diff --git a/Cargo.toml b/Cargo.toml
index cf542a9..56f5760 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,8 +3,6 @@ name = "rudus"
 version = "0.0.1"
 edition = "2021"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
 [lib]
 crate-type = ["cdylib", "rlib"]
 
@@ -19,4 +17,3 @@ wasm-bindgen-futures = "0.4.50"
 serde = {version = "1.0", features = ["derive"]}
 serde_json = "1.0"
 console_error_panic_hook = "0.1.7"
-# talc = "4.4.3"
diff --git a/may_2025_thoughts.md b/may_2025_thoughts.md
index 56fe5f9..77fdf25 100644
--- a/may_2025_thoughts.md
+++ b/may_2025_thoughts.md
@@ -1183,6 +1183,12 @@ Happy Canada day!
 After a really rough evening, I seem to have the actor model not only working in Ludus, but reasonably debugged in Rust.
 We've got one bug to address in Firefox before I continue:
 * [ ] the event loop isn't returning once something is done, which makes no sense
+    - What seems to be happening is that the javascript behaviour is subtly different
+    - Current situation is that synchronous scripts work just fine
+    - But async scripts work ONCE, and then not again
+    - In FF, `do_io` doesn't return after `complete_main` in the `world` loop the second time.
+    - Which is to say, that last call to `io` isn't completing.
+    - Do I hack around this or do I try to find the source of the problem?
 
 After that:
 * [ ] implement other verbs beside `console`:
@@ -1200,4 +1206,5 @@ After that:
     - [ ] do synchronous programs still work?
     - [ ] animations?
     - [ ] read inputs?
+    - [ ] load url text?
 
diff --git a/pkg/ludus.js b/pkg/ludus.js
index 504895f..cf4ef2f 100644
--- a/pkg/ludus.js
+++ b/pkg/ludus.js
@@ -10,18 +10,18 @@ worker.onmessage = async (e) => {
     msgs = JSON.parse(e.data)    
   } catch {
     console.log(e.data)
-    throw Error("bad json from Ludus")
+    throw Error("Main: bad json from Ludus")
   }
   for (const msg of msgs) {
     switch (msg.verb) {
       case "complete": {
-        console.log("ludus completed with => ", msg.data)
+        console.log("Main: ludus completed with => ", msg.data)
         res = msg.data
         running = false
         break
       }
       case "console": {
-        console.log("ludus says => ", msg.data)
+        console.log("Main: ludus says => ", msg.data)
         break
       }
     }
@@ -35,11 +35,14 @@ let io_interval_id = null
 
 const io_poller = () => {
   if (io_interval_id && !running) {
+    // flush the outbox one last time
+    worker.postMessage(outbox)
+    // cancel the poller
     clearInterval(io_interval_id)
-    return
+  } else {
+    worker.postMessage(outbox)
+    outbox = []
   }
-  worker.postMessage(outbox)
-  outbox = []
 }
 
 function poll_io () {
diff --git a/pkg/rudus.d.ts b/pkg/rudus.d.ts
index 48d7cb8..0e42a14 100644
--- a/pkg/rudus.d.ts
+++ b/pkg/rudus.d.ts
@@ -14,8 +14,8 @@ export interface InitOutput {
   readonly __wbindgen_malloc: (a: number, b: number) => number;
   readonly __wbindgen_realloc: (a: number, b: number, c: number, d: number) => number;
   readonly __wbindgen_export_6: WebAssembly.Table;
-  readonly closure327_externref_shim: (a: number, b: number, c: any) => void;
-  readonly closure340_externref_shim: (a: number, b: number, c: any, d: any) => void;
+  readonly closure343_externref_shim: (a: number, b: number, c: any) => void;
+  readonly closure367_externref_shim: (a: number, b: number, c: any, d: any) => void;
   readonly __wbindgen_start: () => void;
 }
 
diff --git a/pkg/rudus.js b/pkg/rudus.js
index dd00cba..2af7198 100644
--- a/pkg/rudus.js
+++ b/pkg/rudus.js
@@ -17,6 +17,22 @@ function handleError(f, args) {
     }
 }
 
