docs: describe resident component architecture

Document the Host-owned event/effect flow, revision-scoped resource supervision, endpoint policy, versioned resident WIT dependency, and the resident-probe packaging command.

Cargo.lock

@@ -2980,6 +2980,13 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "resident-probe-component"
+version = "0.1.0"
+dependencies = [
+ "wit-bindgen 0.41.0",
+]
+
 [[package]]
 name = "ring"
 version = "0.17.14"

Cargo.toml

@@ -9,6 +9,7 @@ members = [
   "components/spin",
   "components/clock-probe",
   "components/kv-probe",
+  "components/resident-probe",
   "components/wasi-clock-probe",
 ]
 default-members = ["crates/wasmeld-runtime"]

README.md

@@ -13,6 +13,22 @@ imports，只链接实际请求且版本完全匹配的 Host 能力；未知能
 - `wasmeld:clock/monotonic-clock@0.1.0`：Actor 内单调时钟
 - `wasmeld:kv/store@0.1.0`：按服务隔离、跨 Revision 共享的持久化二进制 KV
 
+常驻型 Component 可额外导出 `wasmeld:resident/actor@0.1.0`。Runtime 将定时器、
+TCP/UDP/Unix、消息订阅和扩展事件放入同一个有界 Actor mailbox；Component 每次只处理
+一个事件并返回 effect。系统 socket、timer task 和 broker consumer 始终由 Host 持有，
+Component 只能引用当前 Revision 内不复用的资源 ID，不能直接取得文件描述符或绕过
+端点策略。
+
+```text
+Host driver -> ResidentSession -> Actor mailbox -> Wasm Component
+Host driver <- validated operation <- raw effect <-
+```
+
+`ResidentSession` 负责 deny-by-default 的网络策略、资源归属、数量限制、流的暂停/半关闭/
+关闭状态以及 effect 批量原子校验。TCP、UDP、Unix listener 等异步驱动运行在 Actor
+线程外；协议级驱动以及文件监听、串口、系统信号等其它来源通过独立版本的 WIT 能力演进，
+不需要扩大基础 service world。
+
 ## 结构
 
 ```text
@@ -93,6 +109,16 @@ cargo run -p wasmeld-package --bin wasmeld -- \
 `kv-probe` 接受 `set:<key>:<value>`、`get:<key>` 和 `delete:<key>`，用于验证 Host KV
 能力；它不是公开 Gateway 的业务协议。
 
+常驻事件示例组件：
+
+```bash
+cargo run -p wasmeld-package --bin wasmeld -- \
+  pack components/resident-probe/Cargo.toml --locked
+```
+
+该组件同时实现基础 service world 与 resident actor export，用于验证 stream、datagram、
+timer、message 和扩展 source 的事件/effect 往返。
+
 发布 WIT Package：
 
 ```bash

components/resident-probe/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "resident-probe-component"
+version = "0.1.0"
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+
+[package.metadata.wasmeld]
+id = "resident-probe"
+world = "component:resident-probe/resident-probe-component@0.1.0"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wit-bindgen.workspace = true

components/resident-probe/src/lib.rs

@@ -0,0 +1,72 @@
+use std::sync::atomic::{AtomicU64, Ordering};
+
+mod bindings {
+    wit_bindgen::generate!({
+        path: "wit",
+        world: "resident-probe-component",
+        generate_all,
+    });
+}
+
+use bindings::exports::wasmeld::resident::actor::{
+    DatagramSend, Effect, Event, Guest as ResidentGuest, MessageAck, SourceCommand, StreamWrite,
+    TimerArm,
+};
+
+static EVENTS_HANDLED: AtomicU64 = AtomicU64::new(0);
+
+struct ResidentProbe;
+
+impl bindings::Guest for ResidentProbe {
+    fn init(_config: Vec<u8>) -> Result<(), bindings::ServiceError> {
+        EVENTS_HANDLED.store(0, Ordering::Relaxed);
+        Ok(())
+    }
+
+    fn invoke(_input: Vec<u8>) -> Result<Vec<u8>, bindings::ServiceError> {
+        Ok(EVENTS_HANDLED
+            .load(Ordering::Relaxed)
+            .to_le_bytes()
+            .to_vec())
+    }
+}
+
+impl ResidentGuest for ResidentProbe {
+    fn handle_event(
+        input: Event,
+    ) -> Result<Vec<Effect>, bindings::exports::wasmeld::resident::actor::ResidentError> {
+        EVENTS_HANDLED.fetch_add(1, Ordering::Relaxed);
+        Ok(match input {
+            Event::StreamData(chunk) => vec![Effect::WriteStream(StreamWrite {
+                stream_id: chunk.stream_id,
+                bytes: chunk.bytes,
+            })],
+            Event::Datagram(datagram) => vec![Effect::SendDatagram(DatagramSend {
+                endpoint_id: datagram.endpoint_id,
+                peer: datagram.peer,
+                bytes: datagram.bytes,
+            })],
+            Event::Timer(timer) => vec![Effect::ArmTimer(TimerArm {
+                timer_id: timer.timer_id,
+                delay_ms: 10,
+                interval_ms: None,
+            })],
+            Event::Message(message) => vec![Effect::AcknowledgeMessage(MessageAck {
+                subscription_id: message.subscription_id,
+                message_id: message.message_id,
+            })],
+            Event::Source(source) => vec![Effect::SourceCommand(SourceCommand {
+                source_id: source.source_id,
+                command: source.kind,
+                payload: source.payload,
+            })],
+            Event::StreamOpened(_)
+            | Event::StreamWritable(_)
+            | Event::StreamHalfClosed(_)
+            | Event::StreamClosed(_)
+            | Event::Shutdown => Vec::new(),
+        })
+    }
+}
+
+bindings::export!(ResidentProbe with_types_in bindings);

components/resident-probe/wasmeld.toml

@@ -0,0 +1,11 @@
+schema_version = 1
+
+[dependencies]
+"wasmeld:resident" = "0.1.0"
+"wasmeld:service" = "0.1.0"
+
+[replace."wasmeld:resident"]
+path = "../../wit/resident"
+
+[replace."wasmeld:service"]
+path = "../../wit/service"

components/resident-probe/wit.lock

@@ -0,0 +1,15 @@
+schema_version = 1
+
+[[package]]
+name = "wasmeld:resident"
+version = "0.1.0"
+source = "path+../../wit/resident"
+sha256 = "683a3c7196a6dd77b3f619227aa093430ff6995c097d39bb82d501b7c59a196c"
+replaced = true
+
+[[package]]
+name = "wasmeld:service"
+version = "0.1.0"
+source = "path+../../wit/service"
+sha256 = "d5497307bbcd1e159f7707f385b488a6f2e26362d5256d5bc1080ac603a51305"
+replaced = true

components/resident-probe/wit/world.wit

@@ -0,0 +1,6 @@
+package component:resident-probe@0.1.0;
+
+world resident-probe-component {
+  include wasmeld:service/service-component@0.1.0;
+  export wasmeld:resident/actor@0.1.0;
+}

crates/wasmeld-package/README.md

@@ -156,6 +156,7 @@ url = "http://127.0.0.1:8080"
 [dependencies]
 "wasmeld:service" = "0.1.0"
 "wasmeld:kv" = "0.1.0"
+"wasmeld:resident" = "0.1.0"
 
