Show 90-day uptime bars on the status page

Every check is also counted in a per-day table that outlives the raw checks, so the public page
can draw one bar per UTC day with a tooltip, as most hosted status pages do. Existing databases
are backfilled once from the checks they still have.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

internal/sandbar/api.go

@@ -802,10 +802,11 @@ func (s *Server) heartbeat(w http.ResponseWriter, r *http.Request) {
 // statusJSON feeds the public status page: only monitors and incidents marked public.
 func (s *Server) statusJSON(w http.ResponseWriter, r *http.Request) {
 	type mon struct {
-		Name   string  `json:"name"`
-		Status string  `json:"status"`
-		Uptime float64 `json:"uptime"`
-		Since  int64   `json:"since"`
+		Name   string   `json:"name"`
+		Status string   `json:"status"`
+		Uptime float64  `json:"uptime"`
+		Since  int64    `json:"since"`
+		Days   [][2]int `json:"days"` // [checks, failed] per UTC day, oldest first, ending today
 	}
 	type inc struct {
 		Title    string  `json:"title"`
@@ -819,14 +820,24 @@ func (s *Server) statusJSON(w http.ResponseWriter, r *http.Request) {
 		Monitors  []mon  `json:"monitors"`
 		Incidents []inc  `json:"incidents"`
 		Overall   string `json:"overall"`
-	}{[]mon{}, []inc{}, "operational"}
+		Today     string `json:"today"` // the UTC date of the last bar
+	}{[]mon{}, []inc{}, "operational", s.now().UTC().Format("2006-01-02")}
 	mons, _ := listOf[Monitor](s.st, "monitor")
 	for _, m := range mons {
 		if !m.Public || !m.Enabled {
 			continue
 		}
 		st := s.monitorState(m.ID)
-		out.Monitors = append(out.Monitors, mon{m.Name, st.Status, st.Uptime30, st.Since})
+		days := s.dailyUptime(m.ID, uptimeDays, s.now())
+		var checks, fails int
+		for _, d := range days {
+			checks, fails = checks+d[0], fails+d[1]
+		}
+		uptime := -1.0 // no checks yet
+		if checks > 0 {
+			uptime = float64(checks-fails) * 100 / float64(checks)
+		}
+		out.Monitors = append(out.Monitors, mon{m.Name, st.Status, uptime, st.Since, days})
 		if st.Status == "down" {
 			out.Overall = "outage"
 		}

internal/sandbar/bars_test.go

@@ -0,0 +1,88 @@
+package sandbar
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+)
+
+// Every check lands in a per-day count that outlives the raw checks, and the status page
+// gets one [checks, failed] pair per day, oldest first and ending today.
+func TestUptimeBars(t *testing.T) {
+	s, clk, _ := newTestServer(t)
+	m := &Monitor{ID: "m", Name: "Site", Kind: "http", Target: "http://x", Enabled: true, Public: true, Retries: 1}
+	s.st.put("monitor", m.ID, m)
+
+	// Two days ago: 4 checks, 1 failed. Yesterday: nothing. Today: 2 checks, both fine.
+	clk.Advance(-48 * time.Hour)
+	for i := 0; i < 4; i++ {
+		var err error
+		if i == 3 {
+			err = errors.New("timeout")
+		}
+		s.recordResult(m, s.monitorState(m.ID), clk.Now(), 10*time.Millisecond, err)
+	}
+	clk.Advance(48 * time.Hour)
+	s.recordResult(m, s.monitorState(m.ID), clk.Now(), 10*time.Millisecond, nil)
+	s.recordResult(m, s.monitorState(m.ID), clk.Now(), 10*time.Millisecond, nil)
+
+	days := s.dailyUptime(m.ID, 5, clk.Now())
+	want := [][2]int{{0, 0}, {0, 0}, {4, 1}, {0, 0}, {2, 0}}
+	for i := range want {
+		if days[i] != want[i] {
+			t.Fatalf("days = %v, want %v", days, want)
+		}
+	}
+
+	// The rollup survives pruning the raw checks.
+	s.st.prune(clk.Now().AddDate(0, 0, 60), 30, 1)
+	if got := s.dailyUptime(m.ID, 5, clk.Now()); got[2] != [2]int{4, 1} {
+		t.Fatalf("rollup lost after pruning: %v", got)
+	}
+
+	ts := httptest.NewServer(s.Handler())
+	defer ts.Close()
+	resp, err := http.Get(ts.URL + "/status.json")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer resp.Body.Close()
+	var out struct {
+		Today    string
+		Monitors []struct {
+			Uptime float64
+			Days   [][2]int
+		}
+	}
+	json.NewDecoder(resp.Body).Decode(&out)
+	if out.Today != "2026-01-05" || len(out.Monitors) != 1 || len(out.Monitors[0].Days) != uptimeDays {
+		t.Fatalf("status.json: %+v", out)
+	}
+	m0 := out.Monitors[0]
+	if last := m0.Days[uptimeDays-1]; last != [2]int{2, 0} {
+		t.Fatalf("today's bar: %v", last)
+	}
+	if want := 100 * 5.0 / 6.0; m0.Uptime < want-0.01 || m0.Uptime > want+0.01 {
+		t.Fatalf("uptime %.2f, want %.2f", m0.Uptime, want)
+	}
+}
+
+// A database from before the daily table gets it built from the checks it has.
+func TestDailyBackfill(t *testing.T) {
+	s, clk, _ := newTestServer(t)
+	now := clk.Now().Unix()
+	s.st.db.Exec(`INSERT INTO checks(monitor_id,time,ok,ms,detail) VALUES('m',?,1,5,''),('m',?,0,5,'x')`, now, now+1)
+	s.st.db.Exec(`DELETE FROM daily`)
+	var have int
+	s.st.db.QueryRow(`SELECT count(*) FROM daily`).Scan(&have)
+	if have != 0 {
+		t.Fatal("setup")
+	}
+	s.st.backfillDaily()
+	if got := s.dailyUptime("m", 1, clk.Now()); got[0] != [2]int{2, 1} {
+		t.Fatalf("backfill: %v", got)
+	}
+}

