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+NIP-15
+======
+
+Nostr Marketplace (for resilient marketplaces)
+-----------------------------------
+
+`draft` `optional` `author:fiatjaf` `author:benarc`  `author:motorina0` `author:talvasconcelos` 
+
+> Based on https://github.com/lnbits/Diagon-Alley
+
+> Implemented here https://github.com/lnbits/nostrmarket
+
+## Terms
+
+- `merchant` - seller of products with NOSTR key-pair
+- `customer` - buyer of products with NOSTR key-pair
+- `product` - item for sale by the `merchant`
+- `stall` - list of products controlled by `merchant` (a `merchant` can have multiple stalls)
+- `marketplace` - clientside software for searching `stalls` and purchasing `products`
+
+## Nostr Marketplace Clients
+
+### Merchant admin
+
+Where the `merchant` creates, updates and deletes `stalls` and `products`, as well as where they manage sales, payments and communication with `customers`.
+
+The `merchant` admin software can be purely clientside, but for `convenience` and uptime, implementations will likely have a server client listening for NOSTR events.
+
+### Marketplace
+
+`Marketplace` software should be entirely clientside, either as a stand-alone app, or as a purely frontend webpage. A `customer` subscribes to different merchant NOSTR public keys, and those `merchants` `stalls` and `products` become listed and searchable. The marketplace client is like any other ecommerce site, with basket and checkout. `Marketplaces` may also wish to include a `customer` support area for direct message communication with `merchants`.
+
+## `Merchant` publishing/updating products (event)
+
+A merchant can publish these events:
+| Kind    |                  | Description                                                                                                   | NIP                                     |
+|---------|------------------|---------------------------------------------------------------------------------------------------------------|-----------------------------------------|
+| `0    ` | `set_meta`       | The merchant description (similar with any `nostr` public key).                                               | [NIP01       ](https://github.com/nostr-protocol/nips/blob/master/01.md)                            |
+| `30017` | `set_stall`      | Create or update a stall.                                                                                     | [NIP33](https://github.com/nostr-protocol/nips/blob/master/33.md) (Parameterized Replaceable Event) |
+| `30018` | `set_product`    | Create or update a product.                                                                                   | [NIP33](https://github.com/nostr-protocol/nips/blob/master/33.md) (Parameterized Replaceable Event) |
+| `4    ` | `direct_message` | Communicate with the customer. The messages can be plain-text or JSON. | [NIP09](https://github.com/nostr-protocol/nips/blob/master/09.md)                                            |
+| `5    ` | `delete`         | Delete a product or a stall.                                                                                  | [NIP05](https://github.com/nostr-protocol/nips/blob/master/05.md)                                   |
+
+### Event `30017`: Create or update a stall.
+
+**Event Content**:
+```json
+{
+    "id": <String, UUID generated by the merchant. Sequential IDs (`0`, `1`, `2`...) are discouraged>,
+    "name": <String, stall name>,
+    "description": <String (optional), stall description>,
+    "currency": <String, currency used>,
+    "shipping": [
+        {
+            "id": <String, UUID of the shipping zone, generated by the merchant>,
+            "name": <String (optional), zone name>,
+            "cost": <float, cost for shipping. The currency is defined at the stall level>,
+            "countries": [<String, countries included in this zone>],
+        }
+    ]
+}
+```
+
+Fields that are not self-explanatory:
+ - `shipping`:
+   - an array with possible shipping zones for this stall. The customer MUST choose exactly one shipping zone.
+   - shipping to different zones can have different costs. For some goods (digital for examle) the cost can be zero.
+   - the `id` is an internal value used by the merchant. This value must be sent back as the customer selection.
+
+**Event Tags**:
+```json
+  "tags": [["d", <String, id of stall]]
+```
+ - the `d` tag is required by [NIP33](https://github.com/nostr-protocol/nips/blob/master/33.md). Its value MUST be the same as the stall `id`.
