feat: add result transaction SQL boundary

server/store/result_sql.go

@@ -0,0 +1,38 @@
+package store
+
+// ResultReceiptInsertSQL intentionally uses DO NOTHING. The adapter must
+// select the existing receipt afterward and compare its digest; an identical
+// retry is acknowledged, while a different payload is a conflict with no
+// update side effect.
+const ResultReceiptInsertSQL = `INSERT INTO result_receipts
+    (result_id, match_id, result_nonce, payload_digest, integrity_state, received_at)
+VALUES ($1, $2, $3, $4, $5, $6)
+ON CONFLICT DO NOTHING`
+
+const ResultReceiptSelectSQL = `SELECT result_id, match_id, result_nonce, payload_digest,
+    integrity_state, received_at, committed_at
+FROM result_receipts
+WHERE match_id = $1
+FOR UPDATE`
+
+// ResultCommitLockSQL establishes the match lock before participant/rating
+// locks. Rating rows are then locked in lexical player-ID order by the
+// adapter, ensuring every concurrent result computes from one snapshot.
+const ResultCommitLockSQL = `SELECT match_id, playlist, state
+FROM matches
+WHERE match_id = $1 AND server_id = $2
+FOR UPDATE`
+
+const ResultMatchCompleteSQL = `UPDATE matches
+SET state = 'COMPLETED', revision = revision + 1, completed_at = $2
+WHERE match_id = $1 AND state = 'RESULT_PENDING'`
+
+const ResultOutboxSQL = `INSERT INTO outbox
+    (event_id, aggregate_type, aggregate_id, revision, event_type, payload)
+VALUES ($1, 'match', $2, $3, 'match_completed', $4)`
+
+const RatingLockSQL = `SELECT player_id, rating, deviation, volatility, ranked_games, revision
+FROM ratings
+WHERE player_id = ANY($1)
+ORDER BY player_id
+FOR UPDATE`

server/store/result_sql_test.go

@@ -0,0 +1,30 @@
+package store
+
+import "testing"
+
+func TestResultSQLPreservesReceiptConflictAndAtomicCommitBoundaries(t *testing.T) {
+	checks := map[string][]string{
+		ResultReceiptInsertSQL: {"ON CONFLICT DO NOTHING", "payload_digest", "integrity_state"},
+		ResultReceiptSelectSQL: {"FOR UPDATE", "committed_at"},
+		ResultCommitLockSQL:    {"server_id = $2", "FOR UPDATE"},
+		ResultMatchCompleteSQL: {"state = 'RESULT_PENDING'", "revision = revision + 1"},
+		ResultOutboxSQL:        {"match_completed", "aggregate_id", "revision"},
+		RatingLockSQL:          {"ORDER BY player_id", "FOR UPDATE"},
+	}
+	for query, fragments := range checks {
+		for _, fragment := range fragments {
+			if !contains(query, fragment) {
+				t.Fatalf("query %q missing %q", query, fragment)
+			}
+		}
+	}
+}
+
+func contains(value, fragment string) bool {
+	for i := 0; i+len(fragment) <= len(value); i++ {
+		if value[i:i+len(fragment)] == fragment {
+			return true
+		}
+	}
+	return false
+}