internal/sandbar/monitor.go

@@ -233,6 +233,37 @@ func (s *Server) monitorState(id string) MonitorState {
 	return st
 }
 
+// uptimeDays is how many days of bars the status page shows.
+const uptimeDays = 90
+
+// dailyUptime returns [checks, failed] for each of the last n UTC days, oldest first, so the
+// last entry is today. A day with no checks is [0, 0].
+func (s *Server) dailyUptime(monitorID string, n int, now time.Time) [][2]int {
+	out := make([][2]int, n)
+	today := now.UTC().Truncate(24 * time.Hour)
+	rows, err := s.st.db.Query(`SELECT day,checks,fails FROM daily WHERE monitor_id=? AND day>=?`,
+		monitorID, today.AddDate(0, 0, -(n-1)).Format("2006-01-02"))
+	if err != nil {
+		return out
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var day string
+		var c, f int
+		if rows.Scan(&day, &c, &f) != nil {
+			continue
+		}
+		d, err := time.Parse("2006-01-02", day)
+		if err != nil {
+			continue
+		}
+		if i := n - 1 - int(today.Sub(d).Hours()/24); i >= 0 && i < n {
+			out[i] = [2]int{c, f}
+		}
+	}
+	return out
+}
+
 func (s *Server) saveState(st MonitorState) {
 	s.st.db.Exec(`INSERT INTO mstate(monitor_id,status,since,last_check,last_ms,fails,last_ping,detail) VALUES(?,?,?,?,?,?,?,?)
 		ON CONFLICT(monitor_id) DO UPDATE SET status=excluded.status, since=excluded.since, last_check=excluded.last_check,
@@ -309,6 +340,8 @@ func (s *Server) recordResult(m *Monitor, st MonitorState, now time.Time, dur ti
 		okInt = 1
 	}
 	s.st.db.Exec(`INSERT INTO checks(monitor_id,time,ok,ms,detail) VALUES(?,?,?,?,?)`, m.ID, now.Unix(), okInt, dur.Milliseconds(), errText(err))
+	s.st.db.Exec(`INSERT INTO daily(monitor_id,day,checks,fails) VALUES(?,?,1,?)
+		ON CONFLICT(monitor_id,day) DO UPDATE SET checks=checks+1, fails=fails+excluded.fails`, m.ID, now.UTC().Format("2006-01-02"), 1-okInt)
 	st.LastCheck, st.LastMS, st.Detail = now.Unix(), int(dur.Milliseconds()), errText(err)
 	key := "monitor:" + m.ID
 	if ok {
@@ -369,6 +402,7 @@ func (s *Server) Heartbeat(token string) bool {
 func (s *Server) deleteMonitorData(id string) {
 	s.st.db.Exec(`DELETE FROM mstate WHERE monitor_id=?`, id)
 	s.st.db.Exec(`DELETE FROM checks WHERE monitor_id=?`, id)
+	s.st.db.Exec(`DELETE FROM daily WHERE monitor_id=?`, id)
 	s.ResolveAlertKey("monitor:"+id, "monitor deleted")
 }
 

