gatewayd: a turn's speaker, the username of the one person who wrote its burst

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

crates/gatewayd/src/deliver.rs

@@ -151,6 +151,7 @@ fn one_turn(
     socket: &Path,
     batch: &Batch,
     resume: bool,
+    speaker: Option<&str>,
     on_event: &mut dyn FnMut(&TurnEvent),
 ) -> Outcome {
     // 1. Connect to the socket (else LoopDown("cannot connect to <path>: <e>")).
@@ -167,8 +168,8 @@ fn one_turn(
         session: batch.session.clone(),
         content: batch.text.clone(),
         resume,
-        // Set in M5c-1 task 03. Until then no turn has a speaker, and none is synced.
-        speaker: None,
+        // On the turn only, never in its text: `memoryd` reads it from the log, the model never.
+        speaker: speaker.map(str::to_string),
     };
     if let Err(e) = write_frame(
         &mut stream,
@@ -207,14 +208,20 @@ fn one_turn(
     }
 }
 
-/// A turn for a batch. A reply in a thread `loopd` does not know creates the session, as
-/// `bxctl chat --session` does.
-pub fn run_turn(socket: &Path, batch: &Batch, on_event: &mut dyn FnMut(&TurnEvent)) -> Outcome {
+/// A turn for a batch, spoken by `speaker` (a Mattermost username) when one person wrote all of
+/// it. A reply in a thread `loopd` does not know creates the session, as `bxctl chat --session`
+/// does.
+pub fn run_turn(
+    socket: &Path,
+    batch: &Batch,
+    speaker: Option<&str>,
+    on_event: &mut dyn FnMut(&TurnEvent),
+) -> Outcome {
     // `one_turn` with batch.resume. When that is Refused with NoSuchSession and batch.resume was
     // true, one more `one_turn` with resume false. Otherwise the first outcome.
-    match one_turn(socket, batch, batch.resume, on_event) {
+    match one_turn(socket, batch, batch.resume, speaker, on_event) {
         Outcome::Refused(err) if err.code == ErrorCode::NoSuchSession && batch.resume => {
-            one_turn(socket, batch, false, on_event)
+            one_turn(socket, batch, false, speaker, on_event)
         }
         outcome => outcome,
     }
@@ -230,11 +237,13 @@ fn post(poster: &dyn Poster, thread: &Thread, text: String, log: &dyn Fn(&str))
     }
 }
 
-/// Run a batch's turn and post what comes of it in its thread. A post that fails is logged.
+/// Run a batch's turn, spoken by `speaker`, and post what comes of it in its thread. A post that
+/// fails is logged.
 pub fn deliver(
     poster: &dyn Poster,
     socket: &Path,
     batch: &Batch,
+    speaker: Option<&str>,
     log: &dyn Fn(&str),
     notice: &Notice,
 ) {
@@ -244,7 +253,7 @@ pub fn deliver(
     // LoopDown(why) -> log "gatewayd: <session>: <why>" and post LOOP_DOWN. A post that fails is
     // logged, exactly "gatewayd: cannot post in <channel> (thread <root>): <error>", and the rest
     // goes on.
-    let outcome = run_turn(socket, batch, &mut |event| {
+    let outcome = run_turn(socket, batch, speaker, &mut |event| {
         if let TurnEvent::ApprovalPending { approval, .. } = event
             && !notice.arrives(*approval)
         {