diff --git a/.woodpecker.yml b/.woodpecker.yml
index 0dfa225..849f6f1 100644
--- a/.woodpecker.yml
+++ b/.woodpecker.yml
@@ -9,27 +9,27 @@ clone:
       recursive: false
 pipeline:
   lint:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - ./tools/fmt-check.sh
   test:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - zig build test
   sdl2:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - zig build -Ddriver=sdl2
   x11:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - zig build -Ddriver=x11
   aarch64:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - zig build -Ddriver=fbev -Dtarget=aarch64-linux-musl -Doptimize=ReleaseSafe -Dstrip
       - sha256sum zig-out/bin/nd zig-out/bin/ngui
   playground:
-    image: git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    image: git.qcode.ch/nakamochi/ci-zig0.12.0:v1
     commands:
       - zig build guiplay btcrpc lndhc
diff --git a/README.md b/README.md
index 9a26726..f427ed2 100644
--- a/README.md
+++ b/README.md
@@ -61,17 +61,17 @@ to make a new image and switch the CI to use it, first modify the
 [ci-containerfile](tools/ci-containerfile) and produce the image locally:
 
     podman build --rm -t ndg-ci -f ./tools/ci-containerfile \
-      --build-arg ZIGURL=https://ziglang.org/download/0.11.0/zig-linux-x86_64-0.11.0.tar.xz
+      --build-arg ZIGURL=https://ziglang.org/download/0.12.0/zig-linux-x86_64-0.12.0.tar.xz
 
 then tag it with the target URL, for example:
 
-    podman tag localhost/ndg-ci git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    podman tag localhost/ndg-ci git.qcode.ch/nakamochi/ci-zig0.12.0:v1
 
 generate an [access token](https://git.qcode.ch/user/settings/applications),
 login to the container registry and push the image to remote:
 
     podman login git.qcode.ch
-    podman push git.qcode.ch/nakamochi/ci-zig0.11.0:v2
+    podman push git.qcode.ch/nakamochi/ci-zig0.12.0:v1
 
 the image will be available at
 https://git.qcode.ch/nakamochi/-/packages/
diff --git a/build.zig b/build.zig
index 92a8e28..ac00456 100644
--- a/build.zig
+++ b/build.zig
@@ -11,18 +11,16 @@ pub fn build(b: *std.Build) void {
     const inver = b.option([]const u8, "version", "semantic version of the build; must match git tag when available");
 
     const buildopts = b.addOptions();
+    const buildopts_mod = buildopts.createModule();
     buildopts.addOption(DriverTarget, "driver", drv);
     const semver_step = VersionStep.create(b, buildopts, inver);
     buildopts.step.dependOn(semver_step);
 
     // network interface (nif) standalone library used by the daemon and tests.
-    const libnif_dep = b.anonymousDependency("lib/nif", @import("lib/nif/build.zig"), .{
-        .target = target,
-        .optimize = optimize,
-    });
+    const libnif_dep = b.lazyDependency("nif", .{ .target = target, .optimize = optimize }) orelse return;
     const libnif = libnif_dep.artifact("nif");
     // ini file format parser
-    const libini = b.addModule("ini", .{ .source_file = .{ .path = "lib/ini/src/ini.zig" } });
+    const libini_dep = b.lazyDependency("ini", .{ .target = target, .optimize = optimize }) orelse return;
 
     const common_cflags = .{
         "-Wall",
@@ -35,16 +33,16 @@ pub fn build(b: *std.Build) void {
     // gui build
     const ngui = b.addExecutable(.{
         .name = "ngui",
-        .root_source_file = .{ .path = "src/ngui.zig" },
+        .root_source_file = b.path("src/ngui.zig"),
         .target = target,
         .optimize = optimize,
         .link_libc = true,
+        .strip = strip,
     });
     ngui.pie = true;
-    ngui.strip = strip;
-    ngui.addOptions("build_options", buildopts);
-    ngui.addIncludePath(.{ .path = "lib" });
-    ngui.addIncludePath(.{ .path = "src/ui/c" });
+    ngui.root_module.addImport("build_options", buildopts_mod);
+    ngui.addIncludePath(b.path("lib"));
+    ngui.addIncludePath(b.path("src/ui/c"));
 
     const lvgl_flags = .{
         "-std=c11",
@@ -52,7 +50,7 @@ pub fn build(b: *std.Build) void {
         "-Wformat",
         "-Wformat-security",
     } ++ common_cflags;
-    ngui.addCSourceFiles(lvgl_generic_src, &lvgl_flags);
+    ngui.addCSourceFiles(.{ .files = lvgl_generic_src, .flags = &lvgl_flags });
 
     const ngui_cflags = .{
         "-std=c11",
@@ -60,39 +58,46 @@ pub fn build(b: *std.Build) void {
         "-Wunused-parameter",
         "-Werror",
     } ++ common_cflags;
-    ngui.addCSourceFiles(&.{
-        "src/ui/c/ui.c",
-        "src/ui/c/lv_font_courierprimecode_14.c",
-        "src/ui/c/lv_font_courierprimecode_16.c",
-        "src/ui/c/lv_font_courierprimecode_24.c",
-    }, &ngui_cflags);
-
-    ngui.defineCMacroRaw(b.fmt("NM_DISP_HOR={}", .{disp_horiz}));
-    ngui.defineCMacroRaw(b.fmt("NM_DISP_VER={}", .{disp_vert}));
-    ngui.defineCMacro("LV_CONF_INCLUDE_SIMPLE", null);
+    ngui.addCSourceFiles(.{
+        .root = b.path("src/ui/c"),
+        .files = &.{
+            "ui.c",
+            "lv_font_courierprimecode_14.c",
+            "lv_font_courierprimecode_16.c",
+            "lv_font_courierprimecode_24.c",
+        },
+        .flags = &ngui_cflags,
+    });
+
+    ngui.root_module.addCMacro("NM_DISP_HOR", b.fmt("{d}", .{disp_horiz}));
+    ngui.root_module.addCMacro("NM_DISP_VER", b.fmt("{d}", .{disp_vert}));
+    ngui.defineCMacro("LV_CONF_INCLUDE_SIMPLE", "1");
     ngui.defineCMacro("LV_LOG_LEVEL", lvgl_loglevel.text());
     ngui.defineCMacro("LV_TICK_CUSTOM", "1");
     ngui.defineCMacro("LV_TICK_CUSTOM_INCLUDE", "\"lv_custom_tick.h\"");
     ngui.defineCMacro("LV_TICK_CUSTOM_SYS_TIME_EXPR", "(nm_get_curr_tick())");
     switch (drv) {
         .sdl2 => {
-            ngui.addCSourceFiles(lvgl_sdl2_src, &lvgl_flags);
-            ngui.addCSourceFile(.{ .file = .{ .path = "src/ui/c/drv_sdl2.c" }, .flags = &ngui_cflags });
+            ngui.addCSourceFiles(.{ .files = lvgl_sdl2_src, .flags = &lvgl_flags });
+            ngui.addCSourceFile(.{ .file = b.path("src/ui/c/drv_sdl2.c"), .flags = &ngui_cflags });
             ngui.defineCMacro("USE_SDL", "1");
             ngui.linkSystemLibrary("SDL2");
         },
         .x11 => {
-            ngui.addCSourceFiles(lvgl_x11_src, &lvgl_flags);
-            ngui.addCSourceFiles(&.{
-                "src/ui/c/drv_x11.c",
-                "src/ui/c/mouse_cursor_icon.c",
-            }, &ngui_cflags);
+            ngui.addCSourceFiles(.{ .files = lvgl_x11_src, .flags = &lvgl_flags });
+            ngui.addCSourceFiles(.{
+                .files = &.{
+                    "src/ui/c/drv_x11.c",
+                    "src/ui/c/mouse_cursor_icon.c",
+                },
+                .flags = &ngui_cflags,
+            });
             ngui.defineCMacro("USE_X11", "1");
             ngui.linkSystemLibrary("X11");
         },
         .fbev => {
-            ngui.addCSourceFiles(lvgl_fbev_src, &lvgl_flags);
-            ngui.addCSourceFile(.{ .file = .{ .path = "src/ui/c/drv_fbev.c" }, .flags = &ngui_cflags });
+            ngui.addCSourceFiles(.{ .files = lvgl_fbev_src, .flags = &lvgl_flags });
+            ngui.addCSourceFile(.{ .file = b.path("src/ui/c/drv_fbev.c"), .flags = &ngui_cflags });
             ngui.defineCMacro("USE_FBDEV", "1");
             ngui.defineCMacro("USE_EVDEV", "1");
         },
@@ -104,15 +109,15 @@ pub fn build(b: *std.Build) void {
     // daemon build
     const nd = b.addExecutable(.{
         .name = "nd",
-        .root_source_file = .{ .path = "src/nd.zig" },
+        .root_source_file = b.path("src/nd.zig"),
         .target = target,
         .optimize = optimize,
+        .strip = strip,
     });
     nd.pie = true;
-    nd.strip = strip;
-    nd.addOptions("build_options", buildopts);
-    nd.addModule("nif", libnif_dep.module("nif"));
-    nd.addModule("ini", libini);
+    nd.root_module.addImport("build_options", buildopts_mod);
+    nd.root_module.addImport("nif", libnif_dep.module("nif"));
+    nd.root_module.addImport("ini", libini_dep.module("ini"));
     nd.linkLibrary(libnif);
 
