Validate output table window bounds

src/telemetry_window_demo/io.py

@@ -108,6 +108,7 @@ def load_feature_table(path: str | Path) -> pd.DataFrame:
         FEATURE_TABLE_NUMERIC_COLUMNS,
         source=str(table_path),
     )
+    _require_window_bounds(frame, source=str(table_path))
     return frame
 
 
@@ -120,6 +121,8 @@ def load_alert_table(path: str | Path) -> pd.DataFrame:
         ALERT_TABLE_DATETIME_COLUMNS,
         source=str(table_path),
     )
+    _require_window_bounds(frame, source=str(table_path))
+    _require_alert_time_bounds(frame, source=str(table_path))
     _require_text_columns(frame, ALERT_TABLE_TEXT_COLUMNS, source=str(table_path))
     return frame
 
@@ -209,6 +212,26 @@ def _parse_numeric_columns(
         frame[column] = parsed.astype("int64" if require_integer else "float64")
 
 
+def _require_window_bounds(frame: pd.DataFrame, *, source: str) -> None:
+    invalid_windows = frame["window_end"] <= frame["window_start"]
+    if invalid_windows.any():
+        raise ValueError(
+            f"Window end must be after window start in {source}: "
+            f"{int(invalid_windows.sum())} row(s)"
+        )
+
+
+def _require_alert_time_bounds(frame: pd.DataFrame, *, source: str) -> None:
+    out_of_bounds = (frame["alert_time"] < frame["window_start"]) | (
+        frame["alert_time"] > frame["window_end"]
+    )
+    if out_of_bounds.any():
+        raise ValueError(
+            f"Alert time must fall within window bounds in {source}: "
+            f"{int(out_of_bounds.sum())} row(s)"
+        )
+
+
 def _require_text_columns(
     frame: pd.DataFrame,
     text_columns: tuple[str, ...],

tests/test_io.py

@@ -294,6 +294,22 @@ def test_load_feature_table_rejects_out_of_range_error_rate(tmp_path) -> None:
     assert "error_rate" in message
 
 
+def test_load_feature_table_rejects_non_positive_window_bounds(tmp_path) -> None:
+    path = tmp_path / "features.csv"
+    path.write_text(
+        "window_start,window_end,event_count,error_rate\n"
+        "2026-03-10T10:01:00Z,2026-03-10T10:01:00Z,10,0.25\n",
+        encoding="utf-8",
+    )
+
+    with pytest.raises(ValueError) as excinfo:
+        load_feature_table(path)
+
+    message = str(excinfo.value)
+    assert "Window end must be after window start" in message
+    assert "1 row(s)" in message
+
+
 def test_load_alert_table_rejects_invalid_csv(tmp_path) -> None:
     path = tmp_path / "alerts.csv"
     path.write_text(
@@ -344,6 +360,40 @@ def test_load_alert_table_rejects_missing_alert_timestamp(tmp_path) -> None:
     assert "alert_time" in message
 
 
+def test_load_alert_table_rejects_non_positive_window_bounds(tmp_path) -> None:
+    path = tmp_path / "alerts.csv"
+    path.write_text(
+        "alert_time,window_start,window_end,rule_name,severity\n"
+        "2026-03-10T10:00:30Z,2026-03-10T10:01:00Z,"
+        "2026-03-10T10:00:00Z,high_error_rate,medium\n",
+        encoding="utf-8",
+    )
+
+    with pytest.raises(ValueError) as excinfo:
+        load_alert_table(path)
+
+    message = str(excinfo.value)
+    assert "Window end must be after window start" in message
+    assert "1 row(s)" in message
+
+
+def test_load_alert_table_rejects_alert_time_outside_window(tmp_path) -> None:
+    path = tmp_path / "alerts.csv"
+    path.write_text(
+        "alert_time,window_start,window_end,rule_name,severity\n"
+        "2026-03-10T10:02:00Z,2026-03-10T10:00:00Z,"
+        "2026-03-10T10:01:00Z,high_error_rate,medium\n",
+        encoding="utf-8",
+    )
+
+    with pytest.raises(ValueError) as excinfo:
+        load_alert_table(path)
+
+    message = str(excinfo.value)
+    assert "Alert time must fall within window bounds" in message
+    assert "1 row(s)" in message
+
+
 def test_load_alert_table_rejects_missing_rule_name(tmp_path) -> None:
     path = tmp_path / "alerts.csv"
     path.write_text(