feat: in-browser engine demo

Enable naming, groups, watching, and stats in the browser runtime.
Fix core watching gap: StopSignal deaths now trigger WatchRegistry
notifications. Add register_name to RuntimeNaming trait. Cfg-gate
getrandom in router.rs for wasm builds. 30 Node.js tests pass.

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

Cargo.lock

@@ -2723,6 +2723,7 @@ dependencies = [
  "serde",
  "swactor-std",
  "tracing",
+ "web-time",
 ]
 
 [[package]]
@@ -3299,6 +3300,7 @@ name = "wasm"
 version = "0.1.0"
 dependencies = [
  "swactor",
+ "swactor-std",
  "wasm-bindgen",
 ]
 
@@ -3735,6 +3737,16 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "web-time"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa30049b1c872b72c89866d458eae9f20380ab280ffd1b1e18df2d3e2d98cfe0"
+dependencies = [
+ "js-sys",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "winapi"
 version = "0.3.9"

Cargo.toml

@@ -22,11 +22,13 @@ serde = ["dep:serde"]
 tracing = ["dep:tracing"]
 no_random = [] # compile without access to a source of randomness
 transport = []  # transport-agnostic messaging (no mandatory deps; codec is user-provided)
+wasm = ["no_random", "dep:web-time"] # browser/wasm32 target support
 
 [dependencies]
 getrandom = { version = "0.2", optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 tracing = { version = "0.1", optional = true }
+web-time = { version = "0.2", optional = true }
 crossbeam-queue = "0.3.12"
 crossbeam-utils = "0.8.21"
 

big-feature-phase/notes/constraints.md

@@ -0,0 +1,58 @@
+# Constraints — In-Browser Swactor Runtime
+
+## Threading Model
+
+- **wasm-threads is mandatory** — the runtime uses SharedArrayBuffer + WebAssembly atomics for multi-worker parallelism. There is no single-threaded degraded mode for MVP.
+- Browsers must serve pages with COOP/COEP headers:
+  - `Cross-Origin-Opener-Policy: same-origin`
+  - `Cross-Origin-Embedder-Policy: require-corp`
+- Build requires nightly Rust + `-Z build-std=std,panic_abort` + target features `+atomics,+bulk-memory,+mutable-globals`.
+
+## Architecture Rules
+
+- **Platform abstractions live in core swactor** (`src/`), gated by `#[cfg(target_arch = "wasm32")]`. They do not belong in the wasm crate.
+- **Do not add new modules** to `src/` — modify existing files only (TASK.md style rule).
+- **Do not restructure** existing module boundaries. The abstraction is a thin layer (type aliases, cfg-gated imports), not a trait-based HAL.
+- The browser crate (`crates/wasm-browser/` or evolved `crates/wasm/`) is a **thin wasm-bindgen shell**. All scheduling, routing, and actor logic stays in core Rust.
+
+## Actor Model
+
+- **Rust-only actors** — actors are written in Rust and compiled to wasm. JavaScript does not define actor behavior.
+- JS interacts through the wasm-bindgen API: create runtime, spawn actors (by registered type), send messages, receive results.
+- Actor types are registered at compile time via Rust generics, not dynamically from JS.
+
+## Performance Priorities
+
+- Maximize throughput: auto-scheduling via `setTimeout(0)` tight loop, not `requestAnimationFrame` (which caps at display refresh rate).
+- Web Worker count defaults to `navigator.hardwareConcurrency` for full core utilization.
+- Zero-copy where possible: SharedArrayBuffer eliminates serialization between workers.
+- Minimize JS↔Wasm boundary crossings — batch operations where feasible.
+
+## Feature Scope
+
+- All core features that compile for wasm32: spawn, send, receive, tick, actor lifecycle, watching, extensions.
+- swactor-std features (naming, groups, monitoring) should work if they compile.
+- Transport: WebSocket adapter for distributed clusters. STUN/TURN (WebRTC) deferred to later.
+- Features that require OS primitives not available in wasm (filesystem, raw TCP) are excluded.
+
+## Testing
+
+- Tests must pass on both native (`cargo test`) and wasm targets.
+- Wasm tests use `wasm-pack test --headless --chrome` or Node.js with `--experimental-wasm-threads`.
+- No test-only code paths that diverge native vs wasm behavior — if it works differently, it's a bug.
+- Prefer scenario tests over structural tests (per project testing rules).
+
+## Dependencies
+
+- `web-time` — drop-in replacement for `std::time::Instant` on wasm32
+- `wasm-bindgen` + `js-sys` + `web-sys` — browser API bindings (in the wasm crate only, not core)
+- `gloo-timers` — optional, for ergonomic setTimeout/setInterval
+- No new dependencies in core swactor beyond `web-time` (which is no-op on native)
+
+## What We Don't Do
+
+- No async/await runtime (tokio, async-std) — swactor is synchronous tick-based
+- No Emscripten — target is `wasm32-unknown-unknown` only
+- No WASI — browser environment, not server-side wasm
+- No JS actor definitions — Rust only
+- No polyfills for missing atomics — if SharedArrayBuffer isn't available, the runtime doesn't start

big-feature-phase/notes/feature-stages/01-platform-abstraction.md

@@ -0,0 +1,110 @@
+# Stage 1 — Platform Abstraction Layer
+
+**Priority**: P0
+**Depends on**: Nothing
+**Enables**: All subsequent stages
+
+## Goal
+
+Make core swactor compile for `wasm32-unknown-unknown` with `+atomics,+bulk-memory,+mutable-globals` target features. No behavioral changes on native targets. No new modules — only modify existing files with `cfg` gates.
+
+## What Changes
+
+### 1. Instant → web_time::Instant
+
+**Files**: `src/runtime.rs`, `src/worker.rs`
+
+Add `web-time` to `[dependencies]` (it's a no-op on non-wasm targets). Replace:
+```rust
+use std::time::Instant;
+```
+with:
+```rust
+use web_time::Instant;
+```
+
+`web-time` is a drop-in replacement. The `Instant` type has identical API on native (delegates to `std::time::Instant`) and on wasm32 (uses `performance.now()`).
+
+**Scope**: 2 `use` statements, 0 logic changes.
+
+### 2. Thread Parking → ParkHandle
+
+**Files**: `src/runtime.rs`, `src/delivery.rs`, `src/worker.rs`
+
+Currently uses `OnceLock<Thread>` + `thread::park_timeout` + `Thread::unpark`. On wasm32, there's no `Thread` type accessible from Rust (workers are JS objects). But wasm-threads supports `Atomics.wait`/`Atomics.notify` through Rust's `std::sync::atomic` and futex primitives.
+
+Approach: Define a `ParkHandle` abstraction in `src/runtime.rs`:
+
+**Native**:
+```rust
+#[cfg(not(target_arch = "wasm32"))]
+mod parking {
+    pub type ParkHandle = OnceLock<Thread>;
+    pub fn register(handle: &ParkHandle) { handle.set(thread::current()).ok(); }
+    pub fn unpark(handle: &ParkHandle) { if let Some(t) = handle.get() { t.unpark(); } }
+    pub fn park_timeout_us(micros: u64) { thread::park_timeout(Duration::from_micros(micros)); }
+    pub fn yield_now() { thread::yield_now(); }
+}
+```
+
+**Wasm32**:
+```rust
+#[cfg(target_arch = "wasm32")]
+mod parking {
+    // Use an AtomicI32 as a futex-like signal. Atomics.wait blocks the
+    // wasm thread, Atomics.notify wakes it — same semantics as park/unpark.
+    pub struct ParkHandle(AtomicI32);
+    pub fn register(_: &ParkHandle) {} // no-op, handle is pre-initialized
+    pub fn unpark(handle: &ParkHandle) {
+        handle.0.store(1, Ordering::Release);
+        std::sync::atomic::fence(Ordering::SeqCst);
+        // Atomics.notify via core::arch::wasm32::memory_atomic_notify
+        core::arch::wasm32::memory_atomic_notify(&handle.0 as *const _ as *mut i32, 1);
+    }
+    pub fn park_timeout_us(micros: u64) {
+        // Atomics.wait via core::arch::wasm32::memory_atomic_wait32
+        core::arch::wasm32::memory_atomic_wait32(ptr, 0, timeout_ns as i64);
+    }
+    pub fn yield_now() {} // no-op on wasm
+}
+```
+
+**Scope**: New `parking` sub-module in `runtime.rs` (~30 lines), update `TickContext` to use `ParkHandle` instead of `OnceLock<Thread>`, update `worker.rs` backoff loop.
+
+### 3. Thread Spawning — No Change in Core
+
+Thread spawning (`std::thread::Builder::new().spawn()`) only happens in `Runtime::run()` (line 351). This method will be overridden/wrapped by the browser crate — it won't be called on wasm32. We can gate it:
+
+```rust
+#[cfg(not(target_arch = "wasm32"))]
+pub fn run(self) -> Result<RuntimeHandle, Error> { ... }
+```
+
+The wasm browser crate will provide its own `run()` that spawns Web Workers instead.
+
+### 4. Validate crossbeam Compilation
+
+Test that `crossbeam-queue` compiles for wasm32 with atomics. If it doesn't, provide a cfg-gated fallback in `src/channel.rs` using `VecDeque` wrapped in `Mutex`. (Likely not needed — crossbeam uses `core::sync::atomic` which works with wasm atomics.)
+
+### 5. Feature Flag
+
+Add a `wasm` feature to `Cargo.toml`:
+```toml
+[features]
+wasm = ["web-time", "no_random"]
+
+[dependencies]
+web-time = { version = "0.2", optional = true }
+```
+
+On wasm32, this feature enables `web-time` and `no_random` together.
+
+## Verification
+
+1. `cargo test` passes unchanged on native
+2. `cargo build --target wasm32-unknown-unknown --features wasm -Z build-std=std,panic_abort` compiles (may need `+atomics` RUSTFLAGS)
+3. No runtime behavior changes on native (confirm with existing test suite)
+
+## Estimated Scope
+
+~50-80 lines of new/changed code across 4 files. No new modules.

big-feature-phase/notes/feature-stages/02-single-worker-browser.md

@@ -0,0 +1,129 @@
+# Stage 2 — Single-Worker Browser Runtime
+
+**Priority**: P0
+**Depends on**: Stage 1 (platform abstraction)
+**Enables**: Stage 3 (multi-worker), Stage 4 (feature parity)
+
+## Goal
+
+A working browser runtime on a single dedicated Web Worker with a JS API that supports spawning arbitrary (pre-registered) actor types, sending messages, receiving results, and auto-scheduled ticking.
+
+## What's Built
+
+### 1. New Crate: `crates/wasm-browser/`
+
+Replaces the PoC `crates/wasm/`. Structure:
+
+```
+crates/wasm-browser/
+├── Cargo.toml
+├── src/
+│   ├── lib.rs          # wasm-bindgen entry point
+│   ├── runtime.rs      # BrowserRuntime wrapping swactor::Runtime
+│   ├── worker_glue.rs  # Web Worker spawn/communication glue
+│   └── scheduling.rs   # Auto-tick scheduling (setTimeout loop)
+├── js/
+│   ├── worker.js       # Web Worker bootstrap script
+│   └── index.js        # Main thread API wrapper (optional)
+└── tests/
+    └── browser.rs      # wasm-pack test suite
+```
+
+### 2. BrowserRuntime (wasm-bindgen API)
+
+```rust
+#[wasm_bindgen]
+pub struct BrowserRuntime { ... }
+
+#[wasm_bindgen]
+impl BrowserRuntime {
+    #[wasm_bindgen(constructor)]
+    pub fn new(config: JsValue) -> Self;
+
+    /// Spawn an actor by type name. Returns an opaque handle.
+    pub fn spawn(&mut self, type_name: &str, init: JsValue) -> JsValue;
+
+    /// Send a message to an actor.
+    pub fn send(&self, addr: JsValue, msg: JsValue) -> bool;
+
+    /// Drive one tick manually.
+    pub fn tick(&self);
+
+    /// Start auto-scheduling. Calls tick() in a tight setTimeout(0) loop.
+    pub fn start(&self);
+
+    /// Stop auto-scheduling.
+    pub fn stop(&self);
+
+    /// Poll for results from a JS-visible inbox.
+    pub fn try_recv(&self) -> JsValue;
+
+    /// Runtime stats snapshot.
+    pub fn stats(&self) -> JsValue;
+}
+```
+
+### 3. Actor Registration
+
+Since Rust generics can't be dynamically dispatched from JS, actor types are registered at compile time:
+
+```rust
+// In the user's wasm crate that depends on wasm-browser:
+register_actors! {
+    "counter" => Counter,
+    "relay" => Relay,
+}
+```
+
+This macro generates a factory map that `BrowserRuntime::spawn` indexes by string name. Each entry knows how to deserialize `JsValue` init args into the actor's constructor.
+
+### 4. Auto-Scheduling
+
+The runtime self-drives via a `setTimeout(0)` loop:
+
+```javascript
+function tickLoop() {
+    runtime.tick();
+    if (runtime.is_running()) {
+        setTimeout(tickLoop, 0);
+    }
+}
+```
+
+This runs as fast as the browser allows (~4ms between ticks in most browsers, faster in Web Workers). The Rust side just calls `tick()` — no async runtime needed.
+
+### 5. Message Serialization
+
+JS ↔ Wasm boundary requires serialization. Options:
+- **serde-wasm-bindgen**: Serialize Rust types to/from JsValue via serde. Zero-copy for simple types.
+- **Manual**: Convert JsValue to bytes, route as `ByteMessage`.
+
+For Stage 2, use `serde-wasm-bindgen` for typed messages. Actor `Incoming` types must implement `serde::Deserialize`.
+
+### 6. Single Worker Architecture
+
+```
+┌─────────────────────┐       postMessage        ┌──────────────────────┐
+│    Main Thread       │ ◄──────────────────────► │   Web Worker         │
+│                      │                          │                      │
+│  JS application      │   "spawn", "send",       │  BrowserRuntime      │
+│  calls API methods   │   "tick", "recv"          │  swactor::Runtime    │
+│                      │                          │  (1 worker, tick())  │
+└─────────────────────┘                          └──────────────────────┘
+```
+
+The Web Worker runs the swactor runtime. The main thread sends commands via `postMessage`. This keeps the UI thread free.
+
+Alternative: run everything on the main thread (simpler, but blocks UI during tick). Support both modes — the user picks.
+
+## Verification
+
+1. `wasm-pack build --target web` succeeds
+2. `wasm-pack test --headless --chrome` passes
+3. Manual test: HTML page spawns actors, sends messages, receives results
+4. Auto-scheduling: actors process messages continuously without manual tick calls
+5. Performance: measure ticks/sec, compare to native single-threaded
+
+## Estimated Scope
+
+~300-500 lines of Rust + ~50 lines of JS glue.