     const nd_build_step = b.step("nd", "build nd (nakamochi daemon)");
@@ -121,15 +126,15 @@ pub fn build(b: *std.Build) void {
     // automated tests
     {
         const tests = b.addTest(.{
-            .root_source_file = .{ .path = "src/test.zig" },
+            .root_source_file = b.path("src/test.zig"),
             .target = target,
             .optimize = optimize,
             .link_libc = true,
             .filter = b.option([]const u8, "test-filter", "run tests matching the filter"),
         });
-        tests.addOptions("build_options", buildopts);
-        tests.addModule("nif", libnif_dep.module("nif"));
-        tests.addModule("ini", libini);
+        tests.root_module.addImport("build_options", buildopts_mod);
+        tests.root_module.addImport("nif", libnif_dep.module("nif"));
+        tests.root_module.addImport("ini", libini_dep.module("ini"));
         tests.linkLibrary(libnif);
 
         const run_tests = b.addRunArtifact(tests);
@@ -141,11 +146,11 @@ pub fn build(b: *std.Build) void {
     {
         const guiplay = b.addExecutable(.{
             .name = "guiplay",
-            .root_source_file = .{ .path = "src/test/guiplay.zig" },
+            .root_source_file = b.path("src/test/guiplay.zig"),
             .target = target,
             .optimize = optimize,
         });
-        guiplay.addModule("comm", b.createModule(.{ .source_file = .{ .path = "src/comm.zig" } }));
+        guiplay.root_module.addImport("comm", b.createModule(.{ .root_source_file = b.path("src/comm.zig") }));
 
         const guiplay_build_step = b.step("guiplay", "build GUI playground");
         guiplay_build_step.dependOn(&b.addInstallArtifact(guiplay, .{}).step);
@@ -156,12 +161,12 @@ pub fn build(b: *std.Build) void {
     {
         const btcrpc = b.addExecutable(.{
             .name = "btcrpc",
-            .root_source_file = .{ .path = "src/test/btcrpc.zig" },
+            .root_source_file = b.path("src/test/btcrpc.zig"),
             .target = target,
             .optimize = optimize,
+            .strip = strip,
         });
-        btcrpc.strip = strip;
-        btcrpc.addModule("bitcoindrpc", b.createModule(.{ .source_file = .{ .path = "src/bitcoindrpc.zig" } }));
+        btcrpc.root_module.addImport("bitcoindrpc", b.createModule(.{ .root_source_file = b.path("src/bitcoindrpc.zig") }));
 
         const btcrpc_build_step = b.step("btcrpc", "bitcoind RPC client playground");
         btcrpc_build_step.dependOn(&b.addInstallArtifact(btcrpc, .{}).step);
@@ -171,12 +176,12 @@ pub fn build(b: *std.Build) void {
     {
         const lndhc = b.addExecutable(.{
             .name = "lndhc",
-            .root_source_file = .{ .path = "src/test/lndhc.zig" },
+            .root_source_file = b.path("src/test/lndhc.zig"),
             .target = target,
             .optimize = optimize,
+            .strip = strip,
         });
-        lndhc.strip = strip;
-        lndhc.addModule("lightning", b.createModule(.{ .source_file = .{ .path = "src/lightning.zig" } }));
+        lndhc.root_module.addImport("lightning", b.createModule(.{ .root_source_file = b.path("src/lightning.zig") }));
 
         const lndhc_build_step = b.step("lndhc", "lnd HTTP API client playground");
         lndhc_build_step.dependOn(&b.addInstallArtifact(lndhc, .{}).step);
@@ -423,7 +428,7 @@ const VersionStep = struct {
     }
 
     fn make(step: *std.Build.Step, _: *std.Progress.Node) anyerror!void {
-        const self = @fieldParentPtr(VersionStep, "step", step);
+        const self: *@This() = @fieldParentPtr("step", step);
         const semver = try self.eval();
         std.log.info("build version: {any}", .{semver});
         self.buildopts.addOption(std.SemanticVersion, "semver", semver);
@@ -460,7 +465,7 @@ const VersionStep = struct {
         const matchTag = self.b.fmt("{s}*.*.*", .{prefix});
         const cmd = [_][]const u8{ git, "-C", self.b.pathFromRoot("."), "describe", "--match", matchTag, "--tags", "--abbrev=8" };
         var code: u8 = undefined;
-        const git_describe = self.b.execAllowFail(&cmd, &code, .Ignore) catch return null;
+        const git_describe = self.b.runAllowFail(&cmd, &code, .Ignore) catch return null;
         const repotag = std.mem.trim(u8, git_describe, " \n\r")[prefix.len..];
         return std.SemanticVersion.parse(repotag) catch |err| ret: {
             std.log.err("unparsable git tag semver '{s}': {any}", .{ repotag, err });
diff --git a/build.zig.zon b/build.zig.zon
new file mode 100644
index 0000000..326febc
--- /dev/null
+++ b/build.zig.zon
@@ -0,0 +1,17 @@
+.{
+    .name = "ndg",
+    .version = "0.8.1",
+    .dependencies = .{
+        .nif = .{
+            .path = "lib/nif",
+        },
+        .ini = .{
+            .path = "lib/ini",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+    },
+}
diff --git a/lib/ini/build.zig.zon b/lib/ini/build.zig.zon
new file mode 100644
index 0000000..8ff2aeb
--- /dev/null
+++ b/lib/ini/build.zig.zon
@@ -0,0 +1,10 @@
+.{
+    .name = "libini",
+    .version = "0.0.0",
+    .dependencies = .{},
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+    },
+}
diff --git a/lib/nif/build.zig b/lib/nif/build.zig
index 6a32113..307afdb 100644
--- a/lib/nif/build.zig
+++ b/lib/nif/build.zig
@@ -1,30 +1,33 @@
 const std = @import("std");
 
 pub fn build(b: *std.Build) void {
-    _ = b.addModule("nif", .{ .source_file = .{ .path = "nif.zig" } });
+    _ = b.addModule("nif", .{ .root_source_file = b.path("nif.zig") });
 
