Linter Rule: Validate data-herb-name slot names

Rule: herb-valid-slot-names

Description

Validates data-herb-name attributes. A name must be a static, non-empty value, unique among the named slots in its scope, distinct from the attribute slots in that scope, and placed on an element that actually holds something dynamic.

Rationale

A slot name is an address client code resolves through the schema, so it cannot be computed, and two slots answering to one name would make slotInItem(file, collection, key, "body") ambiguous. An attribute slot is already addressable by its attribute, so authoring the same name shadows nothing and confuses everything. A name on a fully static element names no slot at all, which is a leftover or a typo.

The engine raises each of these as a compile error when the template renders. This rule reports the same findings in the editor first. The same name may repeat across nesting levels, an item-scoped body beside a region-scoped body is the loop running, not a duplicate.

Examples

✅ Good

<ul data-herb-name="messages">
  <% @messages.each do |message| %>
    <li id="<%= dom_id(message) %>">
      <p data-herb-name="body"><%= message.body %></p>
    </li>
  <% end %>
</ul>

🚫 Bad

<p data-herb-name="<%= field %>"><%= message.body %></p>
`data-herb-name` on `<p>` must be a static, non-empty value. Write the name out, since a slot name is an address client code resolves and cannot be computed. (herb-valid-slot-names)

<p data-herb-name="body"><%= @intro %></p>
<p data-herb-name="body"><%= @outro %></p>
Two slots in the same scope are both named `body`. Rename one of them, since `body` has to resolve to a single slot. (herb-valid-slot-names)

<p data-herb-name="body">just static text</p>
Two slots in the same scope are both named `body`. Rename one of them, since `body` has to resolve to a single slot. (herb-valid-slot-names)

<div data-herb-name="row"><span data-herb-name="body"><%= message.body %></span></div>
Two slots in the same scope are both named `body`. Rename one of them, since `body` has to resolve to a single slot. (herb-valid-slot-names)

References

-