デモ実行記録 · claude-sonnet-5-5 · 2026年10月

Stress-test this component for me. I can't give you a browser or a dev server, so reason from the code and say which findings are inferred. Do not write any files; give me the report only. The schema allows name up to 255 chars, email up to 254, title up to 120, and there is no limit on member count. ```jsx function MemberRow({ member }) { const initials = member.name.split(' ')[0][0] + member.name.split(' ')[1][0]; return ( <div style={{ display: 'flex', alignItems: 'center', gap: 12 }}> <img src={member.avatar} className="avatar" style={{ width: 40, height: 40, borderRadius: '50%' }} /> <div> <div className="name">{member.name}</div> <div className="email">{member.email}</div> <div className="role">{member.title || '-'}</div> </div> <span className="badge">{member.status}</span> <button className="menu">...</button> </div> ); } function Header({ count }) { return <h2>{count} members</h2>; } ``` Demo data: { name: 'Jane Doe', email: '[email protected]', title: 'Designer', status: 'active', avatar: '/a/jane.png' }, count 12.

Skill: break-ui

Stress test: `MemberRow` and `Header`

I built no toggle and wrote no files, as you asked. I didn't render anything either, so every finding below is inferred from the JSX. I couldn't see your CSS for .avatar, .name, .email, .role, .badge or .menu, nor the parent list. Any finding that depends on those is marked.

Surface map

Field	Source	Limit	Optional?
`name`	`member.name`	255	No
`email`	`member.email`	254	No
`title`	`member.title`	120	Yes (`\|\| '-'`)
`status`	`member.status`	Enum values unknown	No
`avatar`	`member.avatar`	Unknown	Probably, since there's no fallback
`count`	`Header` prop	Unbounded	No
Member list	Parent (not shown)	Unbounded	Can be empty

Part 1: What broke

#	Severity	Field	Worst-case value	What happens	Fix
1	Broken	`name`	`'Jo'`, `'Madonna'`, `'张伟'`, `''`	`name.split(' ')[1]` is `undefined`, so `undefined[0]` throws a `TypeError`. The row crashes during render. Without an error boundary, the whole member list unmounts. One-word names and Chinese or Japanese names (which have no spaces) are common. The `initials` variable is never used, so the crash buys nothing.	Delete the line, or replace it with a safe helper that takes the first and last word, uses `Intl.Segmenter` for graphemes and falls back to an icon. Then use it as the avatar fallback (see #4).
2	Broken	`email`	254-char email, or a realistic `[email protected]`	An email has no break opportunities. The text column is a flex child with `min-width: auto`, so it can't shrink below the string's width. It pushes the badge and `...` menu off the row or clips them, and the menu becomes unreachable.	`min-width: 0` on the text column. `overflow-wrap: anywhere` on `.email` (or ellipsis plus a `title`). `flex-shrink: 0` on the badge and the button.
3	Ugly	avatar	Any long name or email	The `<img>` has `width: 40` but the default `flex-shrink: 1`, so it can squash into a narrow oval when the text column is wide.	`flex-shrink: 0` on the avatar. Add `object-fit: cover` for non-square photos.
4	Ugly	`avatar`	`undefined`, `''`, or a 404 URL	There's a broken-image icon, or an empty `src` that may re-request the page. There's no `onError` and no initials fallback.	Fall back to an initials circle on missing `src` or `onError`.
5	Ugly	`name`	255 chars with spaces (such as a full legal name with several surnames)	It wraps to many lines. With `align-items: center`, the avatar, badge and menu float mid-height. With no `margin-left: auto`, the badge and menu sit right after the text, so they don't line up between rows. That last part may already show with demo data, depending on your CSS.	`align-items: flex-start`. Clamp `.name` to 2 lines (with a `title`). `margin-left: auto` on the badge.
6	Ugly	`title`	Missing, `''`, or `' '`	A bare `-` shows under the email. Whitespace-only passes the `\|\|` check and renders an empty line.	Trim the title. Omit the line when empty.
7	Ugly	`status`	Raw enum value such as `pending_invite`, or a localized label	The badge shows the raw value, so underscores and lowercase appear. A long label can wrap because the badge may shrink. An unknown value or `null` gives a blank or meaningless pill.	Map status to a label and a style, with a fallback. `white-space: nowrap; flex-shrink: 0`.
8	Ugly	`count`	`1`, `0`, `1284`, `null`	"1 members", "0 members", unseparated `1284`, and " members" when `null`.	`Intl.PluralRules` (or separate strings). `Intl.NumberFormat`. Guard `null`.
9	Fragile	member list	1,000+ members	The schema has no limit, and nothing here paginates or virtualizes. If the parent maps every member, that is thousands of rows with inline style objects, with no `React.memo`. The `Header` count can also disagree with the number of rows rendered if the list is paginated.	Virtualize or paginate (decide in Part 2). Make sure `count` comes from the total, not `list.length`.
10	Fragile	`...` button	Any	It has no accessible name (screen readers read "dot dot dot"). It has no `type="button"`, so it submits if the row is ever inside a `<form>`.	`aria-label="Member actions"` and `type="button"`.
11	Fragile	`<img>`	Any	There's no `alt`, so the screen reader may read the filename.	`alt=""` if decorative, or `alt={member.name}`.
12	Fragile	RTL, 200% zoom, dark mode	n/a	These depend on your CSS. The inline `gap` and `flexbox` are direction-safe. Zoom will make #2 and #5 worse. Dark mode can't be judged from the JSX.	Check these once the fixes are in.

