Establish the widget execution model (the extension process, app groups, the timeline lifecycle, the reload budget) using references/fundamentals.md.
Validate the timeline provider (placeholder/snapshot/timeline, reload policy, WidgetCenter reloads, entry relevance) using references/timeline-provider.md.
Validate the configuration and any user-configurable parameters (StaticConfiguration, AppIntentConfiguration, WidgetConfigurationIntent) using references/configuration-and-intents.md.
Check whether any legacy API is in use and route it to the modern equivalent (SiriKit .intentdefinition → App Intents, ClockKit → WidgetKit, PreviewProvider → #Preview) using references/migration-and-deprecations.md.
Validate data loading - networking, persistence, images, location - in the provider and intents using references/data-and-networking.md.
Validate family support and per-family layout (WidgetFamily, sizing, content margins, ViewThatFits) using references/families-and-layout.md.
Validate Lock Screen / accessory widgets and watch complications (widgetLabel, AccessoryWidgetBackground, the transparent-container trick, ClockKit migration) using references/lock-screen-and-watch.md.
Validate rendering across full-color, accented, tinted, and vibrant modes (widgetRenderingMode, widgetAccentable, widgetAccentedRenderingMode, the luminance-to-alpha trick) using references/rendering-modes-and-tinting.md.
Validate interactivity (Button(intent:), Toggle(intent:), the app-process boundary, reloadTimelines, invalidatableContent) using references/interactive-widgets.md.
Validate deep links and navigation into the app (widgetURL, Link, onOpenURL, OpenIntent) using references/deep-linking-and-navigation.md.
Validate animations and entry transitions (contentTransition, .transition + identity, invalidatableContent, what doesn't animate) using references/animations-and-transitions.md.
Validate Control Center controls (ControlWidget, toggle vs button, SetValueIntent, value providers, ControlCenter reloads) using references/controls.md.
Validate Live Activities and the Dynamic Island (ActivityAttributes, ActivityConfiguration, DynamicIsland, request/update/end, push, supplementalActivityFamilies) using references/live-activities.md.
Validate Smart Stack relevance (TimelineEntryRelevance, relevance() / WidgetRelevance, RelevanceConfiguration, push-based relevance) using references/relevance-and-smart-stacks.md.
Check the design and gallery presentation (glanceability, sizes, the don'ts, configurationDisplayName/description, the placeholder) using references/design-and-gallery.md.
Validate previews and the testing/debugging workflow (#Preview(as:), WidgetKit developer mode, the reload budget) using references/previews-and-testing.md.
Validate platform-specific surfaces (visionOS spatial widgets, CarPlay, macOS menu bar, the availability map) using references/platforms.md.
Catch common mistakes using references/anti-patterns.md.

If doing partial work, load only the relevant reference files.

Task-based routing

Match the user's goal to the read order. Load only what you need.

"Create my first widget" / "show me a complete widget"

references/fundamentals.md - the extension, the widget bundle, the timeline lifecycle
references/worked-example.md - one widget built end to end (entry → provider → layout → links → tinting → animation → preview)
references/timeline-provider.md - TimelineProvider, entries, reload policy
references/families-and-layout.md - pick families, per-family layout
references/previews-and-testing.md - #Preview(as:) to iterate

"Let the user configure my widget"

references/configuration-and-intents.md - AppIntentConfiguration + WidgetConfigurationIntent, dynamic options, defaults
references/timeline-provider.md - AppIntentTimelineProvider (the intent is the first argument)

"Add a Lock Screen widget / watch complication"

references/lock-screen-and-watch.md - accessory families, widgetLabel, AccessoryWidgetBackground, gauges, ClockKit migration
references/rendering-modes-and-tinting.md - accessory widgets are always rendered in a tint mode

"My widget looks wrong in tinted / dark / accented mode"

references/rendering-modes-and-tinting.md - widgetRenderingMode, widgetAccentable, widgetAccentedRenderingMode, the luminance-to-alpha trick, designing for the accent group
references/lock-screen-and-watch.md - the transparent containerBackground for accessory widgets

"Add a button / toggle inside my widget"

references/interactive-widgets.md - Button(intent:) / Toggle(intent:), the app-process boundary, App Group store, reloadTimelines, invalidatableContent
references/configuration-and-intents.md - isDiscoverable = false on helper intents

"Add a Control Center control / Action button / Lock Screen control"

references/controls.md - ControlWidget, ControlWidgetToggle (SetValueIntent) vs ControlWidgetButton (AppIntent), value providers, ControlCenter.shared.reloadControls
references/interactive-widgets.md - the same app-process / shared-store rules apply

