[1.x] Breadcrumb Pro

I reviewed the SD Breadcrumb Pro module code for security issues.

## Files Reviewed
- sd_breadcrumb.module
- src/Breadcrumb/SdBreadcrumbBuilder.php
- src/Controller/PreviewController.php
- src/Form/SettingsForm.php
- src/Form/BreadcrumbPatternForm.php
- src/Service/PatternManager.php
- src/Service/BreadcrumbGenerator.php
- js/breadcrumb-builder.js

## Security Analysis

✅ **XSS Prevention**: The module properly validates user input using `strip_tags()` in both `sd_breadcrumb_node_form_validate()` and `BreadcrumbPatternForm::validateForm()` to prevent HTML injection in breadcrumb labels.

✅ **Form API**: All forms use Drupal's Form API correctly with proper validation handlers.

✅ **Database Queries**: Uses Drupal's database abstraction layer with proper placeholders in `BreadcrumbGenerator.php`.

✅ **Entity Access**: Uses `entity_autocomplete` form elements which respect entity access permissions.

✅ **Configuration**: Uses Drupal's Config API for storing patterns and settings.

✅ **Translations**: All user-facing strings use `t()` or `$this->t()`.

## Minor Suggestions (not security issues)
- Remove .DS_Store files from repository
- Consider reducing debug logging in production
- Remove commented code in .module file

## Conclusion
The code follows Drupal security best practices. No security vulnerabilities found.

Setting to RTBC.

Thank you for applying!

Please read Review process for security advisory coverage: What to expect for more details and Security advisory coverage application checklist to understand what reviewers look for. Tips for ensuring a smooth review gives some hints for a smoother review.

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To the reviewers

Please read How to review security advisory coverage applications, Application workflow, What to cover in an application review, and Tools to use for reviews.

The important notes are the following.

• It is preferable to wait for a project moderator before posting the first comment on newly created applications. Project moderators will do some preliminary checks that are necessary before any change on the project files is suggested.
• Reviewers should show the output of a CLI tool only once per application.
• It may be best to have the applicant fix things before further review.

For new reviewers, I would also suggest to first read In which way the issue queue for coverage applications is different from other project queues.

I am changing priority as per Issue priorities.

The module still needs quite a bit of work.

Here are some things to start with.

(*) No GitLab CI configuration — The .gitlab-ci.yml file is entirely missing. GitLab CI is the first step toward quality for contributed modules and is expected for the security coverage application. See GitLab CI Templates.

(*) XSS in PreviewController — PreviewController.php:103 concatenates unsanitized $label directly into #markup.The $label value comes from stored pattern segments. While admin-entered, stored XSS is still a risk. Use Html::escape() or render arrays with
#plain_text instead. See writing secure code for Drupal.

(*) Debug logging left in production code — SdBreadcrumbBuilder.php:177 logs print_r($pattern, TRUE) and line 227 logs print_r($segments, TRUE) to
the logger on every node page view. The .module file (lines 62, 73) also logs per-segment data on every preprocess. This causes severe log noise, performance degradation, and potential information disclosure. Remove all debug logging before release.