diff --git a/apps/status/src/static/expand.js b/apps/status/src/static/expand.js
index 2d98964..0d3c5ed 100644
--- a/apps/status/src/static/expand.js
+++ b/apps/status/src/static/expand.js
@@ -1,5 +1,8 @@
-// Click-to-expand for compact display mode on the public status page.
-// Loaded by status pages that have at least one monitor in compact mode.
+// Public status page client JS:
+//   1. Bar tooltips (always active) — hover any heartbeat bar to see the
+//      bucket time range and uptime breakdown.
+//   2. Click-to-expand for compact display mode (only fires when there are
+//      compact monitors on the page).
 // Reads its config from window.PINGQL_PAGE.
 (function () {
   var cfg = window.PINGQL_PAGE || {};
@@ -8,6 +11,81 @@
   var showResponseTime = !!cfg.show_response_time;
   if (!slug) return;
 
+  // ── Bar tooltips ──────────────────────────────────────────────────────
+  var tooltip = document.getElementById("bar-tooltip");
+  if (tooltip) {
+    var bucketSpanMs = (defaultWindow === "24h") ? 3600 * 1000
+                     : (defaultWindow === "7d")  ? 86400 * 1000
+                     : (defaultWindow === "30d") ? 86400 * 1000
+                     :                              7 * 86400 * 1000;
+    function fmtBucketRange(startIso) {
+      var start = new Date(startIso);
+      var end   = new Date(start.getTime() + bucketSpanMs);
+      var sameDay = start.toDateString() === new Date(end.getTime() - 1).toDateString();
+      var dateOpts  = { month: "short", day: "numeric" };
+      var timeOpts  = { hour: "2-digit", minute: "2-digit" };
+      if (defaultWindow === "24h") {
+        return start.toLocaleDateString(undefined, dateOpts) + ", " +
+               start.toLocaleTimeString(undefined, timeOpts) + " — " +
+               end.toLocaleTimeString(undefined, timeOpts);
+      }
+      if (defaultWindow === "7d" || defaultWindow === "30d") {
+        return start.toLocaleDateString(undefined, { weekday: "short", month: "short", day: "numeric" });
+      }
+      // 90d → weekly buckets
+      var endLabel = new Date(end.getTime() - 1).toLocaleDateString(undefined, dateOpts);
+      return "Week of " + start.toLocaleDateString(undefined, dateOpts) + " — " + endLabel;
+    }
+    function uptimeBand(p) {
+      if (p == null) return "";
+      if (p >= 99.9) return "good";
+      if (p >= 99.0) return "warn";
+      return "bad";
+    }
+
+    function showTooltipForBar(bar, evt) {
+      var total = parseInt(bar.getAttribute("data-total") || "0", 10);
+      var up    = parseInt(bar.getAttribute("data-up")    || "0", 10);
+      var start = bar.getAttribute("data-start");
+      if (!start) return;
+      var pct   = total > 0 ? Math.round(1000 * up / total) / 10 : null;
+      var pctText = pct == null ? "—" : (pct === 100 ? "100%" : pct.toFixed(1) + "%");
+      var html = '<div class="head">' + fmtBucketRange(start) + "</div>";
+      if (total > 0) {
+        html += '<div class="row"><span>Checks</span><span>' + total + "</span></div>";
+        html += '<div class="row"><span>Successful</span><span>' + up + "</span></div>";
+        html += '<div class="row"><span>Uptime</span><span class="pct ' + uptimeBand(pct) + '">' + pctText + "</span></div>";
+      } else {
+        html += '<div class="row"><span>No data</span><span>—</span></div>';
+      }
+      tooltip.innerHTML = html;
+      tooltip.style.display = "block";
+      var rect = bar.getBoundingClientRect();
+      // Position at top-center of the bar.
+      tooltip.style.left = (rect.left + rect.width / 2) + "px";
+      tooltip.style.top  = rect.top + "px";
+    }
+    function hideTooltip() {
+      tooltip.style.display = "none";
+    }
+
+    // Delegate from each .bars container so dynamically-rendered bars
+    // (compact mode click-to-expand) work too.
+    document.addEventListener("mouseover", function (e) {
+      var bar = e.target && e.target.closest && e.target.closest(".bar");
+      if (bar && bar.parentElement && bar.parentElement.classList.contains("bars")) {