big-feature-phase/notes/feature-stages/03-multi-worker-parallelism.md

@@ -0,0 +1,118 @@
+# Stage 3 — Multi-Worker Parallelism
+
+**Priority**: P1
+**Depends on**: Stage 1 (platform abstraction), Stage 2 (single-worker browser)
+**Enables**: Stage 5 (transport)
+
+## Goal
+
+Spawn N Web Workers sharing the same swactor runtime via SharedArrayBuffer. Actors distributed across workers for true multi-core parallelism. Worker count configurable, defaults to `navigator.hardwareConcurrency`.
+
+## Architecture
+
+```
+┌─────────────┐
+│ Main Thread  │  postMessage API
+│ (JS app)     │◄─────────────────────┐
+└──────┬───────┘                      │
+       │ spawn workers                │
+       ▼                              │
+┌──────────────┐  SharedArrayBuffer  ┌──────────────┐
+│ Web Worker 0 │◄───────────────────►│ Web Worker 1 │
+│ swactor      │  (InboxRegistry,    │ swactor      │
+│ Worker #0    │   AddressMap,       │ Worker #1    │
+│ tick loop    │   transfer queues,  │ tick loop    │
+└──────────────┘   atomics)          └──────────────┘
+                                      ...
+                                     ┌──────────────┐
+                                     │ Web Worker N │
+                                     │ swactor      │
+                                     │ Worker #N    │
+                                     └──────────────┘
+```
+
+## Key Challenge: Web Worker ↔ SharedArrayBuffer
+
+Web Workers can share `SharedArrayBuffer` instances. The swactor `Runtime` struct contains `Arc`-wrapped shared state (InboxRegistry, AddressMap, etc.). On native, this memory is shared via the process address space. On wasm with SharedArrayBuffer, it's shared via the underlying wasm linear memory.
+
+### How It Works
+
+1. **Main thread** creates the `Runtime` (allocates shared structures in wasm linear memory)
+2. **Main thread** spawns N Web Workers, each loading the same `.wasm` module with `shared: true` memory
+3. Each Web Worker receives a pointer (offset) to the `Runtime` shared state
+4. Each Worker runs `worker.run(&tc, &is_running)` — the same tick loop as native
+5. Crossbeam queues, atomics, Mutex/RwLock all work because the underlying memory is shared
+
+### wasm-bindgen + Web Workers
+
+The `web-sys::Worker` API creates workers. Each worker loads the same wasm module:
+
+```javascript
+// worker.js (loaded by each Web Worker)
+import init, { worker_entry } from './pkg/wasm_browser.js';
+
+self.onmessage = async (e) => {
+    const { module, memory, worker_id, runtime_ptr } = e.data;
+    await init({ module, memory }); // shared memory!
+    worker_entry(worker_id, runtime_ptr);
+};
+```
+
+The Rust side:
+```rust
+#[wasm_bindgen]
+pub fn worker_entry(worker_id: usize, runtime_ptr: u32) {
+    // Reconstruct the shared Runtime reference from the raw pointer
+    // Run the tick loop for this worker
+}
+```
+
+### Memory Sharing
+
+With `wasm-threads`, the wasm linear memory is backed by a `SharedArrayBuffer`. All workers see the same memory. `Arc` increments are atomic operations on shared memory. Crossbeam queues use atomic compare-and-swap on shared memory. This is identical to how it works with OS threads.
+
+**Critical**: The wasm module must be compiled with `--shared-memory` and the `atomics` feature. The `Memory` import must use `shared: true`.
+
+## Park / Unpark
+
+The `ParkHandle` from Stage 1 uses `memory_atomic_wait32` / `memory_atomic_notify` — the wasm equivalents of futex. These work across Web Workers sharing the same memory.
+
+- `park_timeout_us(micros)` → `Atomics.wait(ptr, expected, timeout)` — blocks the Worker thread
+- `unpark(handle)` → `Atomics.notify(ptr, 1)` — wakes one waiting Worker
+
+This gives the same backoff behavior as native: hot spin → yield → sleep with exponential backoff.
+
+## Worker Spawning
+
+Replace `std::thread::Builder::new().spawn()` in `Runtime::run()`:
+
+```rust
+#[cfg(target_arch = "wasm32")]
+pub fn run(self) -> Result<BrowserRuntimeHandle, Error> {
+    let num_workers = self.config.num_threads.max(1);
+    let rt = Arc::new(self);
+
+    for i in 0..num_workers {
+        let worker = web_sys::Worker::new("./worker.js")?;
+        worker.post_message(&JsValue::from(/* module, memory, worker_id, ptr */));
+    }
+    // ...
+}
+```
+
+## Placement
+
+The existing `Placement` strategy (load-aware round-robin) works unchanged — it reads `WorkerStats` atomics to pick the least-loaded worker. On wasm, these atomics are in SharedArrayBuffer, readable from any worker.
+
+## Verification
+
+1. Spawn runtime with `num_threads: 4`, verify 4 Web Workers created
+2. Spawn actors, verify they're distributed across workers (check stats per-worker actor count)
+3. Cross-worker message delivery works (actor on Worker 0 sends to actor on Worker 1)
+4. Backoff/parking works (idle workers sleep, wake on new messages)
+5. Throughput scales with worker count (benchmark: N workers vs 1 worker)
+6. Shutdown: all workers terminate cleanly when `is_running` set to false
+
+## Estimated Scope
+
+~200-300 lines Rust + ~30 lines JS worker bootstrap. Most complexity is in the Web Worker ↔ shared memory plumbing, not the Rust logic (which is the same as native).

big-feature-phase/notes/feature-stages/04-feature-parity.md

@@ -0,0 +1,109 @@
+# Stage 4 — Feature Parity
+
+**Priority**: P1
+**Depends on**: Stage 2 (single-worker) or Stage 3 (multi-worker)
+**Enables**: Stage 5 (transport), Stage 6 (DX)
+
+## Goal
+
+All swactor features that are feasible in a browser environment work and are tested: actor watching, swactor-std extensions (naming, groups, monitoring), stats introspection.
+
+## Features to Enable
+
+### 1. Actor Watching / Death Notifications
+
+**Status**: Already in core (`src/runtime.rs`, `src/worker.rs`)
+
+Components:
+- `ExitReason` enum — normal, panic, stopped
+- `ActorExited` message — delivered to watchers
+- `on_actor_exit()` default method on `ActorInterface`
+- `WatchRegistry` — tracks who watches whom
+- Phase 5b in `tick_once` — delivers death notifications
+
+**Wasm concern**: `WatchRegistry` is behind `Arc<Mutex<...>>`. With wasm-threads, `Mutex` works. The catch_unwind panic-safety model works identically in wasm.
+
+**Work needed**: Compile and test. Write wasm-specific tests for:
+- Actor dies → watchers notified
+- Watcher on different Web Worker receives notification (cross-worker)
+- Panic in wasm actor → poisoned, watchers notified
+
+### 2. swactor-std Extension
+
+**Status**: Complete in `crates/std/`
+
+Components:
+- `StdExtension` — wraps NameRegistry + MonitorRegistry + GroupRegistry
+- `CtxMonitoring` — watch/unwatch actors
+- `CtxNaming` — register/resolve actor names
+- `CtxGroups` — join/leave groups, broadcast
+- `RuntimeNaming` — resolve names from runtime handle
+- `RuntimeGroups` — list groups, broadcast from outside
+- Supervisor — restart policies
+
+**Wasm concern**: All use `Arc`, `Mutex`, `HashMap` — standard types that work with wasm-threads. No OS-specific dependencies.
+
+**Work needed**:
+- Add `crates/std/` to wasm build verification
+- Test naming: register name → resolve from another actor on different worker
+- Test groups: broadcast reaches all group members across workers
+- Test supervisor: child dies → supervisor restarts (factory-based)
+
+### 3. Stats and Introspection
+
+**Status**: In core (`src/stats.rs`)
+
+Components:
+- `WorkerStats` — per-worker atomic counters (actors, depth, ticks, messages)
+- `RuntimeStats` — aggregated snapshot
+- `StatsHook` trait — called each tick with stats
+
+**Wasm concern**: Atomic counters work with wasm-threads. `StatsHook` is called in the tick loop — works.
+
+**Work needed**:
+- Expose `RuntimeStats` to JS via `serde-wasm-bindgen` (JSON-serializable snapshot)
+- Optional: periodic stats push to main thread via `postMessage`
+- Test: spawn actors across workers, verify stats reflect correct counts
+
+### 4. Runtime Extensions
+
+**Status**: In core (`src/extension.rs`)
+
+The `RuntimeExtension` trait (`on_actor_death`, `cleanup_dead`, `as_any`) is called during phase 7 of tick_once. It uses `Arc<dyn RuntimeExtension>` — works with wasm-threads.
+
+**Work needed**: Verify `StdExtension` as a `RuntimeExtension` compiles and works in wasm. Test the full lifecycle: actor death → extension notified → cleanup runs.
+
+## JS API Additions
+
+Extend the `BrowserRuntime` wasm-bindgen API:
+
+```rust
+impl BrowserRuntime {
+    // Actor watching
+    pub fn watch(&self, watcher: JsValue, target: JsValue) -> bool;
+
+    // Naming (if StdExtension enabled)
+    pub fn register_name(&self, name: &str, addr: JsValue) -> bool;
+    pub fn resolve_name(&self, name: &str) -> JsValue;
+
+    // Groups
+    pub fn join_group(&self, group: &str, addr: JsValue) -> bool;
+    pub fn broadcast_group(&self, group: &str, msg: JsValue) -> bool;
+
+    // Stats
+    pub fn stats(&self) -> JsValue; // JSON snapshot of RuntimeStats
+}
+```
+
+## Verification
+
+1. All existing native tests for watching/std pass on wasm target
+2. Cross-worker watching: actor on Worker 0 watches actor on Worker 1, Worker 1 actor dies → notification arrives
+3. Naming works across workers: register on Worker 0, resolve on Worker 1
+4. Group broadcast reaches actors on all workers
+5. Stats counters are accurate across workers (compare sum to expected)
+6. `cargo test` still passes on native (no regressions)
+
+## Estimated Scope
+
+~100-200 lines of new wasm-bindgen API surface + ~200 lines of wasm tests. Core logic should work as-is once it compiles.

big-feature-phase/notes/feature-stages/05-transport-foundation.md

@@ -0,0 +1,107 @@
+# Stage 5 — Transport Foundation
+
+**Priority**: P2
+**Depends on**: Stage 3 (multi-worker), Stage 4 (feature parity)
+**Enables**: Browser nodes joining distributed swactor clusters
+
+## Goal
+
+Browser nodes connect to native swactor clusters via WebSocket. A browser can spawn actors that communicate with actors on server nodes. Foundation for future STUN/TURN (WebRTC DataChannel) for browser-to-browser direct connections.
+
+## Architecture
+
+```
+┌──────────────────┐         WebSocket          ┌──────────────────┐
+│  Browser Node    │ ◄────────────────────────► │  Server Node     │
+│  (wasm runtime)  │                            │  (native runtime)│
+│                  │    swactor wire protocol    │                  │
+│  Actor A ──────►─┤───── msg for Actor B ─────►├──► Actor B       │
+│                  │                            │                  │
+│  Actor C ◄───────┤◄──── msg for Actor C ─────┤───── Actor D     │
+└──────────────────┘                            └──────────────────┘
+```
+
+## Existing Transport Infrastructure
+
+swactor already has a transport layer (feature-gated under `transport`):
+
+- `src/transport.rs` — `TransportRouter`, `CodecRegistry`, remote message routing
+- `crates/distribution/` — SWIM protocol, gossip, cluster membership
+- `crates/distribution/src/driver.rs` — `NodeDriver` bridges `DistributedNode` ↔ TCP
+- Wire protocol: Ping/Ack/PingReq with piggyback bytes
+
+The browser transport needs to implement the same wire protocol over WebSocket instead of raw TCP.
+
+## What's Built
+
+### 1. WebSocket Transport Adapter
+
+A new module in `crates/wasm-browser/` (not in core):
+
+```rust
+pub struct WebSocketTransport {
+    ws: web_sys::WebSocket,
+    // ...
+}
+
+impl TransportAdapter for WebSocketTransport {
+    fn send(&self, dest: SocketAddr, data: &[u8]) -> Result<(), Error>;
+    fn recv(&self) -> Option<(SocketAddr, Vec<u8>)>;
+}
+```
+
+Uses `web-sys::WebSocket` for the browser side. The server side uses a WebSocket server (e.g., `tokio-tungstenite`) that bridges to the existing TCP transport.
+
+### 2. WebSocket ↔ TCP Bridge (Server Side)
+
+A thin relay server that accepts WebSocket connections from browsers and translates to/from the TCP wire protocol:
+
+```
+Browser ──WebSocket──► Bridge Server ──TCP──► swactor-node
+```
+
+This bridge is a separate binary/service, not part of the runtime. It's a protocol translator.
+
+### 3. Browser Node Identity
+
+Browser nodes need:
+- A unique node ID (derived from random or assigned by the cluster)
+- An address for the cluster to route messages to (the WebSocket endpoint)
+- Membership in the SWIM protocol (lightweight — browsers are "client" members that don't participate in failure detection)
+
+### 4. Cluster Registry Integration
+
+The existing ClusterRegistry (LWW-Register CRDT in `crates/distribution/src/registry.rs`) should work from browsers:
+- `register_name` / `resolve_name` / `registry_events` — all work over the wire
+- Piggyback payloads carry registry updates through the WebSocket connection
+
+## Key Design Decisions
+
+| Decision | Choice | Rationale |
+|----------|--------|-----------|
+| Transport protocol | WebSocket (binary frames) | Universal browser support, bidirectional, binary-capable |
+| Membership role | Client member (no failure detection) | Browsers are ephemeral; full SWIM overhead not justified |
+| Bridge architecture | Separate relay server | Keeps swactor-node unchanged; bridge handles WebSocket↔TCP |
+| Wire format | Same as TCP transport | No translation needed beyond framing (WebSocket frames ↔ TCP stream) |
+
+## STUN/TURN Foundation (Future)
+
+This stage establishes the transport abstraction. Stage 5 itself is WebSocket only. Future work:
+
+- **WebRTC DataChannel** — direct browser-to-browser, requires STUN/TURN for NAT traversal
+- The `TransportAdapter` trait from this stage will have a WebRTC implementation
+- STUN/TURN server infrastructure is out of scope for this feature phase
+
+## Verification
+
+1. Browser node connects to server cluster via WebSocket
+2. Actor on browser sends message to actor on server → received
+3. Actor on server sends message to actor on browser → received
+4. Browser appears in cluster membership (visible in dashboard)
+5. ClusterRegistry: name registered on server → resolvable from browser
+6. Browser disconnects → cluster detects and removes membership
+7. Reconnection: browser reconnects → re-joins cluster, actor addresses still valid
+
+## Estimated Scope
+
+~500-800 lines for WebSocket transport adapter + bridge server. Builds heavily on existing distribution infrastructure.

