Audit Swiftui Previews

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name: audit-swiftui-previews description: Audit macOS SwiftUI previews for correctness, current APIs, and production conventions. Use for that domain or as part of a full audit.

Bundled resource root

Let <swiftui-plugin-root> be the absolute plugin directory two levels above this SKILL.md. Resolve that path before running commands or opening shared references. When these instructions say swiftui-ctx, invoke <swiftui-plugin-root>/scripts/swiftui-ctx; do not assume the command is on PATH.

Audit SwiftUI Previews

AUDIT-ONLY · macOS-only · SwiftUI-only. Run this on a finished or in-progress macOS SwiftUI project to detect — and where certain, fix — every way the #Preview macro and the Xcode canvas go wrong: the legacy PreviewProvider struct, bare @State/@Binding/@Bindable in a #Preview body without @Previewable, hand-rolled EnvironmentKey boilerplate instead of @Entry, the visionOS-only Preview(windowStyle:) overload, manual .frame sizing instead of traits, the wrong .environmentObject injector, and the two canvas-crash traps (a @Query/SwiftData view with no in-memory container, an @Environment-dependent view with no injected dependency). Findings are written to disk in the toolkit's unified schema; certain mechanical defects are fixed under the fix-safety protocol. This is never a from-scratch preview generator.

A preview instantiates the view for real — so a missing container or @Environment dependency traps the canvas, not the app. The preview tooling is also where AI goes stale: it emits the PreviewProvider struct (dominant 2019–2023) and forgets the modern macro era's @Previewable / @Entry.

Boundary / seam note (stay in lane)

• SwiftData model design (@Model, schema, relationships, @ModelActor) belongs to audit-swiftui-swiftdata. This skill owns the preview-construction angle of the canvas crash (the missing in-memory container in a #Preview); emit cross_ref: audit-swiftui-swiftdata and let it own the model itself.
• Live-app @Observable wiring (where the model lives, the sample factory) belongs to audit-swiftui-state-observation. This skill owns only the preview injection of a sample @Observable; cross_ref it for the factory.
• @Entry/FocusedValueKey is a context-conditional seam: if the pattern is co-located with a CommandMenu/CommandGroup → audit-swiftui-menus-commands owns it; in a preview / general environment setup → this skill owns it (per the shared cross-ref graph). cross_ref the other way.
• The blanket "is every floored API gated" sweep is audit-swiftui-availability-gating; macro modernity (PreviewProvider-as-deprecated-era) shares a seam with audit-swiftui-api-currency.

The three non-negotiable preview rules

1. #Preview macro, not PreviewProvider. The freestanding macro is the modern path (Xcode 15+, macOS 14+). One #Preview declaration per named preview — never the legacy struct …_Previews: PreviewProvider { static var previews } for new code.
2. A #Preview body is an expanded view scope — tag dynamic state @Previewable. Bare @State/@Binding/@Bindable at that scope is a compile error; @Previewable @State var … is the only legal stateful-preview shape.
3. Previews run real code — inject every dependency. A @Query/SwiftData view needs an in-memory ModelContainer; an @Environment(Model.self) view needs a sample injected with .environment(_:). Omit either and the canvas crashes on launch.

The instantiation test: ask "does this view read state or a dependency the preview never provides?" If yes, the canvas traps — supply it (@Previewable, .modelContainer(… inMemory: true), .environment(_:)). Full reasoning: references/preview-crashes-and-injection.md.

Defect index (prev-01 … prev-09)

id · tell · severity · fix · open reference. Severities: hard-fail (compile error / canvas crash), warning (compiles but stale/non-idiomatic), advisory (judgment / polish). auto = mechanical single-answer fix; flag = show the ✅, dev applies.

id	One-line tell	Sev	Fix	Reference
prev-01	struct *_Previews: PreviewProvider (legacy struct for new code)	warning	flag	preview-macro-and-state.md
prev-02	bare @State/@Binding/@Bindable in a #Preview body, no @Previewable	hard-fail	flag	preview-macro-and-state.md
prev-03	struct *Key: EnvironmentKey + extension EnvironmentValues boilerplate (use @Entry)	warning	flag	entry-and-environment.md
prev-04	manual .frame(width:height:) in a #Preview body (use a trait)	advisory	flag	preview-macro-and-state.md
prev-05	Preview(…, windowStyle:) on a Mac target (visionOS-only overload)	hard-fail	flag	preview-macro-and-state.md
prev-06	#Preview of a @Query/SwiftData view, no .modelContainer(… inMemory: true)	warning	flag	preview-crashes-and-injection.md
prev-07	#Preview of a view reading @Environment(Model.self), no .environment(_:) injection	advisory	flag	preview-crashes-and-injection.md
prev-08	.environmentObject(…) in a preview whose model is @Observable (wrong injector)	warning	flag	entry-and-environment.md
prev-09	repeated .modelContainer(for:inMemory:true) + re-seed across many #Previews (use PreviewModifier)	advisory	flag	preview-modifier-shared.md