+function logError(f, args) {
+    try {
+        return f.apply(this, args);
+    } catch (e) {
+        let error = (function () {
+            try {
+                return e instanceof Error ? `${e.message}\n\nStack:\n${e.stack}` : e.toString();
+            } catch(_) {
+                return "<failed to stringify thrown value>";
+            }
+        }());
+        console.error("wasm-bindgen: imported JS function that was not marked as `catch` threw an error:", error);
+        throw e;
+    }
+}
+
 const cachedTextDecoder = (typeof TextDecoder !== 'undefined' ? new TextDecoder('utf-8', { ignoreBOM: true, fatal: true }) : { decode: () => { throw Error('TextDecoder not available') } } );
 
 if (typeof TextDecoder !== 'undefined') { cachedTextDecoder.decode(); };
@@ -54,6 +70,8 @@ const encodeString = (typeof cachedTextEncoder.encodeInto === 'function'
 
 function passStringToWasm0(arg, malloc, realloc) {
 
+    if (typeof(arg) !== 'string') throw new Error(`expected a string argument, found ${typeof(arg)}`);
+
     if (realloc === undefined) {
         const buf = cachedTextEncoder.encode(arg);
         const ptr = malloc(buf.length, 1) >>> 0;
@@ -82,7 +100,7 @@ function passStringToWasm0(arg, malloc, realloc) {
         ptr = realloc(ptr, len, len = offset + arg.length * 3, 1) >>> 0;
         const view = getUint8ArrayMemory0().subarray(ptr + offset, ptr + len);
         const ret = encodeString(arg, view);
-
+        if (ret.read !== arg.length) throw new Error('failed to pass whole string');
         offset += ret.written;
         ptr = realloc(ptr, len, offset, 1) >>> 0;
     }
@@ -104,6 +122,12 @@ function isLikeNone(x) {
     return x === undefined || x === null;
 }
 
+function _assertBoolean(n) {
+    if (typeof(n) !== 'boolean') {
+        throw new Error(`expected a boolean argument, found ${typeof(n)}`);
+    }
+}
+
 const CLOSURE_DTORS = (typeof FinalizationRegistry === 'undefined')
     ? { register: () => {}, unregister: () => {} }
     : new FinalizationRegistry(state => {
@@ -210,12 +234,19 @@ export function ludus(src) {
     return ret;
 }
 
+function _assertNum(n) {
+    if (typeof(n) !== 'number') throw new Error(`expected a number argument, found ${typeof(n)}`);
+}
 function __wbg_adapter_22(arg0, arg1, arg2) {
-    wasm.closure327_externref_shim(arg0, arg1, arg2);
+    _assertNum(arg0);
+    _assertNum(arg1);
+    wasm.closure343_externref_shim(arg0, arg1, arg2);
 }
 
 function __wbg_adapter_52(arg0, arg1, arg2, arg3) {
-    wasm.closure340_externref_shim(arg0, arg1, arg2, arg3);
+    _assertNum(arg0);
+    _assertNum(arg1);
+    wasm.closure367_externref_shim(arg0, arg1, arg2, arg3);
 }
 