 [replace."wasmeld:service"]
 path = "../../wit/service"
@@ -164,6 +165,11 @@ path = "../../wit/service"
 依赖解析结果写入 `wit.lock`，源码开发时应提交该文件。解析出的 `wit/deps/` 是生成目录，
 不应提交。
 
+普通请求型 Component 只需要 `wasmeld:service`。需要接收 Host 定时器、网络流、UDP、
+消息订阅或扩展 source 事件时，再依赖并导出 `wasmeld:resident/actor@0.1.0`；例如
+`components/resident-probe`。`resident` 是独立版本化 package，不会把所有 Host 能力
+合并到基础 service world。
+
 同步依赖：
 
 ```bash

crates/wasmeld-runtime/src/bindings.rs

@@ -5,3 +5,11 @@ wasmtime::component::bindgen!({
     path: "../../wit/service",
     world: "service-component",
 });
+
+/// Optional exports implemented only by active resident Components.
+pub(crate) mod resident {
+    wasmtime::component::bindgen!({
+        path: "../../wit/resident",
+        world: "resident-component",
+    });
+}

crates/wasmeld-runtime/src/error.rs

@@ -68,6 +68,18 @@ pub enum RuntimeError {
     #[error("actor for {0} stopped before returning a result")]
     ActorStopped(ServiceKey),
 
+    #[error("service revision {0} does not export the resident actor interface")]
+    NotResident(ServiceKey),
+
+    #[error("resident event for {service} exceeds the {limit}-byte payload limit")]
+    ResidentEventTooLarge { service: ServiceKey, limit: usize },
+
+    #[error("resident event for {service} returned more than {limit} effects")]
+    TooManyResidentEffects { service: ServiceKey, limit: usize },
+
+    #[error("invalid resident effect: {0}")]
+    InvalidResidentEffect(String),
+
     #[error("input for {service} exceeds the {limit}-byte limit")]
     InputTooLarge { service: ServiceKey, limit: usize },
 

crates/wasmeld-runtime/src/lib.rs

@@ -9,6 +9,8 @@ mod bindings;
 mod capability;
 mod error;
 mod manifest;
+mod resident;
+mod resident_host;
 mod runtime;
 
 pub use capability::{
@@ -16,5 +18,14 @@ pub use capability::{
 };
 pub use error::RuntimeError;
 pub use manifest::{ResourceLimits, ServiceKey, ServiceManifest};
+pub use resident::{
+    ComponentExecution, ResidentEffect, ResidentEvent, ResidentLimits, ResourceId,
+    StreamCloseReason,
+};
+pub use resident_host::{
+    NetworkScope, ResidentEndpoint, ResidentHostError, ResidentOperation, ResidentPolicy,
+    ResidentResourceInfo, ResidentResourceKind, ResidentResourceMetadata, ResidentResourceState,
+    ResidentSession,
+};
 pub use runtime::{ActorHandle, Runtime, RuntimeConfig, RuntimeStats};
 pub use wasmeld_package::SERVICE_WORLD;

crates/wasmeld-runtime/src/manifest.rs

@@ -4,7 +4,7 @@ use std::{fmt, time::Duration};
 
 use serde::{Deserialize, Serialize};
 
-use crate::error::RuntimeError;
+use crate::{error::RuntimeError, resident::ResidentLimits};
 
 /// Immutable identity of one service revision.
 #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
@@ -103,6 +103,9 @@ pub struct ResourceLimits {
     pub max_input_bytes: usize,
     /// Maximum response payload size.
     pub max_output_bytes: usize,
+    /// Limits for active events and Host-owned resources.
+    #[serde(default)]
+    pub resident: ResidentLimits,
 }
 
 impl Default for ResourceLimits {
@@ -114,6 +117,7 @@ impl Default for ResourceLimits {
             mailbox_capacity: 16,
             max_input_bytes: 16 * 1024,
             max_output_bytes: 16 * 1024,
+            resident: ResidentLimits::default(),
         }
     }
 }
@@ -151,7 +155,7 @@ impl ResourceLimits {
             ));
         }
 
-        Ok(())
+        self.resident.validate()
     }
 
     /// Returns the configured call deadline.

crates/wasmeld-runtime/src/resident.rs

@@ -0,0 +1,317 @@
+//! Host-owned event and effect protocol for active resident Components.
+//!
+//! A [`ResidentEvent`] is always produced by a Host driver and delivered
+//! through the same bounded Actor mailbox as ordinary service invocations.
+//! The Component never receives an operating-system descriptor. It can only
+//! reference opaque [`ResourceId`] values and return [`ResidentEffect`] values
+//! for the owning driver to validate and apply.
+
+use serde::{Deserialize, Serialize};
+
+use crate::{RuntimeError, bindings::resident::exports::wasmeld::resident::actor as wit};
+
+pub(crate) const RESIDENT_INTERFACE: &str = "wasmeld:resident/actor@0.1.0";
+
+/// Component execution model discovered from its exported WIT interfaces.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ComponentExecution {
+    /// Retains memory but runs only for `invoke` mailbox commands.
+    Service,
+    /// Also accepts Host events and returns effects for Host-owned resources.
+    Resident,
+}
+
+/// Opaque Host resource identity scoped to one resident Actor revision.
+///
+/// IDs are never reused while the Actor is alive. `0` is reserved so an
+/// uninitialized ID cannot accidentally address a real resource.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Ord, PartialEq, PartialOrd, Serialize)]
+#[serde(transparent)]
+pub struct ResourceId(u64);
+
+impl ResourceId {
+    /// Creates a valid opaque resource identity.
+    pub fn new(value: u64) -> Option<Self> {
+        (value != 0).then_some(Self(value))
+    }
+
+    /// Returns the WIT-compatible integer representation.
+    pub const fn get(self) -> u64 {
+        self.0
+    }
+}
+
+/// Why a Host-owned stream stopped accepting events and effects.
+#[derive(Clone, Copy, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum StreamCloseReason {
+    PeerClosed,
+    HostClosed,
+    IdleTimeout,
+    ProtocolError,
+    TransportError,
+}
+
+/// One bounded event delivered to a resident Component.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub enum ResidentEvent {
+    Timer {
+        timer_id: ResourceId,
+        scheduled_at_ns: u64,
+    },
+    StreamOpened {
+        endpoint_id: ResourceId,
+        stream_id: ResourceId,
+        peer: Option<String>,
+    },
+    StreamData {
+        stream_id: ResourceId,
+        bytes: Vec<u8>,
+    },
+    StreamWritable {
+        stream_id: ResourceId,
+    },
+    StreamHalfClosed {
+        stream_id: ResourceId,
+    },
+    StreamClosed {
+        stream_id: ResourceId,
+        reason: StreamCloseReason,
+    },
+    Datagram {
+        endpoint_id: ResourceId,
+        peer: String,
+        bytes: Vec<u8>,
+    },
+    Message {
+        subscription_id: ResourceId,
+        message_id: u64,
