test(wasm-actor): cycle 82 — max byte, own address, rapid engines, 256 bytes (365 tests)

Added 5 tests: compute max byte, echo own address, rapid engine creation, select
conditional value, all 256 single-byte payloads integrity check.
No new bugs found.

Authored by Claude, lovingly guided by Zachery Aaron Shores-Chmielewski

crates/wasm-actor/tests/wasm_actor.rs

@@ -11739,3 +11739,119 @@ proptest! {
         }
     }
 }
+
+// ── Cycle 82 ─────────────────────────────────────────────────────────────────
+
+// Guest computes max of all bytes in payload
+#[test]
+fn guest_computes_max_byte() {
+    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)
+            (local $i i32)
+            (local $max i32)
+            (local $val i32)
+            (local.set $max (i32.const 0))
+            (local.set $i (i32.const 0))
+            (block $exit
+                (loop $loop
+                    (br_if $exit (i32.ge_u (local.get $i) (local.get $len)))
+                    (local.set $val (i32.load8_u (i32.add (local.get $ptr) (local.get $i))))
+                    (if (i32.gt_u (local.get $val) (local.get $max))
+                        (then (local.set $max (local.get $val)))
+                    )
+                    (local.set $i (i32.add (local.get $i) (i32.const 1)))
+                    (br $loop)
+                )
+            )
+            (i32.store (i32.const 0) (local.get $max))
+        )
+    )"#;
+    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![10, 250, 30, 100])).unwrap();
+    rt.tick();
+}
+
+// Echo actor handles message containing its own address bytes
+#[test]
+fn echo_message_containing_own_address() {
+    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();
+
+    // Payload contains the actor's own address bytes
+    rt.send_to(addr, framed_msg(inbox.addr(), &addr.0)).unwrap();
+    rt.tick();
+
+    let resp = inbox.try_recv().expect("echo response");
+    assert_eq!(resp.0, addr.0.to_vec(), "actor's address echoed as payload");
+}
+
+// Rapidly create and destroy engines
+#[test]
+fn rapid_engine_creation_destruction() {
+    for _ in 0..50 {
+        let engine = SharedEngine::new().unwrap();
+        let _ = WasmActorBuilder::new(engine, guest_wasm("echo")).build().unwrap();
+        // engine and actor dropped here
+    }
+}
+
+// Guest uses select instruction to pick between two values
+#[test]
+fn guest_select_conditional_value() {
+    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)
+            ;; select: if len > 10, store 999, else store 111
+            (i32.store (local.get $ptr)
+                (select
+                    (i32.const 999)
+                    (i32.const 111)
+                    (i32.gt_u (local.get $len) (i32.const 10))
+                )
+            )
+        )
+    )"#;
+    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![0u8; 5])).unwrap();
+    rt.send_to(addr, ByteMessage(vec![0u8; 20])).unwrap();
+    rt.tick();
+}
+
+// Echo handles exactly 1 byte — smallest meaningful payload
+#[test]
+fn echo_single_byte_payload_integrity() {
+    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();
+
+    for byte in 0u8..=255 {
+        rt.send_to(addr, framed_msg(inbox.addr(), &[byte])).unwrap();
+    }
+    // Process all 256 in batches
+    for _ in 0..10 {
+        rt.tick();
+    }
+
+    let mut responses: Vec<u8> = std::iter::from_fn(|| inbox.try_recv().map(|m| m.0[0])).collect();
+    responses.sort();
+    assert_eq!(responses.len(), 256);
+    for (i, &b) in responses.iter().enumerate() {
+        assert_eq!(b, i as u8);
+    }
+}