Validate --url parameter, warn on malformed values, and verify multisite site existence

[Copilot]

Description

Malformed --url values like http:/example.com (missing slash) are silently ignored. PHP's parse_url() interprets this as scheme='http', path='/example.com' with no host, causing $_SERVER['HTTP_HOST'] to remain unset. In multisite, this defaults to the primary site.

This PR implements two-layered validation to address the issue:

1. URL malformation detection: Validates URL format early, before WordPress loads
2. Multisite site existence validation: Verifies the site exists in multisite installations after WordPress loads

Changes

php/class-wp-cli.php

• Added validation in WP_CLI::set_url() to check for missing host and invalid schemes
• Emits warnings for common typos without breaking existing workflows

php/WP_CLI/Runner.php

• Added validate_multisite_url() method to check if site exists in multisite
• Called at the end of load_wordpress() after WordPress is fully loaded
• Uses get_sites() WordPress API for clean, reliable site lookup
• Shows error and exits if site not found

features/flags.feature

• Added test scenarios for malformed URLs

Example

# Before: silent failure with malformed URL
$ wp post list --url=http:/example.com
# Uses primary site, no indication of problem

# After: immediate feedback for malformed URL
$ wp post list --url=http:/example.com
Warning: The URL 'http:/example.com' does not appear to be valid. Please check for typos (e.g., missing slashes in the protocol like "http://").

# Before: silent failure with non-existent site
$ wp post list --url=invalid.example.com
# Uses primary site in multisite

# After: immediate error for non-existent site
$ wp post list --url=invalid.example.com
Error: Site 'invalid.example.com' not found. Verify `--url=<url>` matches an existing site.

Validation catches:

• Missing slashes: http:/example.com (warning)
• Scheme typos: htp://example.com (warning)
• Non-existent sites in multisite: invalid.example.com (error after WordPress loads)
• Preserves auto-scheme behavior: example.com → http://example.com

Fixes #5716

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Do not silently ignore typos in --url parameter</issue_title>
<issue_description>I'm working in a multisite instance exporting and importing posts. At some point I realized the --url parameter had a missing / in the protocol and all posts were included in the primary blog.

This due to wp-cli ignoring the --url param without any notice if it's wrong.

It would be ideal to print some info of the site we are currently working on at the beginning of the output, and throw an error if the site in the given url does not exists.</issue_description>

Comments on the Issue (you are @copilot in this section)

@danielbachhuber Thanks for the report, @alekstrust !

I suppose it'd probably be helpful to include some validation for --url=<url>, as long as we didn't cause too many explosions with it.

Feel free to submit a pull request, if you'd like!</comment_new>

• Fixes Do not silently ignore typos in --url parameter #5716

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[swissspidy]

@copilot Scheme validation is nice, but most importantly we'll want to check whether a site with the current URL actually exists in the multisite. We can do that in Runner::start() after WP_CLI::set_url() is called

[Copilot]

@copilot Scheme validation is nice, but most importantly we'll want to check whether a site with the current URL actually exists in the multisite. We can do that in Runner::start() after `WP_CLI::se...

Added proactive multisite URL validation in Runner::validate_multisite_url() after wp-config.php loads. This checks if the site exists in the database before WordPress fully loads, providing immediate error feedback for non-existent sites. Respects exceptions for commands like cache flush and search-replace with network flags. (commit 9f74e93)

[codecov]

Codecov Report

❌ Patch coverage is 76.66667% with 7 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
php/WP_CLI/Runner.php	68.18%	7 Missing ⚠️

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