+        bytes: Vec<u8>,
+    },
+    Source {
+        source_id: ResourceId,
+        event: String,
+        payload: Vec<u8>,
+    },
+    Shutdown,
+}
+
+/// A requested operation returned by a resident Component.
+///
+/// Effects are inert until the Host supervisor checks resource ownership,
+/// payload limits, current stream state, and driver policy.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+#[serde(tag = "kind", rename_all = "snake_case")]
+pub enum ResidentEffect {
+    WriteStream {
+        stream_id: ResourceId,
+        bytes: Vec<u8>,
+    },
+    CloseStream {
+        stream_id: ResourceId,
+    },
+    PauseStream {
+        stream_id: ResourceId,
+    },
+    ResumeStream {
+        stream_id: ResourceId,
+    },
+    SendDatagram {
+        endpoint_id: ResourceId,
+        peer: String,
+        bytes: Vec<u8>,
+    },
+    ArmTimer {
+        timer_id: ResourceId,
+        delay_ms: u64,
+        interval_ms: Option<u64>,
+    },
+    CancelTimer {
+        timer_id: ResourceId,
+    },
+    AcknowledgeMessage {
+        subscription_id: ResourceId,
+        message_id: u64,
+    },
+    SourceCommand {
+        source_id: ResourceId,
+        command: String,
+        payload: Vec<u8>,
+    },
+}
+
+/// Execution limits specific to active resident Components.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct ResidentLimits {
+    /// Maximum number of Host resources owned by one Actor revision.
+    pub max_resources: usize,
+    /// Maximum effects accepted from one event handler call.
+    pub max_effects_per_event: usize,
+    /// Maximum bytes in one stream read or write.
+    pub max_stream_chunk_bytes: usize,
+    /// Maximum bytes in one received or sent datagram.
+    pub max_datagram_bytes: usize,
+    /// Minimum delay accepted for Component-created timers.
+    pub min_timer_delay_ms: u64,
+}
+
+impl Default for ResidentLimits {
+    fn default() -> Self {
+        Self {
+            max_resources: 1024,
+            max_effects_per_event: 64,
+            max_stream_chunk_bytes: 64 * 1024,
+            max_datagram_bytes: 64 * 1024,
+            min_timer_delay_ms: 1,
+        }
+    }
+}
+
+impl ResidentLimits {
+    pub(crate) fn validate(&self) -> Result<(), RuntimeError> {
+        if self.max_resources == 0 {
+            return Err(invalid_limit("max_resources"));
+        }
+        if self.max_effects_per_event == 0 {
+            return Err(invalid_limit("max_effects_per_event"));
+        }
+        if self.max_stream_chunk_bytes == 0 {
+            return Err(invalid_limit("max_stream_chunk_bytes"));
+        }
+        if self.max_datagram_bytes == 0 {
+            return Err(invalid_limit("max_datagram_bytes"));
+        }
+        if self.min_timer_delay_ms == 0 {
+            return Err(invalid_limit("min_timer_delay_ms"));
+        }
+        Ok(())
+    }
+}
+
+pub(crate) fn into_wit_event(event: ResidentEvent) -> wit::Event {
+    match event {
+        ResidentEvent::Timer {
+            timer_id,
+            scheduled_at_ns,
+        } => wit::Event::Timer(wit::TimerFired {
+            timer_id: timer_id.get(),
+            scheduled_at_ns,
+        }),
+        ResidentEvent::StreamOpened {
+            endpoint_id,
+            stream_id,
+            peer,
+        } => wit::Event::StreamOpened(wit::StreamOpened {
+            endpoint_id: endpoint_id.get(),
+            stream_id: stream_id.get(),
+            peer,
+        }),
+        ResidentEvent::StreamData { stream_id, bytes } => {
+            wit::Event::StreamData(wit::StreamChunk {
+                stream_id: stream_id.get(),
+                bytes,
+            })
+        }
+        ResidentEvent::StreamWritable { stream_id } => wit::Event::StreamWritable(stream_id.get()),
+        ResidentEvent::StreamHalfClosed { stream_id } => {
+            wit::Event::StreamHalfClosed(stream_id.get())
+        }
+        ResidentEvent::StreamClosed { stream_id, reason } => {
+            wit::Event::StreamClosed(wit::StreamClosed {
+                stream_id: stream_id.get(),
+                reason: match reason {
+                    StreamCloseReason::PeerClosed => wit::CloseReason::PeerClosed,
+                    StreamCloseReason::HostClosed => wit::CloseReason::HostClosed,
+                    StreamCloseReason::IdleTimeout => wit::CloseReason::IdleTimeout,
+                    StreamCloseReason::ProtocolError => wit::CloseReason::ProtocolError,
+                    StreamCloseReason::TransportError => wit::CloseReason::TransportError,
+                },
+            })
+        }
+        ResidentEvent::Datagram {
+            endpoint_id,
+            peer,
+            bytes,
+        } => wit::Event::Datagram(wit::Datagram {
+            endpoint_id: endpoint_id.get(),
+            peer,
+            bytes,
+        }),
+        ResidentEvent::Message {
+            subscription_id,
+            message_id,
+            bytes,
+        } => wit::Event::Message(wit::Message {
+            subscription_id: subscription_id.get(),
+            message_id,
+            bytes,
+        }),
+        ResidentEvent::Source {
+            source_id,
+            event,
+            payload,
+        } => wit::Event::Source(wit::SourceEvent {
+            source_id: source_id.get(),
+            kind: event,
+            payload,
+        }),
+        ResidentEvent::Shutdown => wit::Event::Shutdown,
+    }
+}
+
+pub(crate) fn from_wit_effects(
+    effects: Vec<wit::Effect>,
+) -> Result<Vec<ResidentEffect>, RuntimeError> {
+    effects.into_iter().map(from_wit_effect).collect()
+}
+
+fn from_wit_effect(effect: wit::Effect) -> Result<ResidentEffect, RuntimeError> {
+    Ok(match effect {
+        wit::Effect::WriteStream(effect) => ResidentEffect::WriteStream {
+            stream_id: resource_id(effect.stream_id)?,
+            bytes: effect.bytes,
+        },
+        wit::Effect::CloseStream(stream_id) => ResidentEffect::CloseStream {
+            stream_id: resource_id(stream_id)?,
+        },
+        wit::Effect::PauseStream(stream_id) => ResidentEffect::PauseStream {
+            stream_id: resource_id(stream_id)?,
+        },
+        wit::Effect::ResumeStream(stream_id) => ResidentEffect::ResumeStream {