Two claims need a floor check at audit time — confirm in VERIFY, never assert from memory: the PreviewModifier / .modifier(_:) floor (macOS 15.0+, carried verify-SDK in floors-master.md); and that @Previewable @Query itself needs macOS 15 (prev-09 fallback path). Both reduce to a gating note, not a hallucination.

The real API, at a glance

Real (exist on macOS): #Preview / Preview(_:traits:_:body:) macro (macOS 14.0+), @Previewable (macOS 14.0+), @Entry (macOS 10.15+, back-deploys; Xcode 15+ to expand → practical floor macOS 14), .fixedLayout(width:height:) / .sizeThatFitsLayout / .defaultLayout traits, PreviewModifier + .modifier(_:) trait (macOS 15.0+), .modelContainer(for:inMemory:), .environment(_:), PreviewProvider (legacy but not deprecated — flag as stale-for-new-code, never as invented).

Hallucinated / platform-wrong (never on macOS): Preview(_:windowStyle:traits:body:) is visionOS-only — there is no windowStyle: #Preview overload on macOS; .environmentObject(_:) for an @Observable is the wrong injector (it takes only an ObservableObject).

✅ Correct — grounded in real macOS code (swiftui-ctx consensus)

The modern shape, from swiftui-ctx lookup Preview → file <recommended.id> --smart (repo utmapp/UTM, 34k★) — the freestanding macro, one declaration per named preview, no PreviewProvider struct:

@available(macOS 13, *)
#Preview {
    UTMServerView()
}

• Source (real permalink): https://github.com/utmapp/UTM/blob/e4a4c34b671284263fc69f81b607de494d7e9b65/Platform/macOS/UTMServerView.swift#L170
• Apple doc (Sosumi): doc: https://sosumi.ai/documentation/swiftui/preview (#Preview macro, introduced_macos: 10.15 — DocC inheritance artifact; authoritative Apple docs badge is macOS 14.0+, same trap as Animation.bouncy in floors files)

This is the live grounding for prev-01: the canonical #Preview { } that replaces the legacy struct …_Previews: PreviewProvider. At FIX time, re-fetch the per-defect consensus shape (swiftui-ctx file <recommended.id> --smart) for that defect's exact ✅, never a hand-written snippet.

Floor values are the reconciled truth in <swiftui-plugin-root>/references/_shared/floors-master.md and the canonical invented-name list in <swiftui-plugin-root>/references/_shared/hallucination-blacklist.md — read, never restate them. The real macOS-26 shape for any symbol comes from swiftui-ctx lookup <api> (step 5), not memory.

The 8-step audit workflow (execute verbatim)