+        showTooltipForBar(bar, e);
+      }
+    });
+    document.addEventListener("mouseout", function (e) {
+      var bar = e.target && e.target.closest && e.target.closest(".bar");
+      if (bar) hideTooltip();
+    });
+    // Hide on scroll so the tooltip doesn't lag behind the bar.
+    window.addEventListener("scroll", hideTooltip, { passive: true });
+  }
+  // ── End bar tooltips ──────────────────────────────────────────────────
+
   function escapeHtml(s) {
     return String(s)
       .replace(/&/g, "&amp;")
diff --git a/apps/status/src/views/page.ejs b/apps/status/src/views/page.ejs
index 2f3840e..7fabaa9 100644
--- a/apps/status/src/views/page.ejs
+++ b/apps/status/src/views/page.ejs
@@ -117,10 +117,18 @@
     .monitor-name .name { font-weight: 600; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
     .monitor-meta { display: flex; gap: 1rem; align-items: center; font-size: 0.85rem; color: var(--muted); }
     .uptime-pct { font-variant-numeric: tabular-nums; font-weight: 600; color: var(--fg); }
-    .bars { display: flex; gap: 0.1rem; height: 32px; margin-top: 0.75rem; align-items: stretch; }
+    .bars { display: flex; gap: 0.1rem; height: 32px; margin-top: 0.75rem; align-items: stretch; position: relative; }
     .bar { flex: 1; min-width: 0; border-radius: 2px; transition: opacity 0.15s; }
     .bar:hover { opacity: 0.8; }
     .bars-meta { display: flex; justify-content: space-between; font-size: 0.7rem; color: var(--muted); margin-top: 0.4rem; }
+    /* Tooltip shown when hovering a bar. Single floating element per page, positioned by JS. */
+    #bar-tooltip { position: fixed; pointer-events: none; background: var(--card); border: 1px solid var(--border); border-radius: 6px; padding: 0.5rem 0.75rem; font-size: 0.75rem; color: var(--fg); box-shadow: 0 8px 24px rgba(0,0,0,0.3); z-index: 100; min-width: 160px; transform: translate(-50%, -100%); margin-top: -8px; display: none; }
+    #bar-tooltip .head { color: var(--muted); margin-bottom: 0.25rem; font-size: 0.7rem; }
+    #bar-tooltip .row  { display: flex; justify-content: space-between; gap: 1rem; }
+    #bar-tooltip .row span:last-child { color: var(--fg); font-weight: 600; font-variant-numeric: tabular-nums; }
+    #bar-tooltip .pct.good { color: var(--bar-up); }
+    #bar-tooltip .pct.warn { color: var(--bar-partial); }
+    #bar-tooltip .pct.bad  { color: var(--bar-down); }
     /* Multi-window uptime row: four labelled cells side by side. */
     .uptime-row { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 0.5rem; margin-top: 0.75rem; }
     .uptime-cell { background: var(--bg); border: 1px solid var(--border); border-radius: 6px; padding: 0.5rem 0.65rem; }
@@ -283,9 +291,9 @@
                   <span class="uptime-pct"><%= fmtUptime(u[page.default_window === '24h' ? 'd24' : page.default_window === '7d' ? 'd7' : page.default_window === '30d' ? 'd30' : 'd90']) %></span>
                 </div>
               </div>
-              <div class="bars" title="<%= statusLabel(m.current_state) %>">
+              <div class="bars" aria-label="<%= statusLabel(m.current_state) %>">
                 <% buckets.forEach(function(b) { %>
-                  <div class="bar" style="background: <%= bucketColor(b) %>;" title="<%= b.total > 0 ? (Math.round(100 * b.up / b.total) + '% up') : 'no data' %>"></div>
+                  <div class="bar" style="background: <%= bucketColor(b) %>;" data-start="<%= b.start %>" data-total="<%= b.total %>" data-up="<%= b.up %>"></div>
                 <% }); %>
               </div>
               <div class="bars-meta">
@@ -339,10 +347,9 @@
     </footer>
   </main>
 
-  <% if (anyCompact) { %>
+  <div id="bar-tooltip" role="tooltip"></div>
   <script>window.PINGQL_PAGE = <%~ JSON.stringify({ slug: page.slug, default_window: page.default_window, show_response_time: !!page.show_response_time }) %>;</script>
   <script src="/_static/expand.js?v=<%= it.expandJsHash %>" defer></script>
-  <% } %>
 
   <% if (page.auto_refresh_s > 0) { %>
   <script>