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+(* State Management - Domain-safe Arvo kernel state
+ *
+ * This module manages the Urbit runtime state with:
+ * - Domain-safe operations using Atomic
+ * - Arvo kernel state (roc)
+ * - Event counter
+ * - Atomic snapshots with Eio.Promise
+ *
+ * Key differences from C implementation:
+ * - No loom! OCaml GC handles memory
+ * - Atomic operations for thread-safety across domains
+ * - Simplified memory management
+ *)
+
+(* Ship state *)
+type t = {
+  (* Arvo core - the kernel state *)
+  mutable roc: Noun.noun;
+
+  (* Event number - using mutable int64 with mutex for now
+   * TODO: Use lock-free approach with Kcas later *)
+  mutable eve: int64;
+
+  (* Wish cache - for compiled expressions *)
+  mutable yot: (string, Noun.noun) Hashtbl.t;
+
+  (* Lock for state updates (Mutex for now, will use lock-free later) *)
+  lock: Mutex.t;
+}
+
+(* Create empty state *)
+let create () =
+  {
+    roc = Noun.atom 0;  (* Empty initial state *)
+    eve = 0L;
+    yot = Hashtbl.create 256;
+    lock = Mutex.create ();
+  }
+
+(* Get current event number *)
+let event_num state =
+  Mutex.lock state.lock;
+  let eve = state.eve in
+  Mutex.unlock state.lock;
+  eve
+
+(* Get Arvo core *)
+let get_arvo state =
+  Mutex.lock state.lock;
+  let roc = state.roc in
+  Mutex.unlock state.lock;
+  roc
+
+(* Set Arvo core *)
+let set_arvo state roc =
+  Mutex.lock state.lock;
+  state.roc <- roc;
+  Mutex.unlock state.lock
+
+(* Increment event number *)
+let inc_event state =
+  Mutex.lock state.lock;
+  let old_eve = state.eve in
+  state.eve <- Int64.succ state.eve;
+  Mutex.unlock state.lock;
+  old_eve
+
+(* Boot from a pill (simplified - just load a noun as the kernel) *)
+let boot state kernel_noun =
+  Mutex.lock state.lock;
+  state.roc <- kernel_noun;
+  state.eve <- 0L;
+  Hashtbl.clear state.yot;
+  Mutex.unlock state.lock
+
+(* Poke: apply an event to the kernel
+ *
+ * In real Arvo:
+ *   - Runs Nock with the poke formula
+ *   - Updates kernel state
+ *   - Increments event number
+ *   - Returns effects
+ *
+ * For now: simplified version that just stores the event
+ *)
+let poke state _event_noun =
+  Mutex.lock state.lock;
+  (* In a real implementation, this would run Nock:
+   *   let effects = Nock.nock_on state.roc poke_formula in
+   *   state.roc <- new_kernel_state;
+   *
+   * For now, we just update event count
+   *)
+  state.eve <- Int64.succ state.eve;
+  Mutex.unlock state.lock;
+
+  (* Return empty effects list for now *)
+  []
+
+(* Peek: query the kernel state (read-only)
+ *
+ * In real Arvo: runs scry requests
+ * For now: simplified
+ *)
+let peek state _path =
+  (* Peek is read-only, multiple domains can do this concurrently *)
+  Some state.roc
+
+(* Save snapshot to file using Eio
+ *
+ * Snapshot format:
+ * - Event number (8 bytes)
+ * - Jammed Arvo core
+ *)
+let save_snapshot state ~fs path =
+  (* Take atomic snapshot of current state *)
+  Mutex.lock state.lock;
+  let eve = state.eve in
+  let roc = state.roc in
+  Mutex.unlock state.lock;
+
+  (* Serialize: 8-byte event number + jammed state *)
+  let jammed = Serial.jam roc in
+  let jam_len = Bytes.length jammed in
+
+  let total_len = 8 + jam_len in
+  let snapshot = Bytes.create total_len in
+
+  (* Write event number (little-endian) *)
+  Bytes.set_int64_le snapshot 0 eve;
+
+  (* Write jammed state *)
+  Bytes.blit jammed 0 snapshot 8 jam_len;
+
+  (* Write to file using Eio *)
+  let file_path = Eio.Path.(fs / path) in
+  Eio.Path.save ~create:(`Or_truncate 0o644) file_path (Bytes.to_string snapshot)
+
+(* Load snapshot from file using Eio *)
+let load_snapshot state ~fs path =
+  let file_path = Eio.Path.(fs / path) in
+
+  try
+    let data = Eio.Path.load file_path in
+    let bytes = Bytes.of_string data in
+
+    if Bytes.length bytes < 8 then
+      Error "Snapshot too short"
+    else
+      (* Read event number *)
+      let eve = Bytes.get_int64_le bytes 0 in
+
+      (* Read jammed state *)
+      let jam_len = Bytes.length bytes - 8 in
+      let jammed = Bytes.sub bytes 8 jam_len in
+
+      (* Cue the state *)
+      let roc = Serial.cue jammed in
+
+      (* Update state *)
+      Mutex.lock state.lock;
+      state.roc <- roc;
+      state.eve <- eve;
+      Hashtbl.clear state.yot;
+      Mutex.unlock state.lock;
+
+      Ok eve
+  with
+  | Sys_error msg -> Error ("Failed to load snapshot: " ^ msg)
+  | e -> Error ("Failed to load snapshot: " ^ Printexc.to_string e)
+
+(* Save snapshot with Eio.Promise for async completion *)
+let save_snapshot_async state ~sw:_ ~fs path =
+  save_snapshot state ~fs path;
+  Eio.Promise.create_resolved ()
+
+(* Load snapshot with promise *)
+let load_snapshot_async state ~sw:_ ~fs path =
+  let result = load_snapshot state ~fs path in
+  Eio.Promise.create_resolved result
+
+(* Clear wish cache (for memory reclamation) *)
+let clear_cache state =
+  Mutex.lock state.lock;
+  Hashtbl.clear state.yot;
+  Mutex.unlock state.lock
+
+(* Get state summary for debugging *)
+let summary state =
+  Mutex.lock state.lock;
+  let eve = state.eve in
+  let cache_size = Hashtbl.length state.yot in
+  Mutex.unlock state.lock;
+  Printf.sprintf "State[eve=%Ld, cache=%d]" eve cache_size