@@ -663,11 +663,12 @@ def secondary_y_coord(value: float) -> float:
         f"<style>{style}</style>",
     ]
     if annotation:
-        # Footer metadata line below the x-axis title, right-aligned to the
-        # plot edge — the top stays legend-only (an earlier top-right placement
+        # Header metadata line centered above the legend: the bottom rows are
+        # reserved for the axis titles, and the earlier bottom-right footer
+        # placement sat too close to the canvas edge (a top-right placement
         # collided with the centered legend at this font size).
         lines.append(
-            f'<text x="{left + plot_width:.2f}" y="{height - 6}" text-anchor="end" font-size="11" '
+            f'<text x="{width / 2:.2f}" y="18" text-anchor="middle" font-size="11" '
             f'fill="#6b7280">{escape(annotation)}</text>'
         )
     legend_entries = [("curve", spec.metric_label["en"])]
@@ -680,8 +681,8 @@ def secondary_y_coord(value: float) -> float:
     for (css_class, label), entry_width in zip(legend_entries, legend_widths):
         lines.extend(
             [
-                f'<line class="{css_class}" x1="{legend_x:.2f}" y1="30" x2="{legend_x + 28:.2f}" y2="30"/>',
-                f'<text x="{legend_x + 36:.2f}" y="34" font-size="13">{escape(label)}</text>',
+                f'<line class="{css_class}" x1="{legend_x:.2f}" y1="34" x2="{legend_x + 28:.2f}" y2="34"/>',
+                f'<text x="{legend_x + 36:.2f}" y="38" font-size="13">{escape(label)}</text>',
             ]
         )
         legend_x += entry_width + 28
@@ -991,6 +992,9 @@ def read_snapshot(
         runs = payload["runs"]
         if not points or not runs:
             raise RuntimeError(f"Performance snapshot is incomplete: {path}")
+        provenance_runs = payload.get("provenance")
+        if provenance_runs is not None and (not isinstance(provenance_runs, list) or len(provenance_runs) != len(runs)):
+            raise RuntimeError(f"Performance snapshot provenance does not match its runs: {path}")
         if all("environment_steps" in point for point in points):
             environment_steps = [point["environment_steps"] for point in points]
         elif all("step" in point for point in points):
@@ -1043,8 +1047,13 @@ def read_snapshot(
                 environment_steps=np.asarray([], dtype=np.float64),
                 elapsed_seconds=np.asarray([], dtype=np.float64),
                 values=np.asarray([], dtype=np.float64),
+                provenance=(
+                    {key: record[key] for key in ("system", "performance") if key in record}
+                    if isinstance((record := provenance_runs[index]), dict)
+                    else None
+                ),
             )
-            for run in runs
+            for index, run in enumerate(runs)
         ]
     except (KeyError, TypeError, ValueError, json.JSONDecodeError) as exc:
         raise RuntimeError(f"Invalid performance snapshot: {path}") from exc