CI-safe debug runners: add ASan LD_PRELOAD + UBSan mailbox targets; add asan_preload script; document sanitizer-safe workflows and results in CURRENT_TASK.md (debug complete).

scripts/run_larson_asan_preload.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Run Larson with AddressSanitizer reliably for 4T by preloading libasan + HAKMEM ASan .so
+# Rationale: some environments fail to reserve ASan shadow when running a fully
+# sanitized binary for multi‑thread runs. Preloading the ASan runtime and the
+# allocator .so while using an unsanitized larson_system binary avoids those
+# mapping conflicts while still sanitizing allocator code paths.
+
+threads=${1:-4}
+sleep_sec=${2:-10}
+min_size=${3:-8}
+max_size=${4:-128}
+chunks_per_thread=${5:-1024}
+rounds=${6:-1}
+seed=${7:-12345}
+
+echo "[build] libhakmem_asan.so and larson_system"
+make -j asan-shared-alloc larson_system >/dev/null
+
+export LSAN_OPTIONS=${LSAN_OPTIONS:-detect_leaks=0}
+
+# Find libasan from the active toolchain
+libasan_path=$(gcc -print-file-name=libasan.so)
+if [[ ! -f "$libasan_path" ]]; then
+  echo "[error] libasan.so not found via gcc -print-file-name" >&2
+  exit 1
+fi
+
+export LD_PRELOAD="${libasan_path}:$PWD/libhakmem_asan.so"
+echo "[run] LD_PRELOAD set to: $LD_PRELOAD"
+
+cmd=("./larson_system" "$sleep_sec" "$min_size" "$max_size" "$chunks_per_thread" "$rounds" "$seed" "$threads")
+echo "[run] ${cmd[*]}"
+"${cmd[@]}"
+