diff --git a/internal/ebooks/enrichment_queue.go b/internal/ebooks/enrichment_queue.go
index 024b7e48..68f7bcf0 100644
--- a/internal/ebooks/enrichment_queue.go
+++ b/internal/ebooks/enrichment_queue.go
@@ -129,6 +129,9 @@ const mergeEbookProtectedFieldsSQL = `
 	)
 `
 
+// Legacy-lane rows (priority < 0) may only leave the lane through a terminal
+// outcome (Complete/Discard); enqueue, fail, and release must preserve the
+// lane so the paced backfill task stays the sole drain for the backlog.
 var enqueueEnrichmentJobQuery = `
 	INSERT INTO ebook_enrichment_state (
 		content_id, status, priority, next_attempt_at, protected_fields, updated_at
@@ -145,6 +148,7 @@ var enqueueEnrichmentJobQuery = `
 		END,
 		priority = CASE
 			WHEN ebook_enrichment_state.status = 'running' THEN ebook_enrichment_state.priority
+			WHEN ebook_enrichment_state.priority < 0 THEN ebook_enrichment_state.priority
 			ELSE GREATEST(ebook_enrichment_state.priority, EXCLUDED.priority)
 		END,
 		next_attempt_at = CASE
@@ -670,7 +674,7 @@ var failEnrichmentJobQuery = `
 			WHEN requeue_requested THEN now()
 			ELSE now() + $4::interval
 		END,
-		priority = CASE WHEN requeue_requested THEN 100 ELSE priority END,
+		priority = CASE WHEN requeue_requested AND priority >= 0 THEN 100 ELSE priority END,
 		requeue_requested = false,
 		outcome = 'failed',
 		last_error_class = $2,
@@ -720,7 +724,7 @@ var releaseEnrichmentJobQuery = `
 		claim_token = NULL,
 		attempts = GREATEST(attempts - 1, 0),
 		next_attempt_at = CASE WHEN requeue_requested THEN now() ELSE next_attempt_at END,
-		priority = CASE WHEN requeue_requested THEN 100 ELSE priority END,
+		priority = CASE WHEN requeue_requested AND priority >= 0 THEN 100 ELSE priority END,
 		requeue_requested = false,
 		updated_at = now()
 	WHERE content_id = $1
diff --git a/internal/ebooks/enrichment_queue_test.go b/internal/ebooks/enrichment_queue_test.go
index ede1d664..58e82695 100644
--- a/internal/ebooks/enrichment_queue_test.go
+++ b/internal/ebooks/enrichment_queue_test.go
@@ -317,6 +317,7 @@ func TestEnrichmentQueueEnqueueMakesPendingRowsDueAndDefersRunningRequeue(t *tes
 		"ON CONFLICT (content_id) DO UPDATE SET",
 		"WHEN ebook_enrichment_state.status = 'running' THEN ebook_enrichment_state.next_attempt_at",
 		"ELSE now()",
+		"WHEN ebook_enrichment_state.priority < 0 THEN ebook_enrichment_state.priority",
 		"requeue_requested = ebook_enrichment_state.requeue_requested OR ebook_enrichment_state.status = 'running'",
 	} {
 		if !strings.Contains(query, fragment) {
@@ -328,6 +329,28 @@ func TestEnrichmentQueueEnqueueMakesPendingRowsDueAndDefersRunningRequeue(t *tes
 	}
 }
 
+func TestEnrichmentQueueKeepsLegacyLaneRowsUntilTerminalOutcome(t *testing.T) {
+	enqueue := strings.Join(strings.Fields(enqueueEnrichmentJobQuery), " ")
+	if !strings.Contains(enqueue, "WHEN ebook_enrichment_state.priority < 0 THEN ebook_enrichment_state.priority") {
+		t.Fatalf("enqueue must keep legacy-lane rows in the legacy lane:\n%s", enqueueEnrichmentJobQuery)
+	}
+	for _, tt := range []struct {
+		name  string
+		query string
+	}{
+		{name: "fail", query: failEnrichmentJobQuery},
+		{name: "release", query: releaseEnrichmentJobQuery},
+	} {
+		query := strings.Join(strings.Fields(tt.query), " ")
+		if strings.Contains(query, "WHEN requeue_requested THEN 100") {
+			t.Fatalf("%s requeue must not promote legacy-lane rows without a terminal outcome:\n%s", tt.name, tt.query)
+		}
+		if !strings.Contains(query, "WHEN requeue_requested AND priority >= 0 THEN 100 ELSE priority END") {
+			t.Fatalf("%s requeue must stay within the row's lane:\n%s", tt.name, tt.query)
+		}
+	}
+}
+
 func TestEnrichmentQueueMigrationIsCrashSafeAndSeedsAllLegacyEbooks(t *testing.T) {
 	body, err := os.ReadFile("../../migrations/sql/20260719090000_ebook_enrichment_jobs.sql")
 	if err != nil {
@@ -436,7 +459,7 @@ func TestEnrichmentQueueTransitionsKeepDurableRowsAndReleaseLeases(t *testing.T)
 	failure := strings.Join(strings.Fields(failEnrichmentJobQuery), " ")
 	for _, fragment := range []string{
 		"WHEN requeue_requested THEN now()",
-		"WHEN requeue_requested THEN 100 ELSE priority END",
+		"WHEN requeue_requested AND priority >= 0 THEN 100 ELSE priority END",
 		"AND claim_token = $5",
 	} {
 		if !strings.Contains(failure, fragment) {