1. ORIENT. tree / find the SwiftUI sources. Read the deployment target (project.pbxproj MACOSX_DEPLOYMENT_TARGET, or Package.swift platforms:). It is load-bearing for prev-09 (PreviewModifier/@Previewable @Query need macOS 15). Record it.
2. LOCATE. Run the shared hybrid lint runner: bash <swiftui-plugin-root>/scripts/swiftui-lint.sh --skill audit-swiftui-previews --dir <sources> --json /tmp/prev.json --sarif /tmp/prev.sarif. It runs this skill's tier-1 grep tells (lint/grep-tells.tsv) + the one tier-2 structural ast-grep rule (lint/ast-grep/prev-02-*.yml — the bare-@State-inside-a-#Preview-body containment rule grep can't express), plus a per-file parse probe, and emits unified JSON + SARIF. (prev-06's un-injected-container case stays a grep co-occurrence tell — a precise structural rule would need cross-declaration data flow ast-grep can't resolve and would false-positive on the correct separate-#Preview injection; READ the located site to confirm. See lint-architecture.md.) Read its parse_warnings — a flagged file did not fully parse, so a structural miss can't masquerade as clean; READ those by hand. The runner only LOCATES. Engine + rule-file format: <swiftui-plugin-root>/references/_shared/lint-architecture.md.
3. READ. Open every located file in full — never pattern-match-and-patch blind. Whether a @State sits at #Preview body scope vs inside the previewed view, whether a previewed view reads @Query/@Environment, and whether a container is already injected upstream are all invisible to grep. Build a per-file inventory: each #Preview + what state it declares + what dependencies the previewed view reads + whether each is provided.
4. DETECT. Apply the index. Assign each candidate a confidence; report a finding only at 100% certainty (e.g. a bare @State at #Preview body scope, a windowStyle: overload on a Mac target, a @Query view with no injected container).
5. VERIFY. For anything ≤ ~70% confidence (a symbol you're unsure exists, a floor you can't place, a behavior claim), run both evidence sources. (a) Practice — bash <swiftui-plugin-root>/scripts/swiftui-ctx lookup <api> --json (and bash <swiftui-plugin-root>/scripts/swiftui-ctx deprecated <api> for a currency/deprecation rule like prev-01): read its consensus (the canonical shape), deprecated+replacement, recommended permalink, introduced_macos, and co_occurs_with (e.g. modelContainer co-occurs with Query / Model — exactly the prev-06 seam); a lookup exit 3 (not-found, with a did-you-mean suggestion) corroborates a hallucination/platform-wrong finding. (b) Spec — confirm via Sosumi: curl -sSL https://sosumi.ai/<apple-path> using references/source-directory.md for the path and <swiftui-plugin-root>/references/_shared/sosumi-reference.md for the protocol (never WebFetch developer.apple.com). Cross-check introduced_macos against floors-master.md and the Sosumi doc: floor. The CLI contract is <swiftui-plugin-root>/references/_shared/swiftui-ctx-reference.md. Promote with the citation or discard. Carry the PreviewModifier floor and @Previewable @Query macOS-15 claim as gating notes with source: verify against Xcode 26 SDK until VERIFY confirms them.
6. REPORT. Write each confirmed finding (output contract below). One finding per file, zero-padded, ordered. Write the run's _index.md.
7. FIX. Apply corrections under the fix-safety protocol (<swiftui-plugin-root>/references/_shared/fix-safety-protocol.md): clean-tree gate, findings-first, only fix_mode: auto (this domain ships none by default — every fix is flag-only; see below), one conventional commit per finding citing its rule_id, never weaken a check. The ✅ "Correct" is not a hand-written snippet — it is the swiftui-ctx consensus shape put in ## Correct, backed by a real macOS example fetched with bash <swiftui-plugin-root>/scripts/swiftui-ctx file <recommended.id> --smart whose GitHub permalink (plus the Sosumi doc:) goes in ## Source. Leave flag-only findings open with that ✅.
8. DOUBLE-CHECK. Re-grep each fixed file to confirm the tell no longer matches; record the evidence in ## Fix applied?. Re-confirm every citation still resolves and still says the floor you claimed. If a fix introduced a new tell (e.g. a .environment(_:) you added now needs a sample factory that itself reads a dependency), loop that file back to DETECT.

Confidence gating (load-bearing)

Report a finding only at 100% certainty. Anything ≤ ~70% goes to VERIFY (step 5) before it can become a finding — never emit a speculative finding. Every defect in this domain is fix_mode: flag-only: the correct preview body depends on the view's real dependencies and sample data, which only the developer (or the swiftui-ctx consensus shape) can supply — there is no safe mechanical single-answer rename. Surface every fix as a suggested diff with the ✅, never auto-applied.

Output contract

Inherits the toolkit's unified contract (full schema + body sections + frontmatter keys: <swiftui-plugin-root>/references/_shared/finding-schema.md — do not restate it). Specialized for this domain:

• Findings: swiftui-audits/previews/<context>/NN-slug.md (one finding per file, zero-padded, ordered). Per-run index: swiftui-audits/previews/_index.md.
• domain: previews. Frontmatter is the canonical schema; fix_mode is flag-only for every prev-NN (see confidence gating). availability reads from floors-master.md. source is an Apple URL + access date (fetched via Sosumi) or verify against Xcode 26 SDK. Emit cross_ref on the shared-seam findings (prev-06 → swiftdata, prev-07 → state-observation, prev-03 → menus-commands when command-co-located, prev-01 → api-currency).