+            stream_id: resource_id(stream_id)?,
+        },
+        wit::Effect::SendDatagram(effect) => ResidentEffect::SendDatagram {
+            endpoint_id: resource_id(effect.endpoint_id)?,
+            peer: effect.peer,
+            bytes: effect.bytes,
+        },
+        wit::Effect::ArmTimer(effect) => ResidentEffect::ArmTimer {
+            timer_id: resource_id(effect.timer_id)?,
+            delay_ms: effect.delay_ms,
+            interval_ms: effect.interval_ms,
+        },
+        wit::Effect::CancelTimer(timer_id) => ResidentEffect::CancelTimer {
+            timer_id: resource_id(timer_id)?,
+        },
+        wit::Effect::AcknowledgeMessage(effect) => ResidentEffect::AcknowledgeMessage {
+            subscription_id: resource_id(effect.subscription_id)?,
+            message_id: effect.message_id,
+        },
+        wit::Effect::SourceCommand(effect) => ResidentEffect::SourceCommand {
+            source_id: resource_id(effect.source_id)?,
+            command: effect.command,
+            payload: effect.payload,
+        },
+    })
+}
+
+fn resource_id(value: u64) -> Result<ResourceId, RuntimeError> {
+    ResourceId::new(value)
+        .ok_or_else(|| RuntimeError::InvalidResidentEffect("resource ID 0 is reserved".to_owned()))
+}
+
+fn invalid_limit(field: &str) -> RuntimeError {
+    RuntimeError::InvalidManifest(format!("limits.resident.{field} must be greater than zero"))
+}

crates/wasmeld-runtime/src/runtime.rs

@@ -31,10 +31,15 @@ use wasmtime_wasi::{
 };
 
 use crate::{
-    CapabilityDescriptor, KvBackend, RuntimeError, ServiceKey, ServiceManifest,
-    bindings::{ServiceComponent, ServiceError},
+    CapabilityDescriptor, ComponentExecution, KvBackend, ResidentEffect, ResidentEvent,
+    RuntimeError, ServiceKey, ServiceManifest,
+    bindings::{
+        ServiceComponent, ServiceError,
+        resident::{ResidentComponent, exports::wasmeld::resident::actor::ResidentError},
+    },
     capability::{Capability, CapabilityRegistry, HostCapabilities},
     manifest::ResourceLimits,
+    resident::{RESIDENT_INTERFACE, from_wit_effects, into_wit_event},
 };
 
 const DEFAULT_EPOCH_TICK: Duration = Duration::from_millis(5);
@@ -171,6 +176,7 @@ struct RegisteredService {
     manifest: ServiceManifest,
     component: Arc<Component>,
     capabilities: Vec<Capability>,
+    execution: ComponentExecution,
 }
 
 impl Runtime {
@@ -231,6 +237,7 @@ impl Runtime {
         let component = Component::new(&self.inner.engine, component_bytes.as_ref())
             .map_err(RuntimeError::ComponentCompilation)?;
         let capabilities = validate_component_imports(&component, &self.inner.engine)?;
+        let execution = component_execution(&component, &self.inner.engine);
         if capabilities.contains(&Capability::KvStore) && self.inner.kv_backend.is_none() {
             return Err(RuntimeError::CapabilityUnavailable(
                 Capability::KvStore.descriptor().interface().to_owned(),
@@ -253,6 +260,7 @@ impl Runtime {
                 manifest,
                 component: Arc::new(component),
                 capabilities,
+                execution,
             },
         );
 
@@ -372,6 +380,34 @@ impl Runtime {
             .collect())
     }
 
+    /// Returns whether a registered Component is passive or event-driven.
+    pub fn execution(&self, key: &ServiceKey) -> Result<ComponentExecution, RuntimeError> {
+        self.inner
+            .services
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?
+            .get(key)
+            .map(|service| service.execution)
+            .ok_or_else(|| RuntimeError::ServiceNotRegistered(key.clone()))
+    }
+
+    /// Delivers one Host event through the Actor's bounded serial mailbox.
+    pub fn dispatch_event(
+        &self,
+        key: &ServiceKey,
+        event: ResidentEvent,
+    ) -> Result<Vec<ResidentEffect>, RuntimeError> {
+        let actor = self
+            .inner
+            .actors
+            .lock()
+            .map_err(|_| RuntimeError::LockPoisoned)?
+            .get(key)
+            .cloned()
+            .ok_or_else(|| RuntimeError::ActorUnavailable(key.clone()))?;
+        actor.dispatch_event(event)
+    }
+
     /// Stops one Actor and releases its Store and Component Instance.
     pub fn stop(&self, key: &ServiceKey) -> Result<(), RuntimeError> {
         let _lifecycle = self
@@ -528,6 +564,7 @@ impl Runtime {
 #[derive(Clone)]
 pub struct ActorHandle {
     key: ServiceKey,
+    execution: ComponentExecution,
     limits: Arc<ResourceLimits>,
     sender: SyncSender<ActorCommand>,
     status: Arc<ActorStatus>,
@@ -540,6 +577,15 @@ impl ActorHandle {
         &self.key
     }
 
+    /// Returns the execution model detected from the Component exports.
+    pub fn execution(&self) -> ComponentExecution {
+        self.execution
+    }
+
+    pub(crate) fn resident_resource_limit(&self) -> usize {
+        self.limits.resident.max_resources
+    }
+
     /// Sends an invocation and waits up to the remaining service deadline.
     pub fn invoke(&self, input: Vec<u8>) -> Result<Vec<u8>, RuntimeError> {
         if !self.is_available() {
@@ -583,6 +629,45 @@ impl ActorHandle {
         }
     }
 
+    /// Sends a Host-owned resource event and waits for validated effects.
+    pub fn dispatch_event(
+        &self,
+        event: ResidentEvent,
+    ) -> Result<Vec<ResidentEffect>, RuntimeError> {
+        if !self.is_available() {
+            return Err(RuntimeError::ActorUnavailable(self.key.clone()));
+        }
+        validate_resident_event(&self.key, &self.limits, &event)?;
+
+        let (response_sender, response_receiver) = mpsc::sync_channel(1);
+        let deadline = Instant::now() + self.limits.deadline();
+        let command = ActorCommand::ResidentEvent {
+            event,
+            deadline,
+            response_sender,
+        };
+        match self.sender.try_send(command) {
+            Ok(()) => {}
+            Err(TrySendError::Full(_)) => {
+                return Err(RuntimeError::ActorOverloaded(self.key.clone()));
+            }
+            Err(TrySendError::Disconnected(_)) => {
+                return Err(RuntimeError::ActorUnavailable(self.key.clone()));
+            }
+        }
+
