From 5cd26d321b706113afb8431aba35ab8fb32281c4 Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Tue, 3 Nov 2026 02:43:15 +0100
Subject: announcements answered only if heads differ

---
 src/transport/libp2p/tests.rs | 1 +
 src/transport/mod.rs          | 4 ++++
 src/transport/mycelium/mod.rs | 1 +
 src/transport/paths.rs        | 1 +
 src/transport/sim.rs          | 1 +
 src/transport/wire.rs         | 8 ++++++--
 6 files changed, 14 insertions(+), 2 deletions(-)

(limited to 'src/transport')

diff --git a/src/transport/libp2p/tests.rs b/src/transport/libp2p/tests.rs
index 0f52e23..1d7c6ac 100644
--- a/src/transport/libp2p/tests.rs
+++ b/src/transport/libp2p/tests.rs
@@ -59,6 +59,7 @@ fn status() -> ParsedMessage {
         ready: true,
         syncs_with_you: false,
         leaving: false,
+        announcing: false,
     })
 }
 
diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index b8b57af..25f9b7c 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -202,6 +202,10 @@ pub(crate) struct Status {
     /// The sender is shutting down: its farewell (`keepalive::farewell`). The
     /// recipient holds it dormant at once, rather than after `dormant_after` of silence.
     pub(crate) leaving: bool,
+    /// The sender announces new heads (`swarm::relay`), rather than keeping alive: a
+    /// STATUS answered only if the recipient's heads differ. Most announcements reach a
+    /// neighbour that has the changes already, which has nothing to tell.
+    pub(crate) announcing: bool,
 }
 
 /// Cheap to clone: large parts are shared (`bytes::Bytes`).
diff --git a/src/transport/mycelium/mod.rs b/src/transport/mycelium/mod.rs
index 9078134..9850ef0 100644
--- a/src/transport/mycelium/mod.rs
+++ b/src/transport/mycelium/mod.rs
@@ -717,6 +717,7 @@ mod tests {
             ready: true,
             syncs_with_you: true,
             leaving: false,
+            announcing: false,
         };
         let payload = wire::encode(&ParsedMessage::StatusReply(status.clone())).unwrap();
         // Mycelium's message data: a length byte, the topic, then our payload.
diff --git a/src/transport/paths.rs b/src/transport/paths.rs
index 164574d..29b3c23 100644
--- a/src/transport/paths.rs
+++ b/src/transport/paths.rs
@@ -1513,6 +1513,7 @@ mod tests {
             ready: false,
             syncs_with_you: false,
             leaving: false,
+            announcing: false,
         })
     }
 
diff --git a/src/transport/sim.rs b/src/transport/sim.rs
index 2f167dc..7a679fc 100644
--- a/src/transport/sim.rs
+++ b/src/transport/sim.rs
@@ -387,6 +387,7 @@ mod tests {
             ready: true,
             syncs_with_you: false,
             leaving: false,
+            announcing: false,
         })
     }
 
diff --git a/src/transport/wire.rs b/src/transport/wire.rs
index d72fba4..d3bf39d 100644
--- a/src/transport/wire.rs
+++ b/src/transport/wire.rs
@@ -14,7 +14,7 @@ use super::{EncodedMessage, MessageKind, ParsedMessage};
 
 /// The wire format's version, the first byte of every payload. Bump it with every change
 /// to a message type or a codec (`golden_bytes` fails then).
-pub(crate) const VERSION: u8 = 15;
+pub(crate) const VERSION: u8 = 16;
 
 /// What the second byte of a payload says.
 fn tag(kind: MessageKind) -> u8 {
@@ -369,6 +369,7 @@ pub(crate) fn samples() -> Vec<ParsedMessage> {
         ready: true,
         syncs_with_you: true,
         leaving: false,
+        announcing: false,
     };
     let proof = IdentityProof {
         key: [8; 32],
@@ -549,6 +550,7 @@ mod tests {
             ready: true,
             syncs_with_you: false,
             leaving: false,
+            announcing: false,
         };
         let decoded =
             decode(&encode(&ParsedMessage::StatusReply(status.clone())).unwrap()).unwrap();
@@ -572,6 +574,7 @@ mod tests {
             ready: true,
             syncs_with_you: true,
             leaving: false,
+            announcing: false,
         };
         assert!(decode(&encode(&ParsedMessage::Status(status)).unwrap()).is_err());
     }
@@ -669,10 +672,11 @@ mod tests {
             ready: true,
             syncs_with_you: false,
             leaving: false,
+            announcing: true,
         });
         assert_eq!(
             hex(&encode(&status).unwrap()),
-            format!("{v}03969290c400{epoch_hex}01c3c2c2")
+            format!("{v}03979290c400{epoch_hex}01c3c2c2c3")
         );
 
         let who = ParsedMessage::Who(IdentityProof {
-- 
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