fix(core): no SystemTime on wasm32 — fixed boot seed + UTIME Forth error

crates/core/src/outer.rs

@@ -393,6 +393,11 @@ impl<R: Runtime> ForthVM<R> {
             substitutions: Arc::new(Mutex::new(HashMap::new())),
             search_order: Arc::new(Mutex::new(vec![1])),
             next_wid: Arc::new(Mutex::new(2)),
+            // SystemTime::now() PANICS on wasm32-unknown-unknown (no time
+            // source), which turned VM construction into an `unreachable`
+            // trap in the browser. Seed from the wall clock only where one
+            // exists; wasm hosts start deterministic and reseed via RND-SEED.
+            #[cfg(not(target_arch = "wasm32"))]
             rng_state: {
                 use std::time::{SystemTime, UNIX_EPOCH};
                 let seed = SystemTime::now()
@@ -404,6 +409,8 @@ impl<R: Runtime> ForthVM<R> {
                     seed
                 }))
             },
+            #[cfg(target_arch = "wasm32")]
+            rng_state: Arc::new(Mutex::new(0xDEAD_BEEF_CAFE_BABE)),
             compile_frames: Vec::new(),
             compiling_word_addr: 0,
         };
@@ -5383,6 +5390,15 @@ impl<R: Runtime> ForthVM<R> {
     /// UTIME ( -- ud ) push microseconds since epoch as a double-cell value.
     fn register_utime(&mut self) -> anyhow::Result<()> {
         let func: HostFn = Box::new(move |ctx: &mut dyn HostAccess| {
+            // SystemTime::now() panics on wasm32-unknown-unknown; fail as a
+            // catchable Forth error instead of poisoning the VM with a trap.
+            #[cfg(target_arch = "wasm32")]
+            {
+                let _ = ctx;
+                Err(anyhow::anyhow!("UTIME: no time source on this platform"))
+            }
+            #[cfg(not(target_arch = "wasm32"))]
+            {
                 use std::time::{SystemTime, UNIX_EPOCH};
                 let us = SystemTime::now()
                     .duration_since(UNIX_EPOCH)
@@ -5397,6 +5413,7 @@ impl<R: Runtime> ForthVM<R> {
                 ctx.mem_write_slice(new_sp as u32 + 4, &lo.to_le_bytes());
                 ctx.set_dsp((new_sp as i32) as u32);
                 Ok(())
+            }
         });
 
         self.register_host_primitive("UTIME", false, func)?;