diff --git a/scripts/stage-testsuite.py b/scripts/stage-testsuite.py
new file mode 100755
index 000000000..03bfefd19
--- /dev/null
+++ b/scripts/stage-testsuite.py
@@ -0,0 +1,112 @@
+#!/usr/bin/env python3
+"""Stage the built darling-testsuite cases into a container prefix (task #123).
+
+The suite is a regression net for AppKit and libc, and it lives in the container rather than in
+buck-out: the cases are guest binaries, so they have to be run through `cider shell`. Re-creating
+that staging by hand costs an hour and gets one detail wrong every time, which is what this is for.
+
+Two details are the ones that get lost:
+
+RESOURCES KEEP THEIR PATHS. A case asks for its resource by the path it has in the source tree:
+
+    grab_full_resource_path(c, "testsuite/usr/lib/system/libsystem_kernel.dylib/read/resources/read_hello_world.txt")
+
+so DARLING_TESTSUITE_RESOURCE_PATH must point at a directory that still has `testsuite/...` under
+it. Copying every `resource`/`resources` directory into one flat directory makes `test_read_file`
+fail its `fd >= 0` assertion, which reads exactly like a libc defect and is not one.
+
+THE RUNNER MUST NOT EAT THE CASE OUTPUT. An AppKit case prints two lines of backend greeting before
+anything of its own, so a runner that keeps the first two lines keeps nothing that matters. A case
+that prints on its happy path then looks as silent as one that never ran.
+
+Usage: scripts/stage-testsuite.py [--prefix /tmp/cider-appkit-1000/prefix]
+       Build first: buck2 build --keep-going --show-output $(targets) > outputs.txt
+       or let this run buck2 itself with --build.
+"""
+import os
+import re
+import shutil
+import subprocess
+import sys
+
+REPO = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+SUITE = "vendor/src/darling-testsuite"
+
+RUNNER = """#!/bin/sh
+DARLING_TESTSUITE_RESOURCE_PATH=/tmp/dts-res
+export DARLING_TESTSUITE_RESOURCE_PATH
+cd /tmp/dts-res
+for f in /tmp/dts/dts_*; do
+  [ -x "$f" ] || continue
+  out=$("$f" 2>&1)
+  code=$?
+  echo "DTSRESULT $code $(basename $f)"
+  echo "$out" | grep -v "^cider-wayland" | head -3 | sed 's/^/DTSOUT /'
+done
+echo DTSDONE
+"""
+
+
+def case_targets():
+    body = open(os.path.join(REPO, "vendor/src/BUCK"), errors="replace").read()
+    names = re.findall(r'name = "(dts_[A-Za-z0-9_]*)"', body)
+    return ["//vendor/src:" + n for n in names if not n.endswith("_obj")]
+
+
+def build(targets):
+    """--keep-going, because the libxpc group does not build and the rest still should."""
+    out = subprocess.run(
+        ["buck2", "build", "--keep-going", "--show-output"] + targets,
+        cwd=REPO, capture_output=True, text=True,
+    ).stdout
+    return [l.split(None, 1)[1] for l in out.split("\n") if l.startswith("root//") and " " in l]
+
+
+def stage(prefix, paths):
+    dts = os.path.join(prefix, "tmp/dts")
+    res = os.path.join(prefix, "tmp/dts-res")
+    os.makedirs(dts, exist_ok=True)
+    if os.path.exists(res):
+        shutil.rmtree(res)
+    os.makedirs(res)
+
+    staged = 0
+    for p in paths:
+        full = os.path.join(REPO, p)
+        if not os.path.isfile(full):
+            continue
+        shutil.copy2(full, os.path.join(dts, os.path.basename(full)))
+        staged += 1
+
+    dirs = 0
+    for root, _sub, _files in os.walk(os.path.join(REPO, SUITE)):
+        if os.path.basename(root) not in ("resource", "resources"):
+            continue
+        rel = os.path.relpath(root, os.path.join(REPO, SUITE))
+        target = os.path.join(res, rel)
+        os.makedirs(os.path.dirname(target), exist_ok=True)
+        shutil.copytree(root, target, symlinks=True)
+        dirs += 1
+
+    runner = os.path.join(dts, "run.sh")
+    open(runner, "w").write(RUNNER)
+    os.chmod(runner, 0o755)
+    return staged, dirs
+
+
+def main():
+    prefix = "/tmp/cider-appkit-1000/prefix"
+    if "--prefix" in sys.argv:
+        prefix = sys.argv[sys.argv.index("--prefix") + 1]
+    targets = case_targets()
+    print(f"{len(targets)} case targets")
+    paths = build(targets)
+    print(f"{len(paths)} built")
+    staged, dirs = stage(prefix, paths)
+    print(f"staged {staged} binaries and {dirs} resource directories into {prefix}/tmp")
+    print("run it with scratchpad/run-dts-wayland.sh, NEVER headless: an AppKit case dies at its")
+    print("first use of a display that correctly declined to exist, which reads as a crash in us.")
+
+
+if __name__ == "__main__":
+    main()