notifications-and-recovery（通知和恢复）

Notifications and Recovery

When something changes — success, failure, or anything in between — the user must know. And when something goes wrong, they must always have a path forward. A notification without a recovery action is just an apology.

Pattern Selection

Toast Notifications

Toasts confirm that a background action completed. They appear without interrupting the user's flow.

Placement: bottom-center or bottom-right. Never top-center — it competes with page content and navigation.

Duration: 4–6 seconds for information. Errors should persist until dismissed — the user needs time to read and act.

Anatomy:

[Icon] Message text                    [Action] [×]

• Icon: colour-coded (green ✓ success, red ✗ error, orange ⚠ warning, blue ℹ info)
• Message: one sentence, plain language
• Action (optional): "Undo", "Retry", "View" — one action maximum
• Close button: always present on errors; optional on success

✓ "Changes saved."
✓ "Message sent.  [Undo]"
✗ "Could not save. Check your connection.  [Retry]"  ← persists until dismissed

Never: multiple simultaneous toasts. Queue them; show one at a time.

Inline Errors

Inline errors appear adjacent to the element that caused them. They are the most contextual and actionable form of error feedback.

Form validation:

• Validate on blur (leaving a field), not on every keystroke — keystroke validation is noisy
• Validate on submit for the complete form
• Show the error message directly below the field, in red, with an icon
• The field border changes to --color-error
• Error message is associated via aria-describedby for screen readers

<label for="email">Email</label>
<input id="email" aria-describedby="email-error" aria-invalid="true">
<p id="email-error" role="alert">Enter a valid email address.</p>

In-place editing:

• When a field is edited inline (table cell, card title), show save/cancel controls adjacent to the field
• On save: brief success indicator ("✓ Saved") that fades after 2s — do not navigate away
• On error: inline error message below the field with a retry option
• On cancel: restore the original value immediately

Alert Banners

Banners are persistent — they stay until the condition is resolved or the user dismisses them.

Use for:

• Service degradation ("Some features are temporarily unavailable")
• Account issues requiring action ("Your subscription expires in 3 days. [Renew]")
• Ongoing sync errors ("Changes are not saving. [Retry]")
• Important announcements tied to the current page

Placement: top of the affected section, not the entire page unless the issue is truly global.

Anatomy:

[Icon] [Message — describes the issue and its scope] [Action] [×]

• One banner at a time per region — multiple simultaneous banners create alarm fatigue
• Dismissible unless the condition is blocking
• Colour follows status colour conventions: red (error), orange (warning), blue (info), green (success/resolved)

Recovery Patterns

Every error state must have a path forward. Design the recovery action at the same time as the error message.

Retry

For transient failures (network, timeout, rate limit):

"Could not load results."
[Try again]

• Retry button triggers the same action
• After 3 failed retries, escalate: "Still having trouble? [Contact support]"
• Show a spinner during retry — do not let the user click multiple times

Undo

For destructive or irreversible actions (delete, archive, send):

"Message sent.  [Undo]  ×"

• Undo window: 5–10 seconds. Toast persists for this duration.
• After the window closes, the action is final
• Undo is preferable to confirmation dialogs for low-stakes actions — it is faster and less disruptive

Autosave and Draft Recovery

For long-form inputs (forms, documents, editors):

• Autosave every 30–60 seconds silently
• On save failure: "Autosave failed — your changes are stored locally. [Retry save]"
• On return after crash or close: "You have unsaved changes from [time]. [Restore] [Discard]"

Graceful Degradation

When a feature fails but the rest of the product still works:

• Show an error state for the failed section only — do not blank the entire page
• Offer a fallback: "Could not load recommendations. [Browse all products →]"
• Log the error silently; surface only what the user needs to know

Loading and Skeleton States

Loading is not an error, but it is a state that needs design.

• Skeleton screens for content-heavy pages — show the layout shape while data loads
• Spinners for targeted async actions (button loading, inline refresh)
• Progress bars for long operations with known duration (file upload, multi-step processing)
• Never show a blank screen while loading — always show something

Skeleton screens reduce perceived wait time compared to spinners. Match the skeleton shape to the actual content layout.

Notification Accessibility

• Errors use role="alert" — announced immediately by screen readers
• Status updates use role="status" — announced politely (after current speech)
• Toasts must be reachable by keyboard — do not use pointer-events: none on the close button
• Auto-dismissing toasts must have sufficient duration (prefers-reduced-motion users may need more time to read)

<!-- Error: immediate announcement -->
<div role="alert">Could not save. Check your connection.</div>

<!-- Status: polite announcement -->
<div role="status" aria-live="polite">Changes saved.</div>

Review Checklist

• Does every error have a recovery action (retry, undo, contact support)?
• Do toasts auto-dismiss for success but persist for errors?
• Is there never more than one toast visible at a time?
• Are inline errors placed adjacent to the field, not at the top of the form?
• Are form errors associated to their inputs via aria-describedby?
• Do alert banners appear at the top of the affected section, not always full-page?
• Is autosave or draft recovery available for long-form inputs?
• Do loading states use skeletons for content and spinners for targeted actions?
• Are errors announced via role="alert" and status updates via role="status"?