Add pre-upload step

95.md

@@ -55,6 +55,40 @@ Metadata should be added using [NIP-94](94.md) or other metadata-related NIP.
 Client should upload to user's "file relays", which use the [NIP-65](65.md) `f` flag.
 When downloading a file uploaded with this NIP, it should search on the uploader's "file relays".
 
+**Relays must NOT honor `kind:5` deletion events referencing file chunk events.** Deletion
+is expected to be automatic when no uploader is registered (see [Pre-Upload](#pre-upload) section
+to learn how to register an uploader). If an user wants to make sure a file won't be deleted, it
+should become an uploader of that file.
+
+## Pre-Upload
+
+Before uploading `kind:1064` events of a specifc file,
+user MUST publish a single `kind:1065` "Uploader" event,
+which is an event authored by the **user's main pubkey**,
+with empty `.content` and an `f` tag referencing the `kind:1064`
+event set (the `kind:1064` event(s) `.pubkey`).
+
+Its purpose is to register the user as an uploader of the file on a specific relay and to request permission
+for uploading the file chunks.
+
+When receiving the `kind:1065` event, relay may answer with one of the following messages and prefixes:
+
+- `["OK", "<kind:1065-event-id>", false, "auth-required: ..."]`: Authentication is required to register an uploader;
+- `["OK", "<kind:1065-event-id>", true, "uploaded: ..."]`: The corresponding `kind:1064` file chunks are already uploaded, trying to re-upload them will fail;
+- `["OK", "<kind:1065-event-id>", true, "upload: Missing chunks 1, 2, 7, 10"]`: File isn't uploaded yet or incomplete, user is allowed to upload it on this ws connection;
+
+Trying to send a `kind:1064` event before a `kind:1065` one should fail.
+Sending `kind:1065` events with an identifier (pubkey) different from the previously sent `kind:1064`'s `f` tag should fail.
+
+A `kind:5` deletion event referencing a `kind:1065` event is used to unregister the user as an uploader.
+
+Relay may split the burden of a single file by the multiple registered uploaders. For example, when there are 2 uploaders,
+a file relay may charge each of them half of the costs to host the file.
+
+Relay should delete the `kind:1065` event if no corresponding `kind:1064` event is uploaded within a reasonable period.
+
+Clients may download `kind:1065` events from user's file relays to list all user files.
+
 ## Download
 
 This NIP introduces a NIP-94 `f` tag filled with the `kind:1064` pubkey, uniquely identifying the file,