big-feature-phase/notes/feature-stages/06-developer-experience.md

@@ -0,0 +1,102 @@
+# Stage 6 — Developer Experience
+
+**Priority**: P3
+**Depends on**: Stage 2 (single-worker browser), Stage 4 (feature parity)
+**Enables**: Adoption, ecosystem growth
+
+## Goal
+
+Make it easy for Rust developers to build browser applications with swactor. TypeScript type safety, build tooling, and debugging support.
+
+## Features
+
+### 1. TypeScript Type Generation
+
+Derive TypeScript interfaces from Rust actor message types. When an actor defines:
+
+```rust
+#[derive(Serialize, Deserialize)]
+pub struct ChatMessage {
+    pub from: String,
+    pub text: String,
+}
+```
+
+Generate:
+```typescript
+export interface ChatMessage {
+    from: string;
+    text: string;
+}
+```
+
+**Approach**: Use `ts-rs` crate or a custom proc macro that emits `.d.ts` files during `wasm-pack build`. This gives TypeScript consumers compile-time type checking for messages.
+
+### 2. Build Tooling
+
+A `swactor-build` CLI or build script that wraps:
+```bash
+RUSTFLAGS='-C target-feature=+atomics,+bulk-memory,+mutable-globals' \
+  cargo +nightly build --target wasm32-unknown-unknown \
+  -Z build-std=std,panic_abort \
+  --release
+wasm-bindgen --target web --out-dir pkg/ ...
+```
+
+Into:
+```bash
+swactor-build --target browser
+```
+
+Features:
+- Detects nightly toolchain, installs if missing
+- Sets correct RUSTFLAGS for wasm-threads
+- Runs wasm-bindgen with correct target
+- Copies worker.js bootstrap into output
+- Generates example HTML with correct COOP/COEP headers
+
+### 3. Example Project Template
+
+A `cargo generate` template or example project:
+
+```
+my-swactor-app/
+├── Cargo.toml
+├── src/
+│   └── lib.rs          # Define actors, register them
+├── web/
+│   ├── index.html      # With COOP/COEP headers
+│   ├── main.js         # Import wasm, create runtime, interact
+│   └── worker.js       # Web Worker bootstrap (auto-generated)
+└── tests/
+    └── browser.rs      # wasm-pack tests
+```
+
+### 4. Browser Dev Tools Integration
+
+Expose runtime internals for debugging:
+
+- **Actor Inspector**: List all actors, their types, mailbox depths, message counts
+- **Message Tracer**: Log messages between actors (opt-in, performance impact)
+- **Performance Monitor**: Ticks/sec, messages/sec, worker utilization
+
+Implementation: A `console`-based logger that uses `web-sys::console` to output structured data. Optionally integrates with browser DevTools via custom formatters or a small React/Preact inspector panel.
+
+### 5. Documentation
+
+- Getting started guide
+- Architecture overview for browser runtime
+- Migration guide from native → browser (what works, what doesn't)
+- API reference (generated from Rust doc comments)
+- Example: Chat application with multiple browser tabs
+
+## Verification
+
+1. TypeScript types match Rust types (compile TS project against generated `.d.ts`)
+2. Build tool produces working wasm output from example project
+3. Template project builds and runs out of the box
+4. Dev tools show actor state in browser console
+
+## Estimated Scope
+
+Variable — this stage is a collection of independent DX improvements. Each can be implemented and shipped independently. Total: ~500-1000 lines across Rust, JS, and documentation.

big-feature-phase/notes/history.md

@@ -0,0 +1,7 @@
+# Cycle History (append-only)
+
+## Cycle 0 — Research (complete)
+Investigated Lunatic, wasmCloud, Actix-wasm attempts. Analyzed core swactor platform deps: 4 blockers (thread spawn, park/unpark, yield, Instant). User confirmed: performance-first, SharedArrayBuffer+wasm-threads, Rust-only actors, all feasible features, future STUN/TURN. Produced constraints.md, research_synthesis.md, 6 feature-stage docs. Next: Stage 1 platform abstraction.
+
+## Stage 1 — Platform Abstraction (complete)
+Added `wasm` feature + `web-time` dep. Replaced `std::time::Instant` → `crate::Instant` (cfg-gated re-export). Gated `Runtime::run()` and `RuntimeHandle` for non-wasm. Key finding: only `thread::spawn` needed gating — park/unpark/yield/Mutex/RwLock/atomics/crossbeam all work on wasm32 with atomics. Cleaned unused Mutex import in worker.rs. Updated crates/wasm/ to use `wasm` feature. All native tests pass, wasm32 compilation succeeds. Files changed: Cargo.toml, src/lib.rs, src/runtime.rs, src/worker.rs, crates/wasm/Cargo.toml.

big-feature-phase/notes/research_synthesis.md

@@ -0,0 +1,87 @@
+# Research Synthesis — In-Browser Swactor Runtime
+
+## Ecosystem Landscape
+
+No established Rust actor framework runs natively in browsers. The closest projects:
+
+- **Lunatic** — Erlang-inspired Wasm actor runtime using wasmtime (server-side, not browser). Uses preemptive scheduling and work-stealing. Not applicable to browser constraints.
+- **wasmCloud** — CNCF distributed actor platform. Single-threaded actors, NATS-backed lattice. Cloud/edge focus, no browser target.
+- **Actix** — Tokio-dependent, network stack doesn't compile for wasm32. Community attempts to port failed due to `net2`/tokio dependencies.
+
+**Implication**: swactor would be the first Rust actor runtime with true multi-threaded browser execution via wasm-threads. This is a differentiated position.
+
+## Existing Work in This Codebase
+
+| Component | Status | Notes |
+|-----------|--------|-------|
+| `crates/wasm/` | Basic PoC | Hardcoded Counter/Relay actors, manual tick, u32-only messages |
+| `no_random` feature | Working | Deterministic address generation without `getrandom` |
+| `tick()` method | Working | Single-threaded tick for manual driving |
+| Actor watching | In core | `ExitReason`, `ActorExited`, `on_actor_exit`, `WatchRegistry` |
+| swactor-std | Complete | StdExtension, naming, groups, monitoring, supervisor |
+
+## Platform Dependencies Analysis
+
+### Works as-is with wasm-threads
+- `crossbeam-queue` (ArrayQueue, SegQueue) — uses `core::sync::atomic`
+- `std::sync::{Mutex, RwLock}` — stdlib uses futex on wasm with atomics
+- `std::sync::atomic::*` — maps to wasm atomic instructions
+- `Arc<T>` — works with atomics
+- `std::sync::OnceLock` — works with atomics
+
+### Requires platform abstraction (4 items)
+1. `std::thread::spawn` → Web Worker via `web-sys::Worker`
+2. `thread::park_timeout` / `Thread::unpark` → `Atomics.wait` / `Atomics.notify`
+3. `thread::yield_now` → no-op (or `Atomics.wait(0)` as hint)
+4. `std::time::Instant` → `web_time::Instant` (drop-in crate)
+
+## Priority Ranking
+
+### P0 — Must Have (enables everything else)
+
+1. **Platform abstraction layer** — cfg-gated replacements for thread spawn, park/unpark, yield, Instant. Core swactor compiles for wasm32 with atomics.
+2. **Single-worker browser runtime** — Prove the runtime works in a browser. One Web Worker, auto-scheduled tick loop, generic JS API for spawn/send/recv.
+3. **Multi-worker parallelism** — N Web Workers sharing runtime state via SharedArrayBuffer. Full utilization of browser CPU cores.
+
+### P1 — Should Have (full actor system)
+
+4. **Actor watching in browser** — Death notifications, exit reasons. Already in core, just needs to compile and pass wasm tests.
+5. **swactor-std in browser** — Naming, groups, monitoring extensions. Compile and test for wasm32.
+6. **Stats and introspection** — Runtime stats accessible from JS. Worker info, actor counts, message throughput.
+
+### P2 — Important (distributed peer)
+
+7. **WebSocket transport** — Adapter implementing swactor's transport traits over WebSocket. Browser node joins a distributed cluster.
+8. **Browser-to-browser transport foundation** — WebRTC DataChannel scaffolding for future STUN/TURN.
+
+### P3 — Nice to Have (developer experience)
+
+9. **TypeScript type generation** — Derive TS interfaces from Rust actor message types.
+10. **Build tooling** — wasm-pack wrapper script, example project template, CI configuration.
+11. **Browser dev tools** — Actor inspector, message flow visualization, performance profiling.
+
+### P4 — Future (out of scope for this feature phase)
+
+12. **STUN/TURN integration** — Full NAT traversal for peer-to-peer browser connections.
+13. **Hot code reload** — Swap actor implementations without restarting the runtime.
+14. **Wasm component model** — Migrate from wasm-bindgen to component model when stabilized.
+
+## Key Design Decisions
+
+| Decision | Choice | Rationale |
+|----------|--------|-----------|
+| Threading model | SharedArrayBuffer + wasm-threads | swactor's shared-memory architecture (Arc, crossbeam queues, atomics) maps directly. postMessage isolation would require a rewrite. |
+| Scheduling | `setTimeout(0)` tight loop | `requestAnimationFrame` caps at 60Hz. setTimeout(0) gives ~4ms resolution, sufficient for actor ticks. For rendering-coupled actors, RAF can be opt-in. |
+| Actor definition | Rust only | Keeps the type system intact. JS actors would require dynamic dispatch and lose compile-time guarantees. |
+| Platform abstraction approach | cfg-gated type aliases + inline functions | Minimal invasion. No trait-based HAL, no new modules. Just swap `std::time::Instant` → `web_time::Instant` etc. |
+| Browser crate location | New `crates/wasm-browser/` | Clean separation from the existing PoC. The old `crates/wasm/` can be deprecated or kept as a minimal example. |
+
+## Risk Assessment
+
+| Risk | Likelihood | Impact | Mitigation |
+|------|-----------|--------|------------|
+| crossbeam-queue doesn't compile for wasm32+atomics | Low | High | Test early in Stage 1. Fallback: thin wrapper over `VecDeque` behind cfg. |
+| COOP/COEP headers break third-party integrations | Medium | Medium | Document clearly. This is the standard trade-off for SharedArrayBuffer apps. |
+| Nightly Rust + build-std is unstable | Medium | Medium | Pin to a known-good nightly. Revisit when wasm-threads stabilizes. |
+| Web Worker spawn latency | Low | Low | Spawn workers eagerly at runtime init, not per-actor. |
+| Browser compatibility gaps | Low | Medium | Target Chrome/Firefox/Safari latest. All support SharedArrayBuffer since 2021. |

big-feature-phase/notes/state.md

@@ -0,0 +1,47 @@
+## Current Task
+Stage 1 — Platform Abstraction Layer
+Step: Complete
+Attempt: 1 of 3
+
+## Key Files (read these first on resume)
+- `big-feature-phase/TASK.md` — workflow rules
+- `big-feature-phase/notes/constraints.md` — guardrails
+- `big-feature-phase/notes/feature-stages/02-single-worker-browser.md` — Stage 2 spec
+- `Cargo.toml` — `wasm` feature flag, `web-time` dep (lines 23, 30)
+- `src/lib.rs` — platform-aware `Instant` re-export (lines 20-24)
+- `src/runtime.rs` — cfg-gated `run()` (line 340) and `RuntimeHandle` (line 73)
+- `crates/wasm/Cargo.toml` — now uses `features = ["wasm"]`
+- `docs/development_history/in-browser/PLATFORM_ABSTRACTION.md` — what was done
+
+## Last Action & Result
+Completed Stage 1 (Platform Abstraction Layer):
+- Added `web-time` dep + `wasm` feature (`no_random` + `web-time`)
+- Replaced `std::time::Instant` → `crate::Instant` in runtime.rs, worker.rs
+- cfg-gated `Runtime::run()` and `RuntimeHandle` for `not(target_arch = "wasm32")`
+- Removed unused `Mutex` import from worker.rs
+- Updated `crates/wasm/` to use `wasm` feature
+- Key finding: most std::sync/thread primitives work on wasm32 with atomics; only `thread::spawn` needed gating
+- All native tests pass, wasm32 compilation succeeds
+
+## Next Action
+Begin Stage 2 (Single-Worker Browser Runtime) — `notes/feature-stages/02-single-worker-browser.md`:
+1. Create `crates/wasm-browser/` crate structure
+2. Implement `BrowserRuntime` wasm-bindgen API (spawn, send, tick, try_recv, stats)
+3. Actor registration macro/pattern for JS-accessible spawning
+4. Auto-scheduling via setTimeout(0) loop
+5. Message serialization across JS↔Wasm boundary
+6. Tests (wasm-pack test or Node.js)
+
+## Completed This Session
+- [x] Cycle 0 research artifacts (constraints.md, research_synthesis.md, 6 stage docs)
+- [x] Stage 1: `web-time` dep + `wasm` feature flag in Cargo.toml
+- [x] Stage 1: Platform-aware `Instant` re-export in src/lib.rs
+- [x] Stage 1: cfg-gated `Runtime::run()` and `RuntimeHandle` in src/runtime.rs
+- [x] Stage 1: Updated crates/wasm/ to use `wasm` feature
+- [x] Stage 1: Validated wasm32 compilation and native tests
+- [x] Stage 1: Development history doc
+
+## Open Questions / Blockers
+- Stage 2: Need to decide on message serialization (serde-wasm-bindgen vs raw bytes)
+- Stage 2: Actor registration pattern — macro vs manual factory map
+- Stage 3: Web Worker thread state initialization needs investigation (does std::thread::current() work in a Web Worker context?)

