Use when building Apex classes meant to be invoked dynamically — from Flow, external packages, managed-package extensions, or loose-coupling code that cannot directly reference the concrete class. Trigger keywords: Callable, call method, dynamic Apex, action registry, plugin pattern, managed package extension point. NOT for: Invocable methods exposed to Flow (see apex-invocable-methods) or REST endpoints (see apex-rest-services).

Use when sending Custom Notifications (bell icon / mobile push) from Apex via `Messaging.CustomNotification`. Covers target resolution, Notification Type discovery, recipient limits, and async-safe sending. NOT for email (Messaging.SingleEmailMessage), Chatter @mentions, Flow-triggered notifications, or Mobile Publisher push.

Use when writing Apex that calls out to external endpoints via Named Credentials, working with custom header formula tokens ({!$Credential.OAuthToken}), querying per-user auth state through the UserExternalCredential SObject, or diagnosing why Named Credential callouts fail. Trigger keywords: 'callout: prefix', 'named credential header formula', 'UserExternalCredential', 'External Credential per-user principal', 'Named Credential oauth token apex'. NOT for Named Credential setup in the Salesforce Setup UI — use integration/named-credentials-setup. NOT for general HTTP callout mechanics (HttpRequest, HttpResponse, mock patterns) — use integration/callouts-and-http-integrations.

Use this skill when you need guaranteed post-Queueable cleanup, retry, or failure-logging logic that must run even when the parent Queueable throws an unhandled exception. Trigger keywords: FinalizerContext, System.attachFinalizer, Queueable cleanup on failure, post-job compensation, guaranteed async cleanup. NOT for batch job completion callbacks — use apex-batch-chaining. NOT for platform event publishing on failure — use platform-events-apex.

Use when designing wrapper or inner classes in Apex to combine SObjects with computed fields, shape data for LWC consumption, or sort collections with Comparable or Comparator. Trigger keywords: wrapper class, inner class, Comparable, Comparator, @AuraEnabled fields, @JsonAccess. NOT for JSON serialization mechanics — use apex-json-serialization. NOT for LWC data-binding patterns — use lwc-reactive-state-patterns or lwc-lightning-record-forms.

Use this skill to configure and tune search in B2B Commerce or D2C Commerce storefronts: searchable attributes, facetable attributes, sort rules, search index rebuilds, Einstein product recommendations, and BuyerGroup entitlement visibility. Trigger keywords: commerce search ranking, faceted navigation commerce, search index rebuild, Einstein recommendations storefront, product not appearing in search. NOT for SOSL query development, Experience Cloud federated search, Salesforce Search for non-commerce objects, or Einstein Search for Service Cloud.

Use this skill when implementing the Iterable<T> or Iterator<T> interfaces in Apex to create custom traversal logic, build lazy-evaluation data sources for Batch Apex, or stream large result sets without materializing an entire List. Trigger keywords: custom iterator, Iterable interface, Iterator interface, batch start iterable, lazy evaluation apex, streaming apex query, paginated batch. NOT for standard list iteration (use for-each on List directly), NOT for Batch Apex fundamentals (use batch-apex-patterns), NOT for Apex triggers or synchronous bulk patterns.

Use when implementing runtime feature toggles, emergency kill switches, or gradual rollout controls in Apex using Custom Metadata Types, Custom Permissions, or Hierarchical Custom Settings. NOT for Custom Metadata Type fundamentals — see custom-metadata-types skill for CMDT basics.

Use when building custom LWC Quick Actions, Global Actions, deep links, or offline data extensions for the Salesforce Field Service (FSL) native mobile app. Trigger keywords: FSL mobile extension, LWC action FSL, field service deep link, offline custom action, FSL mobile toolkit. NOT for LWC in standard Salesforce mobile app or Lightning Experience.

Use this skill when integrating Salesforce or external systems with Marketing Cloud Engagement REST or SOAP APIs — including OAuth 2.0 authentication, journey injection via /interaction/v1/events, triggered sends, and Data Extension row operations. Trigger keywords: MC API, Marketing Cloud REST, journey injection, triggered send, fire entry event, DE row upsert, dataeventsasync, Installed Package API integration. NOT for Salesforce core REST/SOAP APIs, MCAE/Pardot APIs, or Marketing Cloud Connect (CRM connector sync).

Use this skill when identifying, querying, or troubleshooting the built-in system data views in Salesforce Marketing Cloud (e.g., _Sent, _Open, _Click, _Bounce, _Subscribers, _Job). Trigger keywords: SFMC system data views, underscore data views, _Subscribers status, _Job metadata, data retention marketing cloud, data view schema, MC engagement reporting SQL. NOT for custom Data Extensions, NOT for Data Cloud (CDP) data streams, NOT for SOQL against Salesforce CRM sObjects, NOT for Query Activity SQL syntax in general (use marketing-cloud-sql-queries instead).