build: single-source the default import set; delegate library tests

Review findings from the pilot: the 17-module default import set was
maintained twice (root's array and build-support's userBinary) — drift
would silently make packaged binaries differ from root-built ones. It
now lives once, as build-support.defaultImports; root and userBinary
both draw from it, and root's user-binary wrapper names the shim +
link script through the kernel package like build-support does.
The root aggregate test step likewise duplicated the library domains'
14 test definitions; it now depends on each domain's own standalone
test step (host-only, so root's -Dtarget/-Doptimize deliberately do
not reach them), and the client domain gains an empty test step for
uniformity. Boot-image file list unchanged.

build-support/build.zig

@@ -148,20 +148,20 @@ pub const DomainUserBinaryOptions = struct {
     threaded: bool = false,
 };
 
-/// Build one user binary against the domain packages' default import set —
-/// the library/kernel concern modules (ipc, memory, process, time, logging,
-/// file-system, ...), the device/service clients (driver, block, display,
-/// input), mmio, acpi-ids, and xkeyboard-config. Per-binary extras go through
-/// `programModule(exe).addImport`. This is THE recipe a binary package's
-/// build.zig calls; the root shim and user link script come from the kernel
-/// domain package's directory.
-pub fn userBinary(b: *std.Build, options: DomainUserBinaryOptions) *std.Build.Step.Compile {
-    const kernel = options.domains.kernel;
-    const device = options.domains.device;
-    const client = options.domains.client;
-    const default_imports = [_]std.Build.Module.Import{
+/// THE default import set every user binary sees — the library/kernel concern
+/// modules (ipc, memory, process, time, logging, file-system, ...), the
+/// device/service clients (driver, block, display, input), mmio, acpi-ids,
+/// and xkeyboard-config — assembled from the domain packages. This is the
+/// single authoritative list: the root build's stanzas and every binary
+/// package both draw from here, so adding a default module is a one-place
+/// change (the cross-cutting rule, docs/build-packages-plan.md).
+pub fn defaultImports(libraries: Domains) [17]std.Build.Module.Import {
+    const kernel = libraries.kernel;
+    const device = libraries.device;
+    const client = libraries.client;
+    return .{
         .{ .name = "mmio", .module = device.module("mmio") },
-        .{ .name = "xkeyboard-config", .module = options.domains.xkeyboard_config.module("xkeyboard-config") },
+        .{ .name = "xkeyboard-config", .module = libraries.xkeyboard_config.module("xkeyboard-config") },
         .{ .name = "acpi-ids", .module = device.module("acpi-ids") },
         .{ .name = "system-call", .module = kernel.module("system-call") },
         .{ .name = "ipc", .module = kernel.module("ipc") },
@@ -178,11 +178,20 @@ pub fn userBinary(b: *std.Build, options: DomainUserBinaryOptions) *std.Build.St
         .{ .name = "display", .module = client.module("display") },
         .{ .name = "input", .module = client.module("input") },
     };
+}
+
+/// Build one user binary against the domain packages' default import set
+/// (`defaultImports`). Per-binary extras go through
+/// `programModule(exe).addImport`. This is THE recipe a binary package's
+/// build.zig calls; the root shim and user link script come from the kernel
+/// domain package's directory.
+pub fn userBinary(b: *std.Build, options: DomainUserBinaryOptions) *std.Build.Step.Compile {
+    const default_imports = defaultImports(options.domains);
     return userBinaryFromImports(b, .{
         .name = options.name,
         .root_source_file = options.root_source_file,
-        .shim_source_file = kernel.path("root.zig"),
-        .linker_script = kernel.path("user.ld"),
+        .shim_source_file = options.domains.kernel.path("root.zig"),
+        .linker_script = options.domains.kernel.path("user.ld"),
         .target = freestandingTarget(b),
         .default_imports = &default_imports,
         .threaded = options.threaded,