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
     const lib = b.addStaticLibrary(.{
         .name = "nif",
-        .root_source_file = .{ .path = "nif.zig" },
+        .root_source_file = b.path("nif.zig"),
         .target = target,
         .optimize = optimize,
         .link_libc = true,
     });
     lib.defineCMacro("CONFIG_CTRL_IFACE", null);
     lib.defineCMacro("CONFIG_CTRL_IFACE_UNIX", null);
-    lib.addIncludePath(.{ .path = "wpa_supplicant" });
-    lib.addCSourceFiles(&.{
-        "wpa_supplicant/wpa_ctrl.c",
-        "wpa_supplicant/os_unix.c",
-    }, &.{
-        "-Wall",
-        "-Wextra",
-        "-Wshadow",
-        "-Wundef",
-        "-Wunused-parameter",
-        "-Werror",
+    lib.addIncludePath(b.path("wpa_supplicant"));
+    lib.addCSourceFiles(.{
+        .files = &.{
+            "wpa_supplicant/wpa_ctrl.c",
+            "wpa_supplicant/os_unix.c",
+        },
+        .flags = &.{
+            "-Wall",
+            "-Wextra",
+            "-Wshadow",
+            "-Wundef",
+            "-Wunused-parameter",
+            "-Werror",
+        },
     });
     b.installArtifact(lib);
 }
diff --git a/lib/nif/build.zig.zon b/lib/nif/build.zig.zon
new file mode 100644
index 0000000..9b4af6d
--- /dev/null
+++ b/lib/nif/build.zig.zon
@@ -0,0 +1,10 @@
+.{
+    .name = "libnif",
+    .version = "0.0.1",
+    .dependencies = .{},
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+    },
+}
diff --git a/lib/nif/nif.zig b/lib/nif/nif.zig
index e9c6556..c13bef7 100644
--- a/lib/nif/nif.zig
+++ b/lib/nif/nif.zig
@@ -1,7 +1,7 @@
 const std = @import("std");
 const mem = std.mem;
 const net = std.net;
-const os = std.os;
+const posix = std.posix;
 
 pub const wpa = @import("wpa.zig");
 
@@ -12,11 +12,11 @@ const ifaddrs = extern struct {
     next: ?*ifaddrs,
     name: [*:0]const u8,
     flags: c_uint, // see IFF_xxx SIOCGIFFLAGS in netdevice(7)
-    addr: ?*std.os.sockaddr,
-    netmask: ?*std.os.sockaddr,
+    addr: ?*std.posix.sockaddr,
+    netmask: ?*std.posix.sockaddr,
     ifu: extern union {
-        broad: *os.sockaddr, // flags & IFF_BROADCAST
-        dst: *os.sockaddr, // flags & IFF_POINTOPOINT
+        broad: *posix.sockaddr, // flags & IFF_BROADCAST
+        dst: *posix.sockaddr, // flags & IFF_POINTOPOINT
     },
     data: ?*anyopaque,
 };
@@ -37,8 +37,8 @@ pub fn pubAddresses(allocator: mem.Allocator, ifname: ?[]const u8) ![]net.Addres
     var list = std.ArrayList(net.Address).init(allocator);
     var it: ?*ifaddrs = res;
     while (it) |ifa| : (it = ifa.next) {
-        const sa: *os.sockaddr = ifa.addr orelse continue;
-        if (sa.family != os.AF.INET and sa.family != os.AF.INET6) {
+        const sa: *posix.sockaddr = ifa.addr orelse continue;
+        if (sa.family != posix.AF.INET and sa.family != posix.AF.INET6) {
             // not an IP address
             continue;
         }
@@ -47,7 +47,7 @@ pub fn pubAddresses(allocator: mem.Allocator, ifname: ?[]const u8) ![]net.Addres
             continue;
         }
         const ipaddr = net.Address.initPosix(@alignCast(sa)); // initPosix makes a copy
-        if (ipaddr.any.family == os.AF.INET6 and ipaddr.in6.sa.scope_id > 0) {
+        if (ipaddr.any.family == posix.AF.INET6 and ipaddr.in6.sa.scope_id > 0) {
             // want only global, with 0 scope
             // non-zero scopes make sense for link-local addr only.
             continue;
diff --git a/src/bitcoindrpc.zig b/src/bitcoindrpc.zig
index d937aa2..ed1fb03 100644
--- a/src/bitcoindrpc.zig
+++ b/src/bitcoindrpc.zig
@@ -2,7 +2,7 @@
 
 const std = @import("std");
 const ArenaAllocator = std.heap.ArenaAllocator;
-const Atomic = std.atomic.Atomic;
+const Atomic = std.atomic.Value;
 const base64enc = std.base64.standard.Encoder;
 
 const types = @import("types.zig");
@@ -13,7 +13,7 @@ pub const Client = struct {
     addr: []const u8 = "127.0.0.1",
     port: u16 = 8332,
 
-    // each request gets a new ID with a value of reqid.fetchAdd(1, .Monotonic)
+    // each request gets a new ID with a value of reqid.fetchAdd(1, .monotonic)
     reqid: Atomic(u64) = Atomic(u64).init(1),
 
     pub const Method = enum {
@@ -153,7 +153,7 @@ pub const Client = struct {
     /// callers own returned value.
     fn formatreq(self: *Client, comptime m: Method, args: MethodArgs(m)) ![]const u8 {
         const req = RpcRequest(m){
-            .id = self.reqid.fetchAdd(1, .Monotonic),
+            .id = self.reqid.fetchAdd(1, .monotonic),
             .method = @tagName(m),
             .params = args,
         };
@@ -183,7 +183,7 @@ pub const Client = struct {
         defer file.close();
         const cookie = try file.readToEndAlloc(self.allocator, 1024);
         defer self.allocator.free(cookie);
-        var auth = try self.allocator.alloc(u8, base64enc.calcSize(cookie.len));
+        const auth = try self.allocator.alloc(u8, base64enc.calcSize(cookie.len));
         return base64enc.encode(auth, cookie);
     }
 
diff --git a/src/comm.zig b/src/comm.zig
index ecaece4..c949d51 100644
--- a/src/comm.zig
+++ b/src/comm.zig
@@ -56,15 +56,15 @@ pub const MessageTag = enum(u16) {
     ping = 0x01,
     pong = 0x02,
     poweroff = 0x03,
-    wifi_connect = 0x04,
-    network_report = 0x05,
-    get_network_report = 0x06,
+    // nd -> ngui: reports poweroff progress
+    poweroff_progress = 0x09,
     // ngui -> nd: screen timeout, no user activity; no reply
     standby = 0x07,
     // ngui -> nd: resume screen due to user touch; no reply
     wakeup = 0x08,
-    // nd -> ngui: reports poweroff progress
-    poweroff_progress = 0x09,
+    wifi_connect = 0x04,
+    network_report = 0x05,
+    get_network_report = 0x06,
     // nd -> ngui: bitcoin core daemon status report
     onchain_report = 0x0a,
     // nd -> ngui: lnd status and stats report
@@ -103,12 +103,12 @@ pub const Message = union(MessageTag) {
     ping: void,
     pong: void,
     poweroff: void,
+    poweroff_progress: PoweroffProgress,
     standby: void,
     wakeup: void,
     wifi_connect: WifiConnect,
     network_report: NetworkReport,
     get_network_report: GetNetworkReport,
-    poweroff_progress: PoweroffProgress,
     onchain_report: OnchainReport,
     lightning_report: LightningReport,
     lightning_error: LightningError,
@@ -294,8 +294,8 @@ pub const ParsedMessage = struct {
 /// callers must deallocate resources with ParsedMessage.deinit when done.
 pub fn read(allocator: mem.Allocator, reader: anytype) !ParsedMessage {
     // alternative is @intToEnum(reader.ReadIntLittle(u16)) but it may panic.
-    const tag = try reader.readEnum(MessageTag, .Little);
-    const len = try reader.readIntLittle(u64);
+    const tag = try reader.readEnum(MessageTag, .little);
+    const len = try reader.readInt(u64, .little);
     if (len == 0) {
         return switch (tag) {
             .lightning_get_ctrlconn => .{ .value = .lightning_get_ctrlconn },
@@ -318,7 +318,7 @@ pub fn read(allocator: mem.Allocator, reader: anytype) !ParsedMessage {
         .wakeup,
         => unreachable, // handled above
         inline else => |t| {
-            var bytes = try allocator.alloc(u8, len);
+            const bytes = try allocator.alloc(u8, len);
             defer allocator.free(bytes);
             try reader.readNoEof(bytes);
 