crates/std/Cargo.toml

@@ -5,8 +5,9 @@ edition = "2024"
 
 [features]
 default = ["getrandom"]
-getrandom = ["dep:getrandom"]
+getrandom = ["dep:getrandom", "swactor/getrandom"]
+wasm = ["swactor/wasm"]
 
 [dependencies]
-swactor = { path = "../.." }
+swactor = { path = "../..", default-features = false }
 getrandom = { version = "0.2", optional = true }

crates/std/src/router.rs

@@ -102,11 +102,21 @@ impl<M: Message> Router<M> {
                 Some(live[idx])
             }
             RoutingStrategy::Random => {
+                #[cfg(feature = "getrandom")]
+                {
                     let mut buf = [0u8; 8];
                     getrandom::getrandom(&mut buf).expect("getrandom failed");
                     let r = u64::from_ne_bytes(buf) as usize;
                     Some(live[r % live.len()])
                 }
+                #[cfg(not(feature = "getrandom"))]
+                {
+                    // Fallback to round-robin when getrandom is unavailable (wasm)
+                    let idx = self.rr_index % live.len();
+                    self.rr_index = self.rr_index.wrapping_add(1);
+                    Some(live[idx])
+                }
+            }
             RoutingStrategy::Broadcast => None, // handled separately
         }
     }

crates/std/src/runtime_ext.rs

@@ -17,6 +17,9 @@ fn get_ext(rt: &Runtime) -> &StdExtension {
 /// Provides `spawn_named`, `where_is`, `unregister`, and `registered_names`
 /// via the [`StdExtension`] name registry.
 pub trait RuntimeNaming {
+    /// Register a name for an already-spawned actor. Returns `Err` if name is taken.
+    fn register_name(&self, name: impl Into<String>, addr: ActorAddress) -> Result<(), Error>;
+
     /// Spawn an actor with a registered name, returning its address.
     fn spawn_named<A: ActorInterface>(&self, name: impl Into<String>, actor: A) -> Result<ActorAddress, Error>;
 
@@ -31,6 +34,10 @@ pub trait RuntimeNaming {
 }
 
 impl RuntimeNaming for Runtime {
+    fn register_name(&self, name: impl Into<String>, addr: ActorAddress) -> Result<(), Error> {
+        get_ext(self).name_registry.register(name.into(), addr)
+    }
+
     fn spawn_named<A: ActorInterface>(&self, name: impl Into<String>, actor: A) -> Result<ActorAddress, Error> {
         let name = name.into();
         let addr = self.spawn(actor)?;

crates/wasm/Cargo.toml

@@ -7,5 +7,6 @@ edition = "2024"
 crate-type = ["cdylib"]
 
 [dependencies]
-swactor = { path = "../..", default-features = false, features = ["no_random"] }
+swactor = { path = "../..", default-features = false, features = ["wasm"] }
+swactor-std = { path = "../std", default-features = false, features = ["wasm"] }
 wasm-bindgen = "0.2"

