diff --git a/csaxs_bec/bec_ipython_client/plugins/cSAXS/diagnostics.py b/csaxs_bec/bec_ipython_client/plugins/cSAXS/diagnostics.py
new file mode 100644
index 0000000..14a8cec
--- /dev/null
+++ b/csaxs_bec/bec_ipython_client/plugins/cSAXS/diagnostics.py
@@ -0,0 +1,132 @@
+from __future__ import annotations
+import builtins
+
+if builtins.__dict__.get("dev") is not None:
+    dev = builtins.__dict__.get("dev")
+
+
+# ============================================================
+# Base classes
+# ============================================================
+
+class SingleSignalDiag:
+    """Diagnostics for a single-signal device with gain control."""
+
+    def __init__(self, name, label, gain_dev, signal_dev):
+        self._name = name
+        self._label = label
+        self._gain = gain_dev
+        self._signal = signal_dev
+
+    def show_all(self):
+        cfg = self._gain.get()
+        try:
+            val = self._signal.signal.get()
+            sval = f"{val:.4f}"
+        except Exception:
+            sval = "N/A"
+
+        print(self._label)
+        print("-" * len(self._label))
+        print(f"gain     : {cfg.gain:.0e}")
+        print(f"coupling : {cfg.coupling}")
+        print(f"speed    : {cfg.speed}")
+        print(f"readback : {sval}")
+        print("")
+        print("hint:")
+        print(f"  gain : csaxs.diagnostics.{self._name}.gain(1e5)")
+        print(f"  raw  : dev.{self._signal.name}.signal.get()")
+
+    def gain(self, value):
+        self._gain.set_gain(value)
+
+
+class BPMDiag:
+    """Diagnostics for a BPM device."""
+
+    def __init__(self, name, label, gain_dev, rb_dev):
+        self._name = name
+        self._label = label
+        self._gain = gain_dev
+        self._rb = rb_dev
+
+    def show_all(self):
+        cfg = self._gain.get()
+        rb = self._rb.get()
+
+        print(self._label)
+        print("-" * len(self._label))
+        print(f"gain     : {cfg.gain:.0e}")
+        print(f"coupling : {cfg.coupling}")
+        print(f"speed    : {cfg.speed}")
+        print("readback:")
+        print(f"  pos_x     : {rb.pos_x:.3e}")
+        print(f"  pos_y     : {rb.pos_y:.3e}")
+        print(f"  intensity : {rb.intensity:.3f}")
+        print("")
+        print("hint:")
+        print(f"  gain : csaxs.diagnostics.{self._name}.gain(1e6)")
+        print(f"  raw  : dev.{self._rb.name}.pos_x.get()")
+
+    def gain(self, value):
+        self._gain.set_gain(value)
+
+
+# ============================================================
+# Diagnostics root (user-facing object)
+# ============================================================
+
+class cSAXSDiagnostics:
+    """User-visible diagnostics namespace."""
+
+    def __init__(self):
+        # BPMs
+        self.bpm_xbox1 = BPMDiag(
+            name="bpm_xbox1",
+            label="BPM XBox1 (OP hutch)",
+            gain_dev=dev.gain_bpm_xbox1,
+            rb_dev=dev.bpm_xbox1_slowrb,
+        )
+
+        self.bpm_xbox2 = BPMDiag(
+            name="bpm_xbox2",
+            label="BPM XBox2 (ES hutch)",
+            gain_dev=dev.gain_bpm_xbox2,
+            rb_dev=dev.bpm_xbox2_slowrb,
+        )
+
+        # Single-signal diagnostics
+        self.bim = SingleSignalDiag(
+            name="bim",
+            label="BIM XBox3 (ES)",
+            gain_dev=dev.gain_bim_xbox3,
+            signal_dev=dev.bim_xbox3_slowrb,
+        )
+
+        self.beamstop = SingleSignalDiag(
+            name="beamstop",
+            label="Beamstop diode (flight tube)",
+            gain_dev=dev.gain_beamstop_diode,
+            signal_dev=dev.beamstop_intensity,
+        )
+
+        self.polarization = SingleSignalDiag(
+            name="polarization",
+            label="Polarization diodes (XBox1)",
+            gain_dev=dev.gain_diodes_xbox1,
+            signal_dev=dev.diode_horizontal_xbox1_slowrb,
+        )
+
+    def show_all(self):
+        print("CSAXS diagnostics")
+        print("=================")
+        print("")
+        self.bpm_xbox1.show_all()
+        print("")
+        self.bpm_xbox2.show_all()
+        print("")
+        self.bim.show_all()
+        print("")
+        self.beamstop.show_all()
+        print("")
+        self.polarization.show_all()