diff --git a/shared/management/certposture/challenge_test.go b/shared/management/certposture/challenge_test.go
index 91cb9d8b2..a526799c9 100644
--- a/shared/management/certposture/challenge_test.go
+++ b/shared/management/certposture/challenge_test.go
@@ -51,3 +51,55 @@ func TestChallenger_HonoursAShortenedWindow(t *testing.T) {
 	assert.ErrorIs(t, c.verifyNonce(nonce, peerKey, issued.Add(3*short)), ErrNonceExpired,
 		"a shortened window must actually expire the nonce sooner")
 }
+
+// heldNonceAlwaysAccepted walks ten windows and, at every step, checks the nonce the peer
+// would be holding if it were re-stamped every period starting at offset. It returns how
+// many of those checks would have rejected the peer.
+func heldNonceAlwaysAccepted(c *Challenger, peerKey []byte, period, offset time.Duration) int {
+	start := time.Unix(0, 0).UTC().Add(offset)
+	var rejected int
+	for elapsed := time.Duration(0); elapsed < 10*Window; elapsed += 7 * time.Minute {
+		lastRefresh := start.Add(elapsed / period * period)
+		if c.verifyNonce(c.Nonce(peerKey, lastRefresh), peerKey, start.Add(elapsed)) != nil {
+			rejected++
+		}
+	}
+	return rejected
+}
+
+// TestNonce_StaysValidWhenRestampedWithinAWindow is the reason management keeps no per-peer
+// nonce state. A nonce carries the window it was minted in, not the instant, and is accepted
+// for that window and the next. A peer re-stamped at least once per window therefore can
+// never be holding one that has fallen outside the accepted pair, whoever it is and whenever
+// it was last served. There is nothing to track and nothing to search for: the guarantee
+// comes from the cadence alone.
+//
+// The offsets matter: each account is given a phase of its own so a restart does not fan out
+// to every account at once, so the property has to hold off the window boundary too.
+func TestNonce_StaysValidWhenRestampedWithinAWindow(t *testing.T) {
+	c := &Challenger{secret: []byte("secret"), window: Window}
+	peerKey := []byte("peer-key")
+
+	for _, period := range []time.Duration{Window / 3, Window / 2, Window} {
+		for _, offset := range []time.Duration{0, Window / 7, Window / 2, Window - time.Minute} {
+			t.Run(period.String()+"+"+offset.String(), func(t *testing.T) {
+				assert.Zero(t, heldNonceAlwaysAccepted(c, peerKey, period, offset),
+					"a peer re-stamped every %v is never left holding an expired nonce", period)
+			})
+		}
+	}
+}
+
+func TestNonce_ExpiresWhenRestampedTooSlowly(t *testing.T) {
+	// The counterpart, which is what gives the test above its teeth. Note the aligned case
+	// does not fail: a cadence of exactly two windows that lands on the boundaries is
+	// covered by the grace window. Off the boundary it is not, and real refreshes are off
+	// the boundary by design.
+	c := &Challenger{secret: []byte("secret"), window: Window}
+	peerKey := []byte("peer-key")
+
+	assert.Zero(t, heldNonceAlwaysAccepted(c, peerKey, 2*Window, 0),
+		"two windows exactly on the boundary happens to be covered by the grace window")
+	assert.NotZero(t, heldNonceAlwaysAccepted(c, peerKey, 2*Window, Window/2),
+		"the same cadence off the boundary must leave the peer rejected for a stretch")
+}