feat(wasm): execute client handlers without requests

req: client_local/001\nreq: client_local/004\nreq: client_local/005\nreq: client_local/009\nreq: client_local/010\nreq: client_local/014\nreq: v1_release/001

hemx-wasm/src/lib.rs

@@ -0,0 +1,42 @@
+//! Opt-in browser boundary for client-local hemx handlers.
+//!
+//! Application code reaches this crate through the `hemx` `client` feature and
+//! `#[hemx::handler(client)]`; server-first applications do not depend on it.
+
+use hemx_core::{BuildFingerprint, IntoEffect};
+
+#[doc(hidden)]
+pub use wasm_bindgen::prelude::wasm_bindgen;
+#[doc(hidden)]
+pub use wasm_bindgen::*;
+
+/// Encodes a client handler result with the ordinary hemx effect wire format.
+///
+/// Keeping this conversion here gives generated WASM exports one ABI boundary
+/// instead of teaching the proc macro a second effect protocol.
+#[doc(hidden)]
+pub fn encode_handler_effect(effect: impl IntoEffect, fingerprint: BuildFingerprint) -> Vec<u8> {
+    effect.into_batch(fingerprint).to_wire()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::encode_handler_effect;
+    use hemx_core::{BuildFingerprint, EffectBatch, Slot};
+
+    #[test]
+    fn client_handler_uses_the_ordinary_effect_wire_format() {
+        let fingerprint = BuildFingerprint(17);
+        let effect = Slot::<()>::new(4).text("local");
+        let wire = encode_handler_effect(effect.clone(), fingerprint);
+
+        assert_eq!(
+            EffectBatch::from_wire(&wire).expect("decode client effect"),
+            EffectBatch {
+                abi_version: hemx_core::EFFECT_BATCH_ABI_VERSION,
+                fingerprint,
+                ops: vec![effect],
+            }
+        ); // req: client_local/005 req: client_local/009
+    }
+}