feat(sync): add typed acknowledgement effect

req: sync/006

examples/kanban/tests/browser_e2e.rs

@@ -2200,6 +2200,97 @@ async fn adversarial_wire_inputs_are_rejected_before_partial_application() -> We
     result.and(quit)
 }
 
+#[tokio::test]
+async fn canonical_acknowledgement_updates_generated_atom_over_ordinary_batch(
+) -> WebDriverResult<()> {
+    // test req: sync/006
+    let app_port = available_port();
+    let app_addr = format!("127.0.0.1:{app_port}");
+    let mut app_command = Command::new(env!("CARGO_BIN_EXE_hemx-kanban-example"));
+    app_command.env("HEMX_KANBAN_ADDR", &app_addr);
+    let _app = TestProcess::start(app_command, "hemx-kanban", &app_addr, STARTUP_TIMEOUT)
+        .expect("start hemx-kanban");
+
+    let webdriver_port = available_port();
+    let webdriver_addr = format!("127.0.0.1:{webdriver_port}");
+    let mut webdriver = Command::new("geckodriver");
+    webdriver.arg("--port").arg(webdriver_port.to_string());
+    let _webdriver = TestProcess::start(webdriver, "geckodriver", &webdriver_addr, STARTUP_TIMEOUT)
+        .expect("start ready geckodriver");
+    let mut caps = DesiredCapabilities::firefox();
+    caps.set_headless()?;
+    let driver = WebDriver::new(&format!("http://{webdriver_addr}"), caps).await?;
+
+    let result = async {
+        driver.goto(&format!("http://{app_addr}/")).await?;
+        wait_until(
+            &driver,
+            "return document.querySelector('#sync-ack')?.textContent.trim() === 'pending'",
+        )
+        .await?;
+        let proof = driver
+            .execute_async(
+                r#"
+                const done = arguments[arguments.length - 1];
+                (async () => {
+                  const commandId = 'ack-proof:1';
+                  const accepted = await fetch(`/sync/commands?command_id=${encodeURIComponent(commandId)}&card_id=1&column=done`, { method: 'POST' });
+                  const canonical = await accepted.json();
+                  const root = document.querySelector('[data-hemx-root]');
+                  let acknowledgementEvent;
+                  root.addEventListener('hemx:sync-ack', (event) => { acknowledgementEvent = event.detail; }, { once: true });
+                  const source = new EventSource(`/sync/ack?command_id=${encodeURIComponent(commandId)}`);
+                  await new Promise((resolve, reject) => {
+                    const timeout = setTimeout(() => {
+                      source.close();
+                      reject(new Error('ack batch timed out'));
+                    }, 5000);
+                    source.addEventListener('hemx', (event) => {
+                      clearTimeout(timeout);
+                      const normalized = event.data.replace(/-/g, '+').replace(/_/g, '/');
+                      const padded = normalized + '='.repeat((4 - normalized.length % 4) % 4);
+                      const raw = atob(padded);
+                      const bytes = Uint8Array.from(raw, (character) => character.charCodeAt(0));
+                      window.hemx.applyBatch(bytes.buffer, root);
+                      source.close();
+                      resolve();
+                    });
+                    source.onerror = () => {
+                      clearTimeout(timeout);
+                      source.close();
+                      reject(new Error('ack batch failed'));
+                    };
+                  });
+                  done({
+                    acceptedStatus: accepted.status,
+                    canonical,
+                    atom: document.querySelector('#sync-ack').textContent.trim(),
+                    status: document.body.textContent,
+                    acknowledgementEvent,
+                  });
+                })().catch((error) => done({ error: String(error), stack: error?.stack }));
+                "#,
+                Vec::new(),
+            )
+            .await?
+            .json()
+            .clone();
+        assert!(proof["error"].is_null(), "typed acknowledgement failed: {proof}");
+        assert_eq!(proof["acceptedStatus"], 200);
+        assert_eq!(proof["canonical"]["commandId"], "ack-proof:1");
+        assert_eq!(proof["canonical"]["serverSequence"], 1);
+        assert_eq!(proof["atom"], "acknowledged");
+        assert!(proof["status"]
+            .as_str()
+            .is_some_and(|status| status.contains("ack-proof:1 at server sequence 1")));
+        assert!(proof["acknowledgementEvent"].as_str().is_some_and(|payload| payload.contains("atomId")));
+        Ok(())
+    }
+    .await;
+    let quit = driver.quit().await;
+    result.and(quit)
+}
+
 #[tokio::test]
 async fn typed_presence_join_leave_updates_generated_atom_over_sse() -> WebDriverResult<()> {
     // test req: sync/001 req: sync/004 req: sync/005