feat(sync): add typed flat patch boundary

req: sync/002

req: sync/003

examples/kanban/Cargo.toml

@@ -29,6 +29,7 @@ axum = { version = "0.8", optional = true }
 futures-util = { version = "0.3", optional = true }
 hemx = { path = "../../hemx" }
 hemx-axum = { path = "../../hemx-axum", optional = true }
+hemx-sync = { path = "../../hemx-sync" }
 serde = { version = "1", features = ["derive"], optional = true }
 serde_json = { version = "1", optional = true }
 tokio = { version = "1", features = ["macros", "net", "rt-multi-thread", "time"], optional = true }

examples/kanban/src/lib.rs

@@ -78,14 +78,46 @@ pub fn reorder_card(
     let projected =
         BoardProjection::restore(state).apply(ReorderCommand::from_client(event).decide());
     let card = projected.card.0;
+    let patch = hemx_sync::FlatPatch::for_interaction(
+        "cardColumn",
+        hemx_sync::PatchValue::String("done".to_owned()),
+    )
+    .expect("generated Kanban patch is valid");
     let move_effect = match projected.before {
         Some(before) => ui::client_board::client_cards.move_before(card.clone(), before.0),
         None => ui::client_board::client_cards.move_to_end(card.clone()),
     };
-    vec![
+    (
         move_effect,
         ui::client_board::client_notice.text(format!("Moved {card} with {}", projected.input_kind)),
-    ]
+        hemx_sync::SyncEffect::send_patch(patch),
+    )
+}
+
+#[cfg(all(test, feature = "client"))]
+mod client_tests {
+    use super::*;
+    use hemx::IntoEffect;
+
+    #[test]
+    fn client_reorder_carries_flat_patch_in_ordinary_effect_batch() {
+        let batch = reorder_card(
+            hemx::wasm::ClientEvent {
+                kind: "drop".to_owned(),
+                value: None,
+                checked: None,
+                key: None,
+            },
+            hemx::wasm::ClientState {
+                encoded: "1|2".to_owned(),
+            },
+        )
+        .into_batch(ui::BUILD_FINGERPRINT);
+        assert_eq!(batch.ops.len(), 3);
+        assert!(
+            matches!(&batch.ops[2], hemx::advanced::Effect::Emit { name, payload } if name == hemx_sync::PATCH_EVENT && payload.contains("$hemx-interaction"))
+        );
+    }
 }
 
 #[cfg(all(feature = "fixture", not(target_arch = "wasm32")))]

examples/kanban/templates/client_board.heml

@@ -1,4 +1,4 @@
-<section data-hemx-root="kanban_client" data-hemx-st="1|2" data-hemx-client-state-version="1" data-hemx-client-module="/kanban_client.js">
+<section data-hemx-root="kanban_client" data-hemx-st="1|2" data-hemx-client-state-version="1" data-sync-endpoint="/sync/patches" data-hemx-client-module="/kanban_client.js">
   <p id="kanban-status" data-hemx-slot="client_notice" role="status" aria-live="polite">Ready</p>
   <ul data-hemx-slot="client_cards">
     <template h-for="card in &self.cards" h-key="card.id">