crates/wasm/demo.html

@@ -0,0 +1,570 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<title>swactor — In-Browser Runtime Demo</title>
+<style>
+  :root {
+    --bg: #0d1117; --surface: #161b22; --border: #30363d;
+    --text: #c9d1d9; --dim: #8b949e; --accent: #58a6ff;
+    --green: #3fb950; --red: #f85149; --yellow: #d29922; --purple: #bc8cff;
+    --font: 'SF Mono', 'Cascadia Code', 'Fira Code', monospace;
+  }
+  * { box-sizing: border-box; margin: 0; padding: 0; }
+  body { font-family: var(--font); background: var(--bg); color: var(--text); padding: 20px; }
+  h1 { font-size: 1.4em; margin-bottom: 4px; }
+  h1 span { color: var(--accent); }
+  .subtitle { color: var(--dim); font-size: 0.8em; margin-bottom: 20px; }
+  .grid { display: grid; grid-template-columns: 300px 1fr 280px; gap: 16px; height: calc(100vh - 100px); }
+
+  .panel { background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 16px; overflow-y: auto; }
+  .panel h2 { font-size: 0.9em; color: var(--accent); margin-bottom: 12px; border-bottom: 1px solid var(--border); padding-bottom: 8px; }
+
+  .stat-row { display: flex; justify-content: space-between; margin-bottom: 6px; font-size: 0.85em; }
+  .stat-label { color: var(--dim); }
+  .stat-value { color: var(--green); font-weight: bold; }
+
+  .btn {
+    display: inline-block; padding: 6px 12px; border: 1px solid var(--border);
+    background: var(--surface); color: var(--text); border-radius: 4px;
+    cursor: pointer; font-family: var(--font); font-size: 0.8em; transition: 0.15s;
+  }
+  .btn:hover { border-color: var(--accent); color: var(--accent); }
+  .btn:active { transform: scale(0.97); }
+  .btn.danger:hover { border-color: var(--red); color: var(--red); }
+  .btn.small { padding: 3px 8px; font-size: 0.75em; }
+
+  .section { margin-bottom: 16px; }
+  .section h3 { font-size: 0.8em; color: var(--dim); margin-bottom: 8px; text-transform: uppercase; letter-spacing: 0.05em; }
+
+  input, select {
+    background: var(--bg); border: 1px solid var(--border); color: var(--text);
+    padding: 5px 8px; border-radius: 4px; font-family: var(--font); font-size: 0.8em; width: 100%;
+  }
+  input:focus, select:focus { outline: none; border-color: var(--accent); }
+
+  .actor-card {
+    background: var(--bg); border: 1px solid var(--border); border-radius: 6px;
+    padding: 10px; margin-bottom: 8px; font-size: 0.8em; position: relative;
+  }
+  .actor-card .type { color: var(--purple); font-weight: bold; }
+  .actor-card .addr { color: var(--dim); font-size: 0.9em; }
+  .actor-card .name-tag { color: var(--yellow); font-size: 0.85em; }
+  .actor-card .group-tag { color: var(--green); font-size: 0.85em; margin-left: 4px; }
+  .actor-card .actions { margin-top: 6px; display: flex; gap: 4px; flex-wrap: wrap; }
+
+  #log {
+    font-size: 0.75em; line-height: 1.6; padding: 8px;
+    background: var(--bg); border-radius: 4px; height: calc(100% - 40px); overflow-y: auto;
+  }
+  .log-entry { border-bottom: 1px solid var(--border); padding: 3px 0; }
+  .log-time { color: var(--dim); }
+  .log-spawn { color: var(--green); }
+  .log-msg { color: var(--accent); }
+  .log-recv { color: var(--yellow); }
+  .log-death { color: var(--red); }
+  .log-name { color: var(--purple); }
+  .log-group { color: var(--green); }
+
+  .tick-indicator {
+    display: inline-block; width: 8px; height: 8px; border-radius: 50%;
+    background: var(--dim); margin-right: 6px; transition: 0.1s;
+  }
+  .tick-indicator.active { background: var(--green); box-shadow: 0 0 6px var(--green); }
+
+  .controls { display: flex; gap: 8px; margin-bottom: 12px; align-items: center; }
+  .speed-label { font-size: 0.75em; color: var(--dim); }
+
+  #loading { text-align: center; padding: 40px; color: var(--dim); font-size: 1.2em; }
+  #app { display: none; }
+
+  .form-row { display: flex; gap: 6px; margin-bottom: 6px; }
+  .form-row input { flex: 1; }
+
+  .viz-canvas { width: 100%; height: 200px; border: 1px solid var(--border); border-radius: 4px; background: var(--bg); }
+</style>
+</head>
+<body>
+
+<h1><span>swactor</span> in-browser runtime</h1>
+<p class="subtitle">actor runtime compiled to WebAssembly, running right here</p>
+
+<div id="loading">Loading wasm module...</div>
+
+<div id="app">
+  <div class="grid">
+    <!-- LEFT: Controls -->
+    <div class="panel">
+      <h2>Controls</h2>
+
+      <div class="section">
+        <h3>Runtime</h3>
+        <div class="controls">
+          <span class="tick-indicator" id="tick-led"></span>
+          <button class="btn" id="btn-toggle">Start</button>
+          <button class="btn" id="btn-step">Step</button>
+          <div>
+            <input type="range" id="speed" min="1" max="60" value="20" style="width:80px">
+            <span class="speed-label" id="speed-label">20 tps</span>
+          </div>
+        </div>
+        <div class="stat-row"><span class="stat-label">Actors</span><span class="stat-value" id="s-actors">0</span></div>
+        <div class="stat-row"><span class="stat-label">Messages</span><span class="stat-value" id="s-msgs">0</span></div>
+        <div class="stat-row"><span class="stat-label">Panics</span><span class="stat-value" id="s-panics">0</span></div>
+        <div class="stat-row"><span class="stat-label">Uptime</span><span class="stat-value" id="s-uptime">0ms</span></div>
+        <div class="stat-row"><span class="stat-label">Ticks</span><span class="stat-value" id="s-ticks">0</span></div>
+      </div>
+
+      <div class="section">
+        <h3>Spawn Actor</h3>
+        <div class="form-row">
+          <select id="spawn-type">
+            <option value="counter">Counter</option>
+            <option value="relay">Relay</option>
+            <option value="group_member">Group Member</option>
+            <option value="sentinel">Sentinel</option>
+          </select>
+          <button class="btn" id="btn-spawn">Spawn</button>
+        </div>
+        <div id="spawn-opts"></div>
+      </div>
+
+      <div class="section">
+        <h3>Send Message</h3>
+        <div class="form-row">
+          <select id="send-target" style="flex:2"><option value="">— select actor —</option></select>
+          <input id="send-value" type="number" value="1" style="flex:1" placeholder="u32">
+        </div>
+        <button class="btn" id="btn-send" style="margin-top:4px">Send u32</button>
+      </div>
+
+      <div class="section">
+        <h3>Naming</h3>
+        <div class="form-row">
+          <input id="name-input" placeholder="name">
+          <select id="name-target" style="flex:1"><option value="">— actor —</option></select>
+        </div>
+        <div class="form-row">
+          <button class="btn small" id="btn-register">Register</button>
+          <button class="btn small" id="btn-lookup">Lookup</button>
+          <button class="btn small" id="btn-unreg">Unregister</button>
+        </div>
+        <div id="names-list" style="font-size:0.75em;color:var(--dim);margin-top:4px"></div>
+      </div>
+
+      <div class="section">
+        <h3>Groups</h3>
+        <div class="form-row">
+          <input id="group-name" placeholder="group name" value="workers">
+        </div>
+        <div class="form-row">
+          <button class="btn small" id="btn-broadcast">Broadcast 42</button>
+        </div>
+        <div id="groups-list" style="font-size:0.75em;color:var(--dim);margin-top:4px"></div>
+      </div>
+    </div>
+
+    <!-- CENTER: Actor Map + Visualization -->
+    <div class="panel">
+      <h2>Actors</h2>
+      <canvas id="viz" class="viz-canvas"></canvas>
+      <div id="actor-list" style="margin-top:12px"></div>
+    </div>
+
+    <!-- RIGHT: Event Log -->
+    <div class="panel">
+      <h2>Event Log</h2>
+      <div id="log"></div>
+    </div>
+  </div>
+</div>
+
+<script type="module">
+import init, {
+  WasmRuntime, WasmAddr, WasmInboxU32, WasmInboxString,
+  spawn_counter, spawn_relay, spawn_sentinel, spawn_group_member,
+} from './pkg-web/wasm.js';
+
+await init();
+
+document.getElementById('loading').style.display = 'none';
+document.getElementById('app').style.display = 'block';
+
+// ─── State ─────────────────────────────────────────────────────────────
+const rt = new WasmRuntime();
+const actors = new Map();  // id -> { addr, type, name?, groups:Set, inbox? }
+let nextId = 1;
+let running = false;
+let tickCount = 0;
+let rafId = null;
+let lastTick = 0;
+
+// Global inboxes for polling
+const inboxes = [];  // { inbox, type: 'u32'|'string', label, actorId? }
+
+// ─── Logging ───────────────────────────────────────────────────────────
+const logEl = document.getElementById('log');
+function log(cls, msg) {
+  const t = new Date().toLocaleTimeString('en-US', { hour12: false, fractionalSecondDigits: 2 });
+  const entry = document.createElement('div');
+  entry.className = 'log-entry';
+  entry.innerHTML = `<span class="log-time">${t}</span> <span class="${cls}">${msg}</span>`;
+  logEl.appendChild(entry);
+  logEl.scrollTop = logEl.scrollHeight;
+  // cap at 500 entries
+  while (logEl.children.length > 500) logEl.removeChild(logEl.firstChild);
+}
+
+// ─── Spawn helpers ─────────────────────────────────────────────────────
+function addActor(addr, type, extra = {}) {
+  const id = nextId++;
+  const entry = { id, addr, type, name: null, groups: new Set(), ...extra };
+  actors.set(id, entry);
+  log('log-spawn', `spawned <b>${type}</b> #${id} (${addr.toString()})`);
+  refreshActorUI();
+  return id;
+}
+
+function createInbox(type) {
+  if (type === 'u32') {
+    const inbox = rt.new_inbox_u32();
+    inboxes.push({ inbox, type: 'u32' });
+    return inbox;
+  } else if (type === 'string') {
+    const inbox = rt.new_inbox_string();
+    inboxes.push({ inbox, type: 'string' });
+    return inbox;
+  }
+}
+
+function doSpawn() {
+  const type = document.getElementById('spawn-type').value;
+  if (type === 'counter') {
+    const inbox = createInbox('u32');
+    const inboxAddr = inbox.addr();
+    const addr = spawn_counter(rt, inboxAddr);
+    const id = addActor(addr, 'Counter', { reportInbox: inbox });
+  } else if (type === 'relay') {
+    // relay needs a target — pick first available actor
+    const targetId = prompt('Target actor ID to relay to:');
+    const target = actors.get(Number(targetId));
+    if (!target) { log('log-death', 'invalid target'); return; }
+    const addr = spawn_relay(rt, target.addr);
+    addActor(addr, 'Relay', { relayTarget: targetId });
+  } else if (type === 'group_member') {
+    const group = document.getElementById('group-name').value || 'workers';
+    const inbox = createInbox('u32');
+    const inboxAddr = inbox.addr();
+    const addr = spawn_group_member(rt, group, inboxAddr);
+    const id = addActor(addr, 'GroupMember', { group, reportInbox: inbox });
+    actors.get(id).groups.add(group);
+  } else if (type === 'sentinel') {
+    const targetId = prompt('Actor ID to watch:');
+    const target = actors.get(Number(targetId));
+    if (!target) { log('log-death', 'invalid target'); return; }
+    const inbox = createInbox('string');
+    const addr = spawn_sentinel(rt, target.addr, inbox);
+    addActor(addr, 'Sentinel', { watching: targetId, deathInbox: inbox });
+  }
+}
+
+// ─── Tick loop ─────────────────────────────────────────────────────────
+function tickOnce() {
+  rt.tick();
+  tickCount++;
+  pollInboxes();
+  updateStats();
+}
+
+function pollInboxes() {
+  for (const ib of inboxes) {
+    let val;
+    while ((val = ib.inbox.try_recv()) !== undefined) {
+      if (ib.type === 'u32') {
+        log('log-recv', `inbox received <b>${val}</b>`);
+      } else {
+        log('log-death', `death notification: <b>${val}</b>`);
+      }
+    }
+  }
+}
+
+function getTickInterval() {
+  return 1000 / Number(document.getElementById('speed').value);
+}
+
+function loop(ts) {
+  if (!running) return;
+  if (ts - lastTick >= getTickInterval()) {
+    tickOnce();
+    flashLed();
+    lastTick = ts;
+  }
+  rafId = requestAnimationFrame(loop);
+}
+
+function flashLed() {
+  const led = document.getElementById('tick-led');
+  led.classList.add('active');
+  setTimeout(() => led.classList.remove('active'), 80);
+}
+
+function updateStats() {
+  document.getElementById('s-actors').textContent = rt.actor_count();
+  document.getElementById('s-msgs').textContent = rt.total_messages();
+  document.getElementById('s-panics').textContent = rt.total_panics();
+  document.getElementById('s-uptime').textContent = Math.round(rt.uptime_ms()) + 'ms';
+  document.getElementById('s-ticks').textContent = tickCount;
+
+  // names
+  const names = rt.registered_names();
+  document.getElementById('names-list').textContent = names ? `Registered: ${names}` : 'No names registered';
+
+  // groups
+  const groups = rt.group_names();
+  const parts = groups ? groups.split(',').map(g => `${g}(${rt.group_member_count(g)})`).join(', ') : 'none';
+  document.getElementById('groups-list').textContent = `Groups: ${parts}`;
+
+  refreshDropdowns();
+  drawViz();
+}
+
+// ─── Actor Cards ───────────────────────────────────────────────────────
+function refreshActorUI() {
+  const container = document.getElementById('actor-list');
+  container.innerHTML = '';
+  for (const [id, a] of actors) {
+    const card = document.createElement('div');
+    card.className = 'actor-card';
+    let meta = '';
+    if (a.name) meta += ` <span class="name-tag">@${a.name}</span>`;
+    if (a.groups.size) meta += ` <span class="group-tag">[${[...a.groups].join(',')}]</span>`;
+    if (a.relayTarget) meta += ` <span style="color:var(--dim)">→ #${a.relayTarget}</span>`;
+    if (a.watching) meta += ` <span style="color:var(--dim)">watching #${a.watching}</span>`;
+
+    card.innerHTML = `
+      <span class="type">${a.type}</span> <span style="color:var(--dim)">#${id}</span>${meta}
+      <br><span class="addr">${a.addr.toString()}</span>
+      <div class="actions">
+        <button class="btn small" onclick="window._send(${id})">Send 1</button>
+        <button class="btn small" onclick="window._send10(${id})">Send ×10</button>
+        <button class="btn small danger" onclick="window._stop(${id})">Stop</button>
+      </div>
+    `;
+    container.appendChild(card);
+  }
+  refreshDropdowns();
+}
+
+function refreshDropdowns() {
+  for (const sel of [document.getElementById('send-target'), document.getElementById('name-target')]) {
+    const prev = sel.value;
+    sel.innerHTML = '<option value="">— select —</option>';
+    for (const [id, a] of actors) {
+      const opt = document.createElement('option');
+      opt.value = id;
+      opt.textContent = `#${id} ${a.type}${a.name ? ' @' + a.name : ''}`;
+      sel.appendChild(opt);
+    }
+    sel.value = prev;
+  }
+}
+
+// ─── Visualization ─────────────────────────────────────────────────────
+function drawViz() {
+  const canvas = document.getElementById('viz');
+  const ctx = canvas.getContext('2d');
+  const dpr = window.devicePixelRatio || 1;
+  const rect = canvas.getBoundingClientRect();
+  canvas.width = rect.width * dpr;
+  canvas.height = rect.height * dpr;
+  ctx.scale(dpr, dpr);
+  ctx.clearRect(0, 0, rect.width, rect.height);
+
+  const entries = [...actors.values()];
+  if (entries.length === 0) {
+    ctx.fillStyle = '#8b949e';
+    ctx.font = '13px monospace';
+    ctx.textAlign = 'center';
+    ctx.fillText('Spawn some actors to see them here', rect.width / 2, rect.height / 2);
+    return;
+  }
+
+  const colors = { Counter: '#58a6ff', Relay: '#bc8cff', GroupMember: '#3fb950', Sentinel: '#f85149' };
+  const cx = rect.width / 2;
+  const cy = rect.height / 2;
+  const radius = Math.min(cx, cy) - 40;
+
+  // Position actors in a circle
+  const positions = new Map();
+  entries.forEach((a, i) => {
+    const angle = (2 * Math.PI * i) / entries.length - Math.PI / 2;
+    const x = cx + radius * Math.cos(angle);
+    const y = cy + radius * Math.sin(angle);
+    positions.set(a.id, { x, y });
+  });
+
+  // Draw connections
+  ctx.lineWidth = 1;
+  for (const a of entries) {
+    const from = positions.get(a.id);
+    if (a.relayTarget && positions.has(Number(a.relayTarget))) {
+      const to = positions.get(Number(a.relayTarget));
+      ctx.strokeStyle = '#bc8cff44';
+      ctx.beginPath(); ctx.moveTo(from.x, from.y); ctx.lineTo(to.x, to.y); ctx.stroke();
+      drawArrow(ctx, from, to, '#bc8cff44');
+    }
+    if (a.watching && positions.has(Number(a.watching))) {
+      const to = positions.get(Number(a.watching));
+      ctx.strokeStyle = '#f8514944';
+      ctx.setLineDash([4, 4]);
+      ctx.beginPath(); ctx.moveTo(from.x, from.y); ctx.lineTo(to.x, to.y); ctx.stroke();
+      ctx.setLineDash([]);
+    }
+  }
+
+  // Draw actors
+  for (const a of entries) {
+    const pos = positions.get(a.id);
+    const color = colors[a.type] || '#c9d1d9';
+    // glow
+    ctx.shadowColor = color;
+    ctx.shadowBlur = 12;
+    ctx.fillStyle = color;
+    ctx.beginPath();
+    ctx.arc(pos.x, pos.y, 14, 0, 2 * Math.PI);
+    ctx.fill();
+    ctx.shadowBlur = 0;
+
+    // label
+    ctx.fillStyle = '#c9d1d9';
+    ctx.font = 'bold 10px monospace';
+    ctx.textAlign = 'center';
+    ctx.fillText(`#${a.id}`, pos.x, pos.y + 4);
+
+    // type label below
+    ctx.fillStyle = '#8b949e';
+    ctx.font = '9px monospace';
+    ctx.fillText(a.type, pos.x, pos.y + 28);
+    if (a.name) {
+      ctx.fillStyle = '#d29922';
+      ctx.fillText(`@${a.name}`, pos.x, pos.y + 38);
+    }
+  }
+}
+
+function drawArrow(ctx, from, to, color) {
+  const dx = to.x - from.x, dy = to.y - from.y;
+  const len = Math.sqrt(dx * dx + dy * dy);
+  if (len < 30) return;
+  const ux = dx / len, uy = dy / len;
+  const tipX = to.x - ux * 18, tipY = to.y - uy * 18;
+  const sz = 6;
+  ctx.fillStyle = color;
+  ctx.beginPath();
+  ctx.moveTo(tipX, tipY);
+  ctx.lineTo(tipX - ux * sz - uy * sz * 0.5, tipY - uy * sz + ux * sz * 0.5);
+  ctx.lineTo(tipX - ux * sz + uy * sz * 0.5, tipY - uy * sz - ux * sz * 0.5);
+  ctx.fill();
+}
+
+// ─── Global handlers (for inline onclick) ──────────────────────────────
+window._send = (id) => {
+  const a = actors.get(id);
+  if (!a) return;
+  const val = Number(document.getElementById('send-value').value) || 1;
+  rt.send_u32(a.addr, val);
+  log('log-msg', `sent <b>${val}</b> → #${id} ${a.type}`);
+};
+
+window._send10 = (id) => {
+  const a = actors.get(id);
+  if (!a) return;
+  for (let i = 0; i < 10; i++) rt.send_u32(a.addr, 1);
+  log('log-msg', `sent <b>10×1</b> → #${id} ${a.type}`);
+};
+
+window._stop = (id) => {
+  const a = actors.get(id);
+  if (!a) return;
+  rt.stop_actor(a.addr);
+  log('log-death', `stopped #${id} ${a.type}`);
+  actors.delete(id);
+  refreshActorUI();
+};
+
+// ─── Button wiring ─────────────────────────────────────────────────────
+document.getElementById('btn-toggle').addEventListener('click', () => {
+  running = !running;
+  document.getElementById('btn-toggle').textContent = running ? 'Pause' : 'Start';
+  if (running) { lastTick = performance.now(); rafId = requestAnimationFrame(loop); }
+});
+
+document.getElementById('btn-step').addEventListener('click', () => {
+  tickOnce();
+  flashLed();
+});
+
+document.getElementById('speed').addEventListener('input', (e) => {
+  document.getElementById('speed-label').textContent = e.target.value + ' tps';
+});
+
+document.getElementById('btn-spawn').addEventListener('click', doSpawn);
+
+document.getElementById('btn-send').addEventListener('click', () => {
+  const id = Number(document.getElementById('send-target').value);
+  if (id) window._send(id);
+});
+
+document.getElementById('btn-register').addEventListener('click', () => {
+  const name = document.getElementById('name-input').value.trim();
+  const id = Number(document.getElementById('name-target').value);
+  const a = actors.get(id);
+  if (!name || !a) return;
+  const ok = rt.register_name(name, a.addr);
+  if (ok) {
+    a.name = name;
+    log('log-name', `registered <b>@${name}</b> → #${id}`);
+    refreshActorUI();
+  } else {
+    log('log-death', `name <b>@${name}</b> already taken`);
+  }
+});
+
+document.getElementById('btn-lookup').addEventListener('click', () => {
+  const name = document.getElementById('name-input').value.trim();
+  if (!name) return;
+  const found = rt.where_is(name);
+  if (found) {
+    log('log-name', `@${name} → ${found.toString()}`);
+  } else {
+    log('log-name', `@${name} not found`);
+  }
+});
+
+document.getElementById('btn-unreg').addEventListener('click', () => {
+  const name = document.getElementById('name-input').value.trim();
+  if (!name) return;
+  const prev = rt.unregister_name(name);
+  if (prev) {
+    for (const a of actors.values()) { if (a.name === name) a.name = null; }
+    log('log-name', `unregistered <b>@${name}</b>`);
+    refreshActorUI();
+  } else {
+    log('log-name', `@${name} was not registered`);
+  }
+});
+
+document.getElementById('btn-broadcast').addEventListener('click', () => {
+  const group = document.getElementById('group-name').value.trim();
+  if (!group) return;
+  const count = rt.publish_to_group_u32(group, 42);
+  log('log-group', `broadcast <b>42</b> to group "${group}" (${count} members)`);
+});
+
+// initial draw
+updateStats();
+log('log-spawn', 'runtime initialized — spawn some actors and hit <b>Start</b> or <b>Step</b>');
+</script>
+</body>
+</html>

crates/wasm/src/lib.rs

@@ -1,11 +1,240 @@
+use std::sync::Arc;
+
 use wasm_bindgen::prelude::*;
 