+        match response_receiver.recv_timeout(deadline.saturating_duration_since(Instant::now())) {
+            Ok(result) => result,
+            Err(mpsc::RecvTimeoutError::Timeout) => Err(RuntimeError::DeadlineExceeded {
+                service: self.key.clone(),
+                deadline: self.limits.deadline(),
+            }),
+            Err(mpsc::RecvTimeoutError::Disconnected) => {
+                Err(RuntimeError::ActorStopped(self.key.clone()))
+            }
+        }
+    }
+
     /// Prevents new calls, asks the worker to stop, and waits for acknowledgement.
     pub fn stop(&self) -> Result<(), RuntimeError> {
         if !self.status.accepting.swap(false, Ordering::AcqRel) {
@@ -622,6 +707,11 @@ enum ActorCommand {
         deadline: Instant,
         response_sender: SyncSender<Result<Vec<u8>, RuntimeError>>,
     },
+    ResidentEvent {
+        event: ResidentEvent,
+        deadline: Instant,
+        response_sender: SyncSender<Result<Vec<ResidentEffect>, RuntimeError>>,
+    },
     Stop {
         response_sender: SyncSender<()>,
     },
@@ -719,6 +809,7 @@ struct ActorWorker {
     epoch_tick: Duration,
     store: Store<HostState>,
     bindings: ServiceComponent,
+    resident: Option<ResidentComponent>,
 }
 
 impl ActorWorker {
@@ -750,8 +841,18 @@ impl ActorWorker {
 
         let epoch_ticks = ticks_for(limits.deadline(), epoch_tick);
         configure_call_budget(&mut store, &limits, epoch_ticks)?;
-        let bindings = ServiceComponent::instantiate(&mut store, &service.component, &linker)
+        let instance = linker
+            .instantiate(&mut store, &service.component)
             .map_err(|error| RuntimeError::ActorInitialization(error.to_string()))?;
+        let bindings = ServiceComponent::new(&mut store, &instance)
+            .map_err(|error| RuntimeError::ActorInitialization(error.to_string()))?;
+        let resident = match service.execution {
+            ComponentExecution::Service => None,
+            ComponentExecution::Resident => Some(
+                ResidentComponent::new(&mut store, &instance)
+                    .map_err(|error| RuntimeError::ActorInitialization(error.to_string()))?,
+            ),
+        };
 
         configure_call_budget(&mut store, &limits, epoch_ticks)?;
 
@@ -771,6 +872,7 @@ impl ActorWorker {
             epoch_tick,
             store,
             bindings,
+            resident,
         })
     }
 
@@ -807,6 +909,54 @@ impl ActorWorker {
             }),
         }
     }
+
+    fn dispatch_event(
+        &mut self,
+        event: ResidentEvent,
+        deadline: Instant,
+    ) -> Result<Vec<ResidentEffect>, RuntimeError> {
+        let remaining = deadline.saturating_duration_since(Instant::now());
+        if remaining.is_zero() {
+            return Err(RuntimeError::DeadlineExceeded {
+                service: self.key.clone(),
+                deadline: self.limits.deadline(),
+            });
+        }
+        let resident = self
+            .resident
+            .as_ref()
+            .ok_or_else(|| RuntimeError::NotResident(self.key.clone()))?;
+        configure_call_budget(
+            &mut self.store,
+            &self.limits,
+            ticks_for(remaining, self.epoch_tick),
+        )?;
+
+        match resident
+            .wasmeld_resident_actor()
+            .call_handle_event(&mut self.store, &into_wit_event(event))
+        {
+            Ok(Ok(effects)) => {
+                if effects.len() > self.limits.resident.max_effects_per_event {
+                    return Err(RuntimeError::TooManyResidentEffects {
+                        service: self.key.clone(),
+                        limit: self.limits.resident.max_effects_per_event,
+                    });
+                }
+                let effects = from_wit_effects(effects)?;
+                validate_resident_effects(&self.key, &self.limits, &effects)?;
+                Ok(effects)
+            }
+            Ok(Err(ResidentError::EventFailed(message))) => Err(RuntimeError::ComponentError {
+                kind: "resident-event",
+                message,
+            }),
+            Err(error) => Err(RuntimeError::ActorFault {
+                service: self.key.clone(),
+                message: error.to_string(),
+            }),
+        }
+    }
 }
 
 fn add_restricted_wasi(linker: &mut Linker<HostState>) -> Result<(), RuntimeError> {
@@ -883,6 +1033,18 @@ fn validate_component_imports(
     Ok(capabilities)
 }
 
+fn component_execution(component: &Component, engine: &Engine) -> ComponentExecution {
+    if component
+        .component_type()
+        .exports(engine)
+        .any(|(name, _)| name == RESIDENT_INTERFACE)
+    {
+        ComponentExecution::Resident
+    } else {
+        ComponentExecution::Service
+    }
+}
+
 fn spawn_actor(
     engine: Arc<Engine>,
     ticker: Arc<EpochTicker>,
@@ -892,6 +1054,7 @@ fn spawn_actor(
     init_config: Vec<u8>,
     kv_backend: Option<Arc<dyn KvBackend>>,
 ) -> Result<ActorHandle, RuntimeError> {
+    let execution = service.execution;
     let limits = Arc::new(service.manifest.limits.clone());
     let (sender, receiver) = mpsc::sync_channel(limits.mailbox_capacity);
     let (ready_sender, ready_receiver) = mpsc::sync_channel(1);
@@ -925,6 +1088,7 @@ fn spawn_actor(
 
     Ok(ActorHandle {
         key: thread_key,
+        execution,
         limits,
         sender,
         status,
@@ -961,6 +1125,29 @@ fn run_actor(worker: &mut ActorWorker, receiver: Receiver<ActorCommand>, status:
                     return;
                 }
             }
+            ActorCommand::ResidentEvent {
+                event,
+                deadline,
+                response_sender,
+            } => {
+                let result = if Instant::now() >= deadline {
+                    Err(RuntimeError::DeadlineExceeded {
+                        service: worker.key.clone(),
+                        deadline: worker.limits.deadline(),
+                    })
+                } else {
+                    worker.dispatch_event(event, deadline)
+                };
+                let fatal = is_fatal_resident(&result);
+                if fatal {
+                    status.mark_stopped();
+                }
