1 files changed, 49 insertions, 0 deletions
diff --git a/lib/session.ml b/lib/session.ml
new file mode 100644
index 0000000..5505e7e
--- /dev/null
+++ b/lib/session.ml
@@ -0,0 +1,49 @@
+(* Session: outermost connection object.
+   Each user connection mints a session registered in RNT at
+   /system/sessions/<id>. The session owns exactly one branch at a time;
+   DDL / DML / DRL sublanguages operate through that branch. *)
+
+module Make (NT : Nt.S) = struct
+
+  module B = Branch.Make (NT)
+
+  let ( let* ) = Result.bind
+
+  class session
+    ~(sid    : string)
+    ~(branch : B.branch) =
+  object
+    val mutable br : B.branch = branch
+
+    method id       = sid
+    method branch   = br
+    method snapshot = br#tip
+    method tip      = br#tip
+
+    (* Switch to a different branch within the same session. *)
+    method set_branch (b : B.branch) = br <- b
+
+    method close () =
+      let* () = br#close () in
+      NT.session_close sid
+  end
+
+  (* Open a session on a live (mutable) branch.
+     Creates the branch if it does not exist yet. *)
+  let open_session claims ~branch_name =
+    let* sid    = NT.session_open () in
+    let* branch = B.open_branch claims branch_name in
+    Ok (new session ~sid ~branch)
+
+  (* Open a session pinned to a specific snapshot hash (detached / read-only).
+     Mutations through the returned branch are refused. *)
+  let open_snapshot_session claims ~branch_name ~snapshot_hash =
+    let* sid    = NT.session_open () in
+    let* branch = B.open_snapshot claims ~branch_name ~snapshot_hash in
+    (* Inform RNT of the session's snapshot override so future session-path
+       resolution (once NamespaceReferenceManager handles /system/sessions/...)
+       can route queries through the pinned snapshot. *)
+    let* ()     = NT.session_set_branch sid branch_name snapshot_hash in
+    Ok (new session ~sid ~branch)
+
+end