description: Primary Apex authoring skill for class generation, refactoring, and review. ALWAYS ACTIVATE when the user mentions Apex, .cls, triggers, or asks to create/refactor a class (service, selector, domain, batch, queueable, schedulable, invocable, DTO, utility, interface, abstract, exception, REST resource). Use this skill for requests involving SObject CRUD, mapping collections, fetching related records, scheduled jobs, batch jobs, trigger design, @AuraEnabled controllers, @RestResource endpoints, custom REST APIs, or code review of existing Apex.
All steps are sequential. Do not skip, merge, or reorder. If blocked, stop and ask for missing context. If not applicable, mark `N/A` with a one-line justification in the report.
5.**Generate test classes** -- Load the skill `generating-apex-test` to create `{ClassName}Test.cls` and `{ClassName}Test.cls-meta.xml`. Apex tests are always required to be generated to deploy. No test file creation or edits can occur without loading the `generating-apex-test` skill to generate tests.
### Phase 2 — Validate (required before reporting)
Writing files is the midpoint, not the finish line. Steps 6 and 7 each require a tool invocation and produce output that must appear in the Step 8 report. Do not summarize or present the report until both steps have run and their output is captured.
6.**Run code analyzer**
- Invoke MCP `run_code_analyzer` on all generated/updated `.cls` files.
- Remediate all `sev0`, `sev1`, and `sev2` violations; re-run until clean.
- Capture the final tool output verbatim for the report.
- Fallback: `sf code-analyzer run --target <target>`. If both are unavailable, record `run_code_analyzer=unavailable: <error>` in the report.
7.**Execute Apex tests**
- Run org tests including `{ClassName}Test` via `sf apex run test` or MCP.
| Avoid `System.debug()` in main code paths | Debug statements evaluate even when loggign is not active and consume CPU. Use a logging framework if required on main code paths |
| Never use `@future` methods | Use Queueable with `System.Finalizer`; `@future` cannot chain, cannot be called from Batch, and cannot accept non-primitive types |
### Bulkification & Governor Limits
- All public APIs accept and process collections; single-record overloads delegate to the bulk method
- In batch/bulk flows, prefer partial-success DML (`Database.update(records, false)`) and process `SaveResult` for errors
- Use `Map<Id, SObject>` constructor for efficient ID-based lookups from query results
- Use `Map<Id, List<SObject>>` to group child records by parent; build the map in a single loop before processing
- Use `Set<Id>` for deduplication and membership checks; prefer `Set.contains()` over `List.contains()`
- Use relationship subqueries to fetch parent + child records in a single SOQL when both are needed
- Use `AggregateResult` with `GROUP BY` for rollup calculations instead of querying and counting in Apex
- Only DML records that actually changed — compare against `Trigger.oldMap` or prior state before adding to the update list
- Use `Limits.getQueries()`, `Limits.getDmlStatements()`, `Limits.getCpuTime()` to monitor consumption in complex transactions
### SOQL Optimization
- Use selective queries with proper `WHERE` clauses; use indexed fields (`Id`, `Name`, `OwnerId`, lookup/master-detail fields, `ExternalId` fields, custom indexes) in filters when possible
-`SELECT *` does not exist in SOQL -- always specify the exact fields needed
- Apply `LIMIT` clauses to bound result sets; use `ORDER BY` for deterministic results
- When querying Custom Metadata Types (objects ending with `__mdt`), do NOT use SOQL — use the built-in methods (`{CustomMdt__mdt}.getAll().values()`, `getInstance()`, etc.)
### Caching
- Use Platform Cache (`Cache.Org` / `Cache.Session`) for frequently accessed, rarely changed data; set a TTL and always handle cache misses — cache can be evicted at any time
- Use `private static Map` fields as transaction-scoped caches to prevent duplicate queries within the same execution context; lazy-initialize on first access
Before finalizing, verify: CRUD/FLS enforced (SOQL + DML) · explicit sharing keyword on every class · no hardcoded secrets or Record IDs · PII excluded from logs and error messages · error messages sanitized for end users.
### Error Handling
- Catch specific exceptions before generic `Exception`; include context in messages
- Use `try/catch` only around code that can throw (DML, callouts, JSON parsing, casts); avoid defensive wrapping of simple assignments/collection ops/arithmetic
- Preserve exception cause chains: `new CustomException('message', cause)` (do not replace stack trace with concatenated messages)
- Provide a custom exception class per service domain when meaningful
- In `@AuraEnabled` methods, catch exceptions and rethrow as `AuraHandledException`
- Fallback option: when no meaningful domain exception exists, catch generic `Exception` and either rethrow it or wrap it in a minimal custom exception that preserves the original cause.
- Add guard clauses for null/empty inputs at the top of every public method; match style to context: `return` early in private/trigger-handler methods, `throw` exceptions in public APIs, `record.addError()` in validation services
- Return empty collections instead of `null`
- Use safe navigation (`?.`) for chained property access
- Never dereference `map.get(key)` inline unless presence is guaranteed; use `containsKey`, assignment+null check, or safe navigation first
- Use null coalescing (`??`) for default values
- Prefer `String.isBlank(value)` over manual checks like `value == null || value.trim().isEmpty()`
### Constants & Literals
- Use enums over string constants whenever possible; enum values follow `UPPER_SNAKE_CASE`
- Extract repeated literal strings/numbers into `private static final` constants or a constants class
- Use `Label.` custom labels for user-facing strings
- Use Custom Metadata for configurable values (thresholds, mappings, feature flags)
- Never output HTML-escaped entities in code (e.g., `'`); use literal single quotes `'` in Apex string literals
- Disallowed: methods mixing orchestration with inline SOQL/DML/HTTP; business rules mixed with parsing internals; validation + persistence + cross-system plumbing in one method
| Standard async work | **Queueable** | Job ID, chaining, non-primitive types, configurable delay (up to 10 min via `AsyncOptions`), dedup signatures |
| Very large datasets | **Batch Apex** | Chunked processing, max 5 concurrent; use `QueryLocator` for large scopes |
| Modern batch alternative | **CursorStep** (`Database.Cursor`) | 2000-record chunks, higher throughput, no 5-job limit |
| Recurring schedule | **Scheduled Flow** (preferred) or **Schedulable** | Schedulable has 100-job limit; use only when chaining to Batch or needing complex Apex logic |
-`@InvocableVariable` supports: primitives, `Id`, `SObject`, `List<T>` only (no `Map`/`Set`/`Blob`); use `List<Id>` or `List<SObject>` fields for Flow collection I/O
- Always include `isSuccess`, `errorMessage`, and `errorType` (`e.getTypeName()`) in Response
- Return errors in Response (recommended); throwing an exception triggers the Flow Fault path — reserve for unrecoverable failures only
### REST Resource (`@RestResource`)
- Template: `assets/rest-resource.cls`
-`global with sharing`; both class and methods must be `global`
This skill handles production `.cls`/`.trigger`/`.apex` issues only: compile/parse failures, deployment dependency errors, runtime governor-limit failures. For test execution, assertions, coverage, or `sf apex run test` failures, delegate to `generating-apex-test`.
