diff --git a/tier2/gen-worker/scripts/store_roundtrip_harness.py b/tier2/gen-worker/scripts/store_roundtrip_harness.py
index ee5a89cc..1d042056 100644
--- a/tier2/gen-worker/scripts/store_roundtrip_harness.py
+++ b/tier2/gen-worker/scripts/store_roundtrip_harness.py
@@ -89,18 +89,21 @@ def _rebuild(sp: dict) -> dict:
     if not esbuild:
         return {"source_digest": source_digest, "bundle_sha256": None, "mode": "source-bytes"}
     # 真 esbuild:把源写进临时目录、bundle 出单文件、算 sha256(bundle)。
+    #   关键:cwd=tmp + 相对 entry/outfile 跑 esbuild。esbuild bundle 会把入口【路径】作为模块注释写进
+    #   产物(`// <path>`);若传绝对路径,mkdtemp 每次目录名不同 → 注释不同 → bundle 字节跨目录不稳,
+    #   会把「重建确定性」误判为失败(实为 harness 自身路径泄漏,非 store / esbuild 不确定)。故用 cwd +
+    #   相对路径,让注释恒为 `// src/game-logic.js`,bundle 字节跨目录稳定(2026-07-05 mini-infra 真库窗口实测坐实)。
     tmp = Path(tempfile.mkdtemp(prefix="t2-rebuild-"))
     try:
         for f in files:
             dst = tmp / f["path"]
             dst.parent.mkdir(parents=True, exist_ok=True)
             dst.write_text(f["content"], encoding="utf-8")
-        out = tmp / "bundle.js"
+        entry = sp.get("entry") or "src/game-logic.js"
         subprocess.run(
-            [esbuild, str(tmp / (sp.get("entry") or "src/game-logic.js")),
-             "--bundle", f"--outfile={out}"],
-            check=True, capture_output=True, timeout=60)
-        bundle_sha = hashlib.sha256(out.read_bytes()).hexdigest()
+            [esbuild, entry, "--bundle", "--outfile=bundle.js"],
+            check=True, capture_output=True, timeout=60, cwd=str(tmp))
+        bundle_sha = hashlib.sha256((tmp / "bundle.js").read_bytes()).hexdigest()
         return {"source_digest": source_digest, "bundle_sha256": bundle_sha, "mode": "bundle"}
     finally:
         shutil.rmtree(tmp, ignore_errors=True)