@@ -370,8 +370,8 @@ pub fn write(allocator: mem.Allocator, writer: anytype, msg: Message) !void {
         return Error.CommWriteTooLarge;
     }
 
-    try writer.writeIntLittle(u16, @intFromEnum(msg));
-    try writer.writeIntLittle(u64, data.items.len);
+    try writer.writeInt(u16, @intFromEnum(msg), .little);
+    try writer.writeInt(u64, data.items.len, .little);
     try writer.writeAll(data.items);
 }
 
@@ -401,8 +401,8 @@ test "read" {
 
     var buf = std.ArrayList(u8).init(t.allocator);
     defer buf.deinit();
-    try buf.writer().writeIntLittle(u16, @intFromEnum(msg));
-    try buf.writer().writeIntLittle(u64, data.items.len);
+    try buf.writer().writeInt(u16, @intFromEnum(msg), .little);
+    try buf.writer().writeInt(u64, data.items.len, .little);
     try buf.writer().writeAll(data.items);
 
     var bs = std.io.fixedBufferStream(buf.items);
@@ -424,8 +424,8 @@ test "write" {
     const payload = "{\"ssid\":\"wlan\",\"password\":\"secret\"}";
     var js = std.ArrayList(u8).init(t.allocator);
     defer js.deinit();
-    try js.writer().writeIntLittle(u16, @intFromEnum(msg));
-    try js.writer().writeIntLittle(u64, payload.len);
+    try js.writer().writeInt(u16, @intFromEnum(msg), .little);
+    try js.writer().writeInt(u64, payload.len, .little);
     try js.appendSlice(payload);
 
     try t.expectEqualStrings(js.items, buf.items);
@@ -442,8 +442,8 @@ test "write enum" {
     const payload = "\"edge\"";
     var js = std.ArrayList(u8).init(t.allocator);
     defer js.deinit();
-    try js.writer().writeIntLittle(u16, @intFromEnum(msg));
-    try js.writer().writeIntLittle(u64, payload.len);
+    try js.writer().writeInt(u16, @intFromEnum(msg), .little);
+    try js.writer().writeInt(u64, payload.len, .little);
     try js.appendSlice(payload);
 
     try t.expectEqualStrings(js.items, buf.items);
diff --git a/src/lightning/LndConf.zig b/src/lightning/LndConf.zig
index 7e2a254..3d62d9b 100644
--- a/src/lightning/LndConf.zig
+++ b/src/lightning/LndConf.zig
@@ -36,7 +36,7 @@ pub const Section = struct {
         const vdup = try self.alloc.dupe(u8, value);
         errdefer self.alloc.free(vdup);
 
-        var res = try self.props.getOrPut(try self.alloc.dupe(u8, key));
+        const res = try self.props.getOrPut(try self.alloc.dupe(u8, key));
         if (!res.found_existing) {
             res.value_ptr.* = .{ .str = vdup };
             return;
@@ -180,7 +180,7 @@ pub fn appendDefaultSection(self: *LndConf) !*Section {
 /// the section name ascii is converted to lower case.
 pub fn appendSection(self: *LndConf, name: []const u8) !*Section {
     const alloc = self.arena.allocator();
-    var low_name = try std.ascii.allocLowerString(alloc, name);
+    const low_name = try std.ascii.allocLowerString(alloc, name);
     try self.sections.append(.{
         .name = low_name,
         .props = std.StringArrayHashMap(PropValue).init(alloc),
diff --git a/src/lightning/lndhttp.zig b/src/lightning/lndhttp.zig
index 656c0c3..f08c7c0 100644
--- a/src/lightning/lndhttp.zig
+++ b/src/lightning/lndhttp.zig
@@ -143,22 +143,29 @@ pub const Client = struct {
     pub fn call(self: *Client, comptime apimethod: ApiMethod, args: MethodArgs(apimethod)) !Result(apimethod) {
         const formatted = try self.formatreq(apimethod, args);
         defer formatted.deinit();
+
+        var headersbuf: [8 * 1024]u8 = undefined;
         const reqinfo = formatted.value;
-        const opt = std.http.Client.Options{ .handle_redirects = false }; // no redirects in REST API
-        var req = try self.httpClient.request(reqinfo.httpmethod, reqinfo.url, reqinfo.headers, opt);
+        const opt = std.http.Client.RequestOptions{
+            .redirect_behavior = .not_allowed, // no redirects in REST API
+            .headers = reqinfo.stdheaders,
+            .privileged_headers = reqinfo.xheaders,
+            .server_header_buffer = &headersbuf,
+        };
+        var req = try self.httpClient.open(reqinfo.httpmethod, reqinfo.url, opt);
         defer req.deinit();
         if (reqinfo.payload) |p| {
             req.transfer_encoding = .{ .content_length = p.len };
         }
 
-        try req.start();
+        try req.send();
         if (reqinfo.payload) |p| {
-            req.writer().writeAll(p) catch return Error.LndPayloadWriteFail;
+            req.writeAll(p) catch return Error.LndPayloadWriteFail;
             try req.finish();
         }
         try req.wait();
         if (req.response.status.class() != .success) {
-            // a structured error reporting in lnd is in a less than desirable state.
+            // a structured error reporting in lnd is unclear:
             // https://github.com/lightningnetwork/lnd/issues/5586
             // TODO: return a more detailed error when the upstream improves.
             return Error.LndHttpBadStatusCode;
@@ -181,8 +188,9 @@ pub const Client = struct {
     const HttpReqInfo = struct {
         httpmethod: std.http.Method,
         url: std.Uri,
-        headers: std.http.Headers,
-        payload: ?[]const u8,
+        stdheaders: std.http.Client.Request.Headers = .{}, // overridable standard headers
+        xheaders: []const std.http.Header = &.{}, // any extra headers
+        payload: ?[]const u8 = null,
     };
 
     fn formatreq(self: Client, comptime apimethod: ApiMethod, args: MethodArgs(apimethod)) !types.Deinitable(HttpReqInfo) {
@@ -194,12 +202,10 @@ pub const Client = struct {
             .genseed, .walletstatus => |m| .{
                 .httpmethod = .GET,
                 .url = try std.Uri.parse(try std.fmt.allocPrint(arena, "{s}/{s}", .{ self.apibase, m.apipath() })),
-                .headers = std.http.Headers{ .allocator = arena },
-                .payload = null,
             },
             .initwallet => |m| blk: {
                 const payload = p: {
-                    var params: struct {
+                    const params: struct {
                         wallet_password: []const u8, // base64
                         cipher_seed_mnemonic: []const []const u8,
                         aezeed_passphrase: ?[]const u8 = null, // base64
@@ -215,13 +221,12 @@ pub const Client = struct {
                 break :blk .{
                     .httpmethod = .POST,
                     .url = try std.Uri.parse(try std.fmt.allocPrint(arena, "{s}/{s}", .{ self.apibase, m.apipath() })),
-                    .headers = std.http.Headers{ .allocator = arena },
                     .payload = payload,
                 };
             },
             .unlockwallet => |m| blk: {
                 const payload = p: {
-                    var params: struct {
+                    const params: struct {
                         wallet_password: []const u8, // base64
                     } = .{
                         .wallet_password = try base64EncodeAlloc(arena, args.unlock_password),
@@ -233,20 +238,19 @@ pub const Client = struct {
                 break :blk .{
                     .httpmethod = .POST,
                     .url = try std.Uri.parse(try std.fmt.allocPrint(arena, "{s}/{s}", .{ self.apibase, m.apipath() })),
-                    .headers = std.http.Headers{ .allocator = arena },
                     .payload = payload,
                 };
             },
             .feereport, .getinfo, .getnetworkinfo, .pendingchannels, .walletbalance => |m| .{
                 .httpmethod = .GET,
                 .url = try std.Uri.parse(try std.fmt.allocPrint(arena, "{s}/{s}", .{ self.apibase, m.apipath() })),
-                .headers = blk: {
+                .xheaders = blk: {
                     if (self.macaroon.readonly == null) {
                         return Error.LndHttpMissingMacaroon;
                     }
-                    var h = std.http.Headers{ .allocator = arena };
-                    try h.append(authHeaderName, self.macaroon.readonly.?);
-                    break :blk h;
+                    var h = std.ArrayList(std.http.Header).init(arena);
+                    try h.append(.{ .name = authHeaderName, .value = self.macaroon.readonly.? });
+                    break :blk try h.toOwnedSlice();
                 },
                 .payload = null,
             },
@@ -270,13 +274,13 @@ pub const Client = struct {
                     }
                     break :blk try std.Uri.parse(buf.items); // uri point to the original buf
                 },
-                .headers = blk: {
+                .xheaders = blk: {
                     if (self.macaroon.readonly == null) {
                         return Error.LndHttpMissingMacaroon;
                     }
-                    var h = std.http.Headers{ .allocator = arena };
-                    try h.append(authHeaderName, self.macaroon.readonly.?);
-                    break :blk h;
+                    var h = std.ArrayList(std.http.Header).init(arena);
+                    try h.append(.{ .name = authHeaderName, .value = self.macaroon.readonly.? });
+                    break :blk try h.toOwnedSlice();
                 },
                 .payload = null,
             },
@@ -299,7 +303,7 @@ pub const Client = struct {
     }
 