"Build a Live Activity / Dynamic Island"

references/live-activities.md - ActivityAttributes / ContentState, ActivityConfiguration, DynamicIsland regions, request/update/end, staleness, push, supplementalActivityFamilies, the iOS-27 landscape Dynamic Island
references/interactive-widgets.md - LiveActivityIntent buttons

"Keep my widget fresh from the server"

references/timeline-provider.md - reload policy, the reload budget, reload on app background
references/relevance-and-smart-stacks.md - push-updated widgets (WidgetPushHandler, iOS 26), and when a Live Activity is the right tool instead

"Make my widget show up in the Smart Stack at the right time"

references/relevance-and-smart-stacks.md - TimelineEntryRelevance, relevance() + WidgetRelevance, RelevanceConfiguration (watchOS 26), RelevantContext

"Fetch data / load images / use a database or location in my widget"

references/data-and-networking.md - App Group snapshot, async fetch in the provider, image downsampling, SwiftData/Core Data, NSWidgetUsesLocation
references/timeline-provider.md - where fetching fits in the lifecycle and the budget

"Deep link / open my app from the widget"

references/deep-linking-and-navigation.md - widgetURL vs Link, per-family rules, onOpenURL, OpenIntent

"Animate my widget / make values roll or transition"

references/animations-and-transitions.md - entry diffing, contentTransition(.numericText), .transition + .id, invalidatableContent, what doesn't animate

"Modernize an old widget / I'm seeing IntentConfiguration / ClockKit / PreviewProvider"

references/migration-and-deprecations.md - the old → new map, CustomIntentMigratedAppIntent, the ClockKit migrator, dual-path #available

"Design my widget well / make it gallery-ready"

references/design-and-gallery.md - glanceable/personal/relevant, sizes & tap styles, the don'ts, the snapshot, the placeholder

"Support visionOS / CarPlay / macOS / Apple Watch"

references/platforms.md - spatial widgets (supportedMountingStyles, widgetTexture, levelOfDetail), CarPlay, macOS menu bar, the availability map

"My widget won't update / shows stale data / never appears"

references/previews-and-testing.md - the reload budget, WidgetKit developer mode, debugging
references/anti-patterns.md - the usual causes

"I'm hitting build errors or rendering bugs"

references/anti-patterns.md - catches with before/after fixes

Decision trees

Quick orientation when you know the task but not the right API.

Which configuration should the widget use?

No user configuration, fixed behavior?
  -> StaticConfiguration(kind:provider:)

User picks parameters (account, city, repo)?
  -> AppIntentConfiguration(kind:intent:provider:) + WidgetConfigurationIntent   (iOS 17+)

Migrating an existing iOS 14-16 configurable widget?
  -> WidgetConfigurationIntent + CustomIntentMigratedAppIntent (keep intentClassName)
  -> or keep IntentConfiguration(kind:intent:provider:) with the legacy INIntent

Appears in the Smart Stack only when relevant (watchOS)?
  -> RelevanceConfiguration(kind:provider:)   (watchOS 26+)

Which timeline provider?

StaticConfiguration?
  -> TimelineProvider           (placeholder / getSnapshot / getTimeline, completion-based)

AppIntentConfiguration?
  -> AppIntentTimelineProvider  (placeholder / snapshot(for:in:) / timeline(for:in:), async, intent FIRST)

RelevanceConfiguration (watchOS)?
  -> RelevanceEntriesProvider   (placeholder / relevance() / entry(configuration:context:), one entry per config)

Which reload policy?

Next update time is known (countdown ends, event starts)?
  -> .after(date)

Entries cover a window and the next batch can be computed at the end?
  -> .atEnd

Content only changes from interaction / push, never on a schedule?
  -> .never   (then reload via WidgetCenter from an intent, app, or push)

Which interactive element?

Inside a widget or Live Activity, runs an action?
  -> Button(intent:) with an AppIntent          (iOS 17+)

Inside a widget, binary on/off?
  -> Toggle(isOn:intent:) with an AppIntent      (iOS 17+)

Inside a Control Center control, binary on/off?
  -> ControlWidgetToggle(action:) with a SetValueIntent

Inside a Control Center control, runs an action / opens the app?
  -> ControlWidgetButton(action:) with an AppIntent (or OpenIntent to launch)

Widget vs Live Activity vs Control?