build.zig

@@ -86,11 +86,14 @@ fn addUserBinaryImpl(
     root: []const u8,
     threaded: bool,
 ) *std.Build.Step.Compile {
+    // The shim and link script live in the kernel domain package, so name them
+    // through it — the same spelling build-support's userBinary uses.
+    const kernel_library = b.dependency("kernel", .{});
     return build_support.userBinaryFromImports(b, .{
         .name = name,
         .root_source_file = b.path(root),
-        .shim_source_file = b.path("library/kernel/root.zig"),
-        .linker_script = b.path("library/kernel/user.ld"),
+        .shim_source_file = kernel_library.path("root.zig"),
+        .linker_script = kernel_library.path("user.ld"),
         .target = target,
         .default_imports = default_imports,
         .threaded = threaded,
@@ -251,7 +254,6 @@ pub fn build(b: *std.Build) void {
     const csv_module = csv_library.module("csv");
     const device_registry_module = device_library.module("device-registry");
     const aml_module = device_library.module("aml");
-    const acpi_ids_module = device_library.module("acpi-ids");
     const usb_abi_module = device_library.module("usb-abi");
     const usb_ids_module = device_library.module("usb-ids");
     const usb_transfer_protocol_module = protocol_library.module("usb-transfer-protocol");
@@ -305,27 +307,11 @@ pub fn build(b: *std.Build) void {
     const scanout_protocol_module = protocol_library.module("scanout-protocol");
     const power_protocol_module = protocol_library.module("power-protocol");
 
-    // The library/kernel concern modules (the userspace private-ABI library),
-    // the device-domain driver libraries, and the service clients.
-    const mmio_module = device_library.module("mmio");
-    const system_call_module = kernel_library.module("system-call");
-    const ipc_module = kernel_library.module("ipc");
-    const time_module = kernel_library.module("time");
-    const thread_module = kernel_library.module("thread");
-    const logging_module = kernel_library.module("logging");
-    const process_module = kernel_library.module("process");
-    const file_system_module = kernel_library.module("file-system");
-    const memory_module = kernel_library.module("memory");
-    const service_module = kernel_library.module("service");
-    const start_module = kernel_library.module("start");
-    const driver_module = device_library.module("driver");
-    const block_client_module = device_library.module("block");
-    const display_client_module = client_library.module("display");
-    const input_client_module = client_library.module("input");
+    // The driver-side libraries some binaries name as per-binary extras. (The
+    // rest of the domain modules reach the root only through build-support's
+    // defaultImports below.)
     const pci_module = device_library.module("pci");
     const usb_module = device_library.module("usb");
-    const xkb_layouts_module = xkeyboard_config_library.module("layouts");
-    const xkeyboard_config_module = xkeyboard_config_library.module("xkeyboard-config");
 
     // The initial_ramdisk container format, shared by the kernel (unpacks it) and
     // the EFI loader (packs it in RAM from the boot volume's /system tree). No
@@ -373,28 +359,16 @@ pub fn build(b: *std.Build) void {
     b.getInstallStep().dependOn(&kernel_install.step);
 
