diff --git a/crates/memoryd/src/honcho/mirror.rs b/crates/memoryd/src/honcho/mirror.rs
index fdc2335..9fbf4b9 100644
--- a/crates/memoryd/src/honcho/mirror.rs
+++ b/crates/memoryd/src/honcho/mirror.rs
@@ -225,9 +225,16 @@ impl Mirror {
     /// Decide the journalled edit `id` (the latest when `None`), called under the index lock
     /// right after it was journalled, so the ledger has the journal's order; the ledger's lock is
     /// taken inside the index lock, and before an undo is decided against it. Its parts are
-    /// `Edit { id, part }` from 0, numbering what is decided. An edit already decided, or asking nothing, adds no line. A
-    /// failure is logged; the edit itself stands.
-    pub fn journalled(&self, store: &Store, id: Option<&str>, now: Timestamp, log: &dyn Fn(&str)) {
+    /// `Edit { id, part }` from 0, numbering what is decided. An edit already decided, or asking
+    /// nothing, adds no line. A failure is logged; the edit itself stands. Whether any line was
+    /// added, so that the worker is woken only when there is something new.
+    pub fn journalled(
+        &self,
+        store: &Store,
+        id: Option<&str>,
+        now: Timestamp,
+        log: &dyn Fn(&str),
+    ) -> bool {
         let records = match journal::records(store) {
             Ok(records) => records,
             Err(e) => {
@@ -235,7 +242,7 @@ impl Mirror {
                     "memoryd: {e}; the edit is not mirrored in Honcho; {}",
                     ledger::RUNBOOK
                 ));
-                return;
+                return false;
             }
         };
         let found = match id {
@@ -243,7 +250,7 @@ impl Mirror {
             None => records.last(),
         };
         let Some(record) = found else {
-            return;
+            return false;
         };
         let session = session_of(record, &records);
         let mut book = self.ledger.lock().unwrap_or_else(|p| p.into_inner());
@@ -251,9 +258,10 @@ impl Mirror {
         if record.undoes.is_some() {
             actions.retain(|a| brought_back(&book, a));
         }
+        let mut added = false;
         for (part, action) in actions.into_iter().enumerate() {
             let Ok(part) = u32::try_from(part) else {
-                return;
+                return added;
             };
             let item = Item::Edit {
                 id: record.id.clone(),
@@ -268,8 +276,10 @@ impl Mirror {
                 action,
             }) {
                 log(&format!("memoryd: {e}; {}", ledger::RUNBOOK));
-                return;
+                return added;
             }
+            added = true;
         }
+        added
     }
 }
diff --git a/crates/memoryd/src/serve.rs b/crates/memoryd/src/serve.rs
index 2d4e48e..7d5d691 100644
--- a/crates/memoryd/src/serve.rs
+++ b/crates/memoryd/src/serve.rs
@@ -228,9 +228,12 @@ impl Memoryd {
 
     /// With `[honcho]`: decide journalled edit `id` (the latest when `None`) into the ledger. Called
     /// under the index lock, so edits are decided in the journal's order (M5c spec, section 4).
+    /// What it decided is sent at once: the worker is woken.
     fn mirror(&self, id: Option<&str>) {
-        if let Some(mirror) = &self.mirror {
-            mirror.journalled(&self.store, id, Timestamp::now(), &*self.log);
+        if let Some(mirror) = &self.mirror
+            && mirror.journalled(&self.store, id, Timestamp::now(), &*self.log)
+        {
+            self.wake.notify();
         }
     }
 
diff --git a/crates/memoryd/tests/honcho_wake_serve.rs b/crates/memoryd/tests/honcho_wake_serve.rs
new file mode 100644
index 0000000..15b801b
--- /dev/null
+++ b/crates/memoryd/tests/honcho_wake_serve.rs
@@ -0,0 +1,131 @@
+//! A memory write wakes the Honcho worker (M5c spec, section 4: a write reaches Honcho "at once";
+//! review of M5c-1, finding 3): with the worker asleep for its 30 s idle wait, the memory tool's
+//! conclusion and the owner's undo's deletion both reach the fake Honcho within 5 s.