Glanceable data on a schedule, lives on Home/Lock Screen?
  -> Widget (timeline)

Ongoing, time-bound event the user wants to watch live (delivery, game, workout)?
  -> Live Activity (ActivityKit) - NOT a fast-reloading widget

A quick action or state toggle from Control Center / Lock Screen / Action button?
  -> Control (ControlWidget)

Core Instructions

A widget runs in a separate extension process, not your app. It is always SwiftUI, even in a UIKit app. The system archives your view and renders it later - your code is not running while the widget is on screen. Share data with the app only through an App Group container (shared UserDefaults(suiteName:), a shared file, or a shared ModelContainer/Core Data store) - never UserDefaults.standard, never in-memory singletons.
Never make a widget interactive with a closure or onTapGesture. The only interactivity is Button(intent:) / Toggle(intent:) backed by an AppIntent (iOS 17+), plus Link / widgetURL for deep links. Anything else silently does nothing.
Always mark the widget's background with .containerBackground(for: .widget) { ... } (iOS 17+). Without it the widget is blank in the gallery, can't be removed/relocated cleanly, and the system can't substitute the material background in Lock Screen / StandBy / tinted contexts. The container type is ContainerBackgroundPlacement (value .widget) - there is no WidgetBackgroundPlacement.
Never do blocking or asynchronous work in placeholder(in:) - it must return synchronously with stand-in data. Do real fetching in getSnapshot/getTimeline (or the async snapshot/timeline). Use .redacted(reason: .placeholder) for the first-render stand-in.
getSnapshot (and snapshot(for:in:)) is what the widget gallery shows - return realistic, populated sample data even when the user has none yet, never an empty/loading state.
Treat timeline reloads as a budgeted, opportunistic resource, not a timer. The system gives roughly 40-70 reloads/day per widget and learns from viewing habits. Never assume .after(date) fires exactly on time. Provide multiple entries to cover a window, pick the policy that matches your data (.atEnd / .after / .never), and trigger a final WidgetCenter.shared.reloadAllTimelines() when the app enters the background if data changed.
TimelineReloadPolicy is a struct; .after(_:) takes a Date, not a TimeInterval. WidgetCenter.shared.reloadTimelines(ofKind:) takes the widget's kind string - keep kind values as shared constants so the app and extension can't drift.
For a configurable widget, use AppIntentConfiguration + a WidgetConfigurationIntent (iOS 17+) and an AppIntentTimelineProvider whose snapshot/timeline take the intent as the first argument. WidgetConfigurationIntent lives in the AppIntents module and needs no perform(). Provide sensible @Parameter defaults; never force the user to configure before the widget shows anything.
Never write a new configurable widget with the legacy SiriKit path - IntentConfiguration, an INIntent from a .intentdefinition file, or IntentTimelineProvider. Since iOS 17 the modern path is App Intents (AppIntentConfiguration + WidgetConfigurationIntent + AppIntentTimelineProvider). Only keep the legacy types behind #available when deploying below iOS 17, and when migrating an existing one conform the new intent to CustomIntentMigratedAppIntent with the original intentClassName so saved configurations survive. Likewise build watch complications with WidgetKit (+ a CLKComplicationWidgetMigrator), not ClockKit, and previews with #Preview(as:), not PreviewProvider. See references/migration-and-deprecations.md.
Don't fetch data inside the widget view (no AsyncImage, no network at render time) - the view is an archived snapshot rendered later. Resolve data and downsample images during timeline generation and put them in the entry, prefer reading an App-Group snapshot the app wrote, and always complete the provider (fall back to last-good data on error). See references/data-and-networking.md.
Switch on @Environment(\.widgetFamily) and design each supported family deliberately. List only the families you actually lay out in supportedFamilies - shipping a family you didn't design looks broken. Accessory families (accessoryCircular / accessoryRectangular / accessoryInline) are iOS 16+; accessoryCorner is watchOS only.