+                let _ = response_sender.send(result);
+                if fatal {
+                    drain_after_failure(receiver, &worker.key);
+                    return;
+                }
+            }
             ActorCommand::Stop { response_sender } => {
                 status.mark_stopped();
                 let _ = response_sender.send(());
@@ -980,6 +1167,11 @@ fn drain_after_failure(receiver: Receiver<ActorCommand>, key: &ServiceKey) {
             } => {
                 let _ = response_sender.send(Err(RuntimeError::ActorUnavailable(key.clone())));
             }
+            ActorCommand::ResidentEvent {
+                response_sender, ..
+            } => {
+                let _ = response_sender.send(Err(RuntimeError::ActorUnavailable(key.clone())));
+            }
             ActorCommand::Stop { response_sender } => {
                 let _ = response_sender.send(());
             }
@@ -987,6 +1179,113 @@ fn drain_after_failure(receiver: Receiver<ActorCommand>, key: &ServiceKey) {
     }
 }
 
+fn validate_resident_event(
+    key: &ServiceKey,
+    limits: &ResourceLimits,
+    event: &ResidentEvent,
+) -> Result<(), RuntimeError> {
+    let (payload_len, limit) = match event {
+        ResidentEvent::StreamData { bytes, .. } => {
+            (bytes.len(), limits.resident.max_stream_chunk_bytes)
+        }
+        ResidentEvent::Datagram { bytes, .. } => (bytes.len(), limits.resident.max_datagram_bytes),
+        ResidentEvent::Message { bytes, .. } => (bytes.len(), limits.max_input_bytes),
+        ResidentEvent::Source { event, payload, .. } => (
+            event.len().saturating_add(payload.len()),
+            limits.max_input_bytes,
+        ),
+        ResidentEvent::Timer { .. }
+        | ResidentEvent::StreamOpened { .. }
+        | ResidentEvent::StreamWritable { .. }
+        | ResidentEvent::StreamHalfClosed { .. }
+        | ResidentEvent::StreamClosed { .. }
+        | ResidentEvent::Shutdown => return Ok(()),
+    };
+    if payload_len > limit {
+        Err(RuntimeError::ResidentEventTooLarge {
+            service: key.clone(),
+            limit,
+        })
+    } else {
+        Ok(())
+    }
+}
+
+fn validate_resident_effects(
+    key: &ServiceKey,
+    limits: &ResourceLimits,
+    effects: &[ResidentEffect],
+) -> Result<(), RuntimeError> {
+    for effect in effects {
+        match effect {
+            ResidentEffect::WriteStream { bytes, .. }
+                if bytes.len() > limits.resident.max_stream_chunk_bytes =>
+            {
+                return Err(invalid_resident_effect(
+                    key,
+                    "stream write",
+                    limits.resident.max_stream_chunk_bytes,
+                ));
+            }
+            ResidentEffect::SendDatagram { peer, bytes, .. } => {
+                if peer.is_empty() {
+                    return Err(RuntimeError::InvalidResidentEffect(format!(
+                        "{key} returned a datagram without a peer"
+                    )));
+                }
+                if bytes.len() > limits.resident.max_datagram_bytes {
+                    return Err(invalid_resident_effect(
+                        key,
+                        "datagram",
+                        limits.resident.max_datagram_bytes,
+                    ));
+                }
+            }
+            ResidentEffect::ArmTimer {
+                delay_ms,
+                interval_ms,
+                ..
+            } => {
+                let minimum = limits.resident.min_timer_delay_ms;
+                if *delay_ms < minimum || interval_ms.is_some_and(|value| value < minimum) {
+                    return Err(RuntimeError::InvalidResidentEffect(format!(
+                        "{key} returned a timer below the {minimum} ms minimum"
+                    )));
+                }
+            }
+            ResidentEffect::SourceCommand {
+                command, payload, ..
+            } => {
+                if command.is_empty() {
+                    return Err(RuntimeError::InvalidResidentEffect(format!(
+                        "{key} returned an empty source command"
+                    )));
+                }
+                if command.len().saturating_add(payload.len()) > limits.max_output_bytes {
+                    return Err(invalid_resident_effect(
+                        key,
+                        "source command",
+                        limits.max_output_bytes,
+                    ));
+                }
+            }
+            ResidentEffect::WriteStream { .. }
+            | ResidentEffect::CloseStream { .. }
+            | ResidentEffect::PauseStream { .. }
+            | ResidentEffect::ResumeStream { .. }
+            | ResidentEffect::CancelTimer { .. }
+            | ResidentEffect::AcknowledgeMessage { .. } => {}
+        }
+    }
+    Ok(())
+}
+
+fn invalid_resident_effect(key: &ServiceKey, kind: &str, limit: usize) -> RuntimeError {
+    RuntimeError::InvalidResidentEffect(format!(
+        "{key} returned a {kind} payload above the {limit}-byte limit"
+    ))
+}
+
 fn configure_call_budget(
     store: &mut Store<HostState>,
     limits: &ResourceLimits,
@@ -1017,3 +1316,7 @@ fn component_error(kind: &'static str, error: ServiceError) -> RuntimeError {
 fn is_fatal(result: &Result<Vec<u8>, RuntimeError>) -> bool {
     matches!(result, Err(RuntimeError::ActorFault { .. }))
 }
+
+fn is_fatal_resident(result: &Result<Vec<ResidentEffect>, RuntimeError>) -> bool {
+    matches!(result, Err(RuntimeError::ActorFault { .. }))
+}

crates/wasmeld-runtime/tests/runtime_components.rs

@@ -1,6 +1,7 @@
 use std::{
     collections::HashMap,
     fs,
+    net::SocketAddr,
     path::{Path, PathBuf},
     process::Command,
     sync::{Arc, Mutex, OnceLock},
@@ -9,8 +10,11 @@ use std::{
 };
 
 use wasmeld_runtime::{
-    KV_MAX_VALUE_BYTES, KvBackend, KvBackendError, ResourceLimits, Runtime, RuntimeConfig,
-    RuntimeError, ServiceManifest,
+    ComponentExecution, KV_MAX_VALUE_BYTES, KvBackend, KvBackendError, NetworkScope,
+    ResidentEffect, ResidentEndpoint, ResidentEvent, ResidentHostError, ResidentLimits,
+    ResidentOperation, ResidentPolicy, ResidentResourceKind, ResidentResourceMetadata,