+
+#[path = "support/honcho.rs"]
+mod honcho;
+#[path = "support/tmp.rs"]
+mod tmp;
+
+use std::os::unix::net::UnixStream;
+use std::path::Path;
+use std::sync::{Arc, Mutex};
+use std::time::{Duration, Instant};
+
+use bxcore::{
+    CallId, DataClass, Envelope, MemoryAdmin, MemoryCall, MemoryCommand, Message, SessionId,
+    ToolRequest, read_frame, write_frame,
+};
+use honcho::FakeHoncho;
+use memoryd::config::Config;
+use memoryd::honcho::worker::Tuning;
+use memoryd::serve;
+use tmp::TempDir;
+
+fn ask(socket: &Path, msg: Message) -> Message {
+    let mut stream = UnixStream::connect(socket).unwrap();
+    stream
+        .set_read_timeout(Some(Duration::from_secs(10)))
+        .unwrap();
+    let env = Envelope {
+        v: 1,
+        id: 1,
+        r#final: true,
+        msg,
+    };
+    write_frame(&mut stream, &env).unwrap();
+    read_frame(&mut stream).unwrap().msg
+}
+
+/// How many requests of `method` to a path ending `suffix` the fake has had.
+fn count(fake: &FakeHoncho, method: &str, suffix: &str) -> usize {
+    fake.requests()
+        .iter()
+        .filter(|r| {
+            r.method == method && r.path.contains("/conclusions") && r.path.ends_with(suffix)
+        })
+        .count()
+}
+
+/// Waits up to 5 s for `done`; true if it came.
+fn within_5s(done: impl Fn() -> bool) -> bool {
+    let deadline = Instant::now() + Duration::from_secs(5);
+    while Instant::now() < deadline {
+        if done() {
+            return true;
+        }
+        std::thread::sleep(Duration::from_millis(10));
+    }
+    done()
+}
+
+#[test]
+fn a_memory_write_and_an_undo_wake_the_worker() {
+    // The worker `serve` starts waits this long when idle: far past every deadline here.
+    assert!(Tuning::DEFAULT.idle >= Duration::from_secs(30));
+    let fake = FakeHoncho::start();
+    let dir = TempDir::new("wake-serve");
+    let soul = dir.write("etc/soul.md", "You are Boxmaker.\n");
+    let text = format!(
+        "[paths]\nhome = \"{}\"\n[memory]\nsoul_starter = \"{}\"\n[honcho]\nurl = \"{}\"\nagent = \"boxmaker0\"\nowner = \"kyle\"\ntrusted = \"boxmaker0-trusted\"\nuntrusted = \"boxmaker0-untrusted\"\nfleet = \"fleet\"\n",
+        dir.path().display(),
+        soul.display(),
+        fake.url
+    );
+    let config = Config::parse(&text).unwrap();
+    let lines = Arc::new(Mutex::new(Vec::new()));
+    let sink = Arc::clone(&lines);
+    let log: serve::Log = Arc::new(move |l: &str| sink.lock().unwrap().push(l.to_string()));
+    let running = serve::start(config.clone(), log).unwrap();
+    std::thread::spawn(move || running.run());
+    // Let the worker find nothing to send and fall asleep.
+    std::thread::sleep(Duration::from_millis(200));
+
+    let call = Message::MemoryCall(MemoryCall {
+        request: ToolRequest {
+            session: SessionId::new("mm-a").unwrap(),
+            call: CallId(1),
+            tool: "memory".to_string(),
+            arguments: r#"{"action":"add","file":"user","text":"Prefers UTC."}"#.to_string(),
+        },
+        taint: DataClass::Private,
+        untrusted: false,
+    });
+    assert!(matches!(
+        ask(&config.broker_socket(), call),
+        Message::ToolResponse(_)
+    ));
+    assert!(
+        within_5s(|| count(&fake, "POST", "/conclusions") == 1),
+        "the conclusion waited: {:?} {:?}",
+        fake.requests(),
+        lines.lock().unwrap()
+    );
+    std::thread::sleep(Duration::from_millis(200));
+
+    let log = ask(
+        &config.admin_socket(),
+        Message::MemoryAdmin(MemoryAdmin {
+            command: MemoryCommand::Log,
+            arg: String::new(),
+        }),
+    );
+    let Message::MemoryAdminReply(reply) = log else {
+        panic!("{log:?}")
+    };
+    let id = reply.text.split("  ").next().unwrap().to_string();
+    let undone = ask(
+        &config.admin_socket(),
+        Message::MemoryAdmin(MemoryAdmin {
+            command: MemoryCommand::Undo,
+            arg: id,
+        }),
+    );
+    assert!(matches!(undone, Message::MemoryAdminReply(_)), "{undone:?}");
+    assert!(
+        within_5s(|| count(&fake, "DELETE", "") == 1),
+        "the deletion waited: {:?} {:?}",
+        fake.requests(),
+        lines.lock().unwrap()
+    );
+}