building-omnistudio-callable-apex

What this skill does

# building-omnistudio-callable-apex: Callable Apex for Salesforce Industries Common Core

Specialist for Salesforce Industries Common Core callable Apex implementations. Produce secure,
deterministic, and configurable Apex that cleanly integrates with OmniStudio and Industries
extension points.

## Scope

- **In scope**: Creating `System.Callable` classes for Industries extension points; reviewing callable implementations for correctness and risks; migrating `VlocityOpenInterface` / `VlocityOpenInterface2` to `System.Callable`; 120-point scoring and validation
- **Out of scope**: Generic Apex classes without callable interface (use `generating-apex`); building Integration Procedures (use `building-omnistudio-integration-procedure`); authoring OmniScripts (use `building-omnistudio-omniscript`); deploying Apex classes (use `deploying-metadata`)

---

## Core Responsibilities

1. **Callable Generation**: Build `System.Callable` classes with safe action dispatch
2. **Callable Review**: Audit existing callable implementations for correctness and risks
3. **Validation & Scoring**: Evaluate against the 120-point rubric
4. **Industries Fit**: Ensure compatibility with OmniStudio/Industries extension points

---

## Workflow (4-Phase Pattern)

### Phase 1: Requirements Gathering

Ask for:
- Entry point (OmniScript, Integration Procedure, DataRaptor, or other Industries hook)
- Action names (strings passed into `call`)
- Input/output contract (required keys, types, and response shape)
- Data access needs (objects/fields, CRUD/FLS (Create/Read/Update/Delete and Field-Level Security) rules)
- Side effects (DML, callouts, async requirements)

Then:
1. Scan for existing callable classes: `Glob: **/*Callable*.cls`
2. Identify shared utilities or base classes used for Industries extensions
3. Create a task list

---

### Phase 2: Design & Contract Definition

**Define the callable contract**:
- Action list (explicit, versioned strings)
- Input schema (required keys + types)
- Output schema (consistent response envelope)

**Recommended response envelope**:
```
{
  "success": true|false,
  "data": {...},
  "errors": [ { "code": "...", "message": "..." } ]
}
```

**Action dispatch rules**:
- Use `switch on action`
- Default case throws a typed exception
- No dynamic method invocation or reflection

**VlocityOpenInterface / VlocityOpenInterface2 contract mapping**:

When designing for legacy Open Interface extensions (or dual Callable + Open Interface support), map the signature:

```
invokeMethod(String methodName, Map<String, Object> inputMap, Map<String, Object> outputMap, Map<String, Object> options)
```

| Parameter | Role | Callable equivalent |
|-----------|------|---------------------|
| `methodName` | Action selector (same semantics as `action`) | `action` in `call(action, args)` |
| `inputMap` | Primary input data (required keys, types) | `args.get('inputMap')` |
| `outputMap` | Mutable map where results are written (out-by-reference) | Return value; Callable returns envelope instead |
| `options` | Additional context (parent DataRaptor/OmniScript context, invocation metadata) | `args.get('options')` |

Design rules for Open Interface contracts:
- Treat `inputMap` and `options` as the combined input schema
- Define what keys must be written to `outputMap` per action (success and error cases)
- Preserve `methodName` strings so they align with Callable `action` strings
- Document whether `options` is required, optional, or unused for each action

---

### Phase 3: Implementation Pattern

**Vanilla System.Callable** (flat args, no Open Interface coupling):

**Read `assets/pattern_callable_vanilla.cls`** before generating — use when callers pass flat args and no VlocityOpenInterface integration is required.

**Callable skeleton** (same inputs as VlocityOpenInterface):

**Read `assets/pattern_callable_openinterface.cls`** before generating — use `inputMap` and `options` keys in `args` when integrating with Open Interface or when callers pass that structure.

**Input format**: Callers pass `args` as `{ 'inputMap' => Map<String, Object>, 'options' => Map<String, Object> }`. For backward compatibility with flat callers, if `args` lacks `'inputMap'`, treat `args` itself as `inputMap` and use an empty map for `options`.

**Implementation rules**:
1. Keep `call()` thin; delegate to private methods or service classes
2. Validate and coerce input types early (null-safe)
3. Enforce CRUD/FLS (Create/Read/Update/Delete and Field-Level Security) and sharing (`with sharing`, `Security.stripInaccessible()`)
4. Bulkify when args include record collections
5. Use `WITH USER_MODE` for SOQL when appropriate
6. **Namespace handling**: `System.Callable` is a standard interface (no namespace prefix required); `omnistudio.VlocityOpenInterface2` uses the managed `omnistudio` package namespace — always qualify it. If the callable class will be deployed into a namespaced managed package, ask the user for the namespace prefix and apply it to custom class names (e.g., `myns__Industries_XxxCallable`)

**VlocityOpenInterface / VlocityOpenInterface2 implementation**:

When implementing `omnistudio.VlocityOpenInterface` or `omnistudio.VlocityOpenInterface2`, use the signature:

```apex
global Boolean invokeMethod(String methodName, Map<String, Object> inputMap,
                           Map<String, Object> outputMap, Map<String, Object> options)
```

**Read `assets/pattern_openinterface.cls`** before generating — complete `VlocityOpenInterface2` skeleton with `switch on` dispatch and `outputMap` contract.

Open Interface implementation rules:
- Write results into `outputMap` via `putAll()` or individual `put()` calls; do not return the envelope from `invokeMethod`
- Return `true` for success, `false` for unsupported or failed actions
- Use the same internal private methods as the Callable (same `inputMap` and `options` parameters); only the entry point differs
- Populate `outputMap` with the same envelope shape (`success`, `data`, `errors`) for consistency

Both Callable and Open Interface accept the same inputs (`inputMap`, `options`) and delegate to identical private method signatures for shared logic.

---

### Phase 4: Testing & Validation

Minimum tests:
- **Positive**: Supported action executes successfully
- **Negative**: Unsupported action throws expected exception
- **Contract**: Missing/invalid inputs return error envelope
- **Bulk**: Handles list inputs without hitting limits

**Read `assets/pattern_test_class.cls`** — complete test class skeleton (positive, negative, contract, bulk, and null-args cases) before generating tests.

---

## Migration: VlocityOpenInterface to System.Callable

When modernizing Industries extensions, move `VlocityOpenInterface` or
`VlocityOpenInterface2` implementations to `System.Callable` and keep the
action contract stable.

**Guidance**:
- Preserve action names (`methodName`) as `action` strings in `call()`
- Pass `inputMap` and `options` as keys in `args`: `{ 'inputMap' => inputMap, 'options' => options }`
- Return a consistent response envelope instead of mutating `outMap`
- Keep `call()` thin; delegate to the same internal methods with `(inputMap, options)` signature
- Add tests for each action and unsupported action

**Read `assets/pattern_migration.cls`** — annotated before/after migration example (VlocityOpenInterface2 → System.Callable) before starting migration work.

---

## Best Practices (120-Point Scoring)

| Category | Points | Key Rules |
|----------|--------|-----------|
| **Contract & Dispatch** | 20 | Explicit action list; `switch on`; versioned action strings |
| **Input Validation** | 20 | Required keys validated; types coerced safely; null guards |
| **Security** | 20 | `with sharing`; CRUD/FLS checks; `Security.stripInaccessible()` |
| **Error Handling** | 15 | Typed exceptions; consistent error envelope; no empty catch |
| **Bulkification & Limits** | 20 | No SOQL/DML in loops; supports list inputs |
| **Testing** | 15 | Positi