Starter <context> folders (file here when…):

<context>	File a finding here when…
legacy-preview-struct/	a PreviewProvider struct stands in for the #Preview macro (prev-01)
previewable-state/	bare @State/@Binding/@Bindable lives at #Preview body scope (prev-02)
environment-entry/	hand-rolled EnvironmentKey boilerplate, or the wrong .environmentObject injector (prev-03, prev-08)
preview-traits/	a manual .frame sizing hack, or the visionOS-only windowStyle: overload (prev-04, prev-05)
canvas-crash-injection/	a @Query/SwiftData or @Environment view ships no injected dependency (prev-06, prev-07)
preview-modifier/	repeated inline in-memory containers should collapse to one PreviewModifier (prev-09)

New-folder rule: if a finding does not fit any existing context folder, create a new one under swiftui-audits/previews/ with a lowercase-hyphen slug naming the sub-category, and note it in the run's _index.md. Prefer an existing folder when the fit is reasonable; consistency across runs is a hard requirement. Two runs over the same code produce structurally identical trees.

Reference routing

File	Open when
references/preview-macro-and-state.md	the macro-vs-PreviewProvider call, @Previewable state, traits-vs-.frame, the windowStyle: platform trap (prev-01/02/04/05)
references/entry-and-environment.md	@Entry-vs-EnvironmentKey boilerplate and the .environment vs .environmentObject injector (prev-03/08)
references/preview-crashes-and-injection.md	the two canvas-crash traps — missing in-memory container, missing @Environment injection — and the instantiation test (prev-06/07)
references/preview-modifier-shared.md	collapsing repeated inline in-memory containers into one shared PreviewModifier (macOS 15+) (prev-09)
references/source-directory.md	step VERIFY — the Apple/WWDC/practitioner source map fetched via Sosumi
lint/grep-tells.tsv + lint/ast-grep/*.yml	step LOCATE — this skill's declarative lint rule set fed to the shared runner (tier-1 grep tells + tier-2 structural ast-grep); edit here to tune detection

Shared toolkit references (point in, never restate):

Shared file	For
<swiftui-plugin-root>/references/_shared/floors-master.md	every floor/availability value (@Previewable, @Entry, #Preview, PreviewModifier, ModelContainer.init) — the reconciled truth
<swiftui-plugin-root>/references/_shared/hallucination-blacklist.md	the canonical invented / platform-wrong name list
<swiftui-plugin-root>/references/_shared/macos-arm-gating.md	the macOS-arm gating rule (prev-09 floor gates) + the macOS ABSENT (visionOS-only windowStyle:) rule
<swiftui-plugin-root>/references/_shared/finding-schema.md	the unified finding schema + frontmatter keys
<swiftui-plugin-root>/references/_shared/fix-safety-protocol.md	the 8-point fix-safety protocol (step 7)
<swiftui-plugin-root>/references/_shared/sosumi-reference.md	the Apple-doc spec fetch protocol (step 5 VERIFY)
<swiftui-plugin-root>/references/_shared/swiftui-ctx-reference.md	the practice-corpus CLI contract — lookup/deprecated/file --smart for the consensus shape + permalinked example (steps 5 VERIFY · 7 FIX)
<swiftui-plugin-root>/references/_shared/cross-ref-graph.md	seam ownership + cross_ref targets (the previews row + the @Entry/FocusedValueKey and preview-container tiebreakers)

Detection accelerator

bash <swiftui-plugin-root>/scripts/swiftui-lint.sh --skill audit-swiftui-previews --dir <files-or-dir> [--json out.json] [--sarif out.sarif] — the toolkit's one shared hybrid lint engine, fed this skill's declarative rules: tier-1 grep tells (lint/grep-tells.tsv, prev-01/03/04/05/06/07/08/09 flat presence) + one tier-2 ast-grep structural rule (lint/ast-grep/prev-02-*.yml — bare-@State-inside-a-#Preview-body containment, which grep cannot express). prev-06's un-injected @Query view is a grep co-occurrence tell, not a structural rule (a precise one needs cross-declaration data flow ast-grep can't resolve — lint-architecture.md). It runs a per-file parse probe (surfaces "did not fully parse" so a structural miss can't look clean), emits unified JSON + SARIF, and degrades to grep-only with a notice if ast-grep is unreachable (npx --package @ast-grep/cli ast-grep; faster: brew install ast-grep). This domain ships no tier-1 hard tell, so the runner does not exit 2 — it emits warnings/advisories only (no hard-fail tells — nothing blocks the gate). The located traps (prev-02/05/06/07) are still confirmed by the LLM in DETECT after READ, never by a flat grep. It only LOCATES — always READ each hit in full before reporting (step 3). The thin scripts/preview-lint.sh is a pointer to this runner. Engine + rule-file format + JSON/SARIF shape + safety rails: <swiftui-plugin-root>/references/_shared/lint-architecture.md.