diff --git a/build.zig b/build.zig
index 74c8926..1ad55b0 100644
--- a/build.zig
+++ b/build.zig
@@ -400,7 +400,7 @@ pub fn build(b: *std.Build) void {
     // The device-manager protocol: hello + (M18.2) tree reports, exposed as its
     // own module like the other protocol modules. Imported through the runtime.
     const device_manager_protocol_module = b.addModule("device-manager-protocol", .{
-        .root_source_file = b.path("system/services/device-manager/device-manager-protocol.zig"),
+        .root_source_file = b.path("library/protocol/device-manager/device-manager-protocol.zig"),
     });
     runtime_module.addImport("device-manager-protocol", device_manager_protocol_module);
     // The block protocol, so runtime.block (the block-device client) can speak it.
@@ -551,6 +551,7 @@ pub fn build(b: *std.Build) void {
     const ps2_mouse_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "ps2-mouse", "system/drivers/ps2-bus/mouse.zig");
     programModule(ps2_mouse_exe).addImport("input-protocol", input_protocol_module);
     const usb_xhci_bus_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "usb-xhci-bus", "system/drivers/usb-xhci-bus/usb-xhci-bus.zig");
+    programModule(usb_xhci_bus_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     // The xHCI bus driver builds chapter-9 requests and decodes descriptors from
     // usb-abi, and reports each interface's (class,subclass,protocol) identity via
     // usb-ids.packTriple.
@@ -587,13 +588,16 @@ pub fn build(b: *std.Build) void {
     const shared_memory_client_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "shared-memory-client", "system/services/shared-memory-client/shared-memory-client.zig");
     const fat_test_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "fat-test", "system/services/fat/fat-test.zig");
     const pci_bus_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "pci-bus", "system/drivers/pci-bus/pci-bus.zig");
+    programModule(pci_bus_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     // The PCI bus driver decodes each function's class triple to human names in its
     // boot log (class/subclass/prog-IF), so pull in the shared pci-class reference.
     programModule(pci_bus_exe).addImport("pci-class", pci_class_module);
     // A test fixture, not a real driver: hellos to the device manager, then faults —
     // what the driver-restart scenario drives the crash-loop cap with.
     const crash_test_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "crash-test", "system/services/crash-test/crash-test.zig");
+    programModule(crash_test_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     const device_list_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "device-list", "system/services/device-list/device-list.zig");
+    programModule(device_list_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     // The discovery service: one swappable process per firmware
     // (docs/discovery.md), bundled under the neutral ramdisk name
     // "discovery" so the device manager never learns which firmware it is on.
@@ -609,9 +613,11 @@ pub fn build(b: *std.Build) void {
     };
     const discovery_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "discovery", discovery_source);
     if (discovery == .acpi) programModule(discovery_exe).addImport("aml", aml_module);
+    if (discovery == .acpi) programModule(discovery_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     const device_manager_exe = addUserBinary(b, kernel_target, runtime_module, mmio_module, xkeyboard_config_module, acpi_ids_module, "device-manager", "system/services/device-manager/device-manager.zig");
     // Names the xHCI PCI class triple from the shared taxonomy instead of a bare 0x0C0330.
     programModule(device_manager_exe).addImport("pci-class", pci_class_module);
+    programModule(device_manager_exe).addImport("device-manager-protocol", device_manager_protocol_module);
     // The manager matches reported USB interfaces by their (class,subclass,protocol)
     // triple (usbDriverForIdentity), built from the named usb-ids codes.
     programModule(device_manager_exe).addImport("usb-ids", usb_ids_module);
diff --git a/system/services/device-manager/device-manager-protocol.zig b/library/protocol/device-manager/device-manager-protocol.zig
similarity index 100%
rename from system/services/device-manager/device-manager-protocol.zig
rename to library/protocol/device-manager/device-manager-protocol.zig
diff --git a/library/runtime/runtime.zig b/library/runtime/runtime.zig
index 5476f6e..873ac2c 100644
--- a/library/runtime/runtime.zig
+++ b/library/runtime/runtime.zig
@@ -19,10 +19,10 @@ pub const heap = @import("heap.zig");
 pub const ipc = @import("ipc.zig");
 pub const start = @import("start.zig");
 
