From 58a2fe3046725a48ad9cb0448e658c8978864a0a Mon Sep 17 00:00:00 2001
From: Claude <claude@anthropic.com>
Date: Fri, 14 Aug 2026 13:20:20 +0000
Subject: [PATCH] =?UTF-8?q?feat(cluster):=20RFC=20010=20c1=20=E2=80=94=20c?=
 =?UTF-8?q?luster=20feature=20flag=20+=20optional=20serde/postcard=20deps?=
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Off by default; the default build stays libc-only. serde (payload contract)
and postcard (payload codec) are optional, no default features. src/cluster.rs
is an intentionally empty cfg-gated stub so the flag's default-build
invariance is reviewable in isolation.
---
 Cargo.toml     | 8 ++++++++
 src/cluster.rs | 6 ++++++
 src/lib.rs     | 2 ++
 3 files changed, 16 insertions(+)
 create mode 100644 src/cluster.rs

diff --git a/Cargo.toml b/Cargo.toml
index 8b101b6..362b77d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,6 +33,11 @@ budget-accounting = []
 # and unflagged; only the optional gen_server transport sits behind this, so a
 # release build pays nothing for an observer it never starts.
 observer = []
+# RFC 010 c1: clustering. Off by default — the default build stays libc-only,
+# byte-for-byte (gate checked per phase). serde is the payload contract,
+# postcard the payload codec; both minimal (no default features). Everything
+# cluster-shaped lives behind this flag.
+cluster = ["dep:serde", "dep:postcard"]
 # Run-queue selection: exactly one, compile-time (see src/run_queue.rs).
 # Non-default variants need --no-default-features (features are additive).
 rq-mutex = []
@@ -44,6 +49,9 @@ cc = "1"
 
 [dependencies]
 libc = "0.2"
+# RFC 010 §2 — only compiled under `--features cluster`.
+serde = { version = "1", default-features = false, optional = true }
+postcard = { version = "1", default-features = false, optional = true }
 
 [target.'cfg(loom)'.dependencies]
 loom = "0.7"
diff --git a/src/cluster.rs b/src/cluster.rs
new file mode 100644
index 0000000..9326694
--- /dev/null
+++ b/src/cluster.rs
@@ -0,0 +1,6 @@
+//! RFC 010 — clustering (smarm⇄smarm, explicit remote boundary).
+//!
+//! c1: feature flag + optional deps only. The owned envelope (c2), transport
+//! trait (c3), and everything above them land in later chunks. This module is
+//! intentionally empty so the `cluster` feature's default-build invariance is
+//! reviewable in isolation.
diff --git a/src/lib.rs b/src/lib.rs
index 7dfb3f4..3a6ee80 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -14,6 +14,8 @@
 pub mod actor;
 pub mod causal;
 pub mod channel;
+#[cfg(feature = "cluster")]
+pub mod cluster;
 pub mod context;
 pub mod gen_server;
 pub mod gen_statem;