feat: WebAssembly plugin support with end-to-end host invocation

Cargo.toml

@@ -14,6 +14,7 @@ members = [
     "crates/cpex-sdk",
     "crates/cpex-builtins",
     "crates/cpex-ffi",
+    "crates/cpex-wasm-host",
     "crates/apl-core",
     "crates/apl-cmf",
     "crates/apl-cpex",
@@ -27,6 +28,9 @@ members = [
     "builtins/session/valkey",
     "examples/go-demo/ffi",
 ]
+exclude = [
+    "crates/cpex-wasm-plugin",
+]
 
 # `default-members` controls what `cargo build` / `cargo test` (with no
 # `-p` or `--workspace` flag) picks up. `cpex-session-valkey` pulls a redis

crates/cpex-core/Cargo.toml

@@ -20,9 +20,12 @@ keywords.workspace = true
 categories.workspace = true
 rust-version.workspace = true
 
+[features]
+default = ["runtime"]
+runtime = ["dep:tokio", "dep:tokio-util", "dep:cpex-orchestration", "dep:arc-swap"]
+
 [dependencies]
-tokio = { workspace = true }
-tokio-util = { workspace = true }
+# --- Always-on dependencies (WASM-compatible) ---
 serde = { workspace = true }
 serde_yaml = { workspace = true }
 serde_json = { workspace = true }
@@ -31,17 +34,15 @@ thiserror = { workspace = true }
 tracing = { workspace = true }
 uuid = { workspace = true }
 hashbrown = { workspace = true }
-arc-swap = { workspace = true }
 wildmatch = { workspace = true }
 chrono = { workspace = true }
-# Zeroizing wrapper for raw credential material in RawCredentialsExtension.
-# `derive` feature pulls the proc-macro so we can `#[derive(Zeroize)]` on
-# token-bearing structs in a future slice; for now only the
-# `Zeroizing<String>` wrapper is used directly.
 zeroize = { version = "1.8", features = ["zeroize_derive"] }
-# Shared concurrency primitive used by `executor::run_concurrent_phase`
-# (and apl-core's `Effect::Parallel`). Leaf crate, no cycles back here.
-cpex-orchestration = { workspace = true }
+
+# --- Runtime-only dependencies (require tokio, not WASM-compatible) ---
+tokio = { workspace = true, optional = true }
+tokio-util = { workspace = true, optional = true }
+arc-swap = { workspace = true, optional = true }
+cpex-orchestration = { path = "../cpex-orchestration", optional = true }
 
 [lints]
 workspace = true

crates/cpex-core/src/cmf/message.rs

@@ -227,6 +227,7 @@ pub struct MessagePayload {
 }
 
 crate::impl_plugin_payload!(MessagePayload);
+crate::impl_wasm_payload!(MessagePayload, "cmf.message");
 
 // ---------------------------------------------------------------------------
 // CmfHook — Hook Type Definition

crates/cpex-core/src/config.rs

@@ -19,6 +19,7 @@
 // enabled, conditions on individual plugins are ignored.
 
 use std::collections::{HashMap, HashSet};
+#[cfg(feature = "runtime")]
 use std::path::Path;
 
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
@@ -595,6 +596,7 @@ impl StringOrList {
 // Config Loading
 // ---------------------------------------------------------------------------
 
+#[cfg(feature = "runtime")]
 /// Load and parse a CPEX config from a YAML file.
 pub fn load_config(path: &Path) -> Result<CpexConfig, Box<PluginError>> {
     let content = std::fs::read_to_string(path).map_err(|e| PluginError::Config {

crates/cpex-core/src/delegation/payload.rs

@@ -56,6 +56,7 @@ use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use zeroize::Zeroizing;
 
+#[cfg(feature = "runtime")]
 use crate::executor::PipelineResult;
 use crate::extensions::raw_credentials::DelegationMode;
 use crate::extensions::{
@@ -358,6 +359,7 @@ impl DelegationPayload {
 
     // -------- Host-side application helpers --------
 
+    #[cfg(feature = "runtime")]
     /// Pull the resolved `DelegationPayload` out of a `PipelineResult`
     /// returned by `mgr.invoke_named::<TokenDelegateHook>(...)`.
     /// Returns `None` when the pipeline was denied or when the result's

crates/cpex-core/src/hooks/mod.rs

@@ -16,18 +16,21 @@
 //
 // Hook types are open — hosts define their own using define_hook! alongside the built-ins.
 
-pub mod adapter;
 pub mod macros;
 pub mod metadata;
 pub mod payload;
 pub mod trait_def;
 pub mod types;
 
+#[cfg(feature = "runtime")]
+pub mod adapter;
+
 // Re-export core types at the hooks level
+#[cfg(feature = "runtime")]
 pub use adapter::TypedHandlerAdapter;
 pub use metadata::{
     lookup as lookup_hook_metadata, register_hook_metadata, HookMetadata, HookPhase,
 };
-pub use payload::{Extensions, PluginPayload};
+pub use payload::{Extensions, PluginPayload, WasmSerializablePayload};
 pub use trait_def::{HookHandler, HookTypeDef, PluginResult};
 pub use types::{builtin_hook_types, hook_type_from_str, HookType};