+    ResidentSession, ResourceId, ResourceLimits, Runtime, RuntimeConfig, RuntimeError,
+    ServiceManifest, StreamCloseReason,
 };
 
 static COMPONENTS_BUILT: OnceLock<()> = OnceLock::new();
@@ -192,6 +196,253 @@ fn explicit_clock_capability_is_linked() {
     runtime.stop(&key).unwrap();
 }
 
+#[test]
+fn resident_component_handles_host_events_in_its_actor_mailbox() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let (key, actor) = start_component(&runtime, "resident-probe", "resident_probe_component.wasm");
+    let stream_id = resource_id(1);
+    let endpoint_id = resource_id(2);
+    let timer_id = resource_id(3);
+    let subscription_id = resource_id(4);
+    let source_id = resource_id(5);
+
+    assert_eq!(
+        runtime.execution(&key).unwrap(),
+        ComponentExecution::Resident
+    );
+    assert_eq!(
+        actor
+            .dispatch_event(ResidentEvent::StreamData {
+                stream_id,
+                bytes: b"stream".to_vec(),
+            })
+            .unwrap(),
+        vec![ResidentEffect::WriteStream {
+            stream_id,
+            bytes: b"stream".to_vec(),
+        }]
+    );
+    assert_eq!(
+        runtime
+            .dispatch_event(
+                &key,
+                ResidentEvent::Datagram {
+                    endpoint_id,
+                    peer: "127.0.0.1:9000".to_owned(),
+                    bytes: b"datagram".to_vec(),
+                },
+            )
+            .unwrap(),
+        vec![ResidentEffect::SendDatagram {
+            endpoint_id,
+            peer: "127.0.0.1:9000".to_owned(),
+            bytes: b"datagram".to_vec(),
+        }]
+    );
+    assert_eq!(
+        actor
+            .dispatch_event(ResidentEvent::Timer {
+                timer_id,
+                scheduled_at_ns: 42,
+            })
+            .unwrap(),
+        vec![ResidentEffect::ArmTimer {
+            timer_id,
+            delay_ms: 10,
+            interval_ms: None,
+        }]
+    );
+    assert_eq!(
+        actor
+            .dispatch_event(ResidentEvent::Message {
+                subscription_id,
+                message_id: 99,
+                bytes: b"message".to_vec(),
+            })
+            .unwrap(),
+        vec![ResidentEffect::AcknowledgeMessage {
+            subscription_id,
+            message_id: 99,
+        }]
+    );
+    assert_eq!(
+        actor
+            .dispatch_event(ResidentEvent::Source {
+                source_id,
+                event: "flush".to_owned(),
+                payload: b"source".to_vec(),
+            })
+            .unwrap(),
+        vec![ResidentEffect::SourceCommand {
+            source_id,
+            command: "flush".to_owned(),
+            payload: b"source".to_vec(),
+        }]
+    );
+    assert_eq!(decode_counter(actor.invoke(Vec::new()).unwrap()), 5);
+
+    runtime.stop(&key).unwrap();
+}
+
+#[test]
+fn passive_component_rejects_resident_events_without_stopping() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let (key, actor) = start_component(&runtime, "passive-echo", "echo_component.wasm");
+
+    assert_eq!(
+        runtime.execution(&key).unwrap(),
+        ComponentExecution::Service
+    );
+    assert!(matches!(
+        actor.dispatch_event(ResidentEvent::Shutdown),
+        Err(RuntimeError::NotResident(service)) if service == key
+    ));
+    assert_eq!(
+        actor.invoke(b"still-running".to_vec()).unwrap(),
+        b"still-running"
+    );
+
+    runtime.stop(&key).unwrap();
+}
+
+#[test]
+fn resident_session_owns_resources_and_validates_driver_operations() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let (key, actor) = start_component(
+        &runtime,
+        "resident-session",
+        "resident_probe_component.wasm",
+    );
+    let policy = ResidentPolicy {
+        tcp_listen: NetworkScope::Loopback,
+        udp_bind: NetworkScope::Loopback,
+        unix_listen_roots: vec![std::env::temp_dir()],
+    };
+    let mut session = ResidentSession::new(actor, policy).unwrap();
+    let tcp_id = session
+        .register_endpoint(ResidentEndpoint::Tcp {
+            name: "ingress".to_owned(),
+            bind: socket_addr("127.0.0.1:7000"),
+        })
+        .unwrap();
+    let udp_id = session
+        .register_endpoint(ResidentEndpoint::Udp {
+            name: "discovery".to_owned(),
+            bind: socket_addr("127.0.0.1:7001"),
+        })
+        .unwrap();
+    let unix_id = session
+        .register_endpoint(ResidentEndpoint::Unix {
+            name: "local-ingress".to_owned(),
+            path: std::env::temp_dir().join("wasmeld-resident-test.sock"),
+        })
+        .unwrap();
+    let timer_id = session.register_timer("heartbeat").unwrap();
+    let subscription_id = session.register_message_subscription("jobs").unwrap();
+    let source_id = session
+        .register_source("watcher", "fs-watch@0.1.0")
+        .unwrap();
+
+    let (stream_id, opened) = session
+        .accept_stream(tcp_id, Some("127.0.0.1:51000".to_owned()))
+        .unwrap();
+    assert!(opened.is_empty());
+    assert_eq!(
+        session.stream_data(stream_id, b"stream".to_vec()).unwrap(),
+        vec![ResidentOperation::WriteStream {
+            stream_id,
+            bytes: b"stream".to_vec(),
+        }]
+    );
+    assert_eq!(
+        session
+            .datagram(udp_id, "127.0.0.1:51001".to_owned(), b"datagram".to_vec(),)
+            .unwrap(),
+        vec![ResidentOperation::SendDatagram {
+            endpoint_id: udp_id,
+            peer: "127.0.0.1:51001".to_owned(),
+            bytes: b"datagram".to_vec(),
+        }]
+    );
+    assert_eq!(
+        session.timer_fired(timer_id, 1).unwrap(),
+        vec![ResidentOperation::ArmTimer {
+            timer_id,
+            delay_ms: 10,
+            interval_ms: None,
+        }]
+    );
+    assert!(matches!(
+        session.resource_info(timer_id).unwrap().metadata,
+        ResidentResourceMetadata::Timer { armed: true }
+    ));
+    assert_eq!(
+        session
+            .message(subscription_id, 7, b"work".to_vec())
+            .unwrap(),
+        vec![ResidentOperation::AcknowledgeMessage {
+            subscription_id,
+            message_id: 7,
+        }]
+    );
+    assert_eq!(
+        session