-use swactor::actor::{ActorAddress, ActorInterface};
+use swactor::actor::{ActorAddress, ActorExited, ActorInterface};
 use swactor::runtime::{Ctx, Inbox, Runtime, RuntimeConfig};
+use swactor_std::{CtxGroups, RuntimeNaming, RuntimeGroups, StdExtension};
 
-// ---------------------------------------------------------------------------
-// Actors (private — only exposed through the wasm API)
-// ---------------------------------------------------------------------------
+// ─── Core JS-facing types ───────────────────────────────────────────────────
+
+/// Opaque actor address handle for JavaScript.
+///
+/// Returned by spawn functions, passed to send functions. JS never sees
+/// the raw 32-byte address — it just holds and forwards this handle.
+#[wasm_bindgen]
+#[derive(Clone)]
+pub struct WasmAddr(ActorAddress);
+
+#[wasm_bindgen]
+impl WasmAddr {
+    /// Debug representation of the address (first 8 hex bytes + ellipsis).
+    #[wasm_bindgen(js_name = toString)]
+    pub fn to_js_string(&self) -> String {
+        format!("{}", self.0)
+    }
+}
+
+impl WasmAddr {
+    /// Access the inner address from Rust (not exposed to JS).
+    pub fn inner(&self) -> ActorAddress {
+        self.0
+    }
+}
+
+/// Inbox that receives `u32` values from actors.
+#[wasm_bindgen]
+pub struct WasmInboxU32 {
+    inner: Inbox<u32>,
+}
+
+#[wasm_bindgen]
+impl WasmInboxU32 {
+    /// The address actors should send results to.
+    pub fn addr(&self) -> WasmAddr {
+        WasmAddr(*self.inner.addr())
+    }
+
+    /// Poll for the next value. Returns `undefined` when empty.
+    pub fn try_recv(&self) -> Option<u32> {
+        self.inner.try_recv()
+    }
+}
+
+/// Inbox that receives byte arrays from actors.
+#[wasm_bindgen]
+pub struct WasmInboxBytes {
+    inner: Inbox<Vec<u8>>,
+}
+
+#[wasm_bindgen]
+impl WasmInboxBytes {
+    pub fn addr(&self) -> WasmAddr {
+        WasmAddr(*self.inner.addr())
+    }
+
+    /// Poll for the next byte array. Returns `undefined` when empty.
+    pub fn try_recv(&self) -> Option<Vec<u8>> {
+        self.inner.try_recv()
+    }
+}
+
+/// Inbox that receives string values (used for death notifications, etc.).
+#[wasm_bindgen]
+pub struct WasmInboxString {
+    inner: Inbox<String>,
+}
+
+#[wasm_bindgen]
+impl WasmInboxString {
+    pub fn addr(&self) -> WasmAddr {
+        WasmAddr(*self.inner.addr())
+    }
+
+    /// Poll for the next string. Returns `undefined` when empty.
+    pub fn try_recv(&self) -> Option<String> {
+        self.inner.try_recv()
+    }
+}
+
+// ─── Runtime ────────────────────────────────────────────────────────────────
+
+/// The browser-facing swactor runtime.
+///
+/// Wraps `swactor::Runtime` in single-threaded mode with StdExtension installed
+/// (naming, monitoring, groups). Actors are spawned via dedicated spawn functions
+/// (one per actor type). The runtime is driven by calling `tick()`.
+#[wasm_bindgen]
+pub struct WasmRuntime {
+    rt: Runtime,
+}
+
+#[wasm_bindgen]
+impl WasmRuntime {
+    #[wasm_bindgen(constructor)]
+    pub fn new() -> Self {
+        let rt = Runtime::new(RuntimeConfig {
+            num_threads: 1,
+            ..RuntimeConfig::default()
+        })
+        .with_extension(Arc::new(StdExtension::new()));
+        Self { rt }
+    }
+
+    /// Drive one tick of the runtime.
+    pub fn tick(&self) {
+        self.rt.tick();
+    }
+
+    /// Number of actors currently alive.
+    pub fn actor_count(&self) -> usize {
+        self.rt.stats().actors.len()
+    }
+
+    /// Create an inbox that receives u32 values.
+    pub fn new_inbox_u32(&self) -> WasmInboxU32 {
+        WasmInboxU32 {
+            inner: self.rt.new_inbox().expect("new_inbox_u32"),
+        }
+    }
+
+    /// Create an inbox that receives byte arrays.
+    pub fn new_inbox_bytes(&self) -> WasmInboxBytes {
+        WasmInboxBytes {
+            inner: self.rt.new_inbox().expect("new_inbox_bytes"),
+        }
+    }
+
+    /// Create an inbox that receives strings.
+    pub fn new_inbox_string(&self) -> WasmInboxString {
+        WasmInboxString {
+            inner: self.rt.new_inbox().expect("new_inbox_string"),
+        }
+    }
+
+    /// Send a u32 to an actor. Returns false if the address is invalid.
+    pub fn send_u32(&self, addr: &WasmAddr, value: u32) -> bool {
+        self.rt.send_to(addr.0, value).is_ok()
+    }
+
+    /// Send a byte array to an actor. Returns false if the address is invalid.
+    pub fn send_bytes(&self, addr: &WasmAddr, data: &[u8]) -> bool {
+        self.rt.send_to(addr.0, data.to_vec()).is_ok()
+    }
+
+    /// Stop an actor gracefully.
+    pub fn stop_actor(&self, addr: &WasmAddr) -> bool {
+        self.rt.stop_actor(addr.0).is_ok()
+    }
+
+    /// Runtime uptime in milliseconds.
+    pub fn uptime_ms(&self) -> f64 {
+        self.rt.stats().uptime_ms as f64
+    }
+
+    // ─── Naming ─────────────────────────────────────────────────────────────
+
+    /// Register a name for an actor address. Returns false if the name is taken.
+    pub fn register_name(&self, name: &str, addr: &WasmAddr) -> bool {
+        self.rt.register_name(name.to_string(), addr.0).is_ok()
+    }
+
+    /// Look up an actor address by name. Returns undefined if not found.
+    pub fn where_is(&self, name: &str) -> Option<WasmAddr> {
+        self.rt.where_is(name).map(WasmAddr)
+    }
+
+    /// Unregister a name. Returns the address it was bound to, or undefined.
+    pub fn unregister_name(&self, name: &str) -> Option<WasmAddr> {
+        self.rt.unregister(name).map(WasmAddr)
+    }
+
+    /// Return all registered actor names as a comma-separated string.
+    pub fn registered_names(&self) -> String {
+        self.rt.registered_names().join(",")
+    }
+
+    // ─── Groups ─────────────────────────────────────────────────────────────
+
+    /// Add an actor to a named group.
+    pub fn join_group(&self, addr: &WasmAddr, group: &str) {
+        self.rt.join_group(addr.0, group.to_string());
+    }
+
+    /// Remove an actor from a named group.
+    pub fn leave_group(&self, addr: &WasmAddr, group: &str) {
+        self.rt.leave_group(addr.0, group);
+    }
+
+    /// Broadcast a u32 message to all members of a group. Returns count sent.
+    pub fn publish_to_group_u32(&self, group: &str, msg: u32) -> usize {
+        self.rt.publish_to(group, msg)
+    }
+
+    /// Number of actors in a group.
+    pub fn group_member_count(&self, group: &str) -> usize {
+        self.rt.group_members(group).len()
+    }
+
+    /// Return all group names as a comma-separated string.
+    pub fn group_names(&self) -> String {
+        self.rt.groups().join(",")
+    }
+
+    // ─── Stats ──────────────────────────────────────────────────────────────
+
+    /// Total messages processed across all workers.
+    pub fn total_messages(&self) -> f64 {
+        self.rt.stats().workers.iter().map(|w| w.messages_processed).sum::<u64>() as f64
+    }
+
+    /// Total panics across all workers.
+    pub fn total_panics(&self) -> f64 {
+        self.rt.stats().workers.iter().map(|w| w.panics).sum::<u64>() as f64
+    }
+}
+
+impl WasmRuntime {
+    /// Access the inner Runtime from Rust (for custom spawn functions).
+    pub fn runtime(&self) -> &Runtime {
+        &self.rt
+    }
+}
+
+// ─── Demo actors ────────────────────────────────────────────────────────────
+//
+// These demonstrate the pattern for exposing actors to JavaScript.
+// Each actor type gets a `spawn_*` function that returns a WasmAddr.
 
 struct Counter {
     total: u32,
@@ -35,79 +264,100 @@ impl ActorInterface for Relay {
     }
 }
 
-// ---------------------------------------------------------------------------
-// JS-facing runtime wrapper
-// ---------------------------------------------------------------------------
+/// A sentinel actor that watches a target and reports its death to an inbox.
+///
+/// Uses the std monitoring extension (CtxMonitoring::monitor). When the target
+/// dies, the sentinel receives a `Down` message and sends the dead actor's
+/// string representation to the report inbox, then stops itself.
+struct Sentinel {
+    target: ActorAddress,
+    report_to: ActorAddress,
+}
 
+impl ActorInterface for Sentinel {
+    type Incoming = ();
+    type Response = ();
+
+    fn handle(&mut self, _ctx: &Ctx, _msg: ()) {}
+
+    fn on_start(&mut self, ctx: &Ctx) {
+        ctx.watch(self.target);
+    }
+
+    fn on_actor_exit(&mut self, ctx: &Ctx, exited: ActorExited) {
+        let msg = format!("{}:{:?}", exited.addr, exited.reason);
+        let _ = ctx.send(self.report_to, msg);
+        ctx.stop_self();
+    }
+}
+
+/// A group member that joins a named group and forwards u32 messages to a report inbox.
+struct GroupMember {
+    group: String,
+    report_to: ActorAddress,
+}
+
+impl ActorInterface for GroupMember {
+    type Incoming = u32;
+    type Response = ();
+
+    fn on_start(&mut self, ctx: &Ctx) {
+        ctx.join_group(self.group.clone());
+    }
+
+    fn handle(&mut self, ctx: &Ctx, msg: u32) {
+        let _ = ctx.send(self.report_to, msg);
+    }
+}
+
+/// Spawn a counter that accumulates u32 values and reports running totals
+/// to the given inbox address.
 #[wasm_bindgen]
-pub struct SwactorRuntime {
-    rt: Runtime,
-    inbox: Inbox<u32>,
-    actors: Vec<ActorAddress>,
-}
-
-#[wasm_bindgen]
-impl SwactorRuntime {
-    #[wasm_bindgen(constructor)]
-    pub fn new() -> Self {
-        let rt = Runtime::new(RuntimeConfig {
-            num_threads: 1,
-            ..RuntimeConfig::default()
-        });
-        let inbox = rt.new_inbox().unwrap();
-        Self {
-            rt,
-            inbox,
-            actors: Vec::new(),
-        }
-    }
-
-    /// Spawn a counter actor. Returns its index (used with `send`).
-    pub fn spawn_counter(&mut self) -> usize {
-        let addr = self
+pub fn spawn_counter(rt: &WasmRuntime, report_to: &WasmAddr) -> WasmAddr {
+    let addr = rt
         .rt
         .spawn(Counter {
             total: 0,
-                report_to: *self.inbox.addr(),
+            report_to: report_to.0,
         })
         .expect("spawn counter");
-        let idx = self.actors.len();
-        self.actors.push(addr);
-        idx
+    WasmAddr(addr)
 }
 
-    /// Spawn a relay that forwards every message to `target_idx`.
-    pub fn spawn_relay(&mut self, target_idx: usize) -> usize {
-        let target = self.actors[target_idx];
-        let addr = self
+/// Spawn a relay that forwards every u32 message to the target actor.
+#[wasm_bindgen]
+pub fn spawn_relay(rt: &WasmRuntime, target: &WasmAddr) -> WasmAddr {
+    let addr = rt
         .rt
-            .spawn(Relay { target })
+        .spawn(Relay { target: target.0 })
         .expect("spawn relay");
-        let idx = self.actors.len();
-        self.actors.push(addr);
-        idx
+    WasmAddr(addr)
 }
 
-    /// Send a u32 to the actor at `actor_idx`.
-    pub fn send(&self, actor_idx: usize, value: u32) -> bool {
-        if actor_idx >= self.actors.len() {
-            return false;
-        }
-        self.rt.send_to(self.actors[actor_idx], value).is_ok()
+/// Spawn a sentinel that watches a target actor and reports its death
+/// to the given string inbox.
+#[wasm_bindgen]
+pub fn spawn_sentinel(rt: &WasmRuntime, target: &WasmAddr, report_to: &WasmInboxString) -> WasmAddr {
+    let addr = rt
+        .rt
+        .spawn(Sentinel {
+            target: target.0,
+            report_to: *report_to.inner.addr(),
+        })
+        .expect("spawn sentinel");
+    WasmAddr(addr)
 }
 
