SQLite engine: scheduler + outbox — schedule/unschedule/run_schedules leader loop, outbox enqueue/run_once (task sqlite-engine-scheduler-outbox)

alkstore-sqlite/src/lock.rs

@@ -29,6 +29,12 @@ use alkstore::{BoxedFuture, Lock, Result, validate_local_name, validate_shared_n
 use crate::seam::{closed_store_error, sqlite_error, with_writer};
 use crate::substrate::{Writer, lock_acquire, lock_release, lock_renew};
 
+/// The scheduler's leadership-lock name (ADR-009 §4 — the reserved-
+/// prefix derived name in the lock namespace; engine-internal: every
+/// consumer entry point rejects the same prefix, so a consumer can
+/// never collide with it).
+pub(crate) const SCHEDULER_LEADER_LOCK: &str = concat!("__alkstore_", "scheduler");
+
 /// The acquire path (see the module docs): validation, guard, then the
 /// substrate's `lock_acquire` through the writer slot. `Ok(None)` is
 /// the held-by-someone-else arm.
@@ -94,6 +100,22 @@ impl std::fmt::Debug for SqliteLockHandle {
     }
 }
 
+impl SqliteLockHandle {
+    pub(crate) fn new_internal(
+        name: &str,
+        owner: &str,
+        writer: Arc<Writer>,
+        closed: Arc<AtomicBool>,
+    ) -> Self {
+        Self {
+            name: name.to_string(),
+            owner: owner.to_string(),
+            writer,
+            closed,
+        }
+    }
+}
+
 impl Lock for SqliteLockHandle {
     fn name(&self) -> &str {
         &self.name