internal/sandbar/store.go

@@ -45,6 +45,9 @@ CREATE INDEX IF NOT EXISTS messages_topic ON messages(topic, time);
 CREATE TABLE IF NOT EXISTS checks (
 	monitor_id TEXT NOT NULL, time INTEGER NOT NULL, ok INTEGER NOT NULL, ms INTEGER NOT NULL, detail TEXT NOT NULL);
 CREATE INDEX IF NOT EXISTS checks_monitor ON checks(monitor_id, time);
+-- One row per monitor per UTC day, kept far longer than raw checks: it feeds the status page's uptime bars.
+CREATE TABLE IF NOT EXISTS daily (
+	monitor_id TEXT NOT NULL, day TEXT NOT NULL, checks INTEGER NOT NULL, fails INTEGER NOT NULL, PRIMARY KEY (monitor_id, day));
 CREATE TABLE IF NOT EXISTS mstate (
 	monitor_id TEXT PRIMARY KEY, status TEXT NOT NULL, since INTEGER NOT NULL, last_check INTEGER NOT NULL,
 	last_ms INTEGER NOT NULL, fails INTEGER NOT NULL, last_ping INTEGER NOT NULL, detail TEXT NOT NULL);
@@ -78,7 +81,19 @@ func OpenStore(dir string, box *secretbox.Box) (*Store, error) {
 		db.Close()
 		return nil, err
 	}
-	return &Store{db: db, box: box}, nil
+	st := &Store{db: db, box: box}
+	st.backfillDaily()
+	return st, nil
+}
+
+// backfillDaily fills the daily table from the raw checks, but only when it is empty: a database
+// from before the table existed. After that every check is counted as it is recorded.
+func (s *Store) backfillDaily() {
+	var have int
+	if s.db.QueryRow(`SELECT count(*) FROM daily`).Scan(&have) == nil && have == 0 {
+		s.db.Exec(`INSERT OR IGNORE INTO daily(monitor_id,day,checks,fails)
+			SELECT monitor_id, date(time,'unixepoch'), count(*), count(*)-sum(ok) FROM checks GROUP BY monitor_id, date(time,'unixepoch')`)
+	}
 }
 
 func (s *Store) Close() error { return s.db.Close() }
@@ -234,6 +249,7 @@ func (s *Store) events(scope, ref string) []Event {
 func (s *Store) prune(now time.Time, messageDays, checkDays int) {
 	s.db.Exec(`DELETE FROM messages WHERE time < ?`, now.AddDate(0, 0, -messageDays).Unix())
 	s.db.Exec(`DELETE FROM checks WHERE time < ?`, now.AddDate(0, 0, -checkDays).Unix())
+	s.db.Exec(`DELETE FROM daily WHERE day < ?`, now.UTC().AddDate(0, 0, -400).Format("2006-01-02"))
 	s.db.Exec(`DELETE FROM sessions WHERE expires < ?`, now.Unix())
 	s.db.Exec(`DELETE FROM alerts WHERE status='resolved' AND resolved_at < ? AND incident_id=''`, now.AddDate(0, 0, -90).Unix())
 }

internal/sandbar/web/status.html

@@ -45,6 +45,17 @@
   .card { background:var(--surface); border:var(--border-w) solid var(--border); border-radius:var(--radius-lg); overflow:hidden; }
   .row { display:flex; align-items:center; justify-content:space-between; gap:var(--s3); flex-wrap:wrap; padding:var(--s3) var(--s4); border-bottom:var(--border-w) solid var(--border); }
   .row:last-child { border-bottom:0; }
+  .svc { padding:var(--s3) var(--s4) var(--s4); border-bottom:var(--border-w) solid var(--border); }
+  .svc:last-child { border-bottom:0; }
+  .svc .top { display:flex; align-items:center; justify-content:space-between; gap:var(--s3); flex-wrap:wrap; }
+  .bars { display:flex; gap:2px; height:32px; margin-top:var(--s3); }
+  .bar { flex:1; min-width:0; border-radius:2px; background:var(--neutral-bg); }
+  .bar.ok { background:var(--success); } .bar.warn { background:var(--warning); } .bar.bad { background:var(--danger); }
+  .bar:hover { opacity:.7; }
+  .axis { display:flex; justify-content:space-between; margin-top:var(--s1); font-size:var(--text-xs); color:var(--text-faint); }
+  .tip { position:fixed; z-index:10; pointer-events:none; max-width:240px; padding:var(--s2) var(--s3); border-radius:var(--radius); background:var(--surface); color:var(--text); border:var(--border-w) solid var(--border-strong); font-size:var(--text-sm); }
+  .tip strong { display:block; }
+  @media (max-width:480px) { .bars { gap:1px; } }
   .badge { display:inline-flex; align-items:center; padding:2px var(--s2); border-radius:999px; font-size:var(--text-xs); font-weight:600; background:var(--neutral-bg); color:var(--text-muted); white-space:nowrap; }
   .badge-success { background:var(--success-bg); color:var(--success); }
   .badge-warning { background:var(--warning-bg); color:var(--warning); }
@@ -56,6 +67,7 @@
 </style>
 </head>
 <body>
+<div class="tip" id="tip" role="presentation" hidden></div>
 <main>
   <h1>Status</h1>
   <div id="banner" class="banner" role="status">Loading</div>
@@ -72,6 +84,48 @@ const label = { operational: 'All systems are operational', degraded: 'Some syst
 const statusBadge = s => s === 'up' ? el('span', 'badge badge-success', 'Operational') : s === 'down' ? el('span', 'badge badge-danger', 'Down') : el('span', 'badge', 'Waiting for first check');
 const incStatus = { investigating: 'Investigating', identified: 'Identified', monitoring: 'Monitoring', resolved: 'Resolved' };
 