Design for every rendering mode, not just full color. Read @Environment(\.widgetRenderingMode) (.fullColor / .accented / .vibrant); both WidgetRenderingMode and WidgetAccentedRenderingMode are structs with type properties, not enums. In .accented mode the system flattens your view into two tint groups by alpha - put foreground content in the accent group with .widgetAccentable(), and control how images flatten with .widgetAccentedRenderingMode(.desaturated / .accented / .accentedDesaturated / .fullColor) (the image modifier is iOS 18+).
For a multicolor image or icon that the accent group would crush into a flat silhouette: on iOS 18+ use .widgetAccentedRenderingMode(.desaturated) (the system maps luminance to alpha and recolors for you); on iOS 17 and below that modifier doesn't exist, so apply the manual .luminanceToAlpha() filter (bright pixels opaque, dark transparent) to preserve the shape's internal detail as a clean monochrome glyph - it also stays useful on iOS 18+ for hands-on control. Pair it with a soft gradient background and .widgetAccentable(). (See references/rendering-modes-and-tinting.md.)
For an accessory/Lock Screen widget or watch complication that should let the watch face or wallpaper show through, give it an empty .containerBackground(for: .widget) { }. Omitting containerBackground entirely makes the system add an opaque default material instead of a transparent one.
An interactive AppIntent runs in the app's process (the app is launched in the background if needed), not the widget extension - so it can write to the real data store. After it mutates data a widget displays, call WidgetCenter.shared.reloadTimelines(ofKind:) (or reloadAllTimelines()); for a control, call ControlCenter.shared.reloadControls(ofKind:). Mark helper intents that only back a widget/control button with static let isDiscoverable = false so they don't pollute Shortcuts.
In the 27 releases (iOS 27): a widget button's write intent must run on .main (the widget extension has a read-only view of the shared store). Pin it with static var allowedExecutionTargets: ExecutionTargets { .main }, and pin display-only intents with .widgetKitExtension.
A Control (ControlWidget, iOS 18; macOS/watchOS 26) uses ControlWidgetToggle with a SetValueIntent (its value: Bool is set by the system) or ControlWidgetButton with a plain AppIntent / OpenIntent. The status modifier is controlWidgetStatus(_:) - there is no controlWidgetStatusText. Provide a previewValue and an async currentValue in the value provider.
A Live Activity is the right tool for an ongoing, time-bound event - not a widget that reloads every few seconds. Split immutable data into ActivityAttributes and the only-updatable half into the nested ContentState: Codable, Hashable (keep it under 4 KB). ActivityConfiguration and DynamicIsland live in WidgetKit; Activity.request/update/end and tokens live in ActivityKit. staleDate / relevanceScore are set on ActivityContent.init, not the configuration.
Live Activities require NSSupportsLiveActivities = YES in the app's Info.plist; high-frequency push updates also need NSSupportsLiveActivitiesFrequentUpdates. Push-to-start uses Activity.pushToStartToken (iOS 17.2+) - it is not a PushType case. For mass-audience pushes use a broadcast channel; otherwise per-activity push tokens.
Never put a symbolEffect animation in a Live Activity or widget - they aren't supported and silently no-op. Widget/Live Activity views are static snapshots; only Text(_:style:) timers/dates and the system's transition between timeline entries animate.
widgetAccentedRenderingMode is iOS 18+; Controls are iOS 18+ (macOS/watchOS 26+); push-updated widgets (WidgetPushHandler) and RelevanceConfiguration are iOS 26 / watchOS 26; spatial-widget modifiers (supportedMountingStyles, widgetTexture, levelOfDetail) are iOS/visionOS 26; systemExtraLargePortrait, the landscape Dynamic Island (isDynamicIslandLimitedInWidth), and allowedExecutionTargets are part of the 27 releases. Gate each behind the correct availability and call the WWDC 2026 cohort "the 27 releases", not "iOS 19".
Use the #Preview(as:) macro (iOS 17+) to iterate on widgets across families, color schemes, and rendering modes without running the host app; enable WidgetKit developer mode (Settings ▸ Developer) to lift the reload budget while iterating. The reload budget being exhausted - not a code bug - is the most common reason a widget "stops updating".

