diff --git a/dev/postgres/README.md b/dev/postgres/README.md
index c855e3a..fefd5da 100644
--- a/dev/postgres/README.md
+++ b/dev/postgres/README.md
@@ -117,7 +117,12 @@ tools/checks/postgres-integration-check.py \
 ```
 
 `--reset-schema` drops and recreates the `public` schema before every module
-set. Use it only against this disposable database.
+set. Use it only against this disposable database. Before those permutations,
+the check runs the Files credential-retirement atomicity proof in random,
+test-owned schemas. The proof does not modify `public` and fails the release
+gate if its PostgreSQL or full-stack dependencies are unavailable. The
+`--skip-retirement-atomicity` option is only for bounded migration/smoke
+diagnosis; do not use it for release evidence.
 
 Stop the testbed:
 
diff --git a/tools/checks/postgres-integration-check.py b/tools/checks/postgres-integration-check.py
index 1d7c60e..036f0c3 100644
--- a/tools/checks/postgres-integration-check.py
+++ b/tools/checks/postgres-integration-check.py
@@ -47,6 +47,14 @@ def main() -> int:
     )
     parser.add_argument("--skip-migrate", action="store_true", help="Skip govoplan_core.commands.init_db.")
     parser.add_argument("--skip-smoke", action="store_true", help="Skip govoplan_core.devserver --smoke.")
+    parser.add_argument(
+        "--skip-retirement-atomicity",
+        action="store_true",
+        help=(
+            "Skip the isolated destructive-retirement atomicity proof. "
+            "Do not use this option for a release gate."
+        ),
+    )
     parser.add_argument("--python", default=sys.executable, help="Python executable to use. Defaults to the current interpreter.")
     parser.add_argument("--app-env", default="staging", help="APP_ENV value to pass to subprocesses. Defaults to staging.")
     args = parser.parse_args()
@@ -59,8 +67,21 @@ def main() -> int:
 
     module_sets = _parse_module_sets(args.module_set)
     ok = True
+    if not args.skip_retirement_atomicity:
+        print("\n== destructive retirement atomicity ==", flush=True)
+        retirement_env = _check_env(
+            database_url=database_url,
+            modules="tenancy,access,admin,audit,files",
+            app_env=args.app_env,
+        )
+        retirement_env["GOVOPLAN_POSTGRES_DATABASE_URL"] = database_url
+        retirement_env["GOVOPLAN_REQUIRE_POSTGRES_RETIREMENT_PROOF"] = "1"
+        ok = _run(
+            [args.python, "-m", "unittest", "-v", "tests.test_postgres_retirement_atomicity"],
+            env=retirement_env,
+        ) and ok
     for name, modules in module_sets:
-        print(f"\n== {name}: {modules} ==")
+        print(f"\n== {name}: {modules} ==", flush=True)
         if args.reset_schema:
             _reset_public_schema(database_url)
         env = _check_env(database_url=database_url, modules=modules, app_env=args.app_env)
@@ -100,7 +121,7 @@ def _check_env(*, database_url: str, modules: str, app_env: str) -> dict[str, st
 
 
 def _run(command: list[str], *, env: dict[str, str]) -> bool:
-    print("+ " + " ".join(command))
+    print("+ " + " ".join(command), flush=True)
     result = subprocess.run(command, cwd=ROOT, env=env, check=False)
     if result.returncode != 0:
         print(f"Command failed with exit code {result.returncode}: {' '.join(command)}", file=sys.stderr)