Module: Mermas

The mermas (shrinkage) module is where you declare that some stock was lost: the milk expired, a serving dish broke, the box from the dining room can't be found, a batch of meat was thrown out. It records the loss, deducts the stock instantly, and keeps who reported it, why and at what value.

It's different from the inventory count and complementary to it:

	Merma (this module)	Conteo de inventario
When	At the moment it happens	At the end, comparing what was counted against the system
What it is	A declaration: "3 expired"	A detection: "3 are missing"
Knows the reason	Yes, always	No, only knows it doesn't add up
Who answers for it	One person	The physical count

A merma is what someone knows happened. The count is the net that catches what nobody reported.

Reasons

Reason	When it's used
Vencimiento	The date passed or it spoiled.
Merma	Waste, preparation error, discarded leftovers.
Daño	It broke or was damaged in handling or transport.
Robo	Merchandise is missing with no explanation.

Recording a loss

From Inventario → Mermas, with the Registrar pérdida button.

1. Choose the reason. Each one has a short explanation that helps you decide.
2. Search for the lost products. The search box only offers products and additions with stock control turned on — the others can't be deducted, so they don't appear.
3. Enter the units for each one. You see the current stock of each line and it won't let you go over what there is.
4. Say what happened in the note. It is required for the cashier and the worker.
5. Adjust the date if you're recording something from a previous shift.

As you type, below you see the total in units and the value in money.

What the system complains about when you make a mistake

This module is designed so the inventory ledger is reliable, so it won't let you lie:

• It doesn't clamp. If you report 10 units lost and there are 2 in stock, it rejects it with a 409. It doesn't silently adjust it to 0 as the generic adjustment does. The ledger has to balance.
• It doesn't swallow products without tracking. If the product doesn't have stock control turned on, it tells you exactly that instead of returning a "done" when nothing happened.
• It's all or nothing. If one line out of ten fails, none is deducted.

The value in money (costs)

So that the report answers "how much did I lose?" and not just "how many units did I lose?", each product and addition has a purchase cost on its sheet (only Dueño and Administrador see and edit it).

When recording a merma, the cost is copied to the history line. If tomorrow you correct the product's cost, the history doesn't change: it reflects what it was worth when the loss occurred.

If a product has no cost entered, the loss is counted in units and the report says so explicitly, with how many products have no cost. It never shows $0 as if the loss were free.

Viewing mermas

The Inventario → Mermas subpage shows:

• Four cards: units lost, value of the loss, number of records and main reason.
• Filters by period (7 / 30 / 90 days, one year, or all history) and by reason.
• The list, grouped by event. When you expand a loss you see each product, how many units were lost, how much remained and the value.
• Most-lost products, with a proportional bar. This is the list that tells you what you're throwing away.
• Exportar CSV (Dueño / Administrador), with one row per product.

Reversing a record

If you recorded a loss that didn't happen, Dueño and Administrador can reverse it from the list.

The reversal deletes nothing: the loss existed, what was wrong was the record. An inverse event is created that returns the stock, and the original is marked as "Revertida". It appears in the CSV as such, and the summary excludes it from the total because it's no longer a live loss.

The same loss can't be reversed twice.

Who can record

Role	View	Record merma, expiration and damage	Record theft	Reverse	See the money summary
Dueño	Sí	Sí	Sí	Sí	Sí
Administrador	Sí	Sí	Sí	Sí	Sí
Cajero	Sí	Sí (con nota obligatoria)	No	No	No
Trabajador	Sí	Sí (con nota obligatoria)	No	No	No
Cocinero	No	No	No	No	No

Why theft is restricted. Theft is a vector for losing money, and whoever reports it is, by definition, someone to whom it could be attributed. Merma and expiration are observable facts that the cashier sees every day. Everything is kept in the audit log (stock_loss.registered) with user, IP and request.

Why the note is required for the cashier and the worker. A loss without a written explanation is indistinguishable from a typo.

Plan requirements

The module needs the stock_tracking feature ("Control de stock"), available from the Starter plan. Without per-product stock control there is nothing to deduct.

Related pages

• Historial de stock — the complete ledger of movements, with mermas and counts distinguished by type.
• Productos (Administrador) — where to enter the purchase cost.
• Adiciones (Administrador) — costs of toppings and extras.