NEO-151: Fix Postgres ListForPlayer read race with single CTE query

Bugbot: active and completed rows now load in one statement snapshot so
GET /contracts cannot return the same instance twice after completion.

docs/reviews/2026-06-28-NEO-151.md

@@ -53,6 +53,7 @@ None.
 |----------|----------|---------|--------|
 | Low | `scripts/reset-contract-instances-helper.js` | Reset helper only cleared one capped GET page (active + 10 completed); older rows could survive pre-request cleanup | **Done.** — loop GET → reset until list empty (max 100 passes) |
 | Low | `contracts/scripts/` helper path | Bruno resolves `./scripts/` from collection root, not per-folder — CI module not found | **Done.** — moved helper to `neon-sprawl-server/scripts/`; `.js` suffix on requires |
+| Medium | `PostgresContractInstanceStore.ListForPlayer` | Active + completed read in two queries without snapshot — duplicate row if status flips mid-read | **Done.** — single CTE query for atomic list snapshot |
 
 ## Verification
 

server/NeonSprawl.Server/Game/Contracts/PostgresContractInstanceStore.cs

@@ -330,56 +330,41 @@ public sealed class PostgresContractInstanceStore(Npgsql.NpgsqlDataSource dataSo
             return [];
         }
 
-        ContractInstanceState? active = null;
+        // Single statement snapshot — avoids active+completed duplicate rows if status flips mid-read.
-        using (var activeCmd = new Npgsql.NpgsqlCommand(
+        using var cmd = new Npgsql.NpgsqlCommand(
-                   """
+            """
-                   SELECT contract_instance_id, template_id, player_id, status, seed_bucket, issued_at, completed_at
+            WITH active_row AS (
-                   FROM contract_instance
+                SELECT contract_instance_id, template_id, player_id, status, seed_bucket, issued_at, completed_at, 0 AS section
-                   WHERE player_id = @pid AND status = 'active'
+                FROM contract_instance
-                   LIMIT 1;
+                WHERE player_id = @pid AND status = 'active'
-                   """,
+                LIMIT 1
-                   conn))
+            ),
-        {
+            completed_rows AS (
-            activeCmd.Parameters.AddWithValue("pid", player);
+                SELECT contract_instance_id, template_id, player_id, status, seed_bucket, issued_at, completed_at, 1 AS section
-            using var reader = activeCmd.ExecuteReader();
-            if (reader.Read())
-            {
-                var snapshot = ReadSnapshot(reader);
-                if (snapshot.Status == ContractInstanceStatus.Active)
-                {
-                    active = snapshot;
-                }
-            }
-        }
-
-        var completed = new List<ContractInstanceState>(maxCompletedRows);
-        if (maxCompletedRows > 0)
-        {
-            using var cmd = new Npgsql.NpgsqlCommand(
-                """
-                SELECT contract_instance_id, template_id, player_id, status, seed_bucket, issued_at, completed_at
                 FROM contract_instance
                 WHERE player_id = @pid AND status = 'completed'
                 ORDER BY issued_at DESC, contract_instance_id ASC
-                LIMIT @limit;
+                LIMIT @limit
-                """,
+            )
-                conn);
+            SELECT contract_instance_id, template_id, player_id, status, seed_bucket, issued_at, completed_at
-            cmd.Parameters.AddWithValue("pid", player);
+            FROM (
-            cmd.Parameters.AddWithValue("limit", maxCompletedRows);
+                SELECT * FROM active_row
-            using var reader = cmd.ExecuteReader();
+                UNION ALL
-            while (reader.Read())
+                SELECT * FROM completed_rows
-            {
+            ) AS listed
-                completed.Add(ReadSnapshot(reader));
+            ORDER BY section, issued_at DESC, contract_instance_id ASC;
-            }
+            """,
-        }
+            conn);
+        cmd.Parameters.AddWithValue("pid", player);
+        cmd.Parameters.AddWithValue("limit", maxCompletedRows);
 
-