From 7a0f4e8e4cf4d42346a080421b5e9fe6cf489733 Mon Sep 17 00:00:00 2001
From: colmugx <colmugx@qq.com>
Date: Thu, 24 Sep 2026 13:05:07 +0800
Subject: [PATCH 1/4] perf: specialize the fold actor loop

Give spawn_fold a dedicated serving path that handles Tell directly and treats Unit asks as FIFO receipts, removing the generic query callback and state/reply tuple from the dominant tell-oriented actor shape. Mark the command handler local for MoonBit parameter inlining.
---
 src/fuwaroid.mbt | 85 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 78 insertions(+), 7 deletions(-)

diff --git a/src/fuwaroid.mbt b/src/fuwaroid.mbt
index 0cd542c..a64c8ab 100644
--- a/src/fuwaroid.mbt
+++ b/src/fuwaroid.mbt
@@ -302,13 +302,24 @@ pub fn[State, Cmd] Fuwaroid::spawn_fold(
   on_cmd~ : (Ctx[Cmd, Unit, Unit], State, Cmd) -> State,
   mailbox? : Mailbox = Mailbox::Unbounded,
 ) -> Fuwaroid[Cmd, Unit, Unit] {
-  Fuwaroid::spawn(
-    group~,
-    init~,
-    on_cmd~,
-    on_query=fold_receipt_query,
-    mailbox~,
-  )
+  let kind : @aqueue.Kind = match mailbox {
+    Unbounded => @aqueue.Unbounded
+    Bounded(n) =>
+      match mailbox_capacity_error(n) {
+        Some(message) =>
+          abort("fuwaroid: invalid mailbox configuration: \{message}")
+        None => @aqueue.Blocking(n)
+      }
+  }
+  let queue : @aqueue.Queue[Envelope[Cmd, Unit, Unit]] = @aqueue.Queue(kind~)
+  let stop = LoopStop::fresh()
+  let fuwaroid : Fuwaroid[Cmd, Unit, Unit] = { mailbox: queue, stop, }
+  let ctx : Ctx[Cmd, Unit, Unit] = { group, address: fuwaroid, }
+  let task = group.spawn(no_wait=true, () => {
+    fuwaroid_loop_fold(ctx, init, on_cmd, queue, stop~)
+  })
+  stop.task = Some(task)
+  fuwaroid
 }
 
 ///|
@@ -349,6 +360,66 @@ fn[Cmd, Query, Reply] abandon_envelope(
   }
 }
 
+///|
+async fn[State, Cmd] fuwaroid_loop_fold(
+  ctx : Ctx[Cmd, Unit, Unit],
+  init : State,
+  on_cmd : (Ctx[Cmd, Unit, Unit], State, Cmd) -> State,
+  queue : @aqueue.Queue[Envelope[Cmd, Unit, Unit]],
+  stop~ : LoopStop,
+) -> Unit {
+  match @async.handle_cancellation(() => {
+    fuwaroid_serve_fold(ctx, init, on_cmd, queue, stop~)
+  }) {
+    Some(_) => ()
+    None => {
+      fuwaroid_cleanup(queue, Cancelled, stop)
+      @async.pause()
+    }
+  }
+}
+
+///|
+#locals(on_cmd)
+async fn[State, Cmd] fuwaroid_serve_fold(
+  ctx : Ctx[Cmd, Unit, Unit],
+  init : State,
+  on_cmd : (Ctx[Cmd, Unit, Unit], State, Cmd) -> State,
+  queue : @aqueue.Queue[Envelope[Cmd, Unit, Unit]],
+  stop~ : LoopStop,
+) -> Unit {
+  let reason : StopReason = try {
+    for envelope = queue.get(),
+        state = init,
+        served = 0 {
+      let state = match envelope {
+        Tell(cmd) => on_cmd(ctx, state, cmd)
+        Ask(_, reply) => {
+          let _ = reply.try_put(()) catch { _ => false }
+          state
+        }
+      }
+      let served = served + 1
+      stop.diag.processed += 1L
+
+      if served >= fuwaroid_yield_batch {
+        @async.pause()
+        continue queue.get(), state, 0
+      }
+
+      match queue.try_get() {
+        Some(next) => continue next, state, served
+        None => continue queue.get(), state, served
+      }
+    }
+    Graceful
+  } catch {
+    @aqueue.QueueAlreadyClosed => Graceful
+    original => Failed(original)
+  }
+  fuwaroid_cleanup(queue, reason, stop)
+}
+
 ///|
 /// Cancellation is handled separately from ordinary loop errors.
 async fn[State, Cmd, Query, Reply] fuwaroid_loop(

From 47e81ab08b2d9906bcddc086aed9d14e8fcae606 Mon Sep 17 00:00:00 2001
From: colmugx <colmugx@qq.com>
Date: Thu, 24 Sep 2026 13:05:17 +0800
Subject: [PATCH 2/4] ci: benchmark specialized spawn_fold experiment

---
 .github/workflows/concurrency-benchmark.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/concurrency-benchmark.yml b/.github/workflows/concurrency-benchmark.yml
index 73edf25..371d594 100644
--- a/.github/workflows/concurrency-benchmark.yml
+++ b/.github/workflows/concurrency-benchmark.yml
@@ -9,7 +9,7 @@ on:
         required: true
         type: string
   push:
-    branches: [main]
+    branches: [main, perf/specialize-spawn-fold]
 
 permissions:
   contents: read

From 69f48a8b8b86c0f2bf414c5db8a9f7bfdbfeaaff Mon Sep 17 00:00:00 2001
From: colmugx <colmugx@qq.com>
Date: Thu, 24 Sep 2026 13:08:36 +0800
Subject: [PATCH 3/4] refactor: remove obsolete fold query shim

---
 src/fuwaroid.mbt | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/src/fuwaroid.mbt b/src/fuwaroid.mbt
index a64c8ab..6e2cb99 100644
--- a/src/fuwaroid.mbt
+++ b/src/fuwaroid.mbt
@@ -207,17 +207,6 @@ fn LoopStop::fresh() -> LoopStop {
   { reason: None, cleanup_error: None, task: None, diag: Diag::fresh(), }
 }
 
-///|
-/// No-op query handler for `spawn_fold`.
-#inline
-fn[State, Cmd] fold_receipt_query(
-  _ctx : Ctx[Cmd, Unit, Unit],
-  state : State,
-  _query : Unit,
-) -> (State, Unit) {
-  (state, ())
-}
-
 ///|
 /// Shared admission path for `tell` and `ask`.
 #inline

From 7a7784adf7c30822be3b3077e113dfc4f85f8416 Mon Sep 17 00:00:00 2001
From: colmugx <colmugx@qq.com>
Date: Thu, 24 Sep 2026 13:08:39 +0800
Subject: [PATCH 4/4] ci: remove temporary spawn_fold benchmark trigger

---
 .github/workflows/concurrency-benchmark.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/concurrency-benchmark.yml b/.github/workflows/concurrency-benchmark.yml
index 371d594..73edf25 100644
--- a/.github/workflows/concurrency-benchmark.yml
+++ b/.github/workflows/concurrency-benchmark.yml
@@ -9,7 +9,7 @@ on:
         required: true
         type: string
   push:
-    branches: [main, perf/specialize-spawn-fold]
+    branches: [main]
 
 permissions:
   contents: read