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SwiftUI Motion · athevon | DecimalAI

frontendby athevon

SwiftUI Motion

athevon/swiftui-motion

Source athevon/genjutsu ↗License NOASSERTION

SwiftUI animation foundations - withAnimation, transitions, matchedGeometryEffect, PhaseAnimator, KeyframeAnimator, springs, gestures.

SkillScore100Maintained

Automatic

Frontend / UI pack

Last verified 9/25/2026

What it changes

Passed 22 of 22 test cases with the skill, and 18 of 22 without it.

Without skill82%

With skill100%

Checks it passed that the model alone missed

Reads accessibilityReduceMotion from the environment.
Uses a spring animation parameter instead of easeInOut.
Binds implicit animation modifiers with an explicit value parameter.

and 1 more in the full report

4 fixed18 passed either way0 still failing0 broke

Pass-rate lift: +18 pp
Tokens: +140%
Agent turns: 0%
Response time: -16%

Model gemini-3.6-flashMeasured 9/25/2026v222 of 22 cases passed with skill

Tokens, turns and time describe resource use, not a dollar price.

Use this skill

Save it into your project's skills folder. Claude Code picks it up in its next session.

curl -fsSL --create-dirs -o .claude/skills/athevon-swiftui-motion/SKILL.md https://app.decimal.ai/s/athevon-swiftui-motion/SKILL.md

Want it pinned and updatable? pip install "decimalai>=0.15", then decimalai skills add athevon-swiftui-motion, and start Claude Code with claude --plugin-dir "$(git rev-parse --show-toplevel)/.agents"

1 · One-time — install the CLI (docs ↗)

pip install "decimalai>=0.15"

2 · Get the skill — writes .agents/skills/athevon-swiftui-motion/ and pins it in .decimal/skills.lock

decimalai skills add athevon-swiftui-motion

No CLI? Get the same file — curl · raw file

curl -fsSL --create-dirs -o .claude/skills/athevon-swiftui-motion/SKILL.md https://app.decimal.ai/s/athevon-swiftui-motion/SKILL.md

Raw file: /s/athevon-swiftui-motion/SKILL.md ↗ · machine-readable summary at /s/athevon-swiftui-motion.json ↗

Safety checks: 3 of 3 passed

Code scan CleanIntent PassedContent Clean

See it in action

One of 4 test cases the skill fixed. Same model, same prompt, with and without the skill.

1 of 4

Prompt

My SwiftUI expandable detail card stutters during frame size changes and feels jarring when removed from the screen. Here is my current view toggled by an expanded state variable. Could you refactor this view so the layout transitions feel natural, entry and exit effects are smooth, and animation modifiers are applied according to performance best practices?

What was checked, without and with the skill
Checked	Without skill	With skill
Replaces direct frame size animation with scale transformations or layout transitions.	Passed	Passed
Combines opacity with scale or move transitions to avoid scaling down to zero.	Passed	Passed
Reads accessibilityReduceMotion from the environment.	Missed	Passed

case-02 · gemini-3.6-flash · 9/25/2026 · answers are capped and redacted

What's inside

The instructions your model reads when the skill loads.

SKILL.md383 lines4 files

Version-sensitive. Every API name, SDK gate and browser-support claim below was verified on 2026-09-08 against primary sources. What against, and when, is in _jutsu/VERSIONS.md. If that date is old, re-verify before acting on a version number.

SwiftUI Motion

SwiftUI animation core. Loaded for any SwiftUI project (iOS, macOS, multi-target Apple). Concise rules here. Deep-dive in references/. Pair with ../motion-principles/SKILL.md (foundation) and ../mobile-principles/SKILL.md (touch UX).

Animation API decision tree

Need	API
Single value over time	`withAnimation { } + @State` or `.animation(_, value:)`
Multiple coordinated states	`PhaseAnimator(phases)` (iOS 17+)
Time-based keyframes	`KeyframeAnimator(initialValue:repeating:content:)` (iOS 17+)
Custom property animations	`@Animatable` macro (needs Xcode 26 / SwiftUI 2025 SDK to compile; runtime availability iOS 13.0+ / macOS 10.15+ / watchOS 6.0+) or the `Animatable` protocol by hand (iOS 13+)
Shared element transitions	`matchedGeometryEffect(id:in:)`
Gesture-driven	`DragGesture` / `MagnifyGesture` + `.offset` / `.scaleEffect`
Loop forever	`.animation(.linear.repeatForever(autoreverses: true), value: ...)` or `.phaseAnimator`

Rule: start with withAnimation. Reach for PhaseAnimator only when you have 3+ ordered states. Reach for KeyframeAnimator only when you need parallel time-based tracks.

Springs (the only easing you should care about)

SwiftUI ships named spring presets (iOS 17+): .snappy, .bouncy, .smooth, plus the parameterised .spring(duration:bounce:blendDuration:) and .interactiveSpring(...). Each of the three named ones also takes (duration:extraBounce:) overloads. Use them. Tune response / dampingFraction only when a preset is wrong.

Preset (iOS 17+)	Equivalent	Mood
`.snappy`	`.spring(response: 0.5, dampingFraction: 0.85)`	UI snappy
`.bouncy`	`.spring(response: 0.5, dampingFraction: 0.7)`	playful
`.smooth`	`.spring(response: 0.5, dampingFraction: 1.0)`	calm, no bounce

Track record

Benchmark

22 / 22

test cases passed, vs 18 / 22 without

Adoption

Users: 0
Times used: 0

Safety and source details

SkillSafety

✓ 3 of 3 passed

Code scan15 of 15 checks clean

0 critical · 0 warning · 0 info — scanner v5 — 9/10/2026

View 15 scanner checks

live_secretremote_code_executionreverse_shelldata_exfiltrationssrf_metadataagent_snoopinganti_refusaldestructive_commandsobfuscated_unicodeunicode_homoglyphopaque_blobsuspicious_urltool_overreachtrigger_abuseprompt_injection_phrasing

IntentSafe

LLM judge · does the skill do what it claims

ContentClean

LLM judge · policy & harmful-content review

Source

Imported

athevon / genjutsu

skills/_jutsu/swiftui-motion/SKILL.md

View on GitHub ↗

License NOASSERTIONImported 10/3/2026Version v2Bundled 3 files

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Ready to supercharge your AI agents?

See it in action

What's inside

SwiftUI Motion

Animation API decision tree

Springs (the only easing you should care about)

Track record

Benchmark

Adoption

SkillSafety

Source

Other skills for the same job

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