We decided not to build inventory management

A message came in from E. E is the Indonesian comrade who has worked beside me since the very beginning (at his own wish, I'll write only his initial here). A friend of his runs a pet shop, and had agreed to sit down and look properly at KAZENA Books. This was the report. Honestly, the feedback was hard to hear. It was also completely right.

The point was this: KAZENA Books had been designed with service businesses in mind. A business that buys goods and resells them has no product master, no purchase line detail, no cost per product. Without those, a pet shop cannot work out its real profit. There was nothing to argue with. All I could do was say thank you, and then think.

I thought about it for a while, and the decision I reached surprised even me: we are not going to build inventory management. The obvious move would have been to add stock counts, warehouses, goods in and out, barcodes. But that ground is already covered, and covered well, by POS and inventory systems. If we fought there, we would simply become a weaker copy of a POS — while handing our customers a new burden of stock takes, barcode scanners and warehouse rules. Worst of all, we would give up the thing people like most about KAZENA Books: its simplicity. That I was not willing to trade.

So I changed the question. The real question is not 'service business or shop?' It is: who owns the truth about quantity, and who owns the truth about money? Quantity — stock counts, barcodes, warehouses — belongs to the POS. Our job is the accounting: cost, cost of sales, the allocation of freight and customs duty, the cost of each product, and the tax treatment. That is where KAZENA Books belongs.

Once that was settled, I went back and looked at the field properly, and something surprised me. Very few people have a clear picture of which costs actually belong in the cost of a product. As far as we could tell, even well-known accounting software either doesn't handle this calculation directly, or puts it behind a higher tier or a heavy ERP. Far from being crowded, this ground is close to empty.

The rule itself is simple once said plainly. Freight, customs duty, insurance and clearance fees belong in the cost of the goods. Import VAT (PPN Impor) and PPh 22 must never go into it. Import VAT is recoverable input tax; PPh 22 is prepaid income tax. Put them into cost and your cost is overstated while the credit you were entitled to is lost. One mistake, two losses.

A small example. You import 10 units at Rp100,000 each: Rp1,000,000 of goods. Add freight of Rp200,000 and duty of Rp100,000, and the cost is Rp1,300,000 — Rp130,000 per unit. Now suppose the import VAT was Rp143,000 and PPh 22 was Rp32,500. Fold those into cost and you get Rp1,475,500, or Rp147,550 per unit — more than 13% above the true figure — and you have also let go of Rp143,000 you could have recovered. Every margin you calculate from then on is wrong.

So this is what went into KAZENA Books. Enter your closing inventory value and your cost of sales comes out right. A products page showing stock, moving-average cost and gross profit for each item. Freight and customs duty allocated across products automatically. Import VAT and PPh 22 correctly kept out of cost. And an AI that reads the line items on a purchase invoice and remembers that supplier's product names the next time.

One condition I set myself before a single line was written: none of this appears unless Retail Mode is switched on. If you run a service business, the KAZENA Books you see is exactly the one you saw before. Not a single pixel changes.

An honest note: this is being tested by real shop owners right now, and I am a product builder, not a tax accountant. Import and tax treatment differ from business to business, so please confirm the final judgement with a professional. What we can do is have the numbers arranged so that the confirmation is quick.

Finally, something I want to put in writing properly. To E's friend: thank you, sincerely. You owed us nothing. You gave your time anyway, and you explained what running a shop is actually like — and you told me the truth instead of a polite compliment. Without that, KAZENA Books would have stayed half-built for anyone who buys goods and sells them. What changed the direction of this product wasn't me; it was what you said. Thank you, truly. And thank you to E, who made that conversation happen.

It was uncomfortable to receive, and it was the most valuable thing anyone gave me this month. I would far rather hear about the next problem early than discover it after release. If you run a shop and something is missing, please tell me — I read every message myself.