diff --git a/crates/wasm-actor/tests/wasm_actor.rs b/crates/wasm-actor/tests/wasm_actor.rs
index 0290749..f46c96e 100644
--- a/crates/wasm-actor/tests/wasm_actor.rs
+++ b/crates/wasm-actor/tests/wasm_actor.rs
@@ -11377,4 +11377,100 @@ fn guest_block_with_result_value() {
     let addr = rt.spawn(actor).unwrap();
     rt.send_to(addr, ByteMessage(vec![0u8; 4])).unwrap();
     rt.tick();
+}
+
+// ── Cycle 79 ─────────────────────────────────────────────────────────────────
+
+// Echo actor handles binary pattern: all zeros then all ones
+#[test]
+fn echo_zeros_then_ones() {
+    let engine = SharedEngine::new().unwrap();
+    let actor = WasmActorBuilder::new(engine, guest_wasm("echo")).build().unwrap();
+    let rt = Runtime::new(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<ByteMessage>().unwrap();
+    let addr = rt.spawn(actor).unwrap();
+
+    let zeros = vec![0u8; 256];
+    let ones = vec![0xFF; 256];
+    rt.send_to(addr, framed_msg(inbox.addr(), &zeros)).unwrap();
+    rt.send_to(addr, framed_msg(inbox.addr(), &ones)).unwrap();
+    rt.tick();
+
+    let r1 = inbox.try_recv().unwrap();
+    let r2 = inbox.try_recv().unwrap();
+    assert!(r1.0.iter().all(|&b| b == 0));
+    assert!(r2.0.iter().all(|&b| b == 0xFF));
+}
+
+// Guest with 3 exported functions (only alloc and handle required)
+#[test]
+fn guest_with_extra_exported_function_and_init() {
+    let wat = r#"(module
+        (memory (export "memory") 1)
+        (func (export "alloc") (param $len i32) (result i32) i32.const 1024)
+        (func (export "handle") (param $ptr i32) (param $len i32))
+        (func (export "init") (result i32) i32.const 42)
+        (func (export "cleanup"))
+    )"#;
+    let engine = SharedEngine::new().unwrap();
+    let actor = WasmActorBuilder::new(engine, wat::parse_str(wat).unwrap())
+        .build().unwrap();
+    let rt = Runtime::new(RuntimeConfig::default());
+    let addr = rt.spawn(actor).unwrap();
+    rt.send_to(addr, ByteMessage(vec![1])).unwrap();
+    rt.tick();
+}
+
+// Property: double actor always sends exactly 2x copies
+proptest! {
+    #[test]
+    fn prop_double_always_sends_two_copies(
+        payload in proptest::collection::vec(0u8..=255, 1..200)
+    ) {
+        let engine = SharedEngine::new().unwrap();
+        let actor = WasmActorBuilder::new(engine, guest_wasm("double")).build().unwrap();
+        let rt = Runtime::new(RuntimeConfig::default());
+        let inbox = rt.new_inbox::<ByteMessage>().unwrap();
+        let addr = rt.spawn(actor).unwrap();
+
+        rt.send_to(addr, framed_msg(inbox.addr(), &payload)).unwrap();
+        rt.tick();
+
+        let msgs: Vec<Vec<u8>> = std::iter::from_fn(|| inbox.try_recv().map(|m| m.0)).collect();
+        assert_eq!(msgs.len(), 2, "double always produces 2 copies");
+        assert_eq!(msgs[0], payload);
+        assert_eq!(msgs[1], payload);
+    }
+}
+
+// Mix of echo, double, and silent actors — 10 of each
+#[test]
+fn thirty_mixed_actors_simultaneous() {
+    let engine = SharedEngine::new().unwrap();
+    let rt = Runtime::new(RuntimeConfig::default());
+    let inbox = rt.new_inbox::<ByteMessage>().unwrap();
+
+    // 10 echo actors
+    for _ in 0..10 {
+        let actor = WasmActorBuilder::new(engine.clone(), guest_wasm("echo")).build().unwrap();
+        let addr = rt.spawn(actor).unwrap();
+        rt.send_to(addr, framed_msg(inbox.addr(), b"e")).unwrap();
+    }
+    // 10 double actors
+    for _ in 0..10 {
+        let actor = WasmActorBuilder::new(engine.clone(), guest_wasm("double")).build().unwrap();
+        let addr = rt.spawn(actor).unwrap();
+        rt.send_to(addr, framed_msg(inbox.addr(), b"d")).unwrap();
+    }
+    // 10 silent actors
+    for _ in 0..10 {
+        let actor = WasmActorBuilder::new(engine.clone(), guest_wasm("silent")).build().unwrap();
+        let addr = rt.spawn(actor).unwrap();
+        rt.send_to(addr, ByteMessage(b"s".to_vec())).unwrap();
+    }
+    rt.tick();
+
+    let total = std::iter::from_fn(|| inbox.try_recv()).count();
+    // 10 echo + 10*2 double + 0 silent = 30
+    assert_eq!(total, 30);
 }
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