lightning-spinner and lightning-breadcrumb not supported (404)

Reproduce the issue with the lightning-spinner and lightning-breadcrumb examples using sf lightning dev site and the stated prerelease plugin version. Trace the plugin's handling of the lightning/spinner and breadcrumb module specifiers; done means both components load in an LWR Experience Cloud site without a 404.

Summary

The lightning-spinner and lightning-breadcrumb components are not supported when developing an LWR experience cloud site.

404: Could not find module with specifier "lightning/spinner"

Steps To Reproduce:

1. Install prerelease plugin version v3.5.0.
2. Create an experience cloud site that uses <lightning-spinner variant="brand"> </lightning-spinner>
3. Run the LWR site using sf lightning dev site

Expected Result

The spinner (or breadcrumb) component should show.

Actual Result

A 404 error is displayed.

System Information

SF CLI:
Bash

{
  "architecture": "linux-x64",
  "cliVersion": "@salesforce/cli/2.93.7",
  "nodeVersion": "node-v22.16.0",
  "osVersion": "Linux 6.12.10-76061203-generic",
  "rootPath": "/home/localusr/.local/share/sf/client/2.93.7-e4d4398",
  "shell": "bash",
  "pluginVersions": [
    "@oclif/plugin-autocomplete 3.2.30 (core)",
    "@oclif/plugin-commands 4.1.26 (core)",
    "@oclif/plugin-help 6.2.28 (core)",
    "@oclif/plugin-not-found 3.2.56 (core)",
    "@oclif/plugin-plugins 5.4.40 (core)",
    "@oclif/plugin-search 1.2.24 (core)",
    "@oclif/plugin-update 4.6.43 (core)",
    "@oclif/plugin-version 2.2.29 (core)",
    "@oclif/plugin-warn-if-update-available 3.1.41 (core)",
    "@oclif/plugin-which 3.2.35 (core)",
    "@salesforce/cli 2.93.7 (core)",
    "agent 1.23.0 (core)",
    "apex 3.6.19 (core)",
    "api 1.3.3 (core)",
    "auth 3.7.0 (core)",
    "community 3.3.27 (user) published 12 days ago (Sat Jun 07 2025) (latest is 3.3.28)",
    "data 4.0.39 (core)",
    "deploy-retrieve 3.22.22 (core)",
    "info 3.4.66 (core)",
    "lightning-dev 3.5.0 (user) published 16 days ago (Mon Jun 02 2025) (latest is 2.10.3)",
    "limits 3.3.56 (core)",
    "marketplace 1.3.8 (core)",
    "org 5.8.0 (core)",
    "packaging 2.15.4 (core)",
    "schema 3.3.66 (core)",
    "settings 2.4.31 (core)",
    "sobject 1.4.60 (core)",
    "telemetry 3.6.44 (core)",
    "templates 56.3.50 (core)",
    "trust 3.7.98 (core)",
    "user 3.6.25 (core)"
  ]
}

OS: Pop OS