diff --git a/sidecar/src/main.rs b/sidecar/src/main.rs
index 050d5fd..779b18c 100644
--- a/sidecar/src/main.rs
+++ b/sidecar/src/main.rs
@@ -103,9 +103,24 @@ use tracing_subscriber::EnvFilter;
 /// rollback as well. `web::CONFIG_RELOAD_WINDOW` is that budget, mirrored from the plugin, and a
 /// test asserts the pairing rather than trusting it.
 ///
+/// # Protocol 6 — first-party clans
+///
+/// One board (`clans`) and five events (`clan.created`, `clan.disbanded`, `clan.member.added`,
+/// `clan.member.left`, `clan.member.kicked`), from which the website builds core's Teams (R5).
+///
+/// **Nothing in this process changed except this number**, and that is protocol 2's promise
+/// kept: the board is filed by `type: "snapshot"` and the events by `type: "event"`, so the
+/// sidecar needs no arm for any of them. The bump exists for the other two declaration sites —
+/// a website that reads clans must not pair with a plugin that never sends them.
+///
+/// One property of this process does bear on the board: [`game::MAX_INBOUND_LINE_BYTES`]
+/// discards a line over 1 MiB outright. The plugin bounds the board well inside it and says
+/// `truncated` when it had to stop, because a board that never arrived would read as a server
+/// with no clans.
+///
 /// `docs/rust-link/PROTOCOL.md` is the specification — §8 the read path, §9 identity, §10 the
-/// mirror, §11 configuration; this constant is one of its four declaration sites.
-pub const PROTOCOL_VERSION: u32 = 5;
+/// mirror, §11 configuration, §12 clans; this constant is one of its four declaration sites.
+pub const PROTOCOL_VERSION: u32 = 6;
 
 fn main() -> anyhow::Result<()> {
     let args = match cli::parse(std::env::args().skip(1)) {