     // --- init: the first user-space program (a system service) ---
-    // The default module set every user binary can import directly: the library/kernel
-    // concern modules, the device/service clients, mmio, the keyboard layouts, and the ACPI
-    // id registry. Per-binary extras are added with programModule(exe).addImport.
-    const default_imports = [_]std.Build.Module.Import{
-        .{ .name = "mmio", .module = mmio_module },
-        .{ .name = "xkeyboard-config", .module = xkeyboard_config_module },
-        .{ .name = "acpi-ids", .module = acpi_ids_module },
-        .{ .name = "system-call", .module = system_call_module },
-        .{ .name = "ipc", .module = ipc_module },
-        .{ .name = "memory", .module = memory_module },
-        .{ .name = "process", .module = process_module },
-        .{ .name = "thread", .module = thread_module },
-        .{ .name = "time", .module = time_module },
-        .{ .name = "logging", .module = logging_module },
-        .{ .name = "file-system", .module = file_system_module },
-        .{ .name = "service", .module = service_module },
-        .{ .name = "start", .module = start_module },
-        .{ .name = "driver", .module = driver_module },
-        .{ .name = "block", .module = block_client_module },
-        .{ .name = "display", .module = display_client_module },
-        .{ .name = "input", .module = input_client_module },
-    };
+    // The default module set every user binary can import directly, drawn from
+    // build-support's single authoritative list so the root stanzas and the
+    // binary packages can never drift apart. Per-binary extras are added with
+    // programModule(exe).addImport.
+    const default_imports = build_support.defaultImports(.{
+        .kernel = kernel_library,
+        .device = device_library,
+        .client = client_library,
+        .xkeyboard_config = xkeyboard_config_library,
+    });
 
     // Built by the shared user-binary recipe (see addUserBinary): freestanding,
     // linked into the kernel's user region against the library/kernel modules, and
@@ -873,24 +847,14 @@ pub fn build(b: *std.Build) void {
         "system/boot-handoff.zig",
         "system/abi.zig",
         "system/initial-ramdisk.zig", // v2 path-named entries: find/basename/magic
-        "library/device/model/device-abi.zig",
-        "library/device/pci/pci-class.zig", // class/subclass/prog-IF name decoding
-        "library/device/acpi/acpi-ids.zig", // _HID name decoding
-        "library/device/acpi/aml/aml.zig", // AML parse + interpret, incl. Notify dispatch (M21)
-        "library/device/usb/usb-abi.zig", // wire sizes + bit packings + set-up packet encodings
-        "library/device/usb/usb-ids.zig", // class/subclass/protocol code assignments
-        "library/csv/csv.zig", // shared /etc/*.csv comment-strip + field-split helpers
-        "library/device/mmio/mmio.zig", // barriers assemble + registers round-trip
         "system/drivers/ps2-bus/scancode.zig", // set-2 decode + keyboard state machine
         "system/drivers/ps2-bus/mouse-packet.zig", // 3-byte mouse packet assembly
         "system/drivers/usb-hid/hid-report.zig", // HID boot-report keyboard/mouse decode
         "system/drivers/usb-storage/bulk-only-transport.zig", // CBW/CSW wrapper sizes
         "system/drivers/usb-storage/scsi.zig", // SCSI CDB encodings (big-endian)
-        "library/protocol/vfs/vfs-protocol.zig", // NodeKind / DirectoryEntry sizes + op values
         "system/services/fat/on-disk.zig", // FAT on-disk struct sizes + type detection
         "system/services/fat/engine.zig", // FAT read/write over a RAM-backed image
         "system/services/display/compositor.zig", // Rect math + fill/composite/blit-tile
-        "library/protocol/display/display-protocol.zig", // pack(): native pixel encoding per format
         "system/drivers/virtio-gpu/virtio-gpu-protocol.zig", // virtio-gpu command struct sizes
         "system/drivers/virtio-gpu/virtio-pci.zig", // virtio 1.0 PCI transport struct sizes
     }) |root| {
@@ -904,33 +868,21 @@ pub fn build(b: *std.Build) void {
         test_step.dependOn(&b.addRunArtifact(mod_tests).step);
     }
 