 async function __wbg_load(module, imports) {
@@ -260,7 +291,7 @@ function __wbg_get_imports() {
         const ret = arg0.call(arg1, arg2);
         return ret;
     }, arguments) };
-    imports.wbg.__wbg_error_7534b8e9a36f1ab4 = function(arg0, arg1) {
+    imports.wbg.__wbg_error_7534b8e9a36f1ab4 = function() { return logError(function (arg0, arg1) {
         let deferred0_0;
         let deferred0_1;
         try {
@@ -270,8 +301,8 @@ function __wbg_get_imports() {
         } finally {
             wasm.__wbindgen_free(deferred0_0, deferred0_1, 1);
         }
-    };
-    imports.wbg.__wbg_io_4b41f8089de924df = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_io_4b41f8089de924df = function() { return logError(function (arg0, arg1) {
         let deferred0_0;
         let deferred0_1;
         try {
@@ -282,8 +313,8 @@ function __wbg_get_imports() {
         } finally {
             wasm.__wbindgen_free(deferred0_0, deferred0_1, 1);
         }
-    };
-    imports.wbg.__wbg_log_86d603e98cc11395 = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_log_86d603e98cc11395 = function() { return logError(function (arg0, arg1) {
         let deferred0_0;
         let deferred0_1;
         try {
@@ -293,11 +324,11 @@ function __wbg_get_imports() {
         } finally {
             wasm.__wbindgen_free(deferred0_0, deferred0_1, 1);
         }
-    };
-    imports.wbg.__wbg_log_9e426f8e841e42d3 = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_log_9e426f8e841e42d3 = function() { return logError(function (arg0, arg1) {
         console.log(getStringFromWasm0(arg0, arg1));
-    };
-    imports.wbg.__wbg_log_edeb598b620f1ba2 = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_log_edeb598b620f1ba2 = function() { return logError(function (arg0, arg1) {
         let deferred0_0;
         let deferred0_1;
         try {
@@ -307,8 +338,8 @@ function __wbg_get_imports() {
         } finally {
             wasm.__wbindgen_free(deferred0_0, deferred0_1, 1);
         }
-    };
-    imports.wbg.__wbg_new_23a2665fac83c611 = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_new_23a2665fac83c611 = function() { return logError(function (arg0, arg1) {
         try {
             var state0 = {a: arg0, b: arg1};
             var cb0 = (arg0, arg1) => {
@@ -325,65 +356,65 @@ function __wbg_get_imports() {
         } finally {
             state0.a = state0.b = 0;
         }
-    };
-    imports.wbg.__wbg_new_8a6f238a6ece86ea = function() {
+    }, arguments) };
+    imports.wbg.__wbg_new_8a6f238a6ece86ea = function() { return logError(function () {
         const ret = new Error();
         return ret;
-    };
-    imports.wbg.__wbg_newnoargs_105ed471475aaf50 = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_newnoargs_105ed471475aaf50 = function() { return logError(function (arg0, arg1) {
         const ret = new Function(getStringFromWasm0(arg0, arg1));
         return ret;
-    };
-    imports.wbg.__wbg_now_8dddb61fa4928554 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_now_8dddb61fa4928554 = function() { return logError(function () {
         const ret = Date.now();
         return ret;
-    };
-    imports.wbg.__wbg_queueMicrotask_97d92b4fcc8a61c5 = function(arg0) {
+    }, arguments) };
+    imports.wbg.__wbg_queueMicrotask_97d92b4fcc8a61c5 = function() { return logError(function (arg0) {
         queueMicrotask(arg0);
-    };
-    imports.wbg.__wbg_queueMicrotask_d3219def82552485 = function(arg0) {
+    }, arguments) };
+    imports.wbg.__wbg_queueMicrotask_d3219def82552485 = function() { return logError(function (arg0) {
         const ret = arg0.queueMicrotask;
         return ret;
-    };
-    imports.wbg.__wbg_random_57c118f142535bb6 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_random_57c118f142535bb6 = function() { return logError(function () {
         const ret = Math.random();
         return ret;
-    };
-    imports.wbg.__wbg_resolve_4851785c9c5f573d = function(arg0) {
+    }, arguments) };
+    imports.wbg.__wbg_resolve_4851785c9c5f573d = function() { return logError(function (arg0) {
         const ret = Promise.resolve(arg0);
         return ret;
-    };
-    imports.wbg.__wbg_stack_0ed75d68575b0f3c = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_stack_0ed75d68575b0f3c = function() { return logError(function (arg0, arg1) {
         const ret = arg1.stack;
         const ptr1 = passStringToWasm0(ret, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
         const len1 = WASM_VECTOR_LEN;
         getDataViewMemory0().setInt32(arg0 + 4 * 1, len1, true);
