chore: import upstream snapshot with attribution

scripts/repro.sh

@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+# repro.sh — Build + run the cumulative BUG-REPRODUCTION suite (test-repro).
+#
+# Unlike test.sh (the gating suite, must be GREEN), this suite is RED by design:
+# every case reproduces an open bug. So we distinguish two outcomes:
+#   - BUILD/LINK failure  → real breakage → exit non-zero (fail the CI job).
+#   - Test redness        → EXPECTED → report the count, exit 0 (green board).
+#
+# Usage: scripts/repro.sh [CC=clang] [CXX=clang++] [--arch arm64|x86_64]
+set -uo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+cd "$ROOT"
+
+# --arch before sourcing env.sh (mirrors test.sh)
+prev_arg=""
+for arg in "$@"; do
+    case "$arg" in
+        arm64|x86_64) [[ "$prev_arg" == "--arch" ]] && export CBM_ARCH="$arg" ;;
+        --arch=*) export CBM_ARCH="${arg#--arch=}" ;;
+    esac
+    prev_arg="$arg"
+done
+
+# shellcheck source=env.sh
+source "$ROOT/scripts/env.sh"
+
+MAKE_ARGS=""
+for arg in "$@"; do
+    case "$arg" in
+        CC=*|CXX=*) export "${arg?}" ;;
+        --arch|--arch=*|arm64|x86_64) ;;
+        *=*) MAKE_ARGS="$MAKE_ARGS $arg" ;;
+    esac
+done
+
+print_env "repro.sh"
+verify_compiler "$CC"
+
+OUT="$ROOT/repro-out.txt"
+# A RED reproduction fails its assertion and returns EARLY — before any cleanup —
+# so LeakSanitizer would flag benign harness leaks on every red store-level test
+# and abort. The board's signal is the FAIL rows, not leak-cleanliness (the leak
+# BUG #581 gets a dedicated RSS-growth test, not LSan). Disable leak detection
+# only; ASan's real checks (use-after-free, overflow) stay ON.
+export ASAN_OPTIONS="detect_leaks=0${ASAN_OPTIONS:+:$ASAN_OPTIONS}"
+
+# test-repro both builds and runs the runner; tolerate its non-zero (red) exit.
+set +e
+make -j"$NPROC" -f Makefile.cbm test-repro $MAKE_ARGS 2>&1 | tee "$OUT"
+set -e
+
+# The runner prints a "<N> passed[, <M> failed]" summary line only if it actually
+# ran. No summary line ⇒ the build/link failed ⇒ real breakage.
+if ! grep -qE '[0-9]+ passed' "$OUT"; then
+    echo "::error::bug-repro runner did not execute — build or link failure"
+    exit 1
+fi
+
+reproduced=$(grep -oE '[0-9]+ failed' "$OUT" | head -1 | grep -oE '[0-9]+' || echo 0)
+green=$(grep -oE '[0-9]+ passed' "$OUT" | head -1 | grep -oE '[0-9]+' || echo 0)
+
+{
+    echo "## Bug-reproduction board — ${OS:-$(uname -s)} ${ARCH:-}"
+    echo ""
+    echo "- **${reproduced}** open bug(s) still reproduced (RED — expected)"
+    echo "- **${green}** case(s) PASSING — candidate-fixed → verify + close the issue + promote the guard to the gating suite"
+} >> "${GITHUB_STEP_SUMMARY:-/dev/stderr}"
+
+echo "=== bug-repro board: ${reproduced} reproduced (RED), ${green} passing (candidate-fixed) ==="
+# Green board: the suite ran. Redness is the data, not a job failure.
+exit 0