feat(ui): interactive graph, strip context menus, days by activity, message times, limit status words

src/beaver_gateway/frontends/api/frontend.py

@@ -750,7 +750,25 @@ def build_app(  # noqa: PLR0915
             )
             gateway = _sum_usage(await _usage_rows(runtime, since, now))
             gateway["since"] = since.isoformat(timespec="seconds")
-            windows.append({**_limit_public(row), "gateway": gateway})
+            # The API sends a figure only when a window nears its limit;
+            # the last one inside this window is the best lower bound.
+            known = next(
+                (
+                    r
+                    for r in rows
+                    if r.window == window
+                    and r.utilization is not None
+                    and _aware(r.ts) >= since
+                ),
+                None,
+            )
+            windows.append(
+                {
+                    **_limit_public(row),
+                    "gateway": gateway,
+                    "last_known": _limit_public(known) if known else None,
+                }
+            )
         windows.sort(
             key=lambda w: (WINDOWS.get(w["window"], timedelta.max), w["window"])
         )