diff --git a/src/magnetics/_slcontour/omfit_compat.py b/src/magnetics/_slcontour/omfit_compat.py
index 9ac49db..4d2b0df 100644
--- a/src/magnetics/_slcontour/omfit_compat.py
+++ b/src/magnetics/_slcontour/omfit_compat.py
@@ -348,16 +348,21 @@ def load_sensor_table(device="DIII-D"):
     return sensor_geometry(device)
 
 
-def load_wall(device="DIII-D"):
+def load_wall(device="DIII-D", shot=None):
     """Return the ``(r, z)`` first-wall outline arrays from the device JSON.
 
-    Returns ``(None, None)`` if no device file or wall section is found.
+    Resolves the shot-segmented ``wall`` (``{segments: [...]}``) through the device
+    SSOT resolver :func:`magnetics.data.devices.feature_at`, which also tolerates a
+    legacy flat ``{r, z}`` record. A ``None`` shot (device-level / plotting) takes
+    the latest segment, since the wall changes rarely between campaigns.
+
+    Returns ``(None, None)`` if no device file or wall segment is found.
     """
     try:
         dev = load_device(device)
     except (FileNotFoundError, OSError):
         return None, None
-    wall = dev.get("wall")
-    if not wall or "r" not in wall or "z" not in wall:
+    seg = _devices.feature_at(dev, "wall", shot if shot is not None else 2_000_000)
+    if not seg or "r" not in seg or "z" not in seg:
         return None, None
-    return np.array(wall["r"], dtype=float), np.array(wall["z"], dtype=float)
+    return np.array(seg["r"], dtype=float), np.array(seg["z"], dtype=float)
diff --git a/src/magnetics/data/fetch/remote.py b/src/magnetics/data/fetch/remote.py
index f8d8ff2..93d4726 100644
--- a/src/magnetics/data/fetch/remote.py
+++ b/src/magnetics/data/fetch/remote.py
@@ -37,6 +37,7 @@
 
 from __future__ import annotations
 
+import re
 import shlex
 import subprocess
 import sys
@@ -63,6 +64,23 @@
 # (its activate.d scripts set nothing PTDATA needs; direct is ~4-5s faster per pull).
 DEFAULT_PYTHON = "/fusion/projects/codes/conda/omega/envs_public/toksearch_env/bin/python"
 
+# ``remote_dir`` is interpolated into remote shell commands (``mkdir -p``, ``cd``) and
+# rsync remote specs, so it must not carry spaces or shell metacharacters. Allow a
+# leading ``~`` (home) then POSIX-safe path chars only. This is an external-input /
+# security boundary (the value can originate from the GUI/API), so a bad value is
+# rejected loudly rather than quoted-around or silently accepted.
+_SAFE_REMOTE_DIR = re.compile(r"^~?[\w./\-]+$")
+
+
+def _validate_remote_dir(remote_dir: str) -> str:
+    if not _SAFE_REMOTE_DIR.match(remote_dir) or remote_dir.startswith("-"):
+        raise ValueError(
+            f"unsafe remote_dir {remote_dir!r}: only '~', letters, digits, '_', '.', "
+            "'-' and '/' are allowed (no spaces or shell metacharacters), and relative "
+            "paths must not start with '-'"
+        )
+    return remote_dir
+
 
 def _log(msg: str) -> None:
     sys.stderr.write(msg + "\n")
@@ -98,6 +116,7 @@ def run_remote(
     the network, no hop needed); pass an explicit host[:port] to force one, or an
     empty string to force none (e.g. an ssh-config alias that carries its own
     ProxyJump)."""
+    remote_dir = _validate_remote_dir(remote_dir)
     login = cluster_login(device)
     host = host or login["host"] or DEFAULT_HOST
     port = login["port"]  # cluster SSH port (22 unless the device overrides it)
diff --git a/src/magnetics/data/fetch/toksearch.py b/src/magnetics/data/fetch/toksearch.py
index f569333..5b5305b 100644
--- a/src/magnetics/data/fetch/toksearch.py
+++ b/src/magnetics/data/fetch/toksearch.py
@@ -626,8 +626,14 @@ def _fetch_toksearch(shot, pointnames, *, tmin, tmax, stride, progress, tree_sig
 
