Add visitor phone lookup flow

server/internal/httpapi/limiter.go

@@ -17,6 +17,52 @@ type loginLimiter struct {
 	now      func() time.Time
 }
 
+type queryLimitEntry struct {
+	windowStart time.Time
+	count       int
+}
+
+// queryLimiter is deliberately small and in-memory for the temporary public
+// phone lookup. The production replacement will be an OTP or external
+// identity provider, so this limiter is only a safety net for the test flow.
+type queryLimiter struct {
+	mu      sync.Mutex
+	entries map[string]queryLimitEntry
+	now     func() time.Time
+	limit   int
+	window  time.Duration
+}
+
+func newQueryLimiter(now func() time.Time, limit int, window time.Duration) *queryLimiter {
+	return &queryLimiter{
+		entries: make(map[string]queryLimitEntry), now: now, limit: limit, window: window,
+	}
+}
+
+func (l *queryLimiter) allow(key string) (bool, time.Duration) {
+	if l == nil || l.limit <= 0 || l.window <= 0 {
+		return true, 0
+	}
+	l.mu.Lock()
+	defer l.mu.Unlock()
+
+	now := l.now()
+	entry, ok := l.entries[key]
+	if !ok || now.Sub(entry.windowStart) >= l.window {
+		entry = queryLimitEntry{windowStart: now}
+	}
+	if entry.count >= l.limit {
+		retry := l.window - now.Sub(entry.windowStart)
+		if retry < 0 {
+			retry = 0
+		}
+		return false, retry
+	}
+	entry.count++
+	l.entries[key] = entry
+	return true, 0
+}
+
 func newLoginLimiter(now func() time.Time) *loginLimiter {
 	return &loginLimiter{attempts: make(map[string]loginAttempt), now: now}
 }