Output Format

If the user asks for a review, organize findings by file. For each issue:

State the file and relevant line(s).
Name the anti-pattern being replaced.
Show a brief before/after code fix.

Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.

If the user asks you to write or fix widget code, make the changes directly instead of returning a findings report.

Example output:

CaffeineWidget.swift

Line 14: placeholder(in:) does a synchronous disk fetch - placeholders must return instantly.

// Before
func placeholder(in context: Context) -> Entry {
    Entry(date: .now, drinks: Store.shared.loadAllDrinks())   // blocks the render
}

// After
func placeholder(in context: Context) -> Entry {
    Entry(date: .now, drinks: .sample)   // synchronous stand-in; real data in getTimeline
}

Line 41: interactive onTapGesture in a widget does nothing - use an App Intent.

// Before
Image(systemName: "plus.circle").onTapGesture { addDrink() }

// After
Button(intent: AddDrinkIntent()) { Image(systemName: "plus.circle") }
// AddDrinkIntent.perform() writes to the App Group store, then:
// WidgetCenter.shared.reloadTimelines(ofKind: "CaffeineWidget")

Summary

Placeholder (high): must be synchronous; move fetching to the timeline.
Interactivity (high): gestures don't work in widgets; back the tap with an AppIntent.

End of example.

References

references/fundamentals.md - the widget execution model: the extension process, app groups, WidgetBundle, the Widget protocol, the timeline lifecycle, containerBackground, content margins, deep linking, kind, and the "which surface" map.
references/timeline-provider.md - TimelineProvider vs AppIntentTimelineProvider, TimelineEntry, Timeline, reload policies, the reload budget, WidgetCenter reloads, reload-on-background, TimelineEntryRelevance.
references/configuration-and-intents.md - StaticConfiguration, AppIntentConfiguration, WidgetConfigurationIntent, dynamic options / entity parameters, recommendations(), defaults.
references/migration-and-deprecations.md - the old → new map: SiriKit .intentdefinition / IntentConfiguration → App Intents, IntentTimelineProvider → AppIntentTimelineProvider, ClockKit → WidgetKit, PreviewProvider → #Preview, what's deprecated vs legacy-but-supported, CustomIntentMigratedAppIntent.
references/data-and-networking.md - loading data for timelines: App Group snapshots, async/background URLSession fetches, image downsampling, SwiftData/Core Data in widgets, location, Lock Screen privacy.
references/families-and-layout.md - WidgetFamily cases, sizing, supportedFamilies, content margins, the per-family switch, ViewThatFits, ContainerRelativeShape.
references/lock-screen-and-watch.md - accessory families, watch complications, widgetLabel, AccessoryWidgetBackground, gauges, the transparent containerBackground trick, ClockKit → WidgetKit migration.
references/rendering-modes-and-tinting.md - widgetRenderingMode (.fullColor/.accented/.vibrant), widgetAccentable, widgetAccentedRenderingMode, the luminance-to-alpha trick, designing for the tinted/clear Home Screen and accent groups.
references/interactive-widgets.md - Button(intent:) / Toggle(intent:), the app-process boundary, @Parameter persistence, the App Group store, reloadTimelines, the optimistic ToggleStyle, invalidatableContent, isDiscoverable, allowedExecutionTargets (the 27 releases).
references/deep-linking-and-navigation.md - widgetURL vs Link, per-family tap rules, URL-scheme design, handling on the app side (onOpenURL / scene delegate), Live Activity widgetURL/keylineTint, control OpenIntent.
references/animations-and-transitions.md - the entry-diffing animation model, contentTransition(.numericText), .transition + .id identity, the optimistic Toggle, invalidatableContent, Live Activity transitions, what does not animate (symbolEffect, loops, video).
references/controls.md - ControlWidget, StaticControlConfiguration / AppIntentControlConfiguration, ControlWidgetToggle (SetValueIntent) vs ControlWidgetButton (AppIntent/OpenIntent), value providers, ControlCenter reloads, status/action-hint modifiers, platforms.
references/live-activities.md - ActivityAttributes / ContentState, ActivityConfiguration, DynamicIsland, Activity.request/update/end, ActivityContent staleness, push (token / channel / push-to-start), supplementalActivityFamilies / activityFamily, the landscape Dynamic Island, StandBy, LiveActivityIntent, entitlements.
references/relevance-and-smart-stacks.md - TimelineEntryRelevance, relevance() + WidgetRelevance / WidgetRelevanceAttribute / RelevantContext, RelevanceConfiguration + RelevanceEntriesProvider (watchOS 26), push-updated widgets (WidgetPushHandler, iOS 26), Smart Stack behavior.
references/design-and-gallery.md - the design rules (glanceable/relevant/personal, not a mini-app), sizes & tap styles, layout margins & type, the explicit don'ts, the gallery (configurationDisplayName/description/snapshot), the placeholder, personalization, Smart Stack etiquette.
references/previews-and-testing.md - the #Preview(as:) macro variants, WidgetPreviewContext, testing rendering modes/families, WidgetKit developer mode, the reload budget, debugging "won't update".
references/platforms.md - visionOS spatial widgets (supportedMountingStyles, widgetTexture, levelOfDetail, systemExtraLargePortrait), CarPlay widgets and Live Activities, macOS menu bar, watchOS, the cross-platform availability map.
references/worked-example.md - one widget built end to end (a systemMedium Quick Actions widget): entry + provider, multi-Link layout, full-color-vs-tinted handling, an entry-driven MeshGradient animation, contentMarginsDisabled, and the preview - with pointers to the deeper reference for each step.
references/anti-patterns.md - the consolidated smell → fix checklist, including the API-name confusions LLMs make (struct vs enum rendering modes, ContainerBackgroundPlacement, pushToStartToken, controlWidgetStatus).

widgets