Platform Custom Lightning Type Generate

When to Use This Skill

Use this skill when you need to:

• Create Custom Lightning Types (CLTs) for structured inputs/outputs
• Generate JSON Schema-based type definitions for Lightning Platform
• Configure CLTs for Einstein Agent actions
• Set up editor and renderer configurations for custom UI
• Troubleshoot deployment errors related to Custom Lightning Types

Specification

CustomLightningType Metadata Specification

Overview & Purpose

Custom Lightning Types (CLTs) are JSON Schema-based type definitions used by the Lightning Platform (including Einstein Agent actions) to describe structured inputs/outputs and drive editor/renderer experiences.

Configuration

• Choose referenced CLT pattern for nested objects - When you need a reusable or separately deployed nested type, create a CLT for that shape and reference it with "lightning:type": "c__<CLTName>". That string is the referenced type’s `lightning:type` value / FQN / registered identifier — not the JSON Schema title.
• Choose standard Lightning types when the structure is simple and can be expressed with properties and supported primitive lightning:type identifiers.
• Choose Apex class types (@apexClassType/...) when the structure already exists server-side and you want the Apex class to define the shape.
• Include editor/renderer config only when you need custom UI behavior (custom LWC input/output components). Otherwise, omit.

Critical Rules (Read First)

• CRITICAL: NEVER include the `"$schema"` field in schema.json
• Salesforce CLT validator WILL REJECT schemas with this field, even if it's a valid JSON Schema $schema declaration.
• Root object schemas MUST include:
• "type": "object"
• "title"
• "lightning:type": "lightning__objectType"
• "unevaluatedProperties": false
• "unevaluatedProperties" is enforced as false by the CLT metaschema. Do not set it to true.
• Root object schemas MUST NOT include "examples" when "unevaluatedProperties": false is set.
• Nested objects (inside `properties`) MUST NOT set "lightning:type": "lightning__objectType".
• Nested objects can be: references to other CLTs using c__<CLTName> syntax.
• List/array properties are highly restricted by the CLT metaschema:
• CRITICAL LIMITATION: the CLT metaschema may reject the items keyword entirely. Treat items as disallowed by default.
• Root-level arrays (direct children of the root properties):
• MUST include "lightning:type": "lightning__listType"
• MUST NOT include "items"
• OPTIONAL "type": "array"
• Nested arrays (arrays inside nested objects) are the most common failure:
• MUST include "type": "array"
• MUST NOT include "lightning:type": "lightning__listType"
• MUST NOT include "items"
• When `"unevaluatedProperties": false` is set, any unknown keyword will fail validation. Prefer removing keywords over relaxing strictness.
• Apex class CLTs are minimal:
• Include only title, description (optional), and lightning:type set to @apexClassType/....
• Do not add type, properties, required, or unevaluatedProperties.
• Custom LWC renderers/editors on an Apex class CLT MUST NOT use `attributes` in the root override — this overrides any prompt wording to the contrary. Since the schema has no properties block, there is nothing for {!$attrs.<name>} to resolve against — unevaluatedProperties: false will reject any attribute key (e.g. "You can't add the flightId property ... because the unevaluatedProperties keyword value is set to false"). Use "componentOverrides": { "$": { "definition": "c/<yourComponent>" } } with no `attributes` key at all. If the user's prompt explicitly asks for attribute mappings to specific fields (e.g. "with attribute mappings for fieldA, fieldB") on an Apex-class CLT renderer/editor, do NOT comply literally — omit attributes from the root override anyway, and say so in your response (e.g. "Note: attribute mappings were omitted because the backing type is an Apex-class CLT, which has no properties block to bind against").
• No shell metacharacters that trigger the Vibes safe-shell filter. In any Bash tool call emitted by this skill, do NOT use command substitution ($(…) or backticks), process substitution (<(…), >(…)), brace expansion ({a,b,c} or {1..N}), or eval / exec. Vibes forces manual approval on these patterns even under Bypass mode and stalls the eval. Emit separate commands (mkdir -p a && mkdir -p b) or print each value with its own command and reason about the output rather than capturing it in a shell variable.

Additional CLT Metaschema Validations

• Org namespace validation: titles/descriptions and other string fields may be validated to ensure you are not using an org namespace in places that are disallowed.
• Lightning type validation: CLTs are validated to prevent referencing internal namespaces (for example, disallowing types from internal namespaces like sfdc_cms where not permitted).
• Object type validation: the CLT root is validated to ensure lightning:type is exactly lightning__objectType.

Primitive Types & Constraints

When you need the full list of supported primitive lightning:type identifiers, their constraints, and the allowed property-level keywords, read assets/primitive-types-and-constraints.md in this skill's directory.

Generation Workflow

1. Confirm the CLT approach

• If referencing Apex: capture the exact class reference (@apexClassType/namespace__ClassName$InnerClass).
• If using standard primitives: list the fields, their Lightning primitive types, and which fields are required.

1. Draft `schema.json`

• DO NOT include `"$schema"` at the top
• Start with the root object structure (required root fields).
• Add properties using valid primitive lightning:type identifiers.
• For nested-object properties, use CLT Reference pattern:
• "lightning:type": "c__<CLTName>" to reference another CLT
• The referenced CLT must be deployed to the org before the parent CLT.
• For Apex-based nested objects: Use @apexClassType/... when structure exists server-side.
• If the prompt explicitly requires true nested object output, prefer an Apex-based CLT (@apexClassType/...) for deploy-safe nested structures.
• For arrays: follow the strict list rules (avoid items; avoid lightning:type on nested arrays).
• Before deployment, verify exact lightning:type spellings (for example, use lightning__richTextType, not misspelled variants).

1. (Optional) Draft `editor.json` (only if custom UI is required)

• Supported shape: Top-level editor object with editor.componentOverrides and editor.layout.
• Top-level editor object.
• Use editor.componentOverrides for component overrides.
• Use editor.layout for layout.
• DEPRECATED: Do NOT use propertyRenderers or view — these are legacy keys. Always use componentOverrides and layout instead.
• Root override pattern (most common for fully custom editing UI):
• editor.componentOverrides["$"] = { "definition": "c/<yourEditorComponent>", "attributes": { ... } }
• When passing schema data into a custom LWC, use attribute mapping with the {!$attrs.<name>} syntax: e.g. "attributes": { "myField": "{!$attrs.value}" } so the runtime binds schema values to your component's attributes.
• CRITICAL: The <name> in {!$attrs.<name>} must be a property defined in your type schema. For example, if your schema has a property called temperature, use {!$attrs.temperature}, not {!$attrs.value} unless value is an actual property.
• Property-level override pattern (for individual fields):
• editor.componentOverrides["<propertyName>"] = { "definition": "es_property_editors/<...>" }