Add 9player and introspect as programs beside the library

9player/: FUSE mount CLI that mounts a 9P2000 tree into a fresh user+mount
namespace and runs a program in it (no root, no libfuse, no libc).
introspect/: the 9P debug/introspection library (freestanding core, value
renderers, Linux probe with threads/stacks/memory/breakpoints/panics) and
its demo server. Each has its own build fragment; the root build.zig wires
them behind -D9player/-Dintrospect with namespaced steps (9player-itest,
introspect-check-freestanding, programs-test, ...) and exports the
introspect module for dependents. This is the layout for related programs.

Co-Authored-By: Claude Fable 5.1 <[email protected]>

1 files changed, 57 insertions, 0 deletions

diff --git a/build.zig b/build.zig
index 3228cf2..63d9735 100644
--- a/build.zig
+++ b/build.zig
@@ -124,4 +124,61 @@ pub fn build(b: *std.Build) void {
     const run_fuzz = b.addRunArtifact(fuzz);
     if (b.args) |args| run_fuzz.addArgs(args);
     b.step("fuzz", "Run deterministic local decoder and server probes (seed, iterations)").dependOn(&run_fuzz.step);
+
+    // ------------------------------------------------------------------
+    // Programs related to cloud9. Each lives in its own directory beside
+    // src/ (introspect/, 9player/) with a build.zig *fragment* exposing
+    // `add(b, ctx)`; it is imported here and runs with this builder, so its
+    // b.path() calls are relative to this root and its steps are namespaced
+    // by the program's name. New related programs follow the same pattern:
+    // add a directory, a fragment, a toggle here, and the path to
+    // build.zig.zon.
+    //
+    //   -Dintrospect=[bool]  library module (any target) + freestanding check;
+    //                        demo server and Linux suites when the target is Linux
+    //   -D9player=[bool]     the FUSE mount CLI (Linux only)
+    //
+    // Both default to true on a Linux target and false elsewhere. Enabled
+    // programs are installed by the plain `zig build` next to cloud9-http
+    // and cloud9-probe.
+    const is_linux = target.result.os.tag == .linux;
+    const want_introspect = b.option(bool, "introspect", "Build the introspect library module and demo (default: target is Linux)") orelse is_linux;
+    const want_9player = b.option(bool, "9player", "Build the 9player FUSE mount CLI (default: target is Linux; Linux only)") orelse is_linux;
+    if (want_9player and !is_linux) {
+        std.debug.print("error: -D9player=true needs a Linux target (got {s})\n", .{@tagName(target.result.os.tag)});
+        std.process.exit(1);
+    }
+    const programs_test = b.step("programs-test", "Run every enabled program's unit tests and checks");
+    const programs_itest = b.step("programs-itest", "Run every enabled program's integration suites");
+
+    const introspect_build = @import("introspect/build.zig");
+    const nineplayer_build = @import("9player/build.zig");
+
+    const introspect: ?introspect_build.Artifacts = if (want_introspect) introspect_build.add(b, .{
+        .target = target,
+        .optimize = optimize,
+        .cloud9 = module,
+    }) else null;
+    if (introspect) |i| {
+        programs_test.dependOn(i.test_step);
+        programs_test.dependOn(i.check_step);
+        if (i.debug_test_step) |s| programs_test.dependOn(s);
+    }
+
+    const nineplayer: ?nineplayer_build.Artifacts = if (want_9player) nineplayer_build.add(b, .{
+        .target = target,
+        .optimize = optimize,
+        .cloud9 = module,
+        .introspect_demo = if (introspect) |i| i.demo else null,
+    }) else null;
+    if (nineplayer) |p| {
+        programs_test.dependOn(p.test_step);
+        programs_itest.dependOn(p.itest_step);
+    }
+
+    // introspect's end-to-end suites drive the demo through a 9player mount,
+    // so they are wired once both fragments have run.
+    if (introspect) |i| {
+        if (introspect_build.addPlayerTests(b, i, if (nineplayer) |p| p.exe else null)) |s| programs_itest.dependOn(s);
+    }
 }