     fn base64EncodeAlloc(gpa: std.mem.Allocator, v: []const u8) ![]const u8 {
-        var buf = try gpa.alloc(u8, base64enc.calcSize(v.len));
+        const buf = try gpa.alloc(u8, base64enc.calcSize(v.len));
         return base64enc.encode(buf, v); // always returns a slice of buf.len
     }
 };
diff --git a/src/nd.zig b/src/nd.zig
index 2fa573f..abf4d56 100644
--- a/src/nd.zig
+++ b/src/nd.zig
@@ -1,7 +1,6 @@
 const buildopts = @import("build_options");
 const std = @import("std");
-const os = std.os;
-const sys = os.system;
+const posix = std.posix;
 const time = std.time;
 const Address = std.net.Address;
 
@@ -137,7 +136,7 @@ fn sighandler(sig: c_int) callconv(.C) void {
         return;
     }
     switch (sig) {
-        os.SIG.INT, os.SIG.TERM => sigquit.set(),
+        posix.SIG.INT, posix.SIG.TERM => sigquit.set(),
         else => {},
     }
 }
@@ -220,13 +219,13 @@ pub fn main() !void {
     try nd.start();
 
     // graceful shutdown; see sigaction(2)
-    const sa = os.Sigaction{
+    const sa = posix.Sigaction{
         .handler = .{ .handler = sighandler },
-        .mask = os.empty_sigset,
+        .mask = posix.empty_sigset,
         .flags = 0,
     };
-    try os.sigaction(os.SIG.INT, &sa, null);
-    try os.sigaction(os.SIG.TERM, &sa, null);
+    try posix.sigaction(posix.SIG.INT, &sa, null);
+    try posix.sigaction(posix.SIG.TERM, &sa, null);
     sigquit.wait();
     logger.info("sigquit: terminating ...", .{});
 
diff --git a/src/nd/Config.zig b/src/nd/Config.zig
index bf00d2a..ba6f319 100644
--- a/src/nd/Config.zig
+++ b/src/nd/Config.zig
@@ -145,7 +145,7 @@ fn inferStaticData(allocator: std.mem.Allocator) !StaticData {
 }
 
 fn inferLndTorHostname(allocator: std.mem.Allocator) ![]const u8 {
-    var raw = try std.fs.cwd().readFileAlloc(allocator, TOR_DATA_DIR ++ "/lnd/hostname", 1024);
+    const raw = try std.fs.cwd().readFileAlloc(allocator, TOR_DATA_DIR ++ "/lnd/hostname", 1024);
     const hostname = std.mem.trim(u8, raw, &std.ascii.whitespace);
     logger.info("inferred lnd tor hostname: [{s}]", .{hostname});
     return hostname;
@@ -156,7 +156,7 @@ fn inferBitcoindRpcPass(allocator: std.mem.Allocator) ![]const u8 {
     // the password was placed on a separate comment line, preceding another comment
     // line containing "rpcauth.py".
     // TODO: get rid of the hack; do something more robust
-    var conf = try std.fs.cwd().readFileAlloc(allocator, BITCOIND_CONFIG_PATH, 1024 * 1024);
+    const conf = try std.fs.cwd().readFileAlloc(allocator, BITCOIND_CONFIG_PATH, 1024 * 1024);
     var it = std.mem.tokenizeScalar(u8, conf, '\n');
     var next_is_pass = false;
     while (it.next()) |line| {
@@ -346,7 +346,7 @@ fn genSysupdatesCronScript(self: Config) !void {
 ///
 /// the caller must serialize this function calls.
 fn runSysupdates(allocator: std.mem.Allocator, scriptpath: []const u8) !void {
-    const res = try std.ChildProcess.exec(.{ .allocator = allocator, .argv = &.{scriptpath} });
+    const res = try std.ChildProcess.run(.{ .allocator = allocator, .argv = &.{scriptpath} });
     defer {
         allocator.free(res.stdout);
         allocator.free(res.stderr);
@@ -383,7 +383,7 @@ pub fn lndConnectWaitMacaroonFile(self: Config, allocator: std.mem.Allocator, ty
     defer allocator.free(macaroon);
 
     const base64enc = std.base64.url_safe_no_pad.Encoder;
-    var buf = try allocator.alloc(u8, base64enc.calcSize(macaroon.len));
+    const buf = try allocator.alloc(u8, base64enc.calcSize(macaroon.len));
     defer allocator.free(buf);
     const macaroon_b64 = base64enc.encode(buf, macaroon);
     const port: u16 = switch (typ) {
@@ -599,7 +599,7 @@ test "ndconfig: switch sysupdates with .run=true" {
     const tt = @import("../test.zig");
 
     // no arena deinit here: expecting Config to auto-deinit.
-    var conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
+    const conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
     conf_arena.* = std.heap.ArenaAllocator.init(std.testing.allocator);
     var tmp = try tt.TempDir.create();
     defer tmp.cleanup();
@@ -644,7 +644,7 @@ test "ndconfig: genLndConfig" {
     const tt = @import("../test.zig");
 
     // Config auto-deinits the arena.
-    var conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
+    const conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
     conf_arena.* = std.heap.ArenaAllocator.init(std.testing.allocator);
     var tmp = try tt.TempDir.create();
     defer tmp.cleanup();
@@ -695,7 +695,7 @@ test "ndconfig: mutate LndConf" {
     const tt = @import("../test.zig");
 
     // Config auto-deinits the arena.
-    var conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
+    const conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
     conf_arena.* = std.heap.ArenaAllocator.init(t.allocator);
     var tmp = try tt.TempDir.create();
     defer tmp.cleanup();
@@ -737,7 +737,7 @@ test "ndconfig: screen lock" {
     const tt = @import("../test.zig");
 
     // Config auto-deinits the arena.
-    var conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
+    const conf_arena = try std.testing.allocator.create(std.heap.ArenaAllocator);
     conf_arena.* = std.heap.ArenaAllocator.init(t.allocator);
     var tmp = try tt.TempDir.create();
     defer tmp.cleanup();
diff --git a/src/nd/Daemon.zig b/src/nd/Daemon.zig
index 6bf16c0..7e32982 100644
--- a/src/nd/Daemon.zig
+++ b/src/nd/Daemon.zig
@@ -548,7 +548,9 @@ fn unlockScreen(self: *Daemon, pincode: []const u8) !void {
     defer self.allocator.free(pindup);
     // TODO: slow down
     self.conf.verifySlockPin(pindup) catch |err| {
-        logger.err("verifySlockPin: {!}", .{err});
+        if (!builtin.is_test) { // logging err makes some tests fail
+            logger.err("verifySlockPin: {!}", .{err});
+        }
         const errmsg: comm.Message = .{ .screen_unlock_result = .{
             .ok = false,
             .err = if (err == error.IncorrectSlockPin) "incorrect pin code" else "unlock failed",
@@ -562,7 +564,7 @@ fn unlockScreen(self: *Daemon, pincode: []const u8) !void {
 
