Nothing to describe yet? — a tidy-capture feature for a hiking journal: turn a messy trail note into a structured entry, on-device for privacy, with two SwiftData types to mirror and progressive UI. Or see a saved scaffold rendered with no run and no charge: or .
Describe the feature
What it does, where it lives, what data it works on — and paste your Swift types so the @Generable mirrors use your names, not invented ones. The fit scanner sizes it up free in your browser.
Read the fit verdict
Strong fit is bounded text-in/structured-out — the framework's home ground. Workable names its caveats. Poor fit comes with the honest alternative, because a 4,096-token on-device model is not a cloud frontier model.
Drop the files into Xcode
1–4 complete Swift files: models, availability-gated view, session, streaming. Integration notes in wiring order, limits with real numbers, and a mirror check against your own types. Download each .swift or all of them at once.
Will it scaffold anything I ask for?
No — and that is the point. FoundationModels is a small on-device model with a 4,096-token window shared by instructions, prompt and output. A feature that needs live web knowledge, whole-document contexts, image generation or cloud-scale reasoning gets an honest Poor fit verdict with the alternative spelled out — a cloud API lane, a simpler heuristic, or a narrower reframing that would fit — instead of a scaffold that will disappoint in review.
Does it use my existing Swift types?
Yes. Paste your structs, enums or SwiftData models alongside the prose and the @Generable counterparts mirror their names and fields exactly, with the mapping between the generated types and yours called out in the integration notes. After the run the app checks the mirror mechanically: a pasted type that never appears in the generated code is flagged before you wire anything in.
Do I have to sign in?
Not to size up the feature. The fit scan — Swift types detected, cloud-dependency phrases, framework-friendly verbs, input sizes — runs entirely in your browser, free, with nothing leaving the page. The scaffold itself is a metered model run, so that step needs an account, and the reserve is shown before you press the button.
What does every scaffold get right by construction?
The framework rules that sink features in review: SystemLanguageModel.default.availability checked before any session exists with every unavailability case handled, sessions created with instructions that set the model's role, structured output through @Generable with @Guide descriptions instead of string parsing, snapshot streaming with PartiallyGenerated types driving SwiftUI state, one request per session with isResponding respected, results read from response.content, and the 4,096-token budget engineered around — the scaffold shows where to chunk or trim.
What can I do with the scaffold afterwards?
Download each file as its own .swift, download all files as one MARK-separated .swift, download the whole reply as markdown, or copy any single file from its card. Every one of those is built in your browser from a result you already ran, so none of them costs another run. Past scaffolds are kept on your account, and when the description sharpens you can re-run it and see which files changed before overwriting your local edits.