Restore the universal VST3 build, GUI example, and parameter store

.gitignore

@@ -8,3 +8,6 @@ zig-cache/
 
 # macOS
 .DS_Store
+
+# Audio test artifacts produced by the standalone processor
+*.wav

build.zig

@@ -1,5 +1,7 @@
 const std = @import("std");
 
+const VERSION = "0.1.0";
+
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
@@ -24,8 +26,9 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
     });
+    danzig_gain.root_module.addImport("danzig", danzig_module);
     danzig_gain.linkLibrary(danzig_lib);
-    
+
     // Install to zig-out/lib/
     b.installArtifact(danzig_gain);
 
@@ -50,18 +53,41 @@ pub fn build(b: *std.Build) void {
     danzig_gain_standalone.linkLibrary(danzig_lib);
     b.installArtifact(danzig_gain_standalone);
 
+    const run_standalone = b.addRunArtifact(danzig_gain_standalone);
+    const run_standalone_step = b.step("run-standalone", "Run the standalone audio processor");
+    run_standalone_step.dependOn(&run_standalone.step);
+
     // Web UI server
     const danzig_webui = b.addExecutable(.{
         .name = "danzig-webui",
         .root_source_file = b.path("examples/danzig-webui/root.zig"),
         .target = target,
         .optimize = optimize,
     });
-
     danzig_webui.root_module.addImport("danzig", danzig_module);
     danzig_webui.linkLibrary(danzig_lib);
     b.installArtifact(danzig_webui);
 
+    // --- Universal VST3 bundle (macOS) ---------------------------------------
+    //
+    // A VST3 plugin ships as a bundle holding one universal binary, so hosts of
+    // either architecture load the same file. Built per-arch and merged with
+    // lipo. Kept behind the `vst3` step rather than the default install,
+    // because it doubles compile work and only applies to macOS.
+    if (target.result.os.tag == .macos) {
+        addVst3Bundle(b, optimize, danzig_module);
+    }
+
+    // --- GUI example (macOS) -------------------------------------------------
+    //
+    // Needs the webview dependency, so it is only wired up when that has been
+    // fetched. Links CoreAudio for device IO and WebKit via webview.
+    if (target.result.os.tag == .macos) {
+        if (b.lazyDependency("webview", .{ .target = target, .optimize = optimize })) |webview_dep| {
+            addGuiExample(b, target, optimize, danzig_module, danzig_lib, webview_dep);
+        }
+    }
+
     // Unit tests — pure Zig, no artifact or host required
     const unit_tests = b.addTest(.{
         .root_source_file = b.path("src/tests.zig"),
@@ -73,10 +99,148 @@ pub fn build(b: *std.Build) void {
     const unit_test_step = b.step("test-unit", "Run unit tests only");
     unit_test_step.dependOn(&run_unit_tests.step);
 
+    // Integration tests — drives the built plugin through the raw VST3 C ABI
+    const run_test = b.addRunArtifact(danzig_test);
+    const integration_test_step = b.step("test-integration", "Run VST3 ABI integration tests only");
+    integration_test_step.dependOn(&run_test.step);
+
     // Test step
     const test_step = b.step("test", "Run tests");
-    const run_test = b.addRunArtifact(danzig_test);
     test_step.dependOn(&run_unit_tests.step);
     test_step.dependOn(&run_test.step);
 }
 