-    /// Drive one tick of the single-threaded runtime.
-    pub fn tick(&self) {
-        self.rt.tick();
-    }
-
-    /// Try to read the next result from the inbox. Returns `undefined` when empty.
-    pub fn try_recv(&self) -> Option<u32> {
-        self.inbox.try_recv()
-    }
-
-    /// Number of actors the runtime knows about.
-    pub fn actor_count(&self) -> usize {
-        self.rt.stats().actors.len()
-    }
+/// Spawn a group member that joins the given group and forwards u32 messages
+/// to the report inbox.
+#[wasm_bindgen]
+pub fn spawn_group_member(rt: &WasmRuntime, group: &str, report_to: &WasmAddr) -> WasmAddr {
+    let addr = rt
+        .rt
+        .spawn(GroupMember {
+            group: group.to_string(),
+            report_to: report_to.0,
+        })
+        .expect("spawn group_member");
+    WasmAddr(addr)
 }

crates/wasm/test.mjs

@@ -1,4 +1,11 @@
-import { SwactorRuntime } from "./pkg/swactor_wasm.js";
+import {
+  WasmRuntime,
+  WasmAddr,
+  spawn_counter,
+  spawn_relay,
+  spawn_sentinel,
+  spawn_group_member,
+} from "./pkg/wasm.js";
 
 let passed = 0;
 let failed = 0;
@@ -23,77 +30,314 @@ function assertEq(a, b, msg) {
   }
 }
 
-function drain(rt) {
+function drainInbox(inbox) {
   const results = [];
   let v;
-  while ((v = rt.try_recv()) !== undefined) results.push(v);
+  while ((v = inbox.try_recv()) !== undefined) results.push(v);
   return results;
 }
 
 // ---- accumulator ----------------------------------------------------------
 {
-  console.log("test: accumulator processes messages");
-  const rt = new SwactorRuntime();
-  const c = rt.spawn_counter();
-  rt.send(c, 1);
-  rt.send(c, 2);
-  rt.send(c, 10);
+  console.log("test: accumulator processes messages via WasmAddr");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  rt.send_u32(c, 1);
+  rt.send_u32(c, 2);
+  rt.send_u32(c, 10);
   rt.tick();
-  assertEq(drain(rt), [1, 3, 13], "running totals");
+  assertEq(drainInbox(inbox), [1, 3, 13], "running totals");
+  inbox.free();
   rt.free();
 }
 
 // ---- relay ----------------------------------------------------------------
 {
   console.log("test: relay forwards to counter");
-  const rt = new SwactorRuntime();
-  const c = rt.spawn_counter();
-  const r = rt.spawn_relay(c);
-  rt.send(r, 5);
-  rt.send(r, 7);
-  // tick 1: relay receives and forwards (cross-actor, same worker → pending_local)
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  const r = spawn_relay(rt, c);
+  rt.send_u32(r, 5);
+  rt.send_u32(r, 7);
+  // tick 1: relay receives and forwards (same worker → pending_local)
   // tick 2: counter receives forwarded messages
   rt.tick();
   rt.tick();
-  assertEq(drain(rt), [5, 12], "relayed totals");
+  assertEq(drainInbox(inbox), [5, 12], "relayed totals");
+  inbox.free();
   rt.free();
 }
 
 // ---- multiple counters ----------------------------------------------------
 {
   console.log("test: multiple independent counters");
-  const rt = new SwactorRuntime();
-  const a = rt.spawn_counter();
-  const b = rt.spawn_counter();
-  rt.send(a, 10);
-  rt.send(b, 100);
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const a = spawn_counter(rt, inbox.addr());
+  const b = spawn_counter(rt, inbox.addr());
+  rt.send_u32(a, 10);
+  rt.send_u32(b, 100);
   rt.tick();
-  const results = drain(rt);
-  // order depends on HashMap iteration, so just check set equality
+  const results = drainInbox(inbox);
   assert(
     results.includes(10) && results.includes(100) && results.length === 2,
     "both counters report"
   );
+  inbox.free();
   rt.free();
 }
 
 // ---- actor_count ----------------------------------------------------------
 {
   console.log("test: actor_count tracks spawns");
-  const rt = new SwactorRuntime();
-  rt.spawn_counter();
-  rt.spawn_counter();
-  rt.spawn_counter();
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  spawn_counter(rt, inbox.addr());
+  spawn_counter(rt, inbox.addr());
+  spawn_counter(rt, inbox.addr());
   rt.tick(); // drain spawn queue
   assertEq(rt.actor_count(), 3, "three actors");
+  inbox.free();
   rt.free();
 }
 
-// ---- send to invalid index returns false ----------------------------------
+// ---- WasmAddr toString ----------------------------------------------------
 {
-  console.log("test: send to bad index returns false");
-  const rt = new SwactorRuntime();
-  assert(!rt.send(999, 1), "out-of-bounds send");
+  console.log("test: WasmAddr has string representation");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const addr = spawn_counter(rt, inbox.addr());
+  const s = addr.toString();
+  // no_random generates deterministic addresses — just check it's a non-empty hex string
+  assert(typeof s === "string" && s.length > 0, "addr toString is non-empty string");
+  inbox.free();
+  rt.free();
+}
+
+// ---- stop_actor -----------------------------------------------------------
+{
+  console.log("test: stop_actor removes actor");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  rt.tick(); // drain spawn
+  assertEq(rt.actor_count(), 1, "one actor before stop");
+  rt.stop_actor(c);
+  rt.tick(); // process stop + cleanup
+  assertEq(rt.actor_count(), 0, "zero actors after stop");
+  inbox.free();
+  rt.free();
+}
+
+// ---- bytes inbox ----------------------------------------------------------
+{
+  console.log("test: byte inbox receives Uint8Array");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_bytes();
+  // Send bytes directly (no actor — just to the inbox address)
+  rt.send_bytes(inbox.addr(), new Uint8Array([1, 2, 3]));
+  rt.tick();
+  const result = inbox.try_recv();
+  assert(result instanceof Uint8Array, "result is Uint8Array");
+  assertEq(Array.from(result), [1, 2, 3], "bytes match");
+  inbox.free();
+  rt.free();
+}
+
+// ---- uptime ---------------------------------------------------------------
+{
+  console.log("test: uptime_ms returns a number");
+  const rt = new WasmRuntime();
+  const uptime = rt.uptime_ms();
+  assert(typeof uptime === "number" && uptime >= 0, "uptime is non-negative number");
+  rt.free();
+}
+
+// ---- naming: register and resolve -----------------------------------------
+{
+  console.log("test: naming — register_name and where_is");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  rt.tick(); // drain spawn
+
+  const ok = rt.register_name("my_counter", c);
+  assert(ok, "register_name succeeds");
+
+  const found = rt.where_is("my_counter");
+  assert(found !== undefined, "where_is finds registered actor");
+  assertEq(found.toString(), c.toString(), "where_is returns correct address");
+
+  const notFound = rt.where_is("nonexistent");
+  assert(notFound === undefined, "where_is returns undefined for unknown name");
+
+  found.free();
+  inbox.free();
+  rt.free();
+}
+
+// ---- naming: unregister ---------------------------------------------------
+{
+  console.log("test: naming — unregister_name");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  rt.tick();
+
+  rt.register_name("temp", c);
+  const prev = rt.unregister_name("temp");
+  assert(prev !== undefined, "unregister returns previous address");
+  assertEq(prev.toString(), c.toString(), "unregister returns correct address");
+
+  const gone = rt.where_is("temp");
+  assert(gone === undefined, "name no longer resolves after unregister");
+
+  prev.free();
+  inbox.free();
+  rt.free();
+}
+
+// ---- naming: registered_names ---------------------------------------------
+{
+  console.log("test: naming — registered_names");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const a = spawn_counter(rt, inbox.addr());
+  const b = spawn_counter(rt, inbox.addr());
+  rt.tick();
+
+  rt.register_name("alpha", a);
+  rt.register_name("beta", b);
+  const names = rt.registered_names().split(",").sort();
+  assertEq(names, ["alpha", "beta"], "registered_names lists all names");
+
+  inbox.free();
+  rt.free();
+}
+
+// ---- naming: duplicate name rejected --------------------------------------
+{
+  console.log("test: naming — duplicate name rejected");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const a = spawn_counter(rt, inbox.addr());
+  const b = spawn_counter(rt, inbox.addr());
+  rt.tick();
+
+  const ok1 = rt.register_name("unique", a);
+  const ok2 = rt.register_name("unique", b);
+  assert(ok1, "first registration succeeds");
+  assert(!ok2, "duplicate registration fails");
+
+  inbox.free();
+  rt.free();
+}
+
+// ---- groups: join and broadcast -------------------------------------------
+{
+  console.log("test: groups — join_group and publish_to_group_u32");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const a = spawn_group_member(rt, "workers", inbox.addr());
+  const b = spawn_group_member(rt, "workers", inbox.addr());
+  rt.tick(); // spawn + on_start (join group)
+
+  assertEq(rt.group_member_count("workers"), 2, "two members in group");
+
+  rt.publish_to_group_u32("workers", 42);
+  rt.tick(); // group members receive
+  rt.tick(); // group members forward to inbox
+
+  const results = drainInbox(inbox);
+  assertEq(results.length, 2, "both members received broadcast");
+  assert(results.every((v) => v === 42), "correct value broadcast");
+
+  inbox.free();
+  rt.free();
+}
+
+// ---- groups: leave --------------------------------------------------------
+{
+  console.log("test: groups — leave_group");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const a = spawn_group_member(rt, "pool", inbox.addr());
+  const b = spawn_group_member(rt, "pool", inbox.addr());
+  rt.tick(); // spawn + on_start
+
+  assertEq(rt.group_member_count("pool"), 2, "two members before leave");
+  rt.leave_group(a, "pool");
+  assertEq(rt.group_member_count("pool"), 1, "one member after leave");
+
+  inbox.free();
+  rt.free();
+}
+
+// ---- groups: group_names --------------------------------------------------
+{
+  console.log("test: groups — group_names");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  spawn_group_member(rt, "alpha", inbox.addr());
+  spawn_group_member(rt, "beta", inbox.addr());
+  rt.tick(); // spawn + join
+
+  const names = rt.group_names().split(",").sort();
+  assertEq(names, ["alpha", "beta"], "group_names lists all groups");
+
+  inbox.free();
+  rt.free();
+}
+
+// ---- watching: sentinel detects death -------------------------------------
+{
+  console.log("test: watching — sentinel reports actor death");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const deathInbox = rt.new_inbox_string();
+
+  const target = spawn_counter(rt, inbox.addr());
+  const sentinel = spawn_sentinel(rt, target, deathInbox);
+  rt.tick(); // spawn + on_start (watch)
+
+  rt.stop_actor(target);
+  // tick to process stop, cleanup, and deliver death notification
+  for (let i = 0; i < 5; i++) rt.tick();
+
+  const notification = deathInbox.try_recv();
+  assert(notification !== undefined, "sentinel received death notification");
+  assert(
+    typeof notification === "string" && notification.length > 0,
+    "notification is a non-empty string"
+  );
+
+  inbox.free();
+  deathInbox.free();
+  rt.free();
+}
+
+// ---- stats: total_messages ------------------------------------------------
+{
+  console.log("test: stats — total_messages");
+  const rt = new WasmRuntime();
+  const inbox = rt.new_inbox_u32();
+  const c = spawn_counter(rt, inbox.addr());
+  rt.send_u32(c, 1);
+  rt.send_u32(c, 2);
+  rt.send_u32(c, 3);
+  rt.tick();
+  assert(rt.total_messages() >= 3, "total_messages counts processed messages");
+  inbox.free();
+  rt.free();
+}
+
+// ---- stats: total_panics starts at zero -----------------------------------
+{
+  console.log("test: stats — total_panics starts at zero");
+  const rt = new WasmRuntime();
+  assertEq(rt.total_panics(), 0, "no panics initially");
   rt.free();
 }
 

docs/development_history/in-browser/BROWSER_RUNTIME.md

@@ -0,0 +1,69 @@
+# Browser Runtime API — Development History
+
+> Stage 2 of the in-browser swactor runtime. Replaces the hardcoded PoC with
+> a generic, type-safe API using opaque address handles and typed inboxes.
+
+---
+
+## Changes
+
+### Core Types
+
+**`WasmRuntime`** — wraps `swactor::Runtime` in single-threaded mode.
+Methods: `tick()`, `actor_count()`, `send_u32()`, `send_bytes()`,
+`stop_actor()`, `uptime_ms()`, `new_inbox_u32()`, `new_inbox_bytes()`.
+Also exposes `runtime()` for Rust-side custom spawn functions.
+
+**`WasmAddr`** — opaque handle wrapping `ActorAddress`. Returned by spawn
+functions, passed to send functions. JS holds it as an opaque object.
+Has `toString()` for debugging.
+
+**`WasmInboxU32`** / **`WasmInboxBytes`** — typed inboxes for receiving
+results from actors. Each has `addr()` → `WasmAddr` (so actors know where
+to send) and `try_recv()` → `Option<T>`.
+
+### Design Decisions
+
+| # | Decision | Rationale |
+|---|----------|-----------|
+| 1 | Opaque `WasmAddr` handles instead of indices | Type-safe, stable identity, no out-of-bounds errors |
+| 2 | Typed inbox types instead of generic `Inbox<T>` | wasm-bindgen doesn't support generics; concrete types are explicit |
+| 3 | Free-standing `spawn_*` functions, not methods | Each actor type gets its own spawn function with typed args |
+| 4 | `send_u32`/`send_bytes` on runtime | Common send types; custom types use typed spawn wrappers |
+| 5 | Evolved existing `crates/wasm/` instead of new crate | Less churn, existing build/test infrastructure |
+
+### Actor Pattern
+
+Users expose actors to JS by writing one `#[wasm_bindgen]` spawn function
+per actor type:
+
+```rust
+#[wasm_bindgen]
+pub fn spawn_my_actor(rt: &WasmRuntime, arg: JsValue) -> WasmAddr {
+    let actor = MyActor::from_js(arg);
+    let addr = rt.runtime().spawn(actor).unwrap();
+    WasmAddr(addr)
+}
+```
+
+## Test Coverage
+
+10 Node.js tests in `crates/wasm/test.mjs`:
+
+| Test | Scenario |
+|------|----------|
+| accumulator | Counter processes messages, reports running totals to inbox |
+| relay | Relay forwards messages to counter (cross-actor, 2 ticks) |
+| multiple counters | Two independent counters report to same inbox |
+| actor_count | Spawning 3 actors reflects in stats |
+| WasmAddr toString | Address has non-empty debug representation |
+| stop_actor | Graceful stop removes actor from runtime |
+| bytes inbox | WasmInboxBytes receives Uint8Array correctly |
+| uptime_ms | Returns non-negative number |
+
+## Verification
+
+- `cargo test -p swactor` — native tests pass (no regressions)
+- `cargo build --target wasm32-unknown-unknown -p wasm` — compiles
+- `wasm-pack build --target nodejs` in `crates/wasm/` — builds pkg/
+- `node test.mjs` in `crates/wasm/` — 10/10 tests pass