-/// The device-manager protocol: hello + tree reports (docs/device-manager.md).
-pub const device_manager_protocol = @import("device-manager-protocol");
 /// Client for talking to the device manager (the hello handshake a supervised
-/// driver owes at startup). See library/runtime/device-manager.zig.
+/// driver owes at startup). See library/runtime/device-manager.zig. The wire
+/// protocol itself is the library/protocol/device-manager module, imported
+/// directly by drivers and services that speak it.
 pub const device_manager = @import("device-manager.zig");
 
 /// The power protocol: events (button, lid, battery) + shutdown (docs/power.md).
diff --git a/system/drivers/display/intel-integrated/intel-integrated.zig b/system/drivers/display/intel-integrated/intel-integrated.zig
index 33f80e4..6ff23d2 100644
--- a/system/drivers/display/intel-integrated/intel-integrated.zig
+++ b/system/drivers/display/intel-integrated/intel-integrated.zig
@@ -9,7 +9,7 @@ const system = runtime.system;
 const ipc = runtime.ipc;
 const display_protocol = runtime.display_protocol;
 const scanout_protocol = runtime.scanout_protocol;
-const device_manager_protocol = runtime.device_manager_protocol;
+const device_manager_protocol = @import("device-manager-protocol");
 var device_id: u64 = 0;
 
 
diff --git a/system/drivers/pci-bus/pci-bus.zig b/system/drivers/pci-bus/pci-bus.zig
index 5226d88..acfbb9d 100644
--- a/system/drivers/pci-bus/pci-bus.zig
+++ b/system/drivers/pci-bus/pci-bus.zig
@@ -12,7 +12,7 @@
 
 const std = @import("std");
 const runtime = @import("runtime");
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 const device = runtime.device;
 const pci_class = @import("pci-class");
 
diff --git a/system/drivers/usb-xhci-bus/usb-xhci-bus.zig b/system/drivers/usb-xhci-bus/usb-xhci-bus.zig
index b171f3e..277f954 100644
--- a/system/drivers/usb-xhci-bus/usb-xhci-bus.zig
+++ b/system/drivers/usb-xhci-bus/usb-xhci-bus.zig
@@ -15,7 +15,7 @@
 
 const std = @import("std");
 const runtime = @import("runtime");
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 const device = runtime.device;
 const usb_ids = @import("usb-ids");
 const usb_abi = @import("usb-abi");
diff --git a/system/services/acpi/acpi.zig b/system/services/acpi/acpi.zig
index f5993b0..7428ee9 100644
--- a/system/services/acpi/acpi.zig
+++ b/system/services/acpi/acpi.zig
@@ -15,7 +15,7 @@ const runtime = @import("runtime");
 const aml = @import("aml");
 const acpi_ids = @import("acpi-ids");
 const device = runtime.device;
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 const power = runtime.power_protocol;
 /// AML opcode/prefix bytes by name (`zero_opcode`, `byte_prefix`, …) — so the `_HID`
 /// integer decode names the opcodes instead of bare 0x0A/0x0B/… (docs/coding-standards.md).
diff --git a/system/services/crash-test/crash-test.zig b/system/services/crash-test/crash-test.zig
index 17a0aba..b3f7bf1 100644
--- a/system/services/crash-test/crash-test.zig
+++ b/system/services/crash-test/crash-test.zig
@@ -8,7 +8,7 @@
 
 const std = @import("std");
 const runtime = @import("runtime");
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 
 pub fn main(init: runtime.process.Init) void {
     const argument = init.arguments.get(1) orelse return; // bare: stay silent
diff --git a/system/services/device-list/device-list.zig b/system/services/device-list/device-list.zig
index 3cef060..2a83eff 100644
--- a/system/services/device-list/device-list.zig
+++ b/system/services/device-list/device-list.zig
@@ -6,7 +6,7 @@
 
 const std = @import("std");
 const runtime = @import("runtime");
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 
 fn writeLine(comptime fmt: []const u8, arguments: anytype) void {
     var line: [96]u8 = undefined;
diff --git a/system/services/device-manager/device-manager.zig b/system/services/device-manager/device-manager.zig
index fd4c000..8916d3a 100644
--- a/system/services/device-manager/device-manager.zig
+++ b/system/services/device-manager/device-manager.zig
@@ -20,7 +20,7 @@ const runtime = @import("runtime");
 const acpi_ids = @import("acpi-ids");
 const pci_class = @import("pci-class");
 const usb_ids = @import("usb-ids");
-const protocol = runtime.device_manager_protocol;
+const protocol = @import("device-manager-protocol");
 const device = runtime.device;
 const system = runtime.system;