 /// sends poweroff progress to uiwriter in comm.Message.PoweroffProgress format.
 fn sendPoweroffReport(self: *Daemon) !void {
-    var svstat = try self.allocator.alloc(comm.Message.PoweroffProgress.Service, self.services.list.len);
+    const svstat = try self.allocator.alloc(comm.Message.PoweroffProgress.Service, self.services.list.len);
     defer self.allocator.free(svstat);
     for (self.services.list, svstat) |*sv, *stat| {
         stat.* = .{
@@ -962,7 +964,7 @@ fn processLndReportError(self: *Daemon, err: anyerror) !void {
         error.FileNotFound, // tls cert file missing, not re-generated by lnd yet
         => return comm.write(self.allocator, self.uiwriter, msg_starting),
         // old tls cert, refused by our http client
-        std.http.Client.ConnectUnproxiedError.TlsInitializationFailed => {
+        std.http.Client.ConnectTcpError.TlsInitializationFailed => {
             try self.resetLndTlsUnguarded();
             return error.LndReportRetryLater;
         },
@@ -1006,7 +1008,7 @@ fn sendLightningPairingConn(self: *Daemon) !void {
     defer self.allocator.free(tor_rpc);
     const tor_http = try self.conf.lndConnectWaitMacaroonFile(self.allocator, .tor_http);
     defer self.allocator.free(tor_http);
-    var conn: comm.Message.LightningCtrlConn = &.{
+    const conn: comm.Message.LightningCtrlConn = &.{
         .{ .url = tor_rpc, .typ = .lnd_rpc, .perm = .admin },
         .{ .url = tor_http, .typ = .lnd_http, .perm = .admin },
     };
@@ -1257,7 +1259,7 @@ fn setNodenameInternal(self: *Daemon, newname: []const u8) !void {
 /// replaces whitespace with space literal and ignores ascii control chars.
 /// caller owns returned value.
 fn allocSanitizeNodename(allocator: std.mem.Allocator, name: []const u8) ![]const u8 {
-    if (name.len == 0 or try std.unicode.utf8CountCodepoints(name) > std.os.HOST_NAME_MAX) {
+    if (name.len == 0 or try std.unicode.utf8CountCodepoints(name) > std.posix.HOST_NAME_MAX) {
         return error.InvalidNodenameLength;
     }
     var sanitized = try std.ArrayList(u8).initCapacity(allocator, name.len);
@@ -1448,7 +1450,7 @@ test "daemon: screen unlock" {
 
 fn dummyTestConfig() !Config {
     const talloc = std.testing.allocator;
-    var arena = try talloc.create(std.heap.ArenaAllocator);
+    const arena = try talloc.create(std.heap.ArenaAllocator);
     arena.* = std.heap.ArenaAllocator.init(talloc);
     return Config{
         .arena = arena,
diff --git a/src/nd/network.zig b/src/nd/network.zig
index 610d315..d669afc 100644
--- a/src/nd/network.zig
+++ b/src/nd/network.zig
@@ -86,7 +86,7 @@ pub fn sendReport(gpa: mem.Allocator, wpa_ctrl: *types.WpaControl, w: anytype) !
     };
 
     // fetch available wifi networks from scan results using WPA ctrl
-    var wifi_networks: ?types.StringList = if (queryWifiScanResults(arena, wpa_ctrl)) |v| v else |err| blk: {
+    const wifi_networks: ?types.StringList = if (queryWifiScanResults(arena, wpa_ctrl)) |v| v else |err| blk: {
         logger.err("queryWifiScanResults: {any}", .{err});
         break :blk null;
     };
diff --git a/src/ngui.zig b/src/ngui.zig
index bf6db69..2f72f3b 100644
--- a/src/ngui.zig
+++ b/src/ngui.zig
@@ -1,6 +1,6 @@
 const buildopts = @import("build_options");
 const std = @import("std");
-const os = std.os;
+const posix = std.posix;
 const time = std.time;
 
 const comm = @import("comm.zig");
@@ -291,7 +291,7 @@ fn commThreadLoopCycle() !void {
 fn uiThreadLoop() void {
     while (true) {
         ui_mutex.lock();
-        var till_next_ms = lvgl.loopCycle(); // UI loop
+        const till_next_ms = lvgl.loopCycle(); // UI loop
         const do_state = state;
         ui_mutex.unlock();
 
@@ -391,7 +391,7 @@ fn sighandler(sig: c_int) callconv(.C) void {
         return;
     }
     switch (sig) {
-        os.SIG.INT, os.SIG.TERM => sigquit.set(),
+        posix.SIG.INT, posix.SIG.TERM => sigquit.set(),
         else => {},
     }
 }
@@ -440,13 +440,13 @@ pub fn main() anyerror!void {
     }
 
     // set up a sigterm handler for clean exit.
-    const sa = os.Sigaction{
+    const sa = posix.Sigaction{
         .handler = .{ .handler = sighandler },
-        .mask = os.empty_sigset,
+        .mask = posix.empty_sigset,
         .flags = 0,
     };
-    try os.sigaction(os.SIG.INT, &sa, null);
-    try os.sigaction(os.SIG.TERM, &sa, null);
+    try posix.sigaction(posix.SIG.INT, &sa, null);
+    try posix.sigaction(posix.SIG.TERM, &sa, null);
     sigquit.wait();
     logger.info("sigquit: terminating ...", .{});
 
diff --git a/src/sys/sysimpl.zig b/src/sys/sysimpl.zig
index 137a6ab..be38d25 100644
--- a/src/sys/sysimpl.zig
+++ b/src/sys/sysimpl.zig
@@ -5,8 +5,8 @@ const types = @import("../types.zig");
 
 /// caller owns memory; must dealloc using `allocator`.
 pub fn hostname(allocator: std.mem.Allocator) ![]const u8 {
-    var buf: [std.os.HOST_NAME_MAX]u8 = undefined;
-    const name = try std.os.gethostname(&buf);
+    var buf: [std.posix.HOST_NAME_MAX]u8 = undefined;
+    const name = try std.posix.gethostname(&buf);
     return allocator.dupe(u8, name);
 }
 
@@ -40,8 +40,8 @@ pub fn setHostname(allocator: std.mem.Allocator, name: []const u8) !void {
     const newname = sanitized.items;
 
     // need not continue if current name matches the new one.
-    var buf: [std.os.HOST_NAME_MAX]u8 = undefined;
-    const currname = try std.os.gethostname(&buf);
+    var buf: [std.posix.HOST_NAME_MAX]u8 = undefined;
+    const currname = try std.posix.gethostname(&buf);
     if (std.mem.eql(u8, currname, newname)) {
         return;
     }
diff --git a/src/test.zig b/src/test.zig
index 5fa23e8..4cc583b 100644
--- a/src/test.zig
+++ b/src/test.zig
@@ -37,7 +37,7 @@ pub fn initGlobal() void {
 fn initGlobalFn() void {
     global_gpa_state = std.heap.GeneralPurposeAllocator(.{}){};
     global_gpa = global_gpa_state.allocator();
-    var pipe = types.IoPipe.create() catch |err| {
+    const pipe = types.IoPipe.create() catch |err| {
         std.debug.panic("IoPipe.create: {any}", .{err});
     };
     comm.initPipe(global_gpa, pipe);
@@ -118,7 +118,7 @@ pub const TestChildProcess = struct {
     argv: []const []const u8,
 
