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name: adversarial-swift-ui description: Use this skill to gate SwiftUI code with a pass/fail adversarial review — a single blind reviewer subagent judges a diff or file set against 31 decidable rules — data modeling and observation (@Observable over ObservableObject, @State ownership, task(id:) re-init guards, environment closures and high-frequency values), view update cost (computed-var extraction, whole-model dependencies, init side effects, uncached derivations, structs on rows), structural identity (applyIf branching, AnyLayout), task lifecycle (.task over onAppear+Task, scalar ids, @concurrent offloading), lists and geometry (ForEach view count, AnyView rows, GeometryReader measurement, feedback loops, visualEffect), animation scope, and accessibility (button semantics, style protocols, accessibilityRepresentation, semantic styling, ScaledMetric spacing). Trigger before merging SwiftUI work or to audit agent-authored views. Verdicts only, never fixes; targets without a SwiftUI surface abort.

Adversarial SwiftUI Gate

A SwiftUI architecture review gate — pass/fail: a single blind reviewer subagent judges the work against this gate's rules with an adversarial mandate, and the work passes only when every rule is PASS or N/A. This skill renders verdicts; it never fixes the work.

The rules are filtered down to the checks a reviewer can decide from code evidence alone. The gate judges the failure modes agents and experienced-but-not-expert developers actually produce: legacy observation stacks, identity-destroying conditionals, work attached to the wrong lifecycle point, laziness-defeating list construction, animations that leak across generic content, and controls that opt out of the system's accessibility semantics.

When to Apply

• A SwiftUI diff, feature, or PR is about to merge and needs an objective PASS/FAIL, not advisory feedback.
• An agent (Claude, Codex) authored the views and you want an independent check that it is not reproducing pre-Observation idioms (ObservableObject/@StateObject, .onAppear { Task { ... } }, AnyView rows, GeometryReader-to-measure) or identity-resetting conditionals (applyIf helpers, container-type switches).
• UIKit-era screens are being ported to SwiftUI and the new surface needs auditing against the framework's update mechanics (subview boundaries, minimal dependencies, cached derivations, stable identity).
• Accessibility and platform-convention compliance must be verified, not assumed — icon-only buttons, tap gestures posing as controls, primitives rebuilt where a style protocol exists, silent Canvas controls, hardcoded fonts, fixed spacing around text.

Do not apply to targets with no SwiftUI surface — server-side Swift, CLI tools, non-UI packages (the reviewer prompt's precondition aborts with "GATE NOT APPLICABLE"). General Swift language quality (concurrency structure, API design, control flow) is the sibling adversarial-swift gate's job, not this one's. Rules whose remedy needs a newer toolchain or deployment target than the project's are N/A, not FAIL — the reviewer prompt carries the version-gate table.

Review Protocol

Follow these steps exactly — the gate's value is that every review runs the same way.

Two preconditions before step 1 — both exist because their violation is the gate family's recorded field-failure mode (July 2026: gates run as cleanup drivers on a moving target rendered zero verdicts while the diff grew to 33 files):

• Frozen target. Dispatch only against a fixed ref — a commit SHA, stash, or saved diff — recorded as the target manifest. If the code under review is still changing (the worktree keeps collecting edits, other agents are active on it), do not dispatch. A target change while the reviewer is in flight voids the run: report GATE VOID — target changed in place of a verdict and re-dispatch against the new frozen state. A dispatched gate must always end in a rendered verdict, a GATE NOT APPLICABLE, or a recorded void — never silence, which is indistinguishable from "reviewed".
• Verdicts, not cleanup. This gate is a terminal check on finished work. "Run the gate and fix everything aggressively" inverts the contract and is the documented path to scope explosion: implement first, freeze, then gate. After a FAIL, the caller applies fixes within the original target only, and the re-gate dispatches a fresh blind reviewer against the same target manifest — the surface never widens between rounds; new code means a new gate invocation with its own manifest.

When other agents may mutate the workspace mid-review, the reviewer reads the rules from an immutable snapshot (e.g. git archive <ref> <skill-dir> | tar -x -C "$TMPDIR") rather than the live checkout — and skill directories are read-only infrastructure, excluded from every cleanup or fix scope.

