protocol: Version 4: sendat

1 files changed, 19 insertions, 1 deletions

diff --git a/protocol.md b/protocol.md
index 5951f11..5b260e7 100644
--- a/protocol.md
+++ b/protocol.md
@@ -1,4 +1,4 @@
-# tomsg protocol (version 3)
+# tomsg protocol (version 4)
 
 The underlying transport of the protocol is a plain TCP socket. However,
 because private information is communicated, the recommended transport is an
@@ -170,6 +170,24 @@ tomsg server.
     The returned `number` response contains the message id of the message sent.
     This number will be non-negative.
   - Returns `number` or `error`.
+- `<tag> sendat <apikey:word> <roomname:word> <replymsgid:i64> <timestamp:i64> <message:string...>`
+  - Inserts a message in the history of the given room at the given timestamp.
+    `roomname`, `replymsgid` and `message` are as in the `send` command; if
+    `replymsgid` is not -1, the referred-to message must be in the same room
+    and have a timestamp that is earlier than `timestamp`. Note that negative
+    timestamps are not valid for `sendat`.
+
+    All room members receive a `_push message` push message on all their
+    sessions (except the session the `send` message was sent from). Contrary to
+    `send`, the current session is _not_ marked active.
+
+    The `apikey` argument is a value whose interpretation is
+    implementation-defined. The intention is to restrict usage of this command
+    to known-to-be well-behaving clients.
+
+    The returned `number` response contains the message id of the message sent.
+    This number will be non-negative.
+  - Returns `number` or `error`.
 - `<tag> history <roomname:word> <number:i64>`
   - Requests the last `<number>` messages in the given room, if the client is a
     member of the room. In the `history` response, `<count>` will be at most