Merge pull request #22 from jeffthibault/nip22-unacceptable-event-time

NIP-22: event created_at limits

22.md

@@ -0,0 +1,42 @@
+NIP-22
+======
+
+Event `created_at` Limits
+---------------------------
+
+`draft` `optional` `author:jeffthibault` `author:Giszmo`
+
+Relays may define both upper and lower limits within which they will consider an event's `created_at` to be acceptable. Both the upper and lower limits MUST be unix timestamps in seconds as defined in [NIP-01](01.md).
+
+If a relay supports this NIP, the relay SHOULD send the client a `NOTICE` message saying the event was not stored for the `created_at` timestamp not being within the permitted limits.
+
+Client Behavior
+---------------
+
+Clients SHOULD use the [NIP-11](11.md) `supported_nips` field to learn if a relay uses event `created_at` time limits as defined by this NIP.
+
+Motivation
+----------
+
+This NIP formalizes restrictions on event timestamps as accepted by a relay and allows clients to be aware of relays that have these restrictions.
+
+The event `created_at` field is just a unix timestamp and can be set to a time in the past or future. Relays accept and share events dated to 20 years ago or 50,000 years in the future. This NIP aims to define a way for relays that do not want to store events with *any* timestamp to set their own restrictions.
+
+[Replaceable events](16.md#replaceable-events) can behave rather unexpected if the user wrote them - or tried to write them - with a wrong system clock. Persisting an update with a backdated system now would result in the update not getting persisted without a `NOTICE` and if they did the last update with a forward dated system, they will again fail to do another update with the now correct time.
+
+A wide adoption of this nip could create a better user experience as it would decrease the amount of events that appear wildly out of order or even from impossible dates in the distant past or future.
+
+Python Example
+--------------
+
+```python
+import time
+
+TIME = int(time.now)
+LOWER_LIMIT = TIME - (60 * 60 * 24) # Define lower limit as 1 day into the past
+UPPER_LIMIT = TIME + (60 * 15)      # Define upper limit as 15 minutes into the future
+
+if event.created_at not in range(LOWER_LIMIT, UPPER_LIMIT):
+  # NOTE: This is one example of a notice message. Relays can change this to notify clients however they like.
+  ws.send('["NOTICE", "The event created_at field is out of the acceptable range (-24h, +15min) for this relay and was not stored."]')
+```

README.md

@@ -18,6 +18,7 @@ NIPs stand for **Nostr Implementation Possibilities**. They exist to document wh
 - [NIP-14: Subject tag in text events.](14.md)
 - [NIP-15: End of Stored Events Notice](15.md)
 - [NIP-16: Event Treatment](16.md)
+- [NIP-22: Event created_at Limits](22.md)
 - [NIP-25: Reactions](25.md)
 
 ## Event Kinds