diff --git a/server/api/errors_test.go b/server/api/errors_test.go
new file mode 100644
index 00000000..8e5e6e29
--- /dev/null
+++ b/server/api/errors_test.go
@@ -0,0 +1,21 @@
+package api
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/cosmic-clash/cosmic-clash/server/domain"
+)
+
+func TestCooldownDomainErrorIsRetryableButNotAConflict(t *testing.T) {
+	recorder := httptest.NewRecorder()
+	writeDomainError(recorder, domain.ErrPlayerCooldown)
+	if recorder.Code != http.StatusTooManyRequests {
+		t.Fatalf("cooldown status = %d, want 429", recorder.Code)
+	}
+	if !strings.Contains(recorder.Body.String(), "matchmaking_cooldown") {
+		t.Fatalf("cooldown response = %q", recorder.Body.String())
+	}
+}
diff --git a/server/store/proposal_recovery_sql.go b/server/store/proposal_recovery_sql.go
index 1b3ee52c..8f242cfc 100644
--- a/server/store/proposal_recovery_sql.go
+++ b/server/store/proposal_recovery_sql.go
@@ -116,15 +116,10 @@ SET state = 'DECLINED', revision = revision + 1
 WHERE proposal_id = $1 AND state = 'OPEN'`
 
 // ProposalDeclineRequeueSQL requeues every participant's ticket, including
-// the decliner's own: nothing yet enforces the decline cooldown §8.17
-// documents as a separate, not-yet-built feature, so leaving any ticket
-// behind at PROPOSED here isn't "cooldown behaviour", it's just a stranded
-// ticket -- invisible to the matcher (which only ever reads state='QUEUED'),
-// still counted as this player's one active ticket (blocking a fresh
-// queue_create), and renewable forever by an ordinary heartbeat, so a player
-// left in this state has no path back into matchmaking without realising
-// they need to cancel and start over. Once §8.17's cooldown exists, it can
-// exempt the decliner from this immediate requeue; today nothing does.
+// the decliner's own. The durable decline penalty separately prevents that
+// player from immediately creating a replacement ticket; leaving this ticket
+// at PROPOSED would not implement a cooldown, it would strand the player and
+// hide the ticket from the matcher.
 const ProposalDeclineRequeueSQL = `UPDATE queue_tickets q
 SET state = 'QUEUED', expires_at = $2, revision = revision + 1
 FROM proposal_participants pp