Every helix-golf example is a differential case, one per step of its walkthrough

The ten examples on helix-golf are imported as 118 cases: each numbered step
of an example's walkthrough is the case whose keys are the command up to and
including that step, so the first mismatch names the step where pardes and
helix part. Six more restart at a step that begins with %, from helix's own
text there, so a later step is tested even when an earlier one misses.
zig build hxgolf compares all 124 with goldens from hx-harness.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/build.zig b/build.zig
index 666e792d..334d3705 100644
--- a/build.zig
+++ b/build.zig
@@ -1097,6 +1097,13 @@ pub fn build(b: *std.Build) void {
         const hxparity_step = b.step("hxparity", "run the file-vs-pty editing parity suite (-- [--waivers w.jsonl] <cases.jsonl>...)");
         hxparity_step.dependOn(&run_hxparity.step);
 
+        // every helix-golf example, one case per step of its walkthrough
+        const run_hxgolf = b.addRunArtifact(hxdiff);
+        run_hxgolf.has_side_effects = true;
+        run_hxgolf.addArgs(&.{ "--strict", "test/hxcases/golf.jsonl", "test/hxcases/golf-goldens.jsonl" });
+        run_hxgolf.setCwd(b.path("."));
+        b.step("hxgolf", "compare the helix-golf examples against their Helix results").dependOn(&run_hxgolf.step);
+
         const lspbench = b.addExecutable(.{
             .name = "pardes-lspbench",
             .root_module = b.createModule(.{