From 3dbacee3b6d790af630e1b3c635ee4750fc2b66c Mon Sep 17 00:00:00 2001
From: brunota20 <brunot.anjos@gmail.com>
Date: Mon, 15 Jun 2026 09:25:25 -0300
Subject: [PATCH] feat(twap-monitor): workspace + skeleton (BLEU-825)
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Add modules/twap-monitor/ as a workspace member. Cargo.toml declares
[lib] crate-type = ["cdylib"] for WASM Component output, and pulls
the deps the TWAP module path needs: cowprotocol (default-features
off — only typed primitives and OrderCreation surface needed),
alloy-sol-types (event/return decoding lands in BLEU-826/827), and
wit-bindgen.

src/lib.rs binds against the shepherd:cow/shepherd world (event-
module imports + cow-api). generate_all is required because the
world include pulls nexum:host/types across packages — without it,
wit-bindgen panics on the missing cross-package mapping. init and
on_event are stubbed: init logs once; on_event is a no-op until the
Event::Log / Event::Block dispatch lands in BLEU-826 / BLEU-827.

Verification: cargo build --target wasm32-wasip2 --release -p
twap-monitor emits a 65 KB .wasm. Engine load is gated on
module.toml (BLEU-834).
---
 Cargo.toml                      |  1 +
 modules/twap-monitor/Cargo.toml | 14 ++++++++++++++
 modules/twap-monitor/src/lib.rs | 29 +++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+)
 create mode 100644 modules/twap-monitor/Cargo.toml
 create mode 100644 modules/twap-monitor/src/lib.rs

diff --git a/Cargo.toml b/Cargo.toml
index b71581a..c83c061 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,6 +2,7 @@
 members = [
     "crates/nexum-engine",
     "modules/example",
+    "modules/twap-monitor",
 ]
 resolver = "2"
 
diff --git a/modules/twap-monitor/Cargo.toml b/modules/twap-monitor/Cargo.toml
new file mode 100644
index 0000000..bafc696
--- /dev/null
+++ b/modules/twap-monitor/Cargo.toml
@@ -0,0 +1,14 @@
+[package]
+name = "twap-monitor"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+cowprotocol = { version = "1.0.0-alpha.3", default-features = false }
+alloy-sol-types = { version = "1.5", default-features = false }
+wit-bindgen = { version = "0.57", default-features = false, features = ["macros", "realloc"] }
diff --git a/modules/twap-monitor/src/lib.rs b/modules/twap-monitor/src/lib.rs
new file mode 100644
index 0000000..72c0763
--- /dev/null
+++ b/modules/twap-monitor/src/lib.rs
@@ -0,0 +1,29 @@
+// wit_bindgen::generate! expands to host-import shims whose arity matches
+// the WIT signatures, which can exceed clippy's too-many-arguments threshold.
+#![allow(clippy::too_many_arguments)]
+
+wit_bindgen::generate!({
+    path: ["../../wit/nexum-host", "../../wit/shepherd-cow"],
+    world: "shepherd:cow/shepherd",
+    generate_all,
+});
+
+use nexum::host::logging;
+use nexum::host::types;
+
+struct TwapMonitor;
+
+impl Guest for TwapMonitor {
+    fn init(_config: Vec<(String, String)>) -> Result<(), HostError> {
+        logging::log(logging::Level::Info, "twap-monitor init");
+        Ok(())
+    }
+
+    fn on_event(_event: types::Event) -> Result<(), HostError> {
+        // Dispatch on Event::Log (ConditionalOrderCreated) and Event::Block
+        // (TWAP poll tick) lands in BLEU-826 / BLEU-827.
+        Ok(())
+    }
+}
+
+export!(TwapMonitor);