         getDataViewMemory0().setInt32(arg0 + 4 * 0, ptr1, true);
-    };
-    imports.wbg.__wbg_static_accessor_GLOBAL_88a902d13a557d07 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_static_accessor_GLOBAL_88a902d13a557d07 = function() { return logError(function () {
         const ret = typeof global === 'undefined' ? null : global;
         return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
-    };
-    imports.wbg.__wbg_static_accessor_GLOBAL_THIS_56578be7e9f832b0 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_static_accessor_GLOBAL_THIS_56578be7e9f832b0 = function() { return logError(function () {
         const ret = typeof globalThis === 'undefined' ? null : globalThis;
         return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
-    };
-    imports.wbg.__wbg_static_accessor_SELF_37c5d418e4bf5819 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_static_accessor_SELF_37c5d418e4bf5819 = function() { return logError(function () {
         const ret = typeof self === 'undefined' ? null : self;
         return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
-    };
-    imports.wbg.__wbg_static_accessor_WINDOW_5de37043a91a9c40 = function() {
+    }, arguments) };
+    imports.wbg.__wbg_static_accessor_WINDOW_5de37043a91a9c40 = function() { return logError(function () {
         const ret = typeof window === 'undefined' ? null : window;
         return isLikeNone(ret) ? 0 : addToExternrefTable0(ret);
-    };
-    imports.wbg.__wbg_then_44b73946d2fb3e7d = function(arg0, arg1) {
+    }, arguments) };
+    imports.wbg.__wbg_then_44b73946d2fb3e7d = function() { return logError(function (arg0, arg1) {
         const ret = arg0.then(arg1);
         return ret;
-    };
-    imports.wbg.__wbg_then_48b406749878a531 = function(arg0, arg1, arg2) {
+    }, arguments) };
+    imports.wbg.__wbg_then_48b406749878a531 = function() { return logError(function (arg0, arg1, arg2) {
         const ret = arg0.then(arg1, arg2);
         return ret;
-    };
+    }, arguments) };
     imports.wbg.__wbindgen_cb_drop = function(arg0) {
         const obj = arg0.original;
         if (obj.cnt-- == 1) {
@@ -391,12 +422,13 @@ function __wbg_get_imports() {
             return true;
         }
         const ret = false;
+        _assertBoolean(ret);
         return ret;
     };
-    imports.wbg.__wbindgen_closure_wrapper974 = function(arg0, arg1, arg2) {
-        const ret = makeMutClosure(arg0, arg1, 328, __wbg_adapter_22);
+    imports.wbg.__wbindgen_closure_wrapper7649 = function() { return logError(function (arg0, arg1, arg2) {
+        const ret = makeMutClosure(arg0, arg1, 344, __wbg_adapter_22);
         return ret;
-    };
+    }, arguments) };
     imports.wbg.__wbindgen_debug_string = function(arg0, arg1) {
         const ret = debugString(arg1);
         const ptr1 = passStringToWasm0(ret, wasm.__wbindgen_malloc, wasm.__wbindgen_realloc);
@@ -416,10 +448,12 @@ function __wbg_get_imports() {
     };
     imports.wbg.__wbindgen_is_function = function(arg0) {
         const ret = typeof(arg0) === 'function';
+        _assertBoolean(ret);
         return ret;
     };
     imports.wbg.__wbindgen_is_undefined = function(arg0) {
         const ret = arg0 === undefined;
+        _assertBoolean(ret);
         return ret;
     };
     imports.wbg.__wbindgen_string_get = function(arg0, arg1) {
diff --git a/pkg/rudus_bg.wasm b/pkg/rudus_bg.wasm
index ca25a5f..82a74b6 100644
Binary files a/pkg/rudus_bg.wasm and b/pkg/rudus_bg.wasm differ
diff --git a/pkg/rudus_bg.wasm.d.ts b/pkg/rudus_bg.wasm.d.ts
index e2bf686..9c99a54 100644
--- a/pkg/rudus_bg.wasm.d.ts
+++ b/pkg/rudus_bg.wasm.d.ts
@@ -9,6 +9,6 @@ export const __wbindgen_free: (a: number, b: number, c: number) => void;
 export const __wbindgen_malloc: (a: number, b: number) => number;
 export const __wbindgen_realloc: (a: number, b: number, c: number, d: number) => number;
 export const __wbindgen_export_6: WebAssembly.Table;
-export const closure327_externref_shim: (a: number, b: number, c: any) => void;
-export const closure340_externref_shim: (a: number, b: number, c: any, d: any) => void;
+export const closure343_externref_shim: (a: number, b: number, c: any) => void;
+export const closure367_externref_shim: (a: number, b: number, c: any, d: any) => void;
 export const __wbindgen_start: () => void;
diff --git a/pkg/worker.js b/pkg/worker.js
index 7bdd3cb..d539da4 100644
--- a/pkg/worker.js
+++ b/pkg/worker.js
@@ -1,39 +1,55 @@
 import init, {ludus} from "./rudus.js";
 