+
+### Event `30018`: Create or update a product
+
+**Event Content**:
+```json
+{
+    "id": <String, UUID generated by the merchant.Sequential IDs (`0`, `1`, `2`...) are discouraged>,
+    "stall_id": <String, UUID of the stall to which this product belong to>,
+    "name": <String, product name>,
+    "description": <String (optional), product description>,
+    "images": <[String], array of image URLs, optional>,
+    "currency": <String, currency used>,
+    "price": <float, cost of product>,
+    "quantity": <int, available items>,
+    "specs": [
+      [ <String, spec key>, <String, spec value>]
+     ]
+}
+```
+
+Fields that are not self-explanatory:
+ - `specs`:
+   - an array of key pair values. It allows for the Customer UI to present present product specifications in a structure mode. It also allows comparison between products
+   - eg: `[["operating_system", "Android 12.0"], ["screen_size", "6.4 inches"], ["connector_type", "USB Type C"]]`
+
+_Open_: better to move `spec` in the `tags` section of the event?
+
+**Event Tags**:
+```json
+  "tags": [
+       ["d", <String, id of product],
+       ["t", <String (optional), product category],
+       ["t", <String (optional), product category],
+       ...
+    ]
+```
+
+ - the `d` tag is required by [NIP33](https://github.com/nostr-protocol/nips/blob/master/33.md). Its value MUST be the same as the product `id`.
+ - the `t` tag is as searchable tag ([NIP12](https://github.com/nostr-protocol/nips/blob/master/12.md)). It represents different categories that the product can be part of (`food`, `fruits`). Multiple `t` tags can be present.
+
+## Checkout events
+
+All checkout events are sent as JSON strings using ([NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md)).
+
+The `merchant` and the `customer` can exchange JSON messages that represent different actions. Each `JSON` message `MUST` have a `type` field indicating the what the JSON represents. Possible types:
+
+| Message Type | Sent By  | Description         |
+|--------------|----------|---------------------|
+| 0            | Customer | New Order           |
+| 1            | Merchant | Payment Request     |
+| 2            | Merchant | Order Status Update |
+
+
+### Step 1: `customer` order (event)
+The below json goes in content of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).
+
+```json
+{
+    "id": <String, UUID generated by the customer>,
+    "type": 0,
+    "name": <String (optional), ???>,
+    "address": <String (optional), for physical goods an address should be provided>
+    "message": "<String (optional), message for merchant>,
+    "contact": {
+        "nostr": <32-bytes hex of a pubkey>,
+        "phone": <String (optional), if the customer whats to be contacted by phone>,
+        "email": <String (optional), if the customer whats to be contacted by email>,
+    },
+    "items": [
+        {
+            "product_id": <String, UUID of the product>,
+            "quantity": <int, how many products have been ordered>
+        }
+    ],
+    "shipping_id": <String, UUID of the shipping zone>
+}
+
+```
+
+_Open_: is `contact.nostr` required?
+  
+
+### Step 2: `merchant` request payment (event)
+
+Sent back from the merchant for payment. Any payment option is valid that the merchant can check.
+
+The below json goes in `content` of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).
+
+`payment_options`/`type` include:
+
+- `url` URL to a payment page, stripe, paypal, btcpayserver, etc
+- `btc` onchain bitcoin address
+- `ln` bitcoin lightning invoice
+- `lnurl` bitcoin lnurl-pay
+
+```json
+{
+    "id": <String, UUID of the order>,
+    "type": 1,
+    "message": <String, message to customer, optional>,
+    "payment_options": [
+        {
+            "type": <String, option type>,
+            "link": <String, url, btc address, ln invoice, etc>
+        },
+        {
+            "type": <String, option type>,
+            "link": <String, url, btc address, ln invoice, etc>
+        },
+                {
+            "type": <String, option type>,
+            "link": <String, url, btc address, ln invoice, etc>
+        }
+    ]
+}
+```
+
+### Step 3: `merchant` verify payment/shipped (event)
+
+Once payment has been received and processed.
+
+The below json goes in `content` of [NIP04](https://github.com/nostr-protocol/nips/blob/master/04.md).
+
+```json
+{
+    "id": <String, UUID of the order>,
+    "type": 2,
+    "message": <String, message to customer>,
+    "paid": <Bool, true/false has received payment>,
+    "shipped": <Bool, true/false has been shipped>,
+}
+```
+
+## Customer support events
+
+Customer support is handled over whatever communication method was specified. If communicating via nostr, NIP-04 is used https://github.com/nostr-protocol/nips/blob/master/04.md.
+
+## Additional
+
+Standard data models can be found here <a href="https://raw.githubusercontent.com/lnbits/nostrmarket/main/models.py">here</a>