Linter Rule: Disallow unused herb:state declarations

Rule: herb-state-no-unused-states

Description

Flags a declared state that is never read by the template and never written by an action attribute or a bound form control.

Rationale

Every declared state travels in the template's schema and dependency map, so a state nothing uses is payload and parked markup for nothing. It is usually a leftover from a refactor or a typo, since a misspelled read no longer matches the declaration.

A state can legitimately be driven only from app code, through stateFor or useState. The rule cannot see JavaScript, so that case is a false positive by design. Disable the line with a herb:disable comment, and the offense message says so.

Examples

✅ Good

<%# herb:slots client %>
<%# herb:state (open: false, attempts: 0) %>

<button data-herb-toggle="open">Details</button>
<p><%= attempts %></p>

🚫 Bad

<%# herb:slots client %>
<%# herb:state (open: false, stale: true) %>
The state `stale` is never read or written in this template. Remove it, or disable this line when only app code uses it through `stateFor` or `useState`. (herb-state-no-unused-states)

<% if open? %>Open<% end %>

References

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