1. Identify the target. Pin down exactly what is under review (a diff, a set of files, a PR) and note the ref/paths so the review runs against an unambiguous, fixed target. Record the Swift toolchain version and minimum deployment target (from Package.swift, the Xcode project, or availability annotations) — several rules version-gate on them. Include the repo root in the target description — update-pass-minimal-data, state-own-models-in-state, and update-cache-expensive-derivations can require reading whole files beyond the diff hunks.
2. Load the rules. Read references/_sections.md and every rule file in references/ (all state-*.md, update-*.md, identity-*.md, task-*.md, list-*.md, anim-*.md, access-*.md files).
3. Compose the reviewer prompt. Fill references/reviewer-prompt.md with the rules, the target, and the toolchain/deployment facts. The composed prompt must be fully self-contained — a reviewer sees no conversation history, so nothing may refer to context outside the prompt.
4. Dispatch one blind reviewer. Launch a single Task subagent whose entire input is the composed prompt — no conversation context, no commentary alongside it.
5. Render fail-closed. The reviewer's structured output is the verdict — there is no merge step. Overall verdict is PASS only when every rule is PASS or N/A; any single FAIL fails the gate. Never average, weigh severity, or waive a rule — a "minor" FAIL is a FAIL. If the reviewer returns "GATE NOT APPLICABLE" (no SwiftUI surface), stop and report that instead of a verdict.
6. Render the verdict. Fill assets/templates/verdict.md. On FAIL, aggregate the reviewer's "missing for PASS" suggestions into the fix list, each with its location, ordered by category importance. Every rule whose final result is FAIL must appear in the fix list with a change concrete enough to apply as written — if the reviewer's suggestion only restates the violation, derive the fix from the rule's Correct example before rendering. The fix list is verification material — proof that each FAIL is decidable and flippable — not a work queue: every fix names the minimal change that flips its rule inside the declared target, and a fix that reaches for an unsafe escape hatch (@unchecked Sendable, try!, force-unwraps) to satisfy a rule does not flip it. Violations the reviewer noticed outside the target manifest go under the verdict's out-of-scope observations — reported for a future gate invocation, never fixed under this one, never counted in the verdict.

If the same rule flips verdicts across re-reviews of an unchanged target, or a human reads the evidence and overrides the verdict, that is a decidability bug in the rule — record it in gotchas.md and sharpen the rule; do not override the gate.

Verdict Format

The reviewer returns, per rule: PASS | FAIL | N/A, evidence (file:line or a quote — required for PASS as well as FAIL), and for every FAIL, the fix that flips the rule to PASS once applied — the named change plus its location, never a restatement of the violation. The final report follows assets/templates/verdict.md.

Rule Categories

#	Category	Prefix	Covers
1	Data Modeling & Observation	state-	@Observable over ObservableObject, @State ownership of view-created models, no State(initialValue:) from init params, identity guards on .task(id:) model re-creation, callAsFunction wrappers for environment closures, no high-frequency values in EnvironmentValues
2	View Update Cost	update-	Subview structs over computed some View vars, minimal data per leaf view, no side effects in view init, cached O(n) derivations, no collection-bearing structs on list rows
3	Structural View Identity	identity-	Branch inside modifier values not around views, no runtime if/else in modifier helpers (applyIf), AnyLayout over container branches
4	Data Loading & Task Lifecycle	task-	.task over .onAppear+Task, .task(id:) over .onChange+Task, scalar compared values, @concurrent offloading of CPU work in @MainActor observables
5	Lists & Geometry	list-	Constant per-element view count in ForEach, no AnyView rows, onGeometryChange over measurement GeometryReader, no geometry feedback loops, visualEffect for scroll-driven transforms
6	Animation Scope	anim-	animation(_:body:) for generic containers over value-based .animation on arbitrary content, built-in animatable attributes over custom Animatable
7	Platform Conventions & Accessibility	access-	Buttons built with title and icon, Button over onTapGesture, style protocols over rebuilt controls, accessibility representations for bespoke controls, semantic fonts and colors, @ScaledMetric for custom spacing near text

Gotchas

Read gotchas.md before dispatching the reviewer — it pre-records rule-fidelity guards (patterns this gate's rules endorse that community lore condemns, such as id: \.self on constant collections and view models held in @State) so the reviewer does not import outside rules.

Related Skills

• adversarial-swift — the sibling gate for Swift language concerns (concurrency, error propagation, API and type design, control flow); run both on mixed Swift+SwiftUI work.
• adversarial-ios-design — the sibling gate for rendered design and UX (HIG grammar, motion, mandatory evidence capture); run it too on user-facing work, and run it first when the diff changes gestures or interaction behavior — recognizer arbitration is invisible to this gate's code-only review.
• ios-taste (curated) — judgment-call iOS design guidance this gate deliberately excludes; use it when the goal is taste, not a verdict.
• search-ios26-docs / search-macos26-docs — verify current-SDK API availability when a version-gate question decides a rule.

Reference Files

File	Description
references/reviewer-prompt.md	Self-contained prompt template for the blind reviewer
assets/templates/verdict.md	Verdict report template
references/_sections.md	Category definitions and ordering
metadata.json	Version and source references