wip(0.S2): migrate - a var nothing writes becomes a let; a state is keyed by its module, directory or program, so every program's plan agrees; paths normalized; program states named SceneDemoState / scene_demo_st; the LSP reads state, mut and entry/handler parameters

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

examples/library/threads.ludic

@@ -6,27 +6,25 @@
 program Threads {
   const N: int = 20000
 
-  state ThreadsState {
-    calls: int = 0        # an atomic handle, made on the main thread before any work
-    lock: int = 0         # a mutex handle
-    total: long = 0       # guarded by `lock`
-  }
+  var calls: int = 0        # an atomic handle, made on the main thread before any work
+  var lock: int = 0         # a mutex handle
+  var total: long = 0       # guarded by `lock`
 
   # out[i] = i * i: every index written exactly once, by whichever thread claimed it
   function square(i: int, out: words) -> void { out[i] = i * i }
 
   # count the call atomically, and add i to a shared total under the mutex
-  function tally(threads_st: mut ThreadsState, i: int, ctx: pointer) -> void {
-    Sync.add(threads_st.calls, 1)
-    Sync.lock(threads_st.lock)
-    threads_st.total = threads_st.total + i
-    Sync.unlock(threads_st.lock)
+  function tally(i: int, ctx: pointer) -> void {
+    Sync.add(calls, 1)
+    Sync.lock(lock)
+    total = total + i
+    Sync.unlock(lock)
   }
 
   # remember which calls ran on a pool thread
   function placed(i: int, out: words) -> void { if Job.is_worker() { out[i] = 1 } else { out[i] = 0 } }
 
-  entry (threads_st: mut ThreadsState) {
+  entry {
     if Sync.cpu_count() >= 1 { print(1) }
     if not Job.is_worker() { print(2) }
 
@@ -36,12 +34,12 @@ program Threads {
     for i in 0 .. N { if sq[i] != i * i { right = false } }
     if right { print(3) }
 
-    threads_st.calls = Sync.atomic()
-    threads_st.lock = Sync.mutex()
+    calls = Sync.atomic()
+    lock = Sync.mutex()
     Job.parallel_for(N, fn tally, null)
-    if Sync.get(threads_st.calls) == N { print(4) }
+    if Sync.get(calls) == N { print(4) }
     let want: long = N * (N - 1) / 2
-    if threads_st.total == want { print(5) }
+    if total == want { print(5) }
 
     let ran = words(N)
     Job.parallel_for(N, fn placed, ran)