/experience-ui-bundle-custom-app-generate

name: experience-ui-bundle-custom-app-generate
description: "MUST activate when the project contains a uiBundles/*/src/ directory and the task involves creating or configuring a Custom Application for hosting a UI bundle in Lightning Experience. Use this skill when creating a CustomApplication metadata record to surface the UI bundle in the App Launcher. Activate when files matching applications/*.app-meta.xml exist and need modification, or when the user wants to expose their app via the Lightning App Launcher without a Digital Experience Site. Do NOT use platform-custom-application-generate for this — UI bundle apps do not use tabs, action overrides, or flexipages."
metadata:
  version: "1.0"
  domains: ["Experience", "Platform"]
  minApiVersion: "65.0"
  relatedSkills:
    - "platform-custom-application-generate"
  cliTools:
    - tool: ["node"]
      semver: ">=18.0.0"
    - tool: ["sf"]
      semver: ">=2.0.0"
  mcpTools:
    salesforce-api-context:
      tools: ["get_metadata_type_fields"]
      semver: ">=1.0.0"

Custom Application for React UI Bundles

Create and configure a Salesforce Custom Application that hosts a React UI bundle in Lightning Experience. This skill generates the CustomApplication metadata so the app appears in the Lightning App Launcher and can be accessed by internal users.

Custom Applications differ from Experience Sites: they don't need Networks, CustomSite, DigitalExperienceConfig, or DigitalExperienceBundle metadata. The Custom Application acts as a thin launcher entry that delegates rendering to the React UI bundle referenced by `uiBundle`.

Required Properties

Resolve all properties before generating any metadata. Each has a fallback chain — work through each option in order until a value is found.

| Property | Format | How to Resolve | |----------|--------|----------------| | **appName** | `lowercamelcase` (e.g., `myInternalApp`) | The UI bundle name from `uiBundles/<name>/` directory | | **appNamespace** | String | `namespace` in `sfdx-project.json` → `sf data query -q "SELECT NamespacePrefix FROM Organization" --target-org ${usernameOrAlias}` → default `c` | | **appLabel** | Human-readable string | User-provided, or derive from appName by converting camelCase to Title Case |

The `appNamespace` and `appName` connect the Custom Application to the correct React UI bundle. In newer API versions this uses `<uiBundle>{appNamespace}__{appName}</uiBundle>`; in older versions it uses `<webApplication>{appName}</webApplication>`. Getting this wrong means the app launcher entry exists but shows a blank page. Step 2 of the workflow determines which field to use.

Generation Workflow

Step 1: Resolve All Required Properties

Determine values for all properties before constructing anything. Use the resolution strategies in the table above.

Step 2: Query API Context (Version-Aware Field Discovery)

Call `salesforce-api-context` MCP tools to discover which fields exist for the target org's API version. This ensures the generated metadata is compatible with the user's Salesforce version.

**Required calls — use the `metadataType` parameter exactly as shown. Do not substitute a `detail` parameter or any other shape; `metadataType` is the only parameter this tool accepts:** 1. `get_metadata_type_fields({ "metadataType": "CustomApplication" })` — check whether the `uiBundle` field exists in the response's field list 2. `get_metadata_type_fields({ "metadataType": "UIBundle" })` — check whether the `target` field exists in the response's field list

**Field resolution based on API response:**

| Field Check | If present | If absent (older API version) | |-------------|-----------|-------------------------------| | `CustomApplication.uiBundle` | Use `<uiBundle>{appNamespace}__{appName}</uiBundle>` | Use `<webApplication>{appName}</webApplication>` (no namespace) | | `UIBundle.target` | Use `<target>CustomApplication</target>` | Omit the `<target>` element entirely |

If `salesforce-api-context` is unavailable after a real attempt, fall back to the newer field names (`uiBundle` + `target`).

Step 3: Create the Project Structure

Create any files and directories that don't already exist:

| Metadata Type | Path | |--------------|------| | CustomApplication | `<sourceDir>/applications/{appName}.app-meta.xml` |

**Note:** `<sourceDir>` is determined from `sfdx-project.json`. Read `packageDirectories[]` and use the entry where `"default": true`; the full source directory is `<path>/main/default`. If no default is set, use the first entry. Commonly `force-app/main/default`, but this path is configurable.

Step 4: Populate All Metadata Fields

Use the default template in the doc below. Values in `{braces}` are resolved property references — substitute them with the actual values from Step 1. Apply the field resolution from Step 2 to determine which XML elements to use.

| Metadata Type | Template Reference | |--------------|-------------------| | CustomApplication | [configure-metadata-custom-application.md](references/configure-metadata-custom-application.md) |

Execution Note for Step 4: Load and use the doc

• Agents MUST read the full contents of the references/*.md file referenced in Step 4 before attempting to populate metadata fields.
• Read the file in full, replace placeholders (e.g. `{appName}`) with the resolved values, then use the expanded template to populate the metadata XML content.
• If Step 2 determined the older field names apply, substitute `<uiBundle>` with `<webApplication>` in the generated output.

Step 5: Update UI Bundle Meta XML

This step edits an **existing** file — it never creates a new one. `UIBundle` is a bundle-style metadata type: its meta XML normally lives inside its own folder at `uiBundles/{appName}/{appName}.uibundle-meta.xml`, alongside the bundle's other source files (e.g. `index.html`, `src/`). Some older or hand-authored projects may instead have it at the flat path `uiBundles/{appName}.uibundle-meta.