Build in the review tool.

build.zig

@@ -47,6 +47,40 @@ pub fn build(b: *std.Build) void {
         .root_source_file = icons_gresource,
     });
 
+    // The review pane's UI. It is a React app (see `web/`), built by Vite here so
+    // the bundle embedded in the binary can never be older than the source it
+    // came from, and embedded rather than installed alongside so a review pane
+    // is a web view pointed at this process and nothing else.
+    //
+    // The four filenames are pinned in `web/vite.config.ts` precisely so they
+    // can be named at compile time; `src/review/assets.zig` is the other half of
+    // that agreement.
+    const web_build = b.addSystemCommand(&.{ "npm", "run", "--silent", "build", "--" });
+    web_build.setCwd(b.path("web"));
+    web_build.setName("vite build (review UI)");
+    web_build.addArg("--outDir");
+    const web_dist = web_build.addOutputDirectoryArg("dist");
+    web_build.addArg("--emptyOutDir");
+
+    // Vite is not told what its inputs are, so the Run step has to be. Without
+    // this the bundle is cached against its argv alone and editing the UI would
+    // rebuild nothing; with it, `zig build` after a `.tsx` edit does the right
+    // thing and `zig build` after a `.zig` edit does not re-run npm.
+    addWebInputs(b, web_build);
+
+    exe.root_module.addAnonymousImport("review-index.html", .{
+        .root_source_file = web_dist.path(b, "index.html"),
+    });
+    exe.root_module.addAnonymousImport("review-app.js", .{
+        .root_source_file = web_dist.path(b, "assets/app.js"),
+    });
+    exe.root_module.addAnonymousImport("review-app.css", .{
+        .root_source_file = web_dist.path(b, "assets/app.css"),
+    });
+    exe.root_module.addAnonymousImport("review-favicon.svg", .{
+        .root_source_file = web_dist.path(b, "favicon.svg"),
+    });
+
     const gobject_imports = .{
         .{ "adw", "adw1" },
         .{ "cairo", "cairo1" },
@@ -149,6 +183,32 @@ pub fn build(b: *std.Build) void {
     // table and a search over it, and it imports nothing at all. It cannot hang
     // off the root above because a test binary has exactly one root, and
     // Layouts.zig has no reason to reach for the emoji table.
+    // The review server's two testable halves. `git.zig` is git's own output
+    // formats and the rule for picking a base ref — text in, text out. `Store.zig`
+    // is the review file, whose round trip is the one piece of this that has to
+    // survive the process. Neither reaches GTK, so both run without a display;
+    // the HTTP layer above them wants a socket and a browser, which is a
+    // different kind of test than this project has.
+    const git_tests = b.addTest(.{
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/review/git.zig"),
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+        }),
+    });
+    test_step.dependOn(&b.addRunArtifact(git_tests).step);
+
+    const store_tests = b.addTest(.{
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/review/Store.zig"),
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+        }),
+    });
+    test_step.dependOn(&b.addRunArtifact(store_tests).step);
+
     const emoji_tests = b.addTest(.{
         .root_module = b.createModule(.{
             .root_source_file = b.path("src/emoji.zig"),
@@ -158,3 +218,37 @@ pub fn build(b: *std.Build) void {
     });
     test_step.dependOn(&b.addRunArtifact(emoji_tests).step);
 }
+
+/// Declare every file the Vite build reads as an input of that build step.
+///
+/// Zig hashes a `Run` step's file *arguments*, but a directory passed as an
+/// argument is hashed by path and not by contents — so the source tree has to be
+/// enumerated here, at configure time, for the cache to be honest about when the
+/// bundle is stale.
+///
+/// `node_modules` is deliberately not walked. It is tens of thousands of files
+/// whose contents are already pinned by `package-lock.json`, which *is* listed.
+fn addWebInputs(b: *std.Build, run: *std.Build.Step.Run) void {
+    for ([_][]const u8{
+        "web/index.html",
+        "web/package.json",
+        "web/package-lock.json",
+        "web/tsconfig.json",
+        "web/vite.config.ts",
+    }) |file| {
+        run.addFileInput(b.path(file));
+    }
+
+    const io = b.graph.io;
+    for ([_][]const u8{ "web/src", "web/public" }) |root| {
+        var dir = b.build_root.handle.openDir(io, root, .{ .iterate = true }) catch continue;
+        defer dir.close(io);
+
+        var walker = dir.walk(b.allocator) catch continue;
+        defer walker.deinit();
+        while (walker.next(io) catch null) |entry| {
+            if (entry.kind != .file) continue;
+            run.addFileInput(b.path(b.pathJoin(&.{ root, entry.path })));
+        }
+    }
+}