Identifies and fixes common Rust anti-patterns. Use during code review, when seeing excessive clones/unwraps/index loops, or when code fights the borrow checker instead of working with it.
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Layer 2: Design Choices
Is this pattern hiding a design problem?
When reviewing code:
| Rank | Mistake | Fix |
|---|---|---|
| 1 | Clone to escape borrow checker | Use references |
| 2 | Unwrap in production | Propagate with ? |
| 3 | String for everything | Use &str |
| 4 | Index loops | Use iterators |
| 5 | Fighting lifetimes | Restructure to own data |
| Anti-Pattern | Why Bad | Better |
|---|---|---|
.clone() everywhere | Hides ownership issues | Proper references or ownership |
.unwrap() in production | Runtime panics | ?, expect, or matching |
Rc when single owner | Unnecessary overhead | Simple ownership |
unsafe for convenience | UB risk | Find safe pattern |
OOP via Deref | Misleading API | Composition, traits |
| Giant match arms | Unmaintainable | Extract to methods |
String everywhere | Allocation waste | &str, Cow<str> |
Ignoring #[must_use] | Lost errors | Handle or let _ = |
| Smell | Indicates | Refactoring |
|---|---|---|
Many .clone() | Ownership unclear | Clarify data flow |
Many .unwrap() | Error handling missing | Add proper handling |
Many pub fields | Encapsulation broken | Private + accessors |
| Deep nesting | Complex logic | Extract methods |
| Long functions | Multiple responsibilities | Split |
| Giant enums | Missing abstraction | Trait + types |
.clone() without justification.unwrap() in library codepub fields with invariantsString where &str suffices#[must_use] warningsunsafe without // SAFETY: comment| Deprecated | Better |
|---|---|
| Index-based loops | .iter(), .enumerate() |
collect::<Vec<_>>() then iterate | Chain iterators |
| Manual unsafe cell | Cell, RefCell |
mem::transmute for casts | as or TryFrom |
| Custom linked list | Vec, VecDeque |
lazy_static! | std::sync::OnceLock |
once_cell::Lazy | std::sync::LazyLock |
ownership — fixing ownership anti-patternserror-handling — replacing unwrap chainsperformance — fixing allocation anti-patternstype-driven-design — fixing primitive obsessionNo reviews yet. Tell others what you thought.
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Add an iOS App Clip target to an Expo app. Use when the user mentions App Clip, AASA, apple-app-site-association, appclips, smart app banner, or wants to ship a lightweight iOS Clip invoked from a URL alongside their parent app.
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Automates browser interactions for web testing, form filling, screenshots, and data extraction. Use when the user needs to navigate websites, interact with web pages, fill forms, take screenshots, test web applications, or extract information from web pages.
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Add Agentation visual feedback toolbar to a Next.js project
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Apple's approach to interface design and fluid, physical motion, translated for the web. Use when building or reviewing gesture-driven UI, spring animations, drag/swipe/sheet interactions, momentum and interruptible transitions, translucent materials and depth, typography (optical sizing, tracking, leading), reduced-motion, or the design foundations (feedback, spatial consistency, restraint) behind Apple-style interfaces.
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Derive and implement first-principles audio-coupled haptic and kinetic UI feedback. Use when designing, reviewing, or coding haptics/audio for mobile apps, native iOS/Android, React Native/Expo, SwiftUI, games, detent pickers, toggles, sliders, page curls, scroll gestures, wallet/signature flows, Solana transactions, backend/realtime state changes, confirmations, settlements, and semantic UI events where feedback should follow signal math instead of ad hoc vibration calls.
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Babysit a GitHub pull request during a user-approved monitoring window by polling review comments, CI checks/workflow runs, and mergeability state. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and report fresh review feedback. Use when the user asks Codex to monitor a PR, watch CI, handle review comments, or keep an eye on failures and feedback on an open PR.
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