+let initialized_wasm = false
+onmessage = run
 
+// exposed in rust as:
+// async fn io (out: String) -> Result<JsValue, JsValue>
+// rust calls this to perform io
 export function io (out) {
+  // only send messages if we have some
   if (out.length > 0) postMessage(out)
-  return new Promise((resolve, _) => {
+  // make an event handler that captures and delivers messages from the main thread
+  // because our promise resolution isn't about calculating a value but setting a global variable, we can't asyncify it
+  // explicitly return a promise
+  return new Promise((resolve, reject) => {
+    // deliver the response to ludus when we get a response from the main thread
     onmessage = (e) => {
-      // console.log("Worker: from Ludus:", e.data)
       resolve(JSON.stringify(e.data))
     }
+    // cancel the response if it takes too long
+    setTimeout(() => reject("io took too long"), 500)
   })
 }
 
-let loaded_wasm = false
 
+// set as default event handler from main thread
 async function run(e) {
-  if (!loaded_wasm) {
-    loaded_wasm = true
+  // we must NEVER run `await init()` twice
+  if (!initialized_wasm) {
+    // this must come before the init call
+    initialized_wasm = true
     await init()
     console.log("Worker: Ludus has been initialized.")
   }
+  // the data is always an array; we only really expect one member tho
   let msgs = e.data
   for (const msg of msgs) {
+    // evaluate source if we get some
     if (msg.verb === "run" && typeof msg.data === 'string') {
-      // console.log("running ludus!")
+      // temporarily stash an empty function so we don't keep calling this one if we receive additional messages
       onmessage = () => {}
-      console.log("Worker: Beginning new Ludus run.")
+      // actually run the ludus--which will call `io`--and replace `run` as the event handler for ipc
       await ludus(msg.data)
+      // once we've returned from `ludus`, make this the event handler again
       onmessage = run
     } else {
+      // report and swallow any malformed startup messages
       console.log("Worker: Did not get valid startup message. Instead got:")
       console.log(e.data)
     }
   }
 }
 
-onmessage = run
 
 
diff --git a/src/io.rs b/src/io.rs
index 6f1e8b0..f91af40 100644
--- a/src/io.rs
+++ b/src/io.rs
@@ -8,7 +8,8 @@ use std::rc::Rc;
 
 #[wasm_bindgen(module = "/pkg/worker.js")]
 extern "C" {
-    async fn io (output: String) -> JsValue;
+    #[wasm_bindgen(catch)]
+    async fn io (output: String) -> Result<JsValue, JsValue>;
 }
 
 #[wasm_bindgen]
@@ -117,6 +118,11 @@ impl MsgIn {
 pub async fn do_io (msgs: Vec<MsgOut>) -> Vec<MsgIn> {
     let outbox = format!("[{}]", msgs.iter().map(|msg| msg.to_json()).collect::<Vec<_>>().join(","));
     let inbox = io (outbox).await;
+    // if our request dies, make sure we return back to the event loop
+    let inbox = match inbox {
+        Ok(msgs) => msgs,
+        Err(_) => return vec![]
+    };
     let inbox = inbox.as_string().expect("response should be a string");
     let inbox: Vec<MsgIn> = serde_json::from_str(inbox.as_str()).expect("response from js should be valid");
     if !inbox.is_empty() {
diff --git a/src/lib.rs b/src/lib.rs
index 6cf7881..b6ffe67 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -114,7 +114,6 @@ extern "C" {
 
