test: cover multi-level actor supervision propagation

STATUS.md

@@ -1,6 +1,6 @@
 # Lx Implementation Status Report
 
-**Last Updated:** November 11, 2025  
+**Last Updated:** November 12, 2025
 **Overall Progress:** ~84% (Core language ~86% complete, LLM-first tooling ~86% complete, Concurrency ~80% complete)
 
 The Lx project has a working **minimal interpreter** covering the foundational subset described in the ROADMAP. Here's the breakdown:
@@ -152,12 +152,13 @@ The Lx project has a working **minimal interpreter** covering the foundational s
 
 ## 🎯 Working Examples
 
-The implementation successfully runs 36 example files (27 runnable + 9 error test cases) including:
+The implementation successfully runs 37 example files (28 runnable + 9 error test cases) including:
 - ✅ `option.lx` - Sum types, pattern matching
 - ✅ `contracts.lx` - Contract enforcement
 - ✅ `logging.lx` - Effect tracking
 - ✅ `median.lx` - Pure functions with tests
 - ✅ `result.lx` - Error handling patterns
+- ✅ `actor_supervision.lx` - Supervision restarts and multi-level failure propagation
 - ✅ `property_basics.lx` - Property-based testing with predicates and assertions
 - ✅ `property_shrinking.lx` - Counterexample shrinking for property tests
 - ✅ `property_deterministic.lx` - Deterministic property testing with --seed flag
@@ -376,6 +377,11 @@ Phase 5 (Long-term): Evolution
   - Created `examples/property_deterministic.lx` demonstrating deterministic property tests
   - Same seed produces reproducible test results for debugging and replay
 
+**Recent Work (November 12, 2025):**
+- ✅ Hardened actor supervision runtime with multi-level failure coverage
+  - Added `RootSupervisor` / `SupervisorNoHandler` actors in `examples/actor_supervision.lx`
+  - New regression test `failure_propagates_without_intermediate_handler` proves `ChildFailed` notifications bubble past supervisors that lack handlers
+
 With the core language, schemas, LLM tooling (including deterministic execution), and actor runtime (including async_group) mostly complete, the next priorities are:
 
 1. **Actor Runtime Enhancements** (Priority 8, continuing):

examples/actor_supervision.lx

@@ -77,6 +77,74 @@ actor Supervisor() {
   }
 }
 
+actor SupervisorNoHandler() {
+  state {
+    worker: ActorRef
+  }
+
+  on Start() -> [Concurrent] ActorRef {
+    let spawned = Worker.spawn()
+    let worker = spawned
+    return spawned
+  }
+
+  on Send(value: Int) -> [Concurrent] Unit {
+    worker.send(DoWork { value: value })
+  }
+
+  on Crash() -> [Concurrent] Unit {
+    worker.send(DoWork { value: -1 })
+  }
+
+  on CurrentWorker() -> [Concurrent] ActorRef {
+    return worker
+  }
+}
+
+actor RootSupervisor() {
+  state {
+    supervisor: ActorRef
+    last_failure: String
+    last_message: String
+    last_actor: String
+    last_child: ActorRef
+  }
+
+  on Start() -> [Concurrent] ActorRef {
+    let supervisor = SupervisorNoHandler.spawn()
+    let initial_worker = SupervisorNoHandler.Start(supervisor)
+    let last_child = initial_worker
+    let last_failure = ""
+    let last_message = ""
+    let last_actor = ""
+    return supervisor
+  }
+
+  on Send(value: Int) -> [Concurrent] Unit {
+    supervisor.send(Send { value: value })
+  }
+
+  on Crash() -> [Concurrent] Unit {
+    supervisor.send(Crash { })
+  }
+
+  on ChildFailed(child: ActorRef, reason: String, message: String, actor: String) -> [Concurrent] Unit {
+    let last_child = child
+    let last_failure = reason
+    let last_message = message
+    let last_actor = actor
+  }
+
+  on FailureSummary() -> [Concurrent] SupervisorMsg {
+    return ChildFailed {
+      child: last_child
+      reason: last_failure
+      message: last_message
+      actor: last_actor
+    }
+  }
+}
+
 test supervisor_restarts_child {
   let supervisor = Supervisor.spawn()
   Supervisor.Start(supervisor)
@@ -111,3 +179,26 @@ test supervisor_restarts_child {
     }
   }
 }
+
+test failure_propagates_without_intermediate_handler {
+  let root = RootSupervisor.spawn()
+  let supervisor = RootSupervisor.Start(root)
+  let worker = SupervisorNoHandler.CurrentWorker(supervisor)
+
+  RootSupervisor.Crash(root)
+  Concurrent.flush()
+  Concurrent.flush()
+
+  let summary = RootSupervisor.FailureSummary(root)
+  match summary {
+    case ChildFailed { child: failed_child , reason: failure_reason , message: failure_message , actor: failure_actor } => {
+      test.assert_equal(worker, failed_child)
+      test.assert_equal("assertion failed", failure_reason)
+      test.assert_equal("DoWork", failure_message)
+      test.assert_equal("Worker", failure_actor)
+    }
+    case _ => {
+      assert(false)
+    }
+  }
+}