experience-ui-bundle-custom-app-generate — Claude Code skill: setup

---
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.xml` (no subfolder).

Run `node scripts/resolve-uibundle-path.mjs "{appName}"` — it prints the path of the existing meta XML (preferring the nested layout, falling back to the flat layout). Always invoke via `node` (never as a bare executable) so this works on Windows as well as macOS/Linux. Edit that exact file in place; do not create a second file at the other path or migrate it to a different layout as part of this skill.

If Step 2 confirmed the `target` field exists on `UIBundle`, add `<target>CustomApplication</target>` inside the existing `<UIBundle>` element of that file, preserving every other existing element and value untouched (skip this step entirely if the field doesn't exist in the org's API version — do not create the file or add `<target>` in that case).

**Do NOT:**
- Create a new `.uibundle-meta.xml` file
- Create a second `.uibundle-meta.xml` file at a different path when one already exists (nested or flat) — edit the existing one in place, wherever it is
- Leave the original `uiBundles/{appName}/{appName}.uibundle-meta.xml` (or `uiBundles/{appName}.uibundle-meta.xml`, if that's the existing layout) unmodified while adding `<target>` somewhere else

The only files this skill produces or modifies are `applications/{appName}.app-meta.xml` (new) and the existing `{appName}.uibundle-meta.xml` (edited in place, only if `<target>` applies). Any other UI-bundle-related file appearing in the output is a bug.

Example of the fully updated file (at `uiBundles/{appName}/{appName}.uibundle-meta.xml`, or the flat path if that's the existing layout) — this illustrates the end state of the existing file, not a new file to create:

```xml
<?xml version="1.0" encoding="UTF-8"?>
<UIBundle xmlns="http://soap.sforce.com/2006/04/metadata">
    <masterLabel>{appName}</masterLabel>
    <description>A Salesforce UI Bundle.</description>
    <isActive>true</isActive>
    <version>1</version>
    <target>CustomApplication</target>
</UIBundle>
```

### Step 6: Do Not Modify Non-Templated Properties
Do not modify any default property values for `CustomApplication` metadata that are not expressed as variables wrapped in `{braces}`.

## Verification Checklist
Before deploying, confirm:

- [ ] All required properties are resolved
- [ ] API context was queried to determine available fields (Step 2)
- [ ] `applications/{appName}.app-meta.xml` exists with correct content
- [ ] The bundle reference field matches the org's API version (`<uiBundle>` or `<webApplication>`)
- [ ] If `target` field is supported: the **existing** `{appName}.uibundle-meta.xml` (nested at `uiBundles/{appName}/`, or flat at `uiBundles/`, whichever already existed) has `<target>CustomApplication</target>`
- [ ] No extra `.uibundle-meta.xml` file was created — exactly one `{appName}.uibundle-meta.xml` exists, at whichever path it already lived at
- [ ] Deployment validates successfully:
```bash
sf project deploy validate --metadata CustomApplication UIBundle --target-org ${usernameOrAlias}
```