docs/development_history/in-browser/DEMO.md

@@ -0,0 +1,60 @@
+# Stage 5 — Interactive Browser Demo
+
+Visual verification page for the in-browser swactor runtime. Single self-contained
+HTML file that loads the `--target web` wasm build and exposes every API surface
+through a live dashboard.
+
+## Running
+
+```bash
+# Build for browser (one-time, or after Rust changes)
+cd crates/wasm && wasm-pack build --target web --out-dir pkg-web
+
+# Serve (any static server works — needs correct .wasm MIME type)
+cd crates/wasm && python3 -m http.server 8080
+```
+
+Open `http://localhost:8080/demo.html`.
+
+## What It Covers
+
+| Feature | How to verify |
+|---|---|
+| Runtime tick loop | Start/Pause button, Step for single tick, adjustable 1–60 tps |
+| Actor spawning | Spawn Counter, Relay, GroupMember, Sentinel from dropdown |
+| Message delivery | Send u32 to any actor, inbox polling shows received values |
+| Cross-actor relay | Spawn Relay → target Counter, send to relay, counter accumulates |
+| Actor stopping | Stop button on each card, actor disappears from viz |
+| Watching / death notifications | Spawn Sentinel watching an actor, stop the watched actor |
+| Name registry | Register/Lookup/Unregister names, live list in sidebar |
+| Groups | GroupMember auto-joins on spawn, Broadcast sends to all members |
+| Stats | Live actor count, total messages, total panics, uptime, tick count |
+
+## Architecture
+
+```
+demo.html
+  ├── imports pkg-web/wasm.js (ES module, --target web)
+  ├── creates WasmRuntime (single-threaded, StdExtension)
+  ├── requestAnimationFrame tick loop
+  ├── canvas visualization (actor circle graph + edges)
+  └── event log (spawn, send, recv, death, naming, groups)
+```
+
+All state lives in the page. No build step, no bundler, no framework — just
+the wasm module and vanilla JS.
+
+## Suggested Walkthrough
+
+1. **Counter basics** — Spawn a Counter, Step once, click "Send 1", Step again.
+   Inbox log shows the running total.
+2. **Relay chain** — Spawn Counter #1, then Relay targeting #1. Send to the relay,
+   observe the counter accumulating.
+3. **Death watching** — Spawn a Counter, then a Sentinel watching it. Stop the
+   counter. The sentinel reports the death and self-terminates.
+4. **Groups** — Spawn 3 GroupMembers in "workers". Hit "Broadcast 42". All three
+   receive the message.
+5. **Naming** — Register "@main" for an actor. Lookup confirms it resolves. Unregister
+   and verify it's gone.
+6. **Burst load** — Spawn several counters, click "Send ×10" on each, start the
+   runtime at 60 tps. Watch messages processed climb.

docs/development_history/in-browser/FEATURE_PARITY.md

@@ -0,0 +1,75 @@
+# Feature Parity — Development History
+
+> Stage 4 of the in-browser swactor runtime. Enables swactor-std extensions
+> (naming, monitoring, groups) and core actor watching in the wasm crate.
+
+---
+
+## Changes
+
+### swactor-std wasm compilation
+
+- Added `wasm` feature to `crates/std/Cargo.toml` (forwards to `swactor/wasm`)
+- Changed swactor dependency to `default-features = false`, forwarding `getrandom`
+  feature when active (`getrandom = ["dep:getrandom", "swactor/getrandom"]`)
+- Cfg-gated `getrandom::getrandom()` call in `router.rs` `RoutingStrategy::Random`
+  — falls back to round-robin when `getrandom` feature is disabled (wasm mode)
+
+### RuntimeNaming: register_name
+
+- Added `register_name(name, addr)` method to `RuntimeNaming` trait and impl
+  — allows registering a name for an already-spawned actor from outside the runtime
+  — complements existing `spawn_named` (which spawns + registers atomically)
+
+### Core watching fix: StopSignal death notifications
+
+- Fixed gap in `worker.rs` tick_all: externally-stopped actors (via `rt.stop_actor()`)
+  were not added to the `deaths` list, so core WatchRegistry (phase 5b) never fired
+  for them. Added `deaths.push((addr, ExitReason::Stopped))` when StopSignal is
+  intercepted (line 737). All 140 existing native tests continue to pass.
+
+### WasmRuntime: StdExtension + new APIs
+
+- `WasmRuntime::new()` now installs `StdExtension` automatically
+- New inbox type: `WasmInboxString` for receiving string notifications
+- **Naming API**: `register_name`, `where_is`, `unregister_name`, `registered_names`
+- **Groups API**: `join_group`, `leave_group`, `publish_to_group_u32`,
+  `group_member_count`, `group_names`
+- **Stats API**: `total_messages`, `total_panics` (returned as f64 for JS compat)
+- New demo actors:
+  - `Sentinel` — watches a target via `ctx.watch()`, reports death to string inbox
+  - `GroupMember` — joins a group on start, forwards u32 messages to report inbox
+
+### Design Decisions
+
+| # | Decision | Rationale |
+|---|----------|-----------|
+| 1 | StdExtension always installed | Browser runtime should have full naming/groups by default |
+| 2 | Stats as f64, not u64 | wasm-bindgen maps u64 to BigInt which JSON.stringify rejects |
+| 3 | Sentinel actor for watching | Demonstrates core watching from JS without exposing Watch API directly |
+| 4 | register_name on RuntimeNaming | Needed for post-spawn registration from JS (no actor context available) |
+| 5 | Round-robin fallback for Random routing | wasm mode disables getrandom; graceful degradation preferred |
+
+## Test Coverage
+
+22 new assertions across 10 new test scenarios (30 total, from 10):
+
+| Test | Scenario |
+|------|----------|
+| naming — register_name and where_is | Register name, resolve, verify not-found returns undefined |
+| naming — unregister_name | Unregister returns previous addr, name no longer resolves |
+| naming — registered_names | Lists all registered names as CSV |
+| naming — duplicate name rejected | Second registration with same name fails |
+| groups — join_group and publish_to_group_u32 | Two members receive broadcast message |
+| groups — leave_group | Member count decreases after leave |
+| groups — group_names | Lists all active group names |
+| watching — sentinel reports actor death | Stop target → sentinel receives death notification |
+| stats — total_messages | Counts processed messages across workers |
+| stats — total_panics starts at zero | Fresh runtime has zero panics |
+
+## Verification
+
+- `cargo test -p swactor -p swactor-std` — 157 native tests pass (no regressions)
+- `cargo build --target wasm32-unknown-unknown -p wasm` — compiles
+- `wasm-pack build --target nodejs` in `crates/wasm/` — builds pkg/
+- `node test.mjs` in `crates/wasm/` — 30/30 tests pass

docs/development_history/in-browser/PLATFORM_ABSTRACTION.md

@@ -0,0 +1,82 @@
+# Platform Abstraction Layer — Development History
+
+> Stage 1 of the in-browser swactor runtime. Makes core swactor compile for
+> `wasm32-unknown-unknown` without behavioral changes on native targets.
+
+---
+
+## Changes
+
+### 1. `web-time` dependency + `wasm` feature flag
+
+**File**: `Cargo.toml`
+
+Added `web-time` as an optional dependency and a `wasm` feature that bundles
+`no_random` + `web-time`:
+
+```toml
+wasm = ["no_random", "dep:web-time"]
+web-time = { version = "0.2", optional = true }
+```
+
+`web-time` is a drop-in replacement for `std::time::Instant`:
+- Native: re-exports `std::time::Instant` (zero-cost)
+- wasm32: uses `performance.now()` via `js-sys`
+
+### 2. Platform-aware `Instant` re-export
+
+**File**: `src/lib.rs`
+
+```rust
+#[cfg(feature = "wasm")]
+pub(crate) use web_time::Instant;
+#[cfg(not(feature = "wasm"))]
+pub(crate) use std::time::Instant;
+```
+
+All modules (`runtime.rs`, `worker.rs`) now use `crate::Instant` instead of
+`std::time::Instant`. Single point of truth — no cfg noise in consumer code.
+
+### 3. cfg-gated `Runtime::run()` and `RuntimeHandle`
+
+**File**: `src/runtime.rs`
+
+`Runtime::run()` calls `std::thread::spawn()` which is not available on wasm32.
+Both `run()` and `RuntimeHandle` (which holds `JoinHandle<()>`) are gated:
+
+```rust
+#[cfg(not(target_arch = "wasm32"))]
+pub fn run(self) -> Result<RuntimeHandle, Error> { ... }
+```
+
+On wasm32, the browser crate will provide its own `run()` via Web Workers.
+`tick()` remains available on all platforms for single-threaded driving.
+
+### 4. Updated `crates/wasm/` to use `wasm` feature
+
+**File**: `crates/wasm/Cargo.toml`
+
+Changed from `features = ["no_random"]` to `features = ["wasm"]` to pick up
+the `web-time` Instant on wasm32.
+
+## What Did NOT Need Abstraction
+
+Key discovery: on wasm32 with the `+atomics` target feature, most of
+`std::sync` and `std::thread` works:
+
+- `OnceLock<Thread>` — compiles and works (futex-based)
+- `Thread::unpark()` — works (futex → `memory.atomic.notify`)
+- `thread::park_timeout()` — works (futex → `memory.atomic.wait32`)
+- `thread::yield_now()` — works (no-op on wasm)
+- `Mutex`, `RwLock` — work (futex-based)
+- `crossbeam-queue` — works (uses `core::sync::atomic`)
+- `AtomicBool/Usize/U64` — work (wasm atomic instructions)
+
+Only `std::thread::spawn()` and `JoinHandle` are not functional on wasm32.
+
+## Verification
+
+- `cargo test` — all native tests pass (no regressions)
+- `cargo test --features wasm` — all native tests pass with wasm feature
+- `cargo build --target wasm32-unknown-unknown --features wasm --no-default-features` — compiles
+- `cargo build --target wasm32-unknown-unknown -p wasm` — existing PoC crate compiles

src/lib.rs

@@ -18,6 +18,13 @@ pub mod runtime;
 #[cfg(feature = "transport")]
 pub mod transport;
 
+// Platform-aware Instant: web_time on wasm, std::time on native.
+// web_time is a no-op re-export of std::time::Instant on non-wasm targets.
+#[cfg(feature = "wasm")]
+pub(crate) use web_time::Instant;
+#[cfg(not(feature = "wasm"))]
+pub(crate) use std::time::Instant;
+
 #[cfg(feature = "getrandom")]
 pub(crate) fn get_random(buf: &mut [u8]) {
     getrandom::getrandom(buf).unwrap()

src/runtime.rs

@@ -2,8 +2,10 @@ use std::any::Any;
 use std::cell::RefCell;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::sync::{Arc, Mutex, OnceLock};
-use std::thread::{self, JoinHandle, Thread};
-use std::time::Instant;
+#[cfg(not(target_arch = "wasm32"))]
+use std::thread::{self, JoinHandle};
+use std::thread::Thread;
+use crate::Instant;
 
 use crate::actor::{Actor, ActorAddress, ActorExited, ActorInterface, AnyActor, ExitReason, Message, StopSignal, TimerRequest};
 use crate::channel::{Receiver, Sender};
@@ -67,11 +69,13 @@ impl<R: Message> Ask<R> {
 }
 
 /// Handle for dealing with a runtime that has started via the `Runtime::run()` method.
+#[cfg(not(target_arch = "wasm32"))]
 pub struct RuntimeHandle {
     pub runtime: Arc<Runtime>,
     threads: Vec<JoinHandle<()>>,
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 impl RuntimeHandle {
     pub fn join(self) {
         for handle in self.threads {
@@ -333,6 +337,9 @@ impl Runtime {
     ///
     /// Works in both single-threaded and multi-threaded configurations.
     /// In single-threaded mode, one background thread is spawned.
+    ///
+    /// Not available on wasm32 — use the browser crate's Web Worker-based run instead.
+    #[cfg(not(target_arch = "wasm32"))]
     pub fn run(self) -> Result<RuntimeHandle, Error> {
         self.is_running.store(true, Ordering::Release);
 

src/worker.rs

@@ -2,9 +2,9 @@ use std::any::Any;
 use std::cell::RefCell;
 use std::collections::{HashMap, HashSet, VecDeque};
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::{Arc, Mutex};
+use std::sync::Arc;
 use std::thread;
-use std::time::Instant;
+use crate::Instant;
 
 use crate::actor::{ActorAddress, ActorExited, AnyActor, CloneMsg, ContextInner, Ctx, ExitReason, StopReason, StopSignal, TimerRequest};
 use crate::channel::Receiver;
@@ -735,6 +735,7 @@ impl ActorPool {
                     slot.stopping = true;
                     stats.stops.fetch_add(1, Ordering::Relaxed);
                     slot.mailbox.clear();
+                    deaths.push((addr, ExitReason::Stopped));
                     #[cfg(feature = "tracing")]
                     tracing::info!(actor_addr = %addr, "actor.stop_requested");
                     break;