diff --git a/src/pygui/backend/wafer/family_spec.py b/src/pygui/backend/wafer/family_spec.py
index 18b9a17..238dd96 100644
--- a/src/pygui/backend/wafer/family_spec.py
+++ b/src/pygui/backend/wafer/family_spec.py
@@ -1,9 +1,14 @@
 """Single source of truth for the wafer sensor-count partition."""
+from __future__ import annotations
+
+from pygui.backend.wafer.wafer_layouts import load_layout_for_wafer_id
 
 
 def sensor_count_for(family_code: str) -> int:
-    """Return the number of valid sensor readings for a wafer family code.
+    """Real sensor count for a wafer family code, from its YAML layout.
 
-    Returns 80 for the "X" family. Returns 244 for every other family
-    code."""
-    return 80 if family_code == "X" else 244
+    0 for an unknown/empty family code."""
+    try:
+        return len(load_layout_for_wafer_id(family_code))
+    except KeyError:
+        return 0
diff --git a/src/pygui/serialcomm/data_parser.py b/src/pygui/serialcomm/data_parser.py
index 092aab2..dea1337 100644
--- a/src/pygui/serialcomm/data_parser.py
+++ b/src/pygui/serialcomm/data_parser.py
@@ -20,17 +20,7 @@ log = logging.getLogger(__name__)
 
 def csv_column_count(family_code: str) -> int:
     """Return the number of columns to display for a family code."""
-    mapping = {
-        "A": 48,
-        "E": 48,
-        "P": 48,
-        "B": 29,
-        "C": 29,
-        "D": 29,
-        "F": 22,
-        "X": 80,
-    }
-    return mapping.get(family_code, 0)
+    return sensor_count_for(family_code)
 
 
 def _hex_to_binary(hex_str: str) -> list[int]:
diff --git a/tests/test_data_parser.py b/tests/test_data_parser.py
index 35c6a71..b4c0439 100644
--- a/tests/test_data_parser.py
+++ b/tests/test_data_parser.py
@@ -42,8 +42,13 @@ class TestCsvColumnCount:
     def test_x_family(self):
         assert csv_column_count("X") == 80
 
+    def test_z_family(self):
+        # Z has a real YAML layout (zwafer.yaml) — not "unknown" like the
+        # old hardcoded table implied by omitting it.
+        assert csv_column_count("Z") == 65
+
     def test_unknown_family_returns_zero(self):
-        assert csv_column_count("Z") == 0
+        assert csv_column_count("Q") == 0
 
     def test_empty_string_returns_zero(self):
         assert csv_column_count("") == 0
@@ -134,11 +139,11 @@ class TestParseBinaryData:
         assert result is not None
         assert len(result) == 1
 
-    def test_p_family_single_block_row_has_244_sensors(self):
+    def test_p_family_single_block_row_has_48_sensors(self):
         data = _make_p_block(1)
         result = parse_binary_data(data, "P")
         assert result is not None
-        assert len(result[0]) == 244
+        assert len(result[0]) == 48
 
     def test_p_family_two_blocks_returns_two_rows(self):
         data = _make_p_block(2)
@@ -170,7 +175,7 @@ class TestParseBinaryData:
         data = _make_p_block(1)
         result = parse_binary_data(data, "A")
         assert result is not None
-        assert len(result[0]) == 244
+        assert len(result[0]) == 48
 
     def test_empty_bytes_returns_empty_list(self):
         result = parse_binary_data(b"", "P")
diff --git a/tests/test_device_controller.py b/tests/test_device_controller.py
index 08a2239..8d088c5 100644
--- a/tests/test_device_controller.py
+++ b/tests/test_device_controller.py
@@ -85,6 +85,10 @@ def test_clear_activity_log(controller):
     controller.clearActivityLog()
     assert len(controller._activity_log) == 0
 
+def test_append_activity_log_appends_to_activity_log(controller):
+    controller.appendActivityLog("Review trial expired")
+    assert "Review trial expired" in controller.activityLog
+
 def test_clear_session(controller):
     controller._connection_status = "Connected"
     controller._selected_port = "COM1"
@@ -236,12 +240,12 @@ def test_parse_and_save_data_and_get_chart_data(controller):
     assert emitted_result is not None
     assert emitted_result.get("success") is True
     assert controller.dataRowCount == 1
-    assert controller.dataColCount == 244
+    assert controller.dataColCount == 48
 
     chart_res = controller.getChartData()
     assert chart_res.get("success") is True
     assert "Sensor1" in chart_res.get("sensor_names")
-    assert len(chart_res.get("series")) == 244
+    assert len(chart_res.get("series")) == 48
 
 def test_logging_handler(controller):
     logger = logging.getLogger("test_logger")
diff --git a/tests/test_family_spec.py b/tests/test_family_spec.py
index 083bb82..f90f44d 100644
--- a/tests/test_family_spec.py
+++ b/tests/test_family_spec.py
@@ -1,4 +1,8 @@
-"""Tests for the shared wafer family sensor-count lookup."""
+"""Tests for the shared wafer family sensor-count lookup.
+
+Real counts, one per YAML layout file — this is the ground truth every
+caller (streaming decode, NVRAM parsing, CSV column count) must agree on.
+"""
 from pygui.backend.wafer.family_spec import sensor_count_for
 
 
@@ -6,18 +10,27 @@ def test_x_family_returns_80():
     assert sensor_count_for("X") == 80
 
 
-def test_p_family_returns_244():
-    assert sensor_count_for("P") == 244
+def test_aep_family_returns_48():
+    for code in ("A", "E", "P"):
+        assert sensor_count_for(code) == 48
 
 
-def test_other_known_families_return_244():
-    for code in ("A", "B", "C", "D", "E", "F"):
-        assert sensor_count_for(code) == 244
+def test_bcd_family_returns_29():
+    for code in ("B", "C", "D"):
+        assert sensor_count_for(code) == 29
 
 
-def test_unknown_family_returns_244():
-    assert sensor_count_for("Z") == 244
+def test_f_family_returns_22():
+    assert sensor_count_for("F") == 22
 
 
-def test_empty_string_returns_244():
-    assert sensor_count_for("") == 244
+def test_z_family_returns_65():
+    assert sensor_count_for("Z") == 65
+
+
+def test_unknown_family_returns_zero():
+    assert sensor_count_for("Q") == 0
+
+
+def test_empty_string_returns_zero():
+    assert sensor_count_for("") == 0