Ghost/ghost/admin/app/templates/components/gh-psm-template-select.hbs

{{#if customTemplates}}
    <div class="form-group for-select" data-test-custom-template-form>
        <label for="author-list">Template</label>
        <span class="gh-input-icon gh-icon-user">
            {{svg-jar "file-text-document"}}
            <span class="gh-select {{if matchedSlugTemplate "disabled"}}">
                {{one-way-select selectedTemplate
                    options=customTemplates
                    optionValuePath="filename"
                    optionLabelPath="name"
                    update=(action "selectTemplate")
                    disabled=matchedSlugTemplate
                    data-test-select="custom-template"}}
                {{svg-jar "arrow-down-small"}}
            </span>
        </span>
        {{#if matchedSlugTemplate}}
            <p>Post URL matches {{matchedSlugTemplate.filename}}</p>
        {{/if}}
    </div>
{{/if}}