-    // The device registry imports the shared `csv` module, so its tests need that
-    // import wired and don't fit the plain loop above. These prove the /etc/devices.csv
-    // parse + most-specific driver match (incl. virtio 1AF4:1050 beating a class rule).
-    const device_registry_tests = b.addTest(.{
-        .root_module = b.createModule(.{
-            .root_source_file = b.path("library/device/registry/device-registry.zig"),
-            .target = target,
-            .optimize = optimize,
-            .imports = &.{.{ .name = "csv", .module = csv_module }},
-        }),
-    });
-    test_step.dependOn(&b.addRunArtifact(device_registry_tests).step);
-
-    // The xkeyboard-config keymap tests need its generated `layouts` import wired, so they
-    // don't fit the plain loop above. Its keycode->character assertions are the end-to-end
-    // proof that the xkb-data -> generator -> Zig-lookup pipeline is correct.
-    const xkb_tests = b.addTest(.{
-        .root_module = b.createModule(.{
-            .root_source_file = b.path("library/xkeyboard-config/xkeyboard-config.zig"),
-            .target = target,
-            .optimize = optimize,
-            .imports = &.{
-                .{ .name = "layouts", .module = xkb_layouts_module },
-            },
-        }),
-    });
-    test_step.dependOn(&b.addRunArtifact(xkb_tests).step);
+    // The library domains own their unit tests (each package's standalone
+    // `zig build test` step); the root aggregate delegates to those steps so
+    // one command still runs everything and a test added inside a domain
+    // package can never be silently skipped here. Domain tests are host-only,
+    // so root's -Dtarget/-Doptimize deliberately do not reach them.
+    for ([_]*std.Build.Dependency{
+        kernel_library,
+        device_library,
+        client_library,
+        protocol_library,
+        csv_library,
+        xkeyboard_config_library,
+    }) |library| {
+        test_step.dependOn(&library.builder.top_level_steps.get("test").?.step);
+    }
 
     // The tagged kernel log ring: append/wrap/reclaim/sequence-gap behavior over
     // a RAM buffer. Needs the `abi` module (record header layout), so it doesn't
@@ -947,37 +899,6 @@ pub fn build(b: *std.Build) void {
     });
     test_step.dependOn(&b.addRunArtifact(log_ring_tests).step);
 
-    // runtime.time's Instant/Duration arithmetic. time.zig pulls in system.zig (the
-    // syscall wrappers), which needs the `abi` module, so it doesn't fit the plain
-    // loop above.
-    const time_tests = b.addTest(.{
-        .root_module = b.createModule(.{
-            .root_source_file = b.path("library/kernel/time.zig"),
-            .target = target,
-            .optimize = optimize,
-            .imports = &.{
-                .{ .name = "abi", .module = abi_module },
-            },
-        }),
-    });
-    test_step.dependOn(&b.addRunArtifact(time_tests).step);
-
-    // runtime.Thread's lock/condvar state machines (Mutex/Condition/RwLock/WaitGroup). Its
-    // Futex seam falls back to std.Thread.Futex off the danos target, so the tests exercise
-    // them with real host threads (docs/threading-plan.md M11). Like time.zig it pulls in
-    // system.zig (syscall wrappers), which needs the `abi` module.
-    const thread_tests = b.addTest(.{
-        .root_module = b.createModule(.{
-            .root_source_file = b.path("library/kernel/thread.zig"),
-            .target = target,
-            .optimize = optimize,
-            .imports = &.{
-                .{ .name = "abi", .module = abi_module },
-            },
-        }),
-    });
-    test_step.dependOn(&b.addRunArtifact(thread_tests).step);
-
     // Convenience: `zig build gen-xkeyboard-config` regenerates the layout tables from the
     // vendored data (offline). `fetch` (the network step) stays a manual script run.
     const gen_xkb = b.addSystemCommand(&.{ "python3", "tools/make-xkeyboard-config.py", "generate" });

library/client/build.zig

@@ -26,4 +26,10 @@ pub fn build(b: *std.Build) void {
             .{ .name = "input-protocol", .module = protocol.module("input-protocol") },
         },
     });
+
+    // Standalone `zig build test`, kept for uniformity across the domains (the
+    // root aggregate depends on every domain's test step). The clients have no
+    // host-runnable unit tests yet — they are thin IPC conversation wrappers —
+    // so the step is empty until one grows some.
+    _ = b.step("test", "Run the client unit tests (none yet)");
 }