diff --git a/guests/pid0/build.rs b/guests/pid0/build.rs
index 965901b3..b11403e8 100644
--- a/guests/pid0/build.rs
+++ b/guests/pid0/build.rs
@@ -3,15 +3,22 @@ use std::path::Path;
 
 fn main() {
     let manifest_dir = env::var("CARGO_MANIFEST_DIR").expect("CARGO_MANIFEST_DIR not set");
-    let capnp_file = Path::new(&manifest_dir)
+    let capnp_dir = Path::new(&manifest_dir)
         .join("..")
         .join("..")
         .join("capnp")
-        .join("peer.capnp");
+        .canonicalize()
+        .expect("capnp dir not found");
 
     capnpc::CompilerCommand::new()
-        .file(&capnp_file)
+        .src_prefix(&capnp_dir)
+        .file(capnp_dir.join("peer.capnp"))
+        .file(capnp_dir.join("membrane.capnp"))
+        .file(capnp_dir.join("stem.capnp"))
         .run()
-        .expect("failed to compile capnp schema");
-    println!("cargo:rerun-if-changed={}", capnp_file.display());
+        .expect("failed to compile capnp schemas");
+
+    println!("cargo:rerun-if-changed={}", capnp_dir.join("peer.capnp").display());
+    println!("cargo:rerun-if-changed={}", capnp_dir.join("membrane.capnp").display());
+    println!("cargo:rerun-if-changed={}", capnp_dir.join("stem.capnp").display());
 }
diff --git a/guests/pid0/src/lib.rs b/guests/pid0/src/lib.rs
index cac36497..8fa97fd2 100644
--- a/guests/pid0/src/lib.rs
+++ b/guests/pid0/src/lib.rs
@@ -5,12 +5,22 @@ use wasip2::exports::cli::run::Guest;
 
 #[allow(dead_code)]
 mod peer_capnp {
-    include!(concat!(
-        env!("OUT_DIR"),
-        "/Users/mikel/Code/github.com/wetware/rs/capnp/peer_capnp.rs"
-    ));
+    include!(concat!(env!("OUT_DIR"), "/peer_capnp.rs"));
 }
 
+#[allow(dead_code)]
+mod stem_capnp {
+    include!(concat!(env!("OUT_DIR"), "/stem_capnp.rs"));
+}
+
+#[allow(dead_code)]
+mod membrane_capnp {
+    include!(concat!(env!("OUT_DIR"), "/membrane_capnp.rs"));
+}
+
+/// Bootstrap capability: a Membrane whose sessions carry our WetwareSession extension.
+type Membrane = stem_capnp::membrane::Client<membrane_capnp::wetware_session::Owned>;
+
 struct StderrLogger;
 
 impl log::Log for StderrLogger {
@@ -52,32 +62,44 @@ fn run_impl() {
     init_logging();
     log::trace!("pid0: start");
 
-    wetware_guest::run(|host: peer_capnp::host::Client| async move {
-        log::trace!("pid0: rpc bootstrapped");
-        const CHILD_WASM: &[u8] =
-            include_bytes!("../../child-echo/target/wasm32-wasip2/release/child_echo.wasm");
-
-        let executor = host.executor_request().send().pipeline.get_executor();
-
-        let mut request = executor.run_bytes_request();
-        {
-            let mut params = request.get();
-            params.set_wasm(CHILD_WASM);
-            params.reborrow().init_args(0);
-            params.reborrow().init_env(0);
-        }
-        log::trace!("pid0: runBytes sent");
-
-        let run_resp = request.send().promise.await?;
-        let process = run_resp.get()?.get_process()?;
-        log::trace!("pid0: got process");
-
-        let wait_resp = process.wait_request().send().promise.await?;
-        let exit_code = wait_resp.get()?.get_exit_code();
-        log::trace!("pid0: child exited with code {}", exit_code);
-
-        Ok(())
-    });
+    // Bootstrap a Membrane(WetwareSession) instead of a bare Host.
+    // The membrane provides epoch-scoped sessions with Host + Executor.
+    wetware_guest::run(
+        |membrane: Membrane| async move {
+            log::trace!("pid0: rpc bootstrapped, grafting onto membrane");
+
+            // Graft onto the membrane to get an epoch-scoped session.
+            // No signer needed — stem's graft() currently ignores it.
+            let graft_resp = membrane.graft_request().send().promise.await?;
+            let session = graft_resp.get()?.get_session()?;
+            let ext = session.get_extension()?;
+            log::trace!("pid0: grafted, got session");
+
+            let executor = ext.get_executor()?;
+
+            const CHILD_WASM: &[u8] =
+                include_bytes!("../../child-echo/target/wasm32-wasip2/release/child_echo.wasm");
+
+            let mut request = executor.run_bytes_request();
+            {
+                let mut params = request.get();
+                params.set_wasm(CHILD_WASM);
+                params.reborrow().init_args(0);
+                params.reborrow().init_env(0);
+            }
+            log::trace!("pid0: runBytes sent");
+
+            let run_resp = request.send().promise.await?;
+            let process = run_resp.get()?.get_process()?;
+            log::trace!("pid0: got process");
+
+            let wait_resp = process.wait_request().send().promise.await?;
+            let exit_code = wait_resp.get()?.get_exit_code();
+            log::trace!("pid0: child exited with code {}", exit_code);
+
+            Ok(())
+        },
+    );
 
     log::trace!("pid0: cleanup complete");
 }
diff --git a/src/cell/executor.rs b/src/cell/executor.rs
index bc1cfdf7..665574fa 100644
--- a/src/cell/executor.rs
+++ b/src/cell/executor.rs
@@ -203,8 +203,21 @@ impl Command {
         let (reader, writer) = handles
             .take_host_split()
             .ok_or_else(|| anyhow::anyhow!("host stream missing; RPC streams already consumed"))?;
-        let rpc_system =
-            crate::rpc::build_peer_rpc(reader, writer, network_state, swarm_cmd_tx, wasm_debug);
+        // Static epoch (never advances) — real epoch wiring is a future concern.
+        let initial_epoch = stem::membrane::Epoch {
+            seq: 0,
+            head: vec![],
+            adopted_block: 0,
+        };
+        let (_epoch_tx, epoch_rx) = tokio::sync::watch::channel(initial_epoch);
+        let rpc_system = crate::rpc::membrane::build_membrane_rpc(
+            reader,
+            writer,
+            network_state,
+            swarm_cmd_tx,
+            wasm_debug,
+            epoch_rx,
+        );
 
         info!("Starting streams RPC server for guest");
         let local = tokio::task::LocalSet::new();