feat(net): capsule inbound TCP bind (bind_tcp) (#1230)

CHANGELOG.md

@@ -459,6 +459,7 @@ Changelog tracking starts with 0.2.0. Prior versions were not tracked.
   refusal or eviction always falls back to verified reads. Cold reopen tests
   corrupt a neighbour frame after recovery and prove that no process-local
   evidence can suppress its checksum failure. Closes #1399.
+- **Capsule inbound TCP bind (`bind_tcp`).** A capsule can bind an inbound TCP port and accept connections from its run loop via the WIT `bind-tcp(host, port) -> tcp-listener` fn (`accept` / `poll-accept` / `local-addr`), gated by the per-capsule `net_bind = ["host:port", "host:*"]` manifest capability (new fail-closed `check_net_tcp_bind` gate reusing the `net_connect` host:port matcher). A post-gate loopback airlock refuses non-loopback binds; accepted connections reuse the existing `NetStream::Tcp` read/write/close plumbing. The runtime primitive the srouter capsule needs (loopback ingress on 127.0.0.1:8788). Closes #1230.
 - **Windows local transport uses authenticated per-user named pipes.** A pipe
   name derived only from the caller's operating-system SID replaces
   filesystem endpoint naming on Windows. Local-only byte-mode instances use a

crates/astrid-audit/src/entry.rs

@@ -288,6 +288,14 @@ pub enum AuditAction {
         addr: String,
     },
 
+    /// Inbound TCP connection accepted by a capsule listener.
+    NetAccept {
+        /// Host-observed local listener endpoint.
+        local_addr: String,
+        /// Host-observed remote peer endpoint.
+        peer_addr: String,
+    },
+
     /// Child-process spawn by a capsule host call (`astrid:process` spawn).
     ///
     /// Recorded for every spawn attempt — allowed, failed, or denied — so a
@@ -540,6 +548,12 @@ impl AuditAction {
             Self::NetBind { addr } => {
                 format!("Bound socket {addr}")
             },
+            Self::NetAccept {
+                local_addr,
+                peer_addr,
+            } => {
+                format!("Accepted connection from {peer_addr} on {local_addr}")
+            },
             Self::ProcessSpawn { command } => {
                 format!("Spawned process {command}")
             },

crates/astrid-capsule/src/audit_sink.rs

@@ -56,6 +56,13 @@ pub enum HostAuditEvent<'a> {
         /// The bind address.
         addr: &'a str,
     },
+    /// An inbound TCP connection accepted by a capsule listener.
+    NetAccept {
+        /// Host-observed local listener endpoint.
+        local_addr: &'a str,
+        /// Host-observed remote peer endpoint.
+        peer_addr: &'a str,
+    },
     /// A child-process spawn.
     ProcessSpawn {
         /// The command being executed.

crates/astrid-capsule/src/engine/wasm/host/audit_sink_tests.rs

@@ -22,6 +22,7 @@ enum CapturedEvent {
     FileDelete(String),
     NetConnect(String, u16),
     NetBind(String),
+    NetAccept(String, String),
     ProcessSpawn(String),
 }
 
@@ -33,6 +34,10 @@ impl CapturedEvent {
             HostAuditEvent::FileDelete { path } => Self::FileDelete(path.to_owned()),
             HostAuditEvent::NetConnect { host, port } => Self::NetConnect(host.to_owned(), port),
             HostAuditEvent::NetBind { addr } => Self::NetBind(addr.to_owned()),
+            HostAuditEvent::NetAccept {
+                local_addr,
+                peer_addr,
+            } => Self::NetAccept(local_addr.to_owned(), peer_addr.to_owned()),
             HostAuditEvent::ProcessSpawn { command } => Self::ProcessSpawn(command.to_owned()),
         }
     }
@@ -167,6 +172,28 @@ async fn audit_net_reports_connect() {
     );
 }
 
+#[tokio::test]
+async fn audit_net_accept_carries_host_observed_endpoints() {
+    let (state, sink) = state_with_sink(tokio::runtime::Handle::current());
+    let alice = PrincipalId::new("alice").unwrap();
+
+    super::net::audit_net_accept(
+        &state,
+        "127.0.0.1:8788",
+        "127.0.0.1:49152",
+        &Ok::<(), ()>(()),
+    );
+
+    assert_eq!(
+        sink.snapshot(),
+        vec![(
+            alice,
+            CapturedEvent::NetAccept("127.0.0.1:8788".into(), "127.0.0.1:49152".into()),
+            CapturedOutcome::Allowed,
+        )]
+    );
+}
+
 #[tokio::test]
 async fn audit_net_reports_bind_denied() {
     // A denied socket bind (capsule lacks `net_bind`) currently leaves no