinned (headed `// ANNUAL: version-pinned`). Current verified anchors are: some first-party engineering listings expect AI-tool fluency and tool-allowed live pairing, but candidate instructions—not anecdotes—define each interview; Claude Code and Codex span documented instruction/workflow surfaces (`CLAUDE.md`/`AGENTS.md`) whose guidance is context rather than enforcement; Xcode 26.3 ships agentic coding and MCP while Xcode 27 beta documents deeper agent customization, protections and Preview Snapshot tools; and the USENIX Security 2025 package-hallucination result applies to recommended packages in its named Python/JavaScript model cohort, not all current AI code. `/maintain` must re-verify the employer examples, tool surfaces, product status and evidence scope each July. The *principles*—risk-calibrated trust, least privilege, independent acceptance evidence, capped verify loops, human ownership and contract revision when facts change—are evergreen. ## Review cadence Once a year, mid-July — after WWDC (early June) and once the first betas have settled so the new frameworks' real shape is known. A scheduled reminder fires around then; the routine is the `/maintain` skill (`.claude/skills/maintain/`). ## Change log - **2026-07-14** — Verification pass: all question version-pinned references confirmed accurate against live platform. Added Core AI to "current new tech" — WWDC 2026 bring-your-own-model LLM framework (iOS 27/Xcode 27 beta preview, distinct from Foundation Models); refreshed Lead iOS and Principal iOS version-pinned questions to surface Core AI as a second AI adoption surface alongside Foundation Models. - **2026-07-10** — Unit 9 truth pass: removed unverified universal employer formats, model lineups, benchmark parity and vulnerability multipliers; scoped the USENIX package result to its tested cohort; separated instruction context from enforcement; corrected Xcode 26.3 shipping versus Xcode 27 beta Preview tooling; aligned Foundation Models claims with model-path status; and added a verification-contract lab. - **2026-07-10** — Annual truth pass: recorded Xcode 26.6/Swift 6.3 as shipping and Xcode 27/Swift 6.4/iOS 27 as beta; added Android 17/API 37 preview and Kotlin 2.4 shipping; separated Foundation Models' shipping on-device path from iOS 27 preview expansion; aligned Unit 8 and Platform Currency banks. - **2026-06-08** — Baseline established at iOS 26 / Swift 6 / Xcode 26 (+ Android 16 / Kotlin 2.x for the Mobile track). Introduced alongside the new `Platform Currency` topic across all 7 roles.