     pub fn init(argv: []const []const u8, allocator: std.mem.Allocator) TestChildProcess {
-        var adup = allocator.alloc([]u8, argv.len) catch unreachable;
+        const adup = allocator.alloc([]u8, argv.len) catch unreachable;
         for (argv, adup) |v, *dup| {
             dup.* = allocator.dupe(u8, v) catch unreachable;
         }
@@ -242,7 +242,7 @@ pub fn expectDeepEqual(expected: anytype, actual: @TypeOf(expected)) !void {
                 .Slice => {
                     switch (@typeInfo(p.child)) {
                         .Pointer, .Struct, .Optional, .Union => {
-                            var err: ?anyerror = blk: {
+                            const err: ?anyerror = blk: {
                                 if (expected.len != actual.len) {
                                     std.debug.print("expected.len = {d}, actual.len = {d}\n", .{ expected.len, actual.len });
                                     break :blk error.ExpectDeepEqual;
@@ -331,6 +331,7 @@ test {
     _ = @import("ngui.zig");
     _ = @import("lightning.zig");
     _ = @import("sys.zig");
+    _ = @import("xfmt.zig");
 
     std.testing.refAllDecls(@This());
 }
diff --git a/src/test/guiplay.zig b/src/test/guiplay.zig
index c0734c3..db6f807 100644
--- a/src/test/guiplay.zig
+++ b/src/test/guiplay.zig
@@ -1,6 +1,6 @@
 const std = @import("std");
 const time = std.time;
-const os = std.os;
+const posix = std.posix;
 
 const comm = @import("comm");
 const types = @import("../types.zig");
@@ -12,9 +12,9 @@ var ngui_proc: std.ChildProcess = undefined;
 var sigquit: std.Thread.ResetEvent = .{};
 
 fn sighandler(sig: c_int) callconv(.C) void {
-    logger.info("received signal {} (TERM={} INT={})", .{ sig, os.SIG.TERM, os.SIG.INT });
+    logger.info("received signal {} (TERM={} INT={})", .{ sig, posix.SIG.TERM, posix.SIG.INT });
     switch (sig) {
-        os.SIG.INT, os.SIG.TERM => sigquit.set(),
+        posix.SIG.INT, posix.SIG.TERM => sigquit.set(),
         else => {},
     }
 }
@@ -79,7 +79,7 @@ fn parseArgs(gpa: std.mem.Allocator) !Flags {
 /// global vars for comm read/write threads
 var state: struct {
     mu: std.Thread.Mutex = .{},
-    nodename: types.BufTrimString(std.os.HOST_NAME_MAX) = .{},
+    nodename: types.BufTrimString(std.posix.HOST_NAME_MAX) = .{},
     slock_pincode: ?[]const u8 = null, // disabled when null
     settings_sent: bool = false,
 
@@ -114,7 +114,7 @@ fn commReadThread(gpa: std.mem.Allocator, r: anytype, w: anytype) void {
             },
             .poweroff => {
                 logger.info("sending poweroff status1", .{});
-                var s1: comm.Message.PoweroffProgress = .{ .services = &.{
+                const s1: comm.Message.PoweroffProgress = .{ .services = &.{
                     .{ .name = "lnd", .stopped = false, .err = null },
                     .{ .name = "bitcoind", .stopped = false, .err = null },
                 } };
@@ -122,7 +122,7 @@ fn commReadThread(gpa: std.mem.Allocator, r: anytype, w: anytype) void {
 
                 time.sleep(2 * time.ns_per_s);
                 logger.info("sending poweroff status2", .{});
-                var s2: comm.Message.PoweroffProgress = .{ .services = &.{
+                const s2: comm.Message.PoweroffProgress = .{ .services = &.{
                     .{ .name = "lnd", .stopped = true, .err = null },
                     .{ .name = "bitcoind", .stopped = false, .err = null },
                 } };
@@ -130,7 +130,7 @@ fn commReadThread(gpa: std.mem.Allocator, r: anytype, w: anytype) void {
 
                 time.sleep(3 * time.ns_per_s);
                 logger.info("sending poweroff status3", .{});
-                var s3: comm.Message.PoweroffProgress = .{ .services = &.{
+                const s3: comm.Message.PoweroffProgress = .{ .services = &.{
                     .{ .name = "lnd", .stopped = true, .err = null },
                     .{ .name = "bitcoind", .stopped = true, .err = null },
                 } };
@@ -149,7 +149,7 @@ fn commReadThread(gpa: std.mem.Allocator, r: anytype, w: anytype) void {
                 time.sleep(3 * time.ns_per_s);
             },
             .lightning_get_ctrlconn => {
-                var conn: comm.Message.LightningCtrlConn = &.{
+                const conn: comm.Message.LightningCtrlConn = &.{
                     .{ .url = "lndconnect://adfkjhadwaepoijsadflkjtrpoijawokjafulkjsadfkjhgjfdskjszd.onion:10009?macaroon=Adasjsadkfljhfjhasdpiuhfiuhawfffoihgpoiadsfjharpoiuhfdsgpoihafdsgpoiheafoiuhasdfhisdufhiuhfewiuhfiuhrfl6prrx", .typ = .lnd_rpc, .perm = .admin },
                     .{ .url = "lndconnect://adfkjhadwaepoijsadflkjtrpoijawokjafulkjsadfkjhgjfdskjszd.onion:10010?macaroon=Adasjsadkfljhfjhasdpiuhfiuhawfffoihgpoiadsfjharpoiuhfdsgpoihafdsgpoiheafoiuhasdfhisdufhiuhfewiuhfiuhrfl6prrx", .typ = .lnd_http, .perm = .admin },
                 };
@@ -374,13 +374,13 @@ pub fn main() !void {
     const th2 = try std.Thread.spawn(.{}, commWriteThread, .{ gpa, uiwriter });
     th2.detach();
 
-    const sa = os.Sigaction{
+    const sa = posix.Sigaction{
         .handler = .{ .handler = sighandler },
-        .mask = os.empty_sigset,
+        .mask = posix.empty_sigset,
         .flags = 0,
     };
-    try os.sigaction(os.SIG.INT, &sa, null);
-    try os.sigaction(os.SIG.TERM, &sa, null);
+    try posix.sigaction(posix.SIG.INT, &sa, null);
+    try posix.sigaction(posix.SIG.TERM, &sa, null);
     sigquit.wait();
 
     logger.info("killing ngui", .{});
diff --git a/src/types.zig b/src/types.zig
index 689567a..d83676f 100644
--- a/src/types.zig
+++ b/src/types.zig
@@ -40,8 +40,8 @@ pub const IoPipe = struct {
     w: std.fs.File,
 
     /// a pipe must be close'ed when done.
-    pub fn create() std.os.PipeError!IoPipe {
-        const fds = try std.os.pipe();
+    pub fn create() std.posix.PipeError!IoPipe {
+        const fds = try std.posix.pipe();
         return .{
             .r = std.fs.File{ .handle = fds[0] },
             .w = std.fs.File{ .handle = fds[1] },
@@ -138,7 +138,7 @@ pub fn Deinitable(comptime T: type) type {
         const Self = @This();
 
         pub fn init(allocator: std.mem.Allocator) !Self {
-            var res = Self{
+            const res = Self{
                 .arena = try allocator.create(std.heap.ArenaAllocator),
                 .value = undefined,
             };
diff --git a/src/ui/drv.zig b/src/ui/drv.zig
index bd94f63..18c3fb4 100644
--- a/src/ui/drv.zig
+++ b/src/ui/drv.zig
@@ -46,9 +46,9 @@ pub usingnamespace switch (buildopts.driver) {
         }
     },
     .fbev => struct {
-        extern "c" fn nm_open_evdev_nonblock() std.os.fd_t;
-        extern "c" fn nm_close_evdev(fd: std.os.fd_t) void;
-        extern "c" fn nm_consume_input_events(fd: std.os.fd_t) bool;
+        extern "c" fn nm_open_evdev_nonblock() std.posix.fd_t;
+        extern "c" fn nm_close_evdev(fd: std.posix.fd_t) void;
+        extern "c" fn nm_consume_input_events(fd: std.posix.fd_t) bool;
 
