{% comment %} The channel cells of one row of the series table.

A partial of its own because the server sends these back alone: which
channels a column may offer depends on the (session, image type) pair the
row names, so choosing another pair re-renders every one of them. Sending
the whole row instead would replace the colour, style and label set in it,
and lose its place under whatever sort is in force.

Takes one context variable, `diagnostic`, as `make_series` builds it.
{% endcomment %}
{% for slot in diagnostic.slots %}
{% if slot.fixed %}
{% comment %} A column with one channel to offer is no choice at all, so
   the cell states what it binds rather than asking, and says so in
   `data-channel`, which is where the client reads a settled binding from.
{% endcomment %}
<td class="slot-cell" data-sort="{{ slot.sort }}" data-channel="{{ slot.value }}">
    {{ slot.value }}
</td>
{% else %}
<td class="slot-cell" data-sort="{{ slot.sort }}">
    <select class="slot-select">
        {% for option in slot.options %}
        <option value="{{ option.value }}"
                {% if option.value == slot.value %}selected{% endif %}>{{ option.text }}</option>
        {% endfor %}
    </select>
</td>
{% endif %}
{% endfor %}