+// One bar per UTC day, oldest first. A day is green with no failed checks, amber when at least 99% passed,
+// and red below that. Color is never the only signal: the tooltip and the label say it in words.
+const dayFmt = new Intl.DateTimeFormat(undefined, {month:'short', day:'numeric', year:'numeric', timeZone:'UTC'});
+const dayClass = ([c, f]) => !c ? '' : !f ? 'ok' : (c - f) / c >= 0.99 ? 'warn' : 'bad';
+function dayText([c, f], i, n, today) {
+  const d = new Date(today + 'T00:00:00Z'); d.setUTCDate(d.getUTCDate() - (n - 1 - i));
+  if (!c) return [dayFmt.format(d), 'No data'];
+  const up = ((c - f) * 100 / c).toFixed(2) + '% uptime';
+  return [dayFmt.format(d), f ? up + ', ' + f.toLocaleString() + ' failed of ' + c.toLocaleString() + ' checks' : up];
+}
+const tip = $('tip');
+function showTip(e, lines) {
+  tip.replaceChildren(el('strong', '', lines[0]), document.createTextNode(lines[1]));
+  tip.hidden = false;
+  const w = tip.offsetWidth, x = Math.min(Math.max(8, e.clientX - w / 2), innerWidth - w - 8);
+  tip.style.left = x + 'px'; tip.style.top = Math.max(8, e.clientY - tip.offsetHeight - 14) + 'px';
+}
+function service(m, today) {
+  const box = el('div', 'svc'), top = el('div', 'top');
+  top.append(el('span', '', m.name));
+  const right = el('span', 'small dim num');
+  right.append(statusBadge(m.status), document.createTextNode(m.uptime >= 0 ? ' ' + m.uptime.toFixed(2) + '% uptime' : ''));
+  top.append(right); box.append(top);
+  const days = m.days || [], bars = el('div', 'bars');
+  const bad = days.filter(d => dayClass(d) === 'bad').length, warn = days.filter(d => dayClass(d) === 'warn').length;
+  bars.setAttribute('role', 'img');
+  bars.setAttribute('aria-label', m.name + ', the last ' + days.length + ' days: ' + (m.uptime >= 0 ? m.uptime.toFixed(2) + '% uptime' : 'no checks yet') +
+    (bad || warn ? ', ' + bad + ' days with an outage and ' + warn + ' with short failures' : ', no failures'));
+  days.forEach((d, i) => {
+    const b = el('span', 'bar ' + dayClass(d));
+    const lines = dayText(d, i, days.length, today);
+    b.addEventListener('pointerenter', e => showTip(e, lines));
+    b.addEventListener('pointermove', e => showTip(e, lines));
+    b.addEventListener('pointerleave', () => { tip.hidden = true; });
+    bars.append(b);
+  });
+  const axis = el('div', 'axis'); axis.setAttribute('aria-hidden', 'true');
+  axis.append(el('span', '', days.length + ' days ago'), el('span', '', 'Today'));
+  if (days.length) box.append(bars, axis);
+  return box;
+}
+
 async function load() {
   let d;
   try { d = await (await fetch('/status.json')).json(); } catch (e) { $('banner').textContent = 'The status could not be loaded. Try again in a moment.'; return; }
@@ -80,13 +134,7 @@ async function load() {
 
   const sv = $('services'); sv.replaceChildren();
   if (!d.monitors.length) sv.append(el('div', 'row dim', 'No services are published yet.'));
-  for (const m of d.monitors) {
-    const r = el('div', 'row');
-    r.append(el('span', '', m.name));
-    const right = el('span', 'small dim num');
-    right.append(statusBadge(m.status), document.createTextNode(m.uptime >= 0 ? ' ' + m.uptime.toFixed(2) + '% uptime' : ''));
-    r.append(right); sv.append(r);
-  }
+  for (const m of d.monitors) sv.append(service(m, d.today));
 
   const ic = $('incidents'); ic.replaceChildren();
   if (!d.incidents.length) ic.append(el('div', 'row dim', 'No incidents in the last 14 days.'));