         pub fn InputWatcher() !EvdevWatcher {
             const fd = nm_open_evdev_nonblock();
@@ -59,7 +59,7 @@ pub usingnamespace switch (buildopts.driver) {
         }
 
         pub const EvdevWatcher = struct {
-            evdev_fd: std.os.fd_t,
+            evdev_fd: std.posix.fd_t,
 
             pub fn consume(self: @This()) bool {
                 return nm_consume_input_events(self.evdev_fd);
diff --git a/src/ui/lightning.zig b/src/ui/lightning.zig
index d178118..778931d 100644
--- a/src/ui/lightning.zig
+++ b/src/ui/lightning.zig
@@ -99,7 +99,7 @@ var tab: struct {
     } = null,
 
     fn initSetup(self: *@This(), topwin: lvgl.Window) !void {
-        var arena = try self.allocator.create(std.heap.ArenaAllocator);
+        const arena = try self.allocator.create(std.heap.ArenaAllocator);
         arena.* = std.heap.ArenaAllocator.init(tab.allocator);
         self.seed_setup = .{ .arena = arena, .topwin = topwin };
     }
diff --git a/src/ui/lvgl.zig b/src/ui/lvgl.zig
index 059a163..3283415 100644
--- a/src/ui/lvgl.zig
+++ b/src/ui/lvgl.zig
@@ -719,7 +719,7 @@ pub const Label = struct {
 
     /// the text value is copied into a heap-allocated alloc.
     pub fn new(parent: anytype, text: ?[*:0]const u8, opt: Opt) !Label {
-        var lv_label = lv_label_create(parent.lvobj) orelse return error.OutOfMemory;
+        const lv_label = lv_label_create(parent.lvobj) orelse return error.OutOfMemory;
         if (text) |s| {
             lv_label_set_text(lv_label, s);
         }
@@ -757,7 +757,7 @@ pub const Label = struct {
     /// formats a new label text and passes it on to `setText`.
     /// the buffer can be dropped once the function returns.
     pub fn setTextFmt(self: Label, buf: []u8, comptime format: []const u8, args: anytype) !void {
-        var s = try std.fmt.bufPrintZ(buf, format, args);
+        const s = try std.fmt.bufPrintZ(buf, format, args);
         self.setText(s);
     }
 
diff --git a/src/ui/settings.zig b/src/ui/settings.zig
index 53f3932..f646057 100644
--- a/src/ui/settings.zig
+++ b/src/ui/settings.zig
@@ -75,7 +75,7 @@ var tab: struct {
 var state: struct {
     // node name
     nodename_change_inprogress: bool = false,
-    curr_nodename: types.BufTrimString(std.os.HOST_NAME_MAX) = .{},
+    curr_nodename: types.BufTrimString(std.posix.HOST_NAME_MAX) = .{},
     // screenlock
     slock_pin_input1: ?[]const u8 = null, // verified against a second time input
     // sysupdates channel
@@ -111,7 +111,7 @@ pub fn initNodenamePanel(cont: lvgl.Container) !lvgl.Card {
     right.setPad(0, .column, .{});
 
     tab.nodename.textarea = try lvgl.TextArea.new(right, .{
-        .maxlen = std.os.HOST_NAME_MAX,
+        .maxlen = std.posix.HOST_NAME_MAX,
         .oneline = true,
     });
     tab.nodename.textarea.setWidth(lvgl.sizePercent(100));
diff --git a/src/xfmt.zig b/src/xfmt.zig
index 0460f86..db7af22 100644
--- a/src/xfmt.zig
+++ b/src/xfmt.zig
@@ -41,12 +41,11 @@ fn formatUnix(sec: u64, comptime fmt: []const u8, opts: std.fmt.FormatOptions, w
 }
 
 fn formatMetricI(value: i64, comptime fmt: []const u8, opts: std.fmt.FormatOptions, w: anytype) !void {
-    const uval: u64 = std.math.absCast(value);
+    const uval: u64 = @abs(value);
     const base: u64 = 1000;
     if (uval < base) {
         return std.fmt.formatIntValue(value, fmt, opts, w);
     }
-
     if (value < 0) {
         try w.writeByte('-');
     }
@@ -64,8 +63,60 @@ fn formatMetricU(value: u64, comptime fmt: []const u8, opts: std.fmt.FormatOptio
     const mags_si = " kMGTPEZY";
     const log2 = std.math.log2(value);
     const m = @min(log2 / comptime std.math.log2(base), mags_si.len - 1);
-    const newval = lossyCast(f64, value) / std.math.pow(f64, lossyCast(f64, base), lossyCast(f64, m));
     const suffix = mags_si[m];
-    try std.fmt.formatFloatDecimal(newval, opts, w);
+    const newval: f64 = lossyCast(f64, value) / std.math.pow(f64, lossyCast(f64, base), lossyCast(f64, m));
+    try std.fmt.formatType(newval, "d", opts, w, 0);
     try w.writeByte(suffix);
 }
+
+test "unix" {
+    const t = std.testing;
+    var buf: [1024]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&buf);
+    try std.fmt.format(fbs.writer(), "{}", .{unix(1136239445)});
+    try t.expectEqualStrings("2006-01-02 22:04:05 UTC", fbs.getWritten());
+}
+
+test "imetric" {
+    const t = std.testing;
+    var buf: [1024]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&buf);
+
+    const table: []const struct { val: i64, str: []const u8 } = &.{
+        .{ .val = 0, .str = "0" },
+        .{ .val = -13, .str = "-13" },
+        .{ .val = 1000, .str = "1k" },
+        .{ .val = -1234, .str = "-1.234k" },
+        .{ .val = 12340, .str = "12.34k" },
+        .{ .val = -123400, .str = "-123.4k" },
+        .{ .val = 1234000, .str = "1.234M" },
+        .{ .val = -1234000000, .str = "-1.234G" },
+    };
+    for (table) |item| {
+        fbs.reset();
+        try std.fmt.format(fbs.writer(), "{}", .{imetric(item.val)});
+        try t.expectEqualStrings(item.str, fbs.getWritten());
+    }
+}
+
+test "umetric" {
+    const t = std.testing;
+    var buf: [1024]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&buf);
+
+    const table: []const struct { val: u64, str: []const u8 } = &.{
+        .{ .val = 0, .str = "0" },
+        .{ .val = 13, .str = "13" },
+        .{ .val = 1000, .str = "1k" },
+        .{ .val = 1234, .str = "1.234k" },
+        .{ .val = 12340, .str = "12.34k" },
+        .{ .val = 123400, .str = "123.4k" },
+        .{ .val = 1234000, .str = "1.234M" },
+        .{ .val = 1234000000, .str = "1.234G" },
+    };
+    for (table) |item| {
+        fbs.reset();
+        try std.fmt.format(fbs.writer(), "{}", .{umetric(item.val)});
+        try t.expectEqualStrings(item.str, fbs.getWritten());
+    }
+}
diff --git a/tools/ci-containerfile b/tools/ci-containerfile
index 021587d..0b94896 100644
--- a/tools/ci-containerfile
+++ b/tools/ci-containerfile
@@ -1,9 +1,9 @@
 # ci container file for compiling and testing zig projects.
 # requires a ZIGURL build arg. for instance:
-# podman build --rm -t ci-zig0.11.0 -f ci-containerfile \
-#   --build-arg ZIGURL=https://ziglang.org/download/0.11.0/zig-linux-x86_64-0.11.0.tar.xz
+# podman build --rm -t ci-zig0.12.0 -f ci-containerfile \
+#   --build-arg ZIGURL=https://ziglang.org/download/0.12.0/zig-linux-x86_64-0.12.0.tar.xz
 
-FROM alpine:3.18.3
+FROM alpine:3.18.6
 
 ARG ZIGURL
 RUN apk add --no-cache git curl xz libc-dev sdl2-dev clang16-extra-tools && \