diff --git a/build.zig b/build.zig
index 28c7786..4e05d0c 100644
--- a/build.zig
+++ b/build.zig
@@ -442,6 +442,7 @@ pub fn build(b: *std.Build) void {
         csv_library,
         xkeyboard_config_library,
         b.dependency("fat", .{}),
+        b.dependency("volume-manager", .{}),
         b.dependency("display", .{}),
         b.dependency("ps2-bus", .{}),
         b.dependency("usb-hid", .{}),
diff --git a/docs/file-system-development/storage-design-rationale.md b/docs/file-system-development/storage-design-rationale.md
index 380204e..a5c2f81 100644
--- a/docs/file-system-development/storage-design-rationale.md
+++ b/docs/file-system-development/storage-design-rationale.md
@@ -215,16 +215,16 @@ matrix-proven shape; genuinely open.
    broke whenever a drive changed ports or enumeration order; `UUID=` entries
    exist because device-path identity failed. danos skips that era: the mount
    map (`volumes.csv` — configuration, read by the volume manager) keys on
-   **content identity, never port or discovery order**. Build status: only
-   rung 4 (MBR signature + partition index) is implemented today; the fuller
-   rungs and the `volumes.csv` map itself land with the identity ladder, so
-   today a single volume mounts at the fixed `/volumes/usb` and its recorded
-   identity is not yet consulted to pick a path. The target ladder the prober
-   reads off the medium, strongest first:
-   1. GPT partition GUID — 128-bit, unique, stable for the volume's life *(planned)*;
+   **content identity, never port or discovery order**. Build status: rungs 1,
+   3, and 4 (GPT partition GUID, FAT serial + label, MBR signature + index) are
+   implemented (S1); rung 2 waits on a non-FAT engine. The `volumes.csv` map and
+   the id-derived mount path land with S2, so today a single volume still mounts
+   at the fixed `/volumes/usb` and its recorded identity is not yet consulted to
+   pick a path. The ladder the prober reads off the medium, strongest first:
+   1. GPT partition GUID — 128-bit, unique, stable for the volume's life — **built (S1)**;
    2. filesystem UUID (ext-family and most modern formats, in the superblock) *(planned)*;
    3. FAT volume serial + label — 32 bits, weak (dd-cloned sticks share it)
-      but what real sticks carry *(planned)*;
+      but what real sticks carry — **built (S1)**;
    4. MBR disk signature + partition index — **built**; a bare FAT with no
       table takes index 0 over the whole device;
    5. nothing — an anonymous volume: generated mount name, no persistence *(planned)*.