crates/cpex-core/src/hooks/payload.rs

@@ -131,3 +131,81 @@ macro_rules! impl_plugin_payload {
         }
     };
 }
+
+// ---------------------------------------------------------------------------
+// WasmSerializablePayload — opt-in WASM transport trait
+// ---------------------------------------------------------------------------
+
+/// Opt-in trait for payload types that can cross the WASM serialization boundary.
+///
+/// Implement this (via [`impl_wasm_payload!`]) for any payload type that WASM
+/// plugins should be able to receive or return. The type discriminator string
+/// is embedded in the WIT `generic-payload` record so the host and guest can
+/// agree on which concrete type to deserialize.
+///
+/// # Example
+///
+/// ```
+/// use serde::{Deserialize, Serialize};
+/// use cpex_core::{impl_plugin_payload, impl_wasm_payload};
+///
+/// #[derive(Debug, Clone, Serialize, Deserialize)]
+/// struct ToolInvokePayload {
+///     tool_name: String,
+///     user: String,
+/// }
+///
+/// impl_plugin_payload!(ToolInvokePayload);
+/// impl_wasm_payload!(ToolInvokePayload, "cpex.tool_invoke");
+/// ```
+pub trait WasmSerializablePayload: PluginPayload {
+    /// Type discriminator used in the WIT `generic-payload` record.
+    ///
+    /// Must be unique across all payload types registered with the host.
+    /// Convention: `"<namespace>.<type>"` (e.g. `"cmf.message"`, `"cpex.tool_invoke"`).
+    fn payload_type_name() -> &'static str
+    where
+        Self: Sized;
+
+    /// Serialize this payload to JSON bytes for WASM transport.
+    fn to_wasm_bytes(&self) -> Result<Vec<u8>, serde_json::Error>;
+
+    /// Deserialize a payload from JSON bytes received from WASM.
+    fn from_wasm_bytes(bytes: &[u8]) -> Result<Self, serde_json::Error>
+    where
+        Self: Sized;
+}
+
+/// Implements [`WasmSerializablePayload`] for a type that is `Serialize + Deserialize`.
+///
+/// The type must already implement [`PluginPayload`] (via [`impl_plugin_payload!`]).
+///
+/// ```
+/// use serde::{Deserialize, Serialize};
+/// use cpex_core::{impl_plugin_payload, impl_wasm_payload};
+///
+/// #[derive(Debug, Clone, Serialize, Deserialize)]
+/// struct ToolInvokePayload {
+///     tool_name: String,
+///     user: String,
+/// }
+///
+/// impl_plugin_payload!(ToolInvokePayload);
+/// impl_wasm_payload!(ToolInvokePayload, "cpex.tool_invoke");
+/// ```
+#[macro_export]
+macro_rules! impl_wasm_payload {
+    ($ty:ty, $name:literal) => {
+        impl $crate::hooks::payload::WasmSerializablePayload for $ty {
+            fn payload_type_name() -> &'static str {
+                $name
+            }
+            fn to_wasm_bytes(&self) -> Result<Vec<u8>, serde_json::Error> {
+                serde_json::to_vec(self)
+            }
+            fn from_wasm_bytes(bytes: &[u8]) -> Result<Self, serde_json::Error> {
+                serde_json::from_slice(bytes)
+            }
+        }
+    };
+}

crates/cpex-core/src/identity/payload.rs

@@ -63,6 +63,7 @@ use chrono::{DateTime, Utc};
 use serde::{Deserialize, Serialize};
 use zeroize::Zeroizing;
 
+#[cfg(feature = "runtime")]
 use crate::executor::PipelineResult;
 use crate::extensions::{
     ClientExtension, DelegationExtension, Extensions, RawCredentialsExtension, SecurityExtension,
@@ -285,6 +286,7 @@ impl IdentityPayload {
 
     // -------- Host-side application helpers --------
 
+    #[cfg(feature = "runtime")]
     /// Pull the resolved `IdentityPayload` out of a `PipelineResult`
     /// returned by `mgr.invoke_named::<IdentityHook>(...)`. Returns
     /// `None` when the pipeline was denied (no `modified_payload`)

crates/cpex-core/src/lib.rs

@@ -31,12 +31,20 @@ pub mod config;
 pub mod context;
 pub mod delegation;
 pub mod error;
-pub mod executor;
 pub mod extensions;
-pub mod factory;
 pub mod hooks;
 pub mod identity;
-pub mod manager;
 pub mod plugin;
+
+// Runtime-only modules — require tokio, task spawning, orchestration.
+// Excluded when building for WASM targets (use `default-features = false`).
+#[cfg(feature = "runtime")]
+pub mod executor;
+#[cfg(feature = "runtime")]
+pub mod factory;
+#[cfg(feature = "runtime")]
+pub mod manager;
+#[cfg(feature = "runtime")]
 pub mod registry;
+#[cfg(feature = "runtime")]
 pub mod visitor;

crates/cpex-wasm-host/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "cpex-wasm-host"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+tokio = { version = "1", features = ["sync", "macros", "io-util", "rt", "rt-multi-thread", "time", "signal", "net"] }
+wasmtime = { version = "45.0", features = ["component-model", "async"] }
+wasmtime-wasi = "45.0"
+wasmtime-wasi-http = { version = "45.0", features = ["default-send-request"] }
+hyper = "1"
+anyhow = "1.0"
+serde = { version = "1", features = ["derive"] }
+serde_yaml = "0.9"
+serde_json = { workspace = true }
+cpex-core = { path = "../cpex-core" }
+async-trait = "0.1"
+chrono = { version = "0.4", features = ["serde"] }

crates/cpex-wasm-host/Makefile

@@ -0,0 +1,17 @@
+.PHONY: build build-plugin run clean
+
+PLUGIN_DIR = ../cpex-wasm-plugin
+WASM_DIR = wasm
+
+build-plugin:
+	$(MAKE) -C $(PLUGIN_DIR) build
+
+build: build-plugin
+	cargo build --release
+
+run: build
+	cargo run --release
+
+clean:
+	cargo clean
+	rm -f $(WASM_DIR)/plugin.wasm