+            .source_event(source_id, "flush".to_owned(), b"state".to_vec())
+            .unwrap(),
+        vec![ResidentOperation::SourceCommand {
+            source_id,
+            command: "flush".to_owned(),
+            payload: b"state".to_vec(),
+        }]
+    );
+    assert!(matches!(
+        session.datagram(tcp_id, "127.0.0.1:1".to_owned(), Vec::new()),
+        Err(ResidentHostError::WrongResourceKind { .. })
+    ));
+
+    session
+        .stream_closed(stream_id, StreamCloseReason::PeerClosed)
+        .unwrap();
+    assert!(matches!(
+        session.resource_info(stream_id),
+        Err(ResidentHostError::UnknownResource { .. })
+    ));
+    assert_eq!(session.owner(), &key);
+    assert_eq!(
+        session.resource_info(tcp_id).unwrap().kind,
+        ResidentResourceKind::TcpEndpoint
+    );
+    assert_eq!(
+        session.resource_info(unix_id).unwrap().kind,
+        ResidentResourceKind::UnixEndpoint
+    );
+
+    session.shutdown().unwrap();
+    assert!(matches!(
+        session.register_timer("late"),
+        Err(ResidentHostError::ShuttingDown(_))
+    ));
+    runtime.stop(&key).unwrap();
+}
+
+#[test]
+fn resident_endpoint_policy_is_deny_by_default() {
+    let runtime = Runtime::new(RuntimeConfig::default()).expect("runtime should start");
+    let (key, actor) =
+        start_component(&runtime, "resident-policy", "resident_probe_component.wasm");
+    let mut session = ResidentSession::new(actor, ResidentPolicy::default()).unwrap();
+
+    assert!(matches!(
+        session.register_endpoint(ResidentEndpoint::Tcp {
+            name: "public".to_owned(),
+            bind: socket_addr("0.0.0.0:8080"),
+        }),
+        Err(ResidentHostError::EndpointDenied(_))
+    ));
+
+    runtime.stop(&key).unwrap();
+}
+
 #[test]
 fn kv_capability_is_service_scoped_and_shared_across_revisions() {
     let backend = Arc::new(MemoryKvBackend::default());
@@ -379,6 +630,7 @@ fn build_components_once() {
             "components/spin/Cargo.toml",
             "components/clock-probe/Cargo.toml",
             "components/kv-probe/Cargo.toml",
+            "components/resident-probe/Cargo.toml",
             "components/wasi-clock-probe/Cargo.toml",
         ] {
             let status = Command::new("rustup")
@@ -421,9 +673,18 @@ fn test_limits() -> ResourceLimits {
         mailbox_capacity: 16,
         max_input_bytes: 16 * 1024,
         max_output_bytes: 16 * 1024,
+        resident: ResidentLimits::default(),
     }
 }
 
+fn resource_id(value: u64) -> ResourceId {
+    ResourceId::new(value).expect("test resource id must be non-zero")
+}
+
+fn socket_addr(value: &str) -> SocketAddr {
+    value.parse().expect("test socket address must be valid")
+}
+
 fn decode_counter(bytes: Vec<u8>) -> u64 {
     let array: [u8; 8] = bytes
         .try_into()
@@ -447,6 +708,9 @@ fn component_world(artifact_name: &str) -> &'static str {
         "spin_component.wasm" => "component:spin/spin-component@0.1.0",
         "clock_probe_component.wasm" => "component:clock-probe/clock-probe-component@0.1.0",
         "kv_probe_component.wasm" => "component:kv-probe/kv-probe-component@0.1.0",
+        "resident_probe_component.wasm" => {
+            "component:resident-probe/resident-probe-component@0.1.0"
+        }
         "wasi_clock_probe_component.wasm" => {
             "component:wasi-clock-probe/wasi-clock-probe-component@0.1.0"
         }

wit/resident/package.wit

@@ -0,0 +1,123 @@
+package wasmeld:resident@0.1.0;
+
+/// Event/effect ABI for Components that remain active without monopolizing
+/// their Actor thread. The Host owns timers, subscriptions, sockets, streams,
+/// and all operating-system handles. A Component handles one bounded event and
+/// returns effects before control goes back to the Runtime.
+interface actor {
+  type resource-id = u64;
+
+  record timer-fired {
+    timer-id: resource-id,
+    scheduled-at-ns: u64,
+  }
+
+  record stream-opened {
+    endpoint-id: resource-id,
+    stream-id: resource-id,
+    peer: option<string>,
+  }
+
+  record stream-chunk {
+    stream-id: resource-id,
+    bytes: list<u8>,
+  }
+
+  enum close-reason {
+    peer-closed,
+    host-closed,
+    idle-timeout,
+    protocol-error,
+    transport-error,
+  }
+
+  record stream-closed {
+    stream-id: resource-id,
+    reason: close-reason,
+  }
+
+  record datagram {
+    endpoint-id: resource-id,
+    peer: string,
+    bytes: list<u8>,
+  }
+
+  record message {
+    subscription-id: resource-id,
+    message-id: u64,
+    bytes: list<u8>,
+  }
+
+  /// Escape hatch for Host-owned event sources such as filesystem watchers,
+  /// serial devices, process signals, or platform-specific buses. `kind` and
+  /// `payload` are interpreted by the separately versioned Host capability
+  /// that created `source-id`.
+  record source-event {
+    source-id: resource-id,
+    kind: string,
+    payload: list<u8>,
+  }
+
+  variant event {
+    timer(timer-fired),
+    stream-opened(stream-opened),
+    stream-data(stream-chunk),
+    stream-writable(resource-id),
+    stream-half-closed(resource-id),
+    stream-closed(stream-closed),
+    datagram(datagram),
+    message(message),
+    source(source-event),
+    shutdown,
+  }
+
+  record stream-write {
+    stream-id: resource-id,
+    bytes: list<u8>,
+  }
+
+  record datagram-send {
+    endpoint-id: resource-id,
+    peer: string,
+    bytes: list<u8>,
+  }
+
+  record timer-arm {
+    timer-id: resource-id,
+    delay-ms: u64,
+    interval-ms: option<u64>,
+  }
+
+  record message-ack {
+    subscription-id: resource-id,
+    message-id: u64,
+  }
+
+  record source-command {
+    source-id: resource-id,
+    command: string,
+    payload: list<u8>,
+  }
+
+  variant effect {
+    write-stream(stream-write),
+    close-stream(resource-id),
+    pause-stream(resource-id),
+    resume-stream(resource-id),
+    send-datagram(datagram-send),
+    arm-timer(timer-arm),
+    cancel-timer(resource-id),
+    acknowledge-message(message-ack),
+    source-command(source-command),
+  }
+
+  variant resident-error {
+    event-failed(string),
+  }
+
+  handle-event: func(input: event) -> result<list<effect>, resident-error>;
+}
+
+world resident-component {
+  export actor;
+}