+/// Build DanzigGain for both macOS architectures, merge them into one
+/// universal binary, and lay out the .vst3 bundle around it.
+fn addVst3Bundle(
+    b: *std.Build,
+    optimize: std.builtin.OptimizeMode,
+    danzig_module: *std.Build.Module,
+) void {
+    const arches = [_]std.Target.Cpu.Arch{ .aarch64, .x86_64 };
+    const suffixes = [_][]const u8{ "arm64", "x86" };
+
+    const lipo = b.addSystemCommand(&.{ "lipo", "-create" });
+
+    inline for (arches, suffixes) |arch, suffix| {
+        const arch_target = b.resolveTargetQuery(.{ .cpu_arch = arch, .os_tag = .macos });
+
+        const lib = b.addStaticLibrary(.{
+            .name = "danzig_" ++ suffix,
+            .root_source_file = b.path("src/root.zig"),
+            .target = arch_target,
+            .optimize = optimize,
+        });
+
+        const plugin = b.addSharedLibrary(.{
+            .name = "DanzigGain_" ++ suffix,
+            .root_source_file = b.path("examples/danzig-gain/root.zig"),
+            .target = arch_target,
+            .optimize = optimize,
+        });
+        plugin.root_module.addImport("danzig", danzig_module);
+        plugin.linkLibrary(lib);
+        b.installArtifact(plugin);
+
+        lipo.addArtifactArg(plugin);
+    }
+
+    lipo.addArg("-output");
+    const universal = lipo.addOutputFileArg("DanzigGain");
+
+    // VST3 bundles carry no file extension on the executable itself.
+    const bundle = b.addWriteFiles();
+    _ = bundle.add("Contents/Info.plist", infoPlist(b));
+    _ = bundle.add("Contents/PkgInfo", "BNDL????");
+    _ = bundle.addCopyFile(universal, "Contents/MacOS/DanzigGain");
+
+    const install_bundle = b.addInstallDirectory(.{
+        .source_dir = bundle.getDirectory(),
+        .install_dir = .prefix,
+        .install_subdir = "DanzigGain.vst3",
+    });
+
+    const vst3_step = b.step("vst3", "Build and package the universal VST3 bundle");
+    vst3_step.dependOn(&install_bundle.step);
+
+    // Hosts scan ~/Library/Audio/Plug-Ins/VST3 on macOS.
+    const install_cmd = b.addSystemCommand(&.{ "sh", "-c", "rm -rf \"$HOME/Library/Audio/Plug-Ins/VST3/DanzigGain.vst3\" && " ++
+        "mkdir -p \"$HOME/Library/Audio/Plug-Ins/VST3\" && " ++
+        "cp -R \"$1\" \"$HOME/Library/Audio/Plug-Ins/VST3/DanzigGain.vst3\"", "sh" });
+    install_cmd.addDirectoryArg(bundle.getDirectory());
+
+    const install_vst3_step = b.step("install-vst3", "Install the VST3 bundle to ~/Library/Audio/Plug-Ins/VST3/");
+    install_vst3_step.dependOn(&install_cmd.step);
+}
+
+/// Standalone GUI host: a webview front end driving the gain processor over
+/// CoreAudio.
+fn addGuiExample(
+    b: *std.Build,
+    target: std.Build.ResolvedTarget,
+    optimize: std.builtin.OptimizeMode,
+    danzig_module: *std.Build.Module,
+    danzig_lib: *std.Build.Step.Compile,
+    webview_dep: *std.Build.Dependency,
+) void {
+    const coreaudio_module = b.addModule("coreaudio", .{
+        .root_source_file = b.path("examples/danzig-gain-ui/coreaudio.zig"),
+    });
+
+    const gui = b.addExecutable(.{
+        .name = "danzig-gain-ui",
+        .root_source_file = b.path("examples/danzig-gain-ui/root.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+    gui.root_module.addImport("danzig", danzig_module);
+    gui.root_module.addImport("coreaudio", coreaudio_module);
+    gui.root_module.addImport("webview", webview_dep.module("webview"));
+    // The Zig bindings are declarations only; the implementation is webview's
+    // C++ core, which the dependency exposes as a static library.
+    gui.linkLibrary(webview_dep.artifact("webviewStatic"));
+    // The UI is embedded rather than read at runtime, so the binary is
+    // self-contained.
+    gui.root_module.addAnonymousImport("ui_html", .{ .root_source_file = b.path("ui/index.html") });
+    gui.linkLibrary(danzig_lib);
+    gui.linkFramework("CoreAudio");
+    gui.linkFramework("CoreFoundation");
+    b.installArtifact(gui);
+
+    const run_gui = b.addRunArtifact(gui);
+    const run_gui_step = b.step("run-gui", "Run the standalone GUI app");
+    run_gui_step.dependOn(&run_gui.step);
+}
+
+fn infoPlist(b: *std.Build) []const u8 {
+    const template =
+        \\<?xml version="1.0" encoding="UTF-8"?>
+        \\<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+        \\<plist version="1.0">
+        \\<dict>
+        \\    <key>CFBundleExecutable</key>
+        \\    <string>DanzigGain</string>
+        \\    <key>CFBundleIdentifier</key>
+        \\    <string>com.danzig.DanzigGain</string>
+        \\    <key>CFBundleName</key>
+        \\    <string>DanzigGain</string>
+        \\    <key>CFBundleDisplayName</key>
+        \\    <string>Danzig Gain</string>
+        \\    <key>CFBundlePackageType</key>
+        \\    <string>BNDL</string>
+        \\    <key>CFBundleSignature</key>
+        \\    <string>????</string>
+        \\    <key>CFBundleVersion</key>
+        \\    <string>{s}</string>
+        \\    <key>CFBundleShortVersionString</key>
+        \\    <string>{s}</string>
+        \\    <key>CFBundleInfoDictionaryVersion</key>
+        \\    <string>6.0</string>
+        \\    <key>CSResourcesFileMapped</key>
+        \\    <true/>
+        \\</dict>
+        \\</plist>
+        \\
+    ;
+    return b.fmt(template, .{ VERSION, VERSION });
+}

build.zig.zon

@@ -0,0 +1,18 @@
+.{
+    .name = .danzig,
+    .version = "0.1.0",
+    .fingerprint = 0x6383fbb1d610c5a6,
+    .dependencies = .{
+        .webview = .{
+            .url = "https://github.com/thechampagne/webview-zig/archive/5abc215.tar.gz",
+            .hash = "webview-0.1.0-ImQK_yb6IADsgQL8f72LGd4xkaSrxqQn9RyYy3U36s1J",
+        },
+    },
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        "examples",
+        "ui",
+    },
+}