 #[wasm_bindgen]
 pub async fn ludus(src: String) -> String {
-    log("Ludus: starting ludus run.");
     console_error_panic_hook::set_once();
     let src = src.to_string().leak();
     let (tokens, lex_errs) = lexer().parse(src).into_output_errors();
@@ -134,7 +133,6 @@ pub async fn ludus(src: String) -> String {
     let parsed: &'static Spanned<Ast> = Box::leak(Box::new(parse_result.unwrap()));
 
     let prelude = prelude();
-    let postlude = prelude.clone();
     // let prelude = imbl::HashMap::new();
 
     let mut validator = Validator::new(&parsed.0, &parsed.1, "user input", src, prelude.clone());
@@ -148,7 +146,7 @@ pub async fn ludus(src: String) -> String {
 
     let mut compiler = Compiler::new(
         parsed,
-        "sandbox",
+        "ludus script",
         src,
         0,
         prelude.clone(),
@@ -156,6 +154,7 @@ pub async fn ludus(src: String) -> String {
     );
 
     compiler.compile();
+
     if DEBUG_SCRIPT_COMPILE {
         println!("=== source code ===");
         println!("{src}");
@@ -173,63 +172,13 @@ pub async fn ludus(src: String) -> String {
     world.run().await;
     let result = world.result.clone().unwrap();
 
-    let console = postlude.get("console").unwrap();
-    let Value::Box(console) = console else {
-        unreachable!()
-    };
-    let Value::List(ref lines) = *console.borrow() else {
-        unreachable!()
-    };
-    let mut console = lines
-        .iter()
-        .map(|line| line.stringify())
-        .collect::<Vec<_>>()
-        .join("\n");
-
-    let turtle_commands = postlude.get("turtle_commands").unwrap();
-    let Value::Box(commands) = turtle_commands else {
-        unreachable!()
-    };
-    let commands = commands.borrow();
-    let commands = commands.to_json().unwrap();
-
     let output = match result {
         Ok(val) => val.show(),
-        Err(panic) => {
-            console = format!("{console}\nLudus panicked! {panic}");
-            "".to_string()
-        }
+        Err(panic) => format!("Ludus panicked! {panic}")
     };
     if DEBUG_SCRIPT_RUN {
         // vm.print_stack();
     }
 
-    // TODO: use serde_json to make this more robust?
-    format!(
-    "{{\"result\":\"{output}\",\"io\":{{\"stdout\":{{\"proto\":[\"text-stream\",\"0.1.0\"],\"data\":\"{console}\"}},\"turtle\":{{\"proto\":[\"turtle-graphics\",\"0.1.0\"],\"data\":{commands}}}}}}}"
-        )
-}
-
-pub fn fmt(src: &'static str) -> Result<String, String> {
-    let (tokens, lex_errs) = lexer().parse(src).into_output_errors();
-    if !lex_errs.is_empty() {
-        println!("{:?}", lex_errs);
-        return Err(format!("{:?}", lex_errs));
-    }
-
-    let tokens = tokens.unwrap();
-
-    let (parse_result, parse_errors) = parser()
-        .parse(Stream::from_iter(tokens).map((0..src.len()).into(), |(t, s)| (t, s)))
-        .into_output_errors();
-    if !parse_errors.is_empty() {
-        return Err(format!("{:?}", parse_errors));
-    }
-
-    // ::sigh:: The AST should be 'static
-    // This simplifies lifetimes, and
-    // in any event, the AST should live forever
-    let parsed: &'static Spanned<Ast> = Box::leak(Box::new(parse_result.unwrap()));
-
-    Ok(parsed.0.show())
+    output
 }
diff --git a/src/world.rs b/src/world.rs
index 7a6767a..e1c5276 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -212,12 +212,6 @@ impl Zoo {
             let mut proc = Status::Nested(proc);
             swap(&mut proc, &mut self.procs[*idx]);
         }
-        // Removed because, well, we shouldn't have creatures we don't know about
-        // And since zoo.next now cleans (and thus kills) before the world releases its active process
-        // We'll die if we execute this check
-        // else {
-        //     unreachable!("tried to return a process the world doesn't know about");
-        // }
     }
 
     pub fn is_available(&self) -> bool {
@@ -233,6 +227,10 @@ impl Zoo {
         let starting_idx = self.active_idx;
         self.active_idx = (self.active_idx + 1) % self.procs.len();
         while !self.is_available() {
+            // we've gone round the process queue already
+            // that means no process is active
+            // but we may have processes that are alive and asleep
+            // if nothing is active, yield back to the world's event loop
             if self.active_idx == starting_idx {
                 return ""
             }