Trade Screens

You can find Trade Screens in the sidebar, under Dynamic Components. The list shows every Trade Screen in this book. Click Add Trade Screen to create one, or click a row to open and edit it.

The editor is split into tabs: the template's own settings, the two sides of the trade, the direction stock can move, and the modifiers that adjust prices.

• Trade screen name: shown in the list and in any Trigger that opens this screen. Required, up to 70 characters. Pick a name you'll recognise later: "Queequeg's harpoons" is better than "trade 3".
• Ignore currency: when on, the trade ignores money. Items swap one for one, with no prices. Use it for pure barter ("trade me your knife for my flint") or for stashes the reader takes items from.
• Ignore weights: when on, the trade ignores container weight caps. The reader can take as much as they want, no matter what their pack can carry. Useful for scripted moments where the inventory shouldn't block the story.

One Glossary Item + one container per side

A Trade Screen has two sides, left and right. Each side needs two picks:

• Glossary Item: who or what this side belongs to. Usually a character, such as the reader's protagonist facing a merchant, but anything with a container fact works: a treasure chest, an offering altar, a fountain.
• Selected Container: which of the Glossary Item's Container facts holds this side's stock. The screen reads from and writes to that container directly. The merchant's stock is whatever is in their container fact, and the reader's pickups land in their own container.

The common setup: the reader's character with their inventory container on one side, the merchant with their wares container on the other. Both containers update live during the trade. Pick up a sword and it leaves the merchant's container the moment it joins yours.

Money is just a Fact

There is no dedicated wallet or money field in Verhaler. Money is simply a Numeric fact, exactly like strength or reputation.

If a reader is buying a harpoon with coins, three things must line up. The harpoon needs a price. The reader's character needs a fact called Coins. The merchant needs one too. These two facts act as the wallets, and the trade simply moves the number from one to the other.

You set the price and currency on the item itself under Glossary Item → Trade Screen Settings, not here on the Trade Screen.

A price of 0 does the same thing, so it's worth a look too.

When you want a free trade

Sometimes you want an item to be free. When you do, use the "Ignore currency" setting on the template. It is much better to use this option than to leave a currency Fact incomplete. That way, when you return to your project later, you will know the free price was intentional.

Who can give to whom

Pick which way items can move:

• Both ways: the default. Items move in either direction. This is the standard buy and sell merchant screen.
• Left to Right: items only move from the left side to the right. Use it for one-way pickups, like taking items from a stash or a chest.
• Right to Left: the reverse. Use it for one-way drops, like offering items at an altar or putting coins in a fountain.

Per-item price adjustments

By default, items trade at the value you set in their Glossary Item's Trade Screen Settings. Modifiers let this screen override that: lower an item's price, raise it, or hide the item from the screen. Up to 10 modifiers per screen.

Each modifier has:

• Glossary Item: the item this modifier acts on. It must be an Item-category Glossary Item with Can be added in containers turned on, the same kind of item you can put in a container fact.
• Container: Left Container or Right Container. This decides which side of the screen the modifier applies to. A discount on the merchant's wares is not the same as a discount in the reader's bag.
• Modifier: one of two options:
  • Add: adjusts the item's price. The next field (Value) supplies the number. Negative numbers discount, positive numbers mark up.
  • Hide: removes the item from that side of the screen, as if it weren't in the container.
• Value: only for Add modifiers. Either a fixed number or a Calculation that resolves to one. A Calculation makes the discount reactive: "discount by the reader's reputation fact ÷ 2", for example.
• Probability: the percent chance the modifier applies. Defaults to 100%, which means every time. Lower it and the modifier applies at random.
• Behavior type: Direct or Conditional. A Direct modifier always applies. A Conditional one only applies when its conditions pass: "only give this discount if the reader has done the quest", "only hide this item if the alarm bell has rung". Conditions can check anything the engine tracks.

Once a Trade Screen ships in a published expansion of a book, it locks: its card in the list shows a lock icon and no longer opens the editor. Hover the card and click Duplicate to get a copy with (Copy) appended to the name, and work on that. The original keeps serving readers of that expansion exactly as they bought it.

A Trade Screen can become invalid in a few ways. The list page marks broken screens with a warning icon and sorts them to the top. The publish check rejects any book with an invalid Trade Screen.

• A side's Glossary Item has been deleted, or its container fact has been deleted or converted to a different fact type. Fix the fact and the side becomes valid again on its own.
• A modifier's Glossary Item has been deleted, or it's no longer an Item-category Glossary Item with Can be added in containers turned on.
• A modifier's value points at a deleted Calculation or fact, or its conditions reference a Glossary Item, fact, tag, or Calculation that has been deleted.

Deleting a Trade Screen that's in use breaks every Trigger pointing at it. The editor warns you when you delete, so you can cancel or fix the Triggers afterwards.