diff --git a/src/tr_api/auth.py b/src/tr_api/auth.py
index 932ab32..c23754f 100644
--- a/src/tr_api/auth.py
+++ b/src/tr_api/auth.py
@@ -93,6 +93,26 @@ def _login_headers(waf_token: str) -> dict[str, str]:
     }
 
 
+# ---------------------------------------------------------------------------
+# Redaction
+# ---------------------------------------------------------------------------
+def _redact_body(text: str | None, limit: int = 120) -> str:
+    """Return a short, safe snippet of an upstream response body for error
+    messages.
+
+    Raw upstream bodies can carry auth-flow detail and, if the exception is
+    logged, leak it. We collapse whitespace and truncate hard so we never
+    attach a full raw body to a user-facing exception, while keeping enough
+    (status code is added by the caller) to debug.
+    """
+    if not text:
+        return "<empty>"
+    snippet = " ".join(text.split())
+    if len(snippet) > limit:
+        snippet = snippet[:limit] + "…"
+    return snippet
+
+
 # ---------------------------------------------------------------------------
 # Errors
 # ---------------------------------------------------------------------------
@@ -176,7 +196,7 @@ def _parse_initiate_response(r: requests.Response) -> InitiateResult:
         try:
             j = r.json()
         except ValueError as e:
-            raise LoginError(f"Initiate succeeded but body wasn't JSON: {r.text[:200]}") from e
+            raise LoginError(f"Initiate succeeded but body wasn't JSON: {_redact_body(r.text)}") from e
         pid = j.get("processId")
         if not pid:
             raise LoginError(f"Initiate returned 200 but no processId: {j}")
@@ -230,7 +250,7 @@ def _parse_initiate_response(r: requests.Response) -> InitiateResult:
         )
 
     raise LoginError(
-        f"Initiate failed: status={r.status_code} body={r.text[:300]}"
+        f"Initiate failed: status={r.status_code} body={_redact_body(r.text)}"
     )
 
 
@@ -291,7 +311,7 @@ def complete_login(
         )
 
     raise LoginError(
-        f"Complete failed: status={r.status_code} body={r.text[:300]}"
+        f"Complete failed: status={r.status_code} body={_redact_body(r.text)}"
     )
 
 
@@ -401,7 +421,7 @@ def initiate_login_v2(
         try:
             j = r.json()
         except ValueError as e:
-            raise LoginError(f"v2 initiate 200 but body wasn't JSON: {r.text[:200]}") from e
+            raise LoginError(f"v2 initiate 200 but body wasn't JSON: {_redact_body(r.text)}") from e
         pid = j.get("processId")
         if not pid:
             raise LoginError(f"v2 initiate 200 but no processId: {j}")
@@ -553,7 +573,7 @@ def refresh_session(profile: Profile) -> RefreshResult:
             ok=False,
             status_code=r.status_code,
             cookies_changed=[],
-            error=f"refresh rejected: status={r.status_code} body={r.text[:200]}",
+            error=f"refresh rejected: status={r.status_code} body={_redact_body(r.text)}",
         )
 
     # TR returned 200 — its Set-Cookie headers have already updated
diff --git a/src/tr_api/cookies.py b/src/tr_api/cookies.py
index 92dc8e2..1f1d6b8 100644
--- a/src/tr_api/cookies.py
+++ b/src/tr_api/cookies.py
@@ -15,6 +15,7 @@
 """
 from __future__ import annotations
 
+import os
 import time
 from http.cookiejar import Cookie, MozillaCookieJar
 from pathlib import Path
@@ -161,9 +162,14 @@ def save_to_file(cookies: dict[str, str], path: Path | str) -> int:
             )
         )
 
-    jar.save(ignore_discard=True, ignore_expires=True)
-    # Restrict permissions: cookies are session secrets.
-    path.chmod(0o600)
+    # Atomic write: cookies are session secrets, so create the real file with
+    # 0600 already in place (write to a sibling .tmp, chmod, then rename).
+    # Chmod-after-write on the final path leaves a umask-race window where the
+    # file is briefly world-readable on a shared host.
+    tmp = path.with_name(path.name + ".tmp")
+    jar.save(str(tmp), ignore_discard=True, ignore_expires=True)
+    os.chmod(tmp, 0o600)
+    os.replace(tmp, path)
     return len(jar)
 
 
diff --git a/src/tr_api/profiles.py b/src/tr_api/profiles.py
index 02ecd58..af5ba92 100644
--- a/src/tr_api/profiles.py
+++ b/src/tr_api/profiles.py
@@ -71,7 +71,9 @@ def _validate_phone(phone: str) -> str:
 
 
 def _ensure_dirs() -> None:
-    PROFILES_DIR.mkdir(parents=True, exist_ok=True)
+    # 0700: this tree holds session cookies — keep names unlistable to others.
+    BASE_DIR.mkdir(mode=0o700, exist_ok=True)
+    PROFILES_DIR.mkdir(mode=0o700, parents=True, exist_ok=True)
 
 
 # ---------------------------------------------------------------------------
@@ -91,7 +93,7 @@ def create(phone: str, jurisdiction: str = "DE", name: str | None = None) -> Pro
         name=name,
         created_at=datetime.now(timezone.utc).isoformat(timespec="seconds"),
     )
-    prof.dir.mkdir(parents=True, exist_ok=True)
+    prof.dir.mkdir(mode=0o700, parents=True, exist_ok=True)
     prof.meta_file.write_text(
         json.dumps(asdict(prof), indent=2, ensure_ascii=False) + "\n",
         encoding="utf-8",