Cart

The /cart page. Lines on the left, a summary column alongside carrying gift wrap, the free-shipping bar, discounts, the subtotal, checkout and an optional shipping estimator.

Most add-to-carts in Signal land in the cart drawer rather than here, so treat this page as the considered view — the one a shopper opens to edit an order, read a note field or estimate shipping.

Section settings

Setting	Type	Default	What it does
Heading	Text	Your bag	The page <h1>
Empty heading	Text	Nothing here yet	Heading when the cart is empty
Empty button label	Text	Shop the drop	Button under it, linking to all products
Allow an order note	Checkbox	true	Allow an order note
Note label	Text	Order note	Label on the note field
Tax note	Text	Tax and shipping calculated at checkout.	Fine print above the checkout button
Free shipping unlocked	Text	Free shipping — unlocked	Shown once the threshold is met
Free shipping remaining	Text	from free shipping	Follows the remaining amount, e.g. “$40.00 from free shipping”
Checkout label	Text	Checkout	Submit button label
Continue label	Text	Continue shopping	Link under the button
Show a shipping estimator	Checkbox	true	Show a shipping estimator so shoppers can check delivery cost before checkout

The section also accepts @app blocks, rendered in their own row under the lines — reviews, loyalty widgets, trust badges.

What each line shows

Element	Source
Thumbnail	item.image at 400w, linking to the product
Title	item.product.title
Variant	item.variant.title, suppressed when it is blank or Default Title
Subscription	item.selling_plan_allocation.selling_plan.name when the line is a subscription
Line item properties	Every entry in item.properties, as Name: value
Discounts	Each line_level_discount_allocations entry as Title −amount in the accent colour
Unit price	item.original_price with “each”
Line total	item.final_line_price, with the original struck through when a discount applied

Line item properties

Properties are what carries per-line customisation — a gift-card recipient, an engraving, an app’s configuration. Signal renders them automatically, and hides two kinds: a property with an empty value, and any property whose name starts with _ (the convention for private/app-internal properties, which Shopify also hides at checkout).

Quantity updates

The +, − and Remove controls all post to /cart/change.js with a line number and a quantity, handled by the theme’s global cart engine. On the cart page they additionally carry data-reload, so the page reloads after a successful change — the totals, the free-shipping bar and the discount rows are all server-rendered here, and a reload is the honest way to keep them consistent.

Errors are surfaced as a toast, with distinct copy for a network failure versus a store-side refusal, and the control is re-enabled rather than left spinning.

Standard Storefront Actions

Signal configures Shopify’s Shopify.actions.updateCart standard action in the layout. Those actions work on any Liquid storefront whether or not a theme does anything — but the default updateCart falls back to a full page reload when it cannot recognise how a theme renders its cart, throwing away scroll position and anything the buyer had typed.

Signal points the action at its own drawer refresh instead, so an app that updates the cart through the standard action re-renders Signal’s drawer in place. This has to be configured above content_for_header, because only the first configure call on an action takes effect and app code loads from there.

The order note

With show_note on, the cart page shows a textarea under the lines. It saves itself:

• typing debounces for 500ms then posts to /cart/update.js
• blurring the field flushes immediately
• submitting the cart form (clicking Checkout) holds the submit just long enough to land a pending note, then lets it through — so a note typed and immediately checked out is never lost

The same behaviour drives the note field in the cart drawer.

Gift wrap

Shared with the drawer, and driven entirely by global settings under Theme settings → Cart:

Setting	What it does
Gift wrap product	The wrap itself. Nothing renders unless this is set and the product is available
gift_wrap_label (default Add gift wrapping)	The checkbox label; the wrap’s price is appended automatically
gift_message_enabled (default on)	Adds a 200-character message field, revealed once wrapping is ticked

The wrap is a real product, not a free-floating attribute — so it is priced, taxed, counted in inventory and fulfilled like anything else, rather than being a flag that never reaches the packing bench. Ticking the box adds that product’s line; unticking finds and removes it.

The checkbox state is derived by looking for the wrap’s variant id in the cart, so swapping the wrap product in settings does not leave a stale line ticked. If the add or remove fails, the checkbox is put back where the cart actually is.

The gift message is stored as the cart attribute Gift message — which is what shows on the order in admin — and saved on a 500ms pause rather than per keystroke.

The free-shipping bar

Driven by the global Cart → Free shipping threshold setting. When that setting is empty or zero, the bar does not render at all. When it is set, the bar shows either ship_unlocked or remaining + ship_away, with a progress track clamped at 100%.

The shipping estimator

With show_estimator on, a <details> panel offers country, province and postal code, then calls /cart/shipping_rates.json and lists each rate with its price.

• The province field is populated from Shopify’s own country data and stays hidden for countries that have no provinces.
• A 422 from Shopify is read rather than replaced with a generic failure, so an invalid postcode produces Shopify’s own explanation.
• With no rates for the address, a dedicated “no rates” message is shown rather than an empty list.
• Output is announced via role="status" and aria-live="polite".

The summary

Above the subtotal, each cart-level discount renders as its own row. The subtotal uses cart.total_price. Below it: the tax_note, the checkout submit, and the continue-shopping link.

Related

• Cart drawer — the overlay version
• Product