Part 2: Decisions for you

Name: I recommend wrapping at 2 lines, with the full value in title. People identify each other by name, so I wouldn't truncate it.
Email: I recommend wrapping with overflow-wrap: anywhere. If you truncate instead, use the middle, because long emails often differ only in the local part or the domain.
Title: I recommend one line with an end ellipsis and a title, since it's secondary info.
Missing title: I recommend omitting the line. This is a minor call, but a lone - looks like a bug.
Long member list: I recommend pagination if the list is mostly searched or filtered. If people scroll it as a roster, virtualize it instead.

Part 3: What held up

Escaping: React escapes all the text, so a name like <b>x</b> or & shows literally. There's no dangerouslySetInnerHTML.
Missing title: A missing or empty title doesn't crash, apart from the cosmetic dash in #6.
Row layout: The row has no fixed width or height, so it can grow with its content.
Avatar shape: borderRadius: '50%' on a fixed 40×40 gives a circle at rest.
Demo data: With Jane Doe, the single-line layout looks fine, and "12 members" is correct.

Not covered

I haven't seen the parent list, its keys, its empty state (zero members) or its loading state. Those are worth a look next. I also didn't test emoji-first names or diacritic clipping, since both depend on CSS I can't see. Once #1 is fixed, an emoji-first name will come out wrong in any initials code that doesn't use graphemes.

The most urgent fix is #1, because it can take down the whole page. Say fix all or fix 1, 2, 3 and I'll apply them, though you asked for no file edits for now.

Test run: a small member-row component pasted as code. No browser or dev server was available, so the model said every finding is inferred and wrote no files, as asked. It did not open the Skill's CATALOG.md in this run. It found a crash for one-word names and several layout breaks.

できること

デモデータだときれいに見える UI から、「選ばれた良いデータ」という前提を外します。まずコンポーネントが描画するすべての値と上限（検証スキーマ、データベース、API から）を洗い出し、壊れやすい値のカタログから最悪ケースのデータを組み立てます。長い名前や発音記号付きの名前、折り返せないメールや URL、1文字の名前や絵文字から始まる名前、ちょうど1件の数、空や巨大なリスト、画像や項目の欠落などです。データはデモデータと同じ入口から入れ、開発専用の「デモデータ / 最悪ケース」トグルの背後に置きます。実際のコンテナ幅、320px、200%ズーム、ダークモード、RTL で確認し、症状、原因、重大度（壊れた、見苦しい、脆い）、直し方とともに報告します。修正の前で止まるので、判断はあなたに残ります。

出力

指摘の表、あなたが決めるべき事項（切り詰めか折り返しか、空状態の表示）、問題なかった点、修正の適用方法。

こんな場面に

実際のユーザーより先にレイアウトやデータの不具合を見つけたい開発者とデザイナー。

補足とリスク

低リスク：指示のみのファイルで、スクリプトはなく、ネットワークにも接続しません。プロジェクト内では開発専用のトグルと最悪ケースのデータファイルを追加することがあります。先に報告し、頼まれたときだけ直しますが、書き込まれたファイルは確認してください。貼り付けたコンポーネントをブラウザなしで一度試用し、すべての指摘が推論であること、ファイルを書かなかったこと、1語の名前でクラッシュすることといくつかのレイアウト崩れを報告しました。この回は同梱のカタログを開きませんでした。質問なしで呼ぶと挨拶だけを返します。作者 Emil Kowalski、MIT。

SKILL.md 原文パッケージ内 3 ファイル