     # Resolve EFIT-tree signals: first candidate key with usable data wins. No
     # decimation (EFIT time bases are already coarse), window-trim only.
-    for name, keys in tree_keys.items():
-        ch = Channel(name, ok=False, error="no data")
+    # Every requested tree signal is recorded, fetched or not: when MdsSignal is
+    # unavailable tree_keys is empty, so iterate the full request set and mark the
+    # unfetched ones missing (parity with the mdsthin path — never silently drop).
+    for name in tree_signals:
+        keys = tree_keys.get(name, [])
+        ch = Channel(
+            name, ok=False, error="MdsSignal unavailable" if MdsSignal is None else "no data"
+        )
         for key, tree, node in keys:
             sig = None if key in errors else (rec[key] if key in rec.keys() else None)
             if not sig or "data" not in sig:
diff --git a/src/magnetics/service/mock.py b/src/magnetics/service/mock.py
index 6998139..6e902ce 100644
--- a/src/magnetics/service/mock.py
+++ b/src/magnetics/service/mock.py
@@ -20,6 +20,8 @@
 
 from __future__ import annotations
 
+import zlib
+
 import numpy as np
 
 from ..data import diiid
@@ -126,7 +128,9 @@ def qs_fit_frames(machine: str, params: dict) -> list[tuple[float, dict]]:
 # ── spectrogram (Burgess) — coarse → fine, mode that locks or rotates ────────
 def spectrogram_frames(machine: str, params: dict) -> list[tuple[float, dict]]:
     p = _profile(machine)
-    rng = np.random.default_rng(abs(hash(machine)) % 2**32)
+    # Stable across process restarts: the builtin str hash() is per-process salted
+    # (PYTHONHASHSEED), which would make the mock non-deterministic between runs.
+    rng = np.random.default_rng(zlib.crc32(machine.encode()))
     t0, t1 = p["t_ms"]
     resolutions = [(60, 45), (120, 90), (240, 180)]  # (nt, nf), → real 360×180
     frames = []
diff --git a/src/magnetics/service/nodes.py b/src/magnetics/service/nodes.py
index c5810f3..03bb407 100644
--- a/src/magnetics/service/nodes.py
+++ b/src/magnetics/service/nodes.py
@@ -1234,7 +1234,7 @@ def _sensor_map_rz(shot, params=None) -> dict:
 
     from .._slcontour.omfit_compat import load_wall
 
-    r_wall, z_wall = load_wall(device)
+    r_wall, z_wall = load_wall(device, int(shot))
 
     series = []
     for c in channels:
diff --git a/tests/test_data_fetch_hardening.py b/tests/test_data_fetch_hardening.py
new file mode 100644
index 0000000..0045133
--- /dev/null
+++ b/tests/test_data_fetch_hardening.py
@@ -0,0 +1,39 @@
+"""Regression tests for the Crucible-confirmed data-layer fixes.
+
+P2  load_wall read the old flat wall schema after the segmented migration → (None,None)
+P5  remote_dir flowed unquoted / as an option into cluster shell commands
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from magnetics._slcontour.omfit_compat import load_wall
+from magnetics.data.fetch import remote
+
+
+# ── P2: load_wall resolves the segmented wall schema ────────────────────────
+def test_load_wall_resolves_segmented_schema():
+    """After the wall was migrated to {segments:[...]}, load_wall read the old flat
+    keys and returned (None, None), dropping the vessel outline from the sensor map."""
+    r, z = load_wall("DIII-D", 184927)
+    assert r is not None and z is not None
+    assert len(r) == len(z) > 0
+    # a None shot (device-level / plotting) takes the latest segment, not (None, None)
+    r0, z0 = load_wall("DIII-D")
+    assert r0 is not None and len(r0) > 0
+
+
+# ── P5: remote_dir shell/option-injection boundary ──────────────────────────
+@pytest.mark.parametrize("safe", ["~/magnetics_fetch", "/scratch/u/fetch", "rel/dir", "~/a.b-c_d"])
+def test_validate_remote_dir_accepts_safe_paths(safe):
+    assert remote._validate_remote_dir(safe) == safe
+
+
+@pytest.mark.parametrize(
+    "bad",
+    ["~/my fetch", "$(touch x)", "a;b", "a&&b", "`id`", "a|b", "a>b", "-tmp", "--help"],
+)
+def test_validate_remote_dir_rejects_metacharacters_and_options(bad):
+    with pytest.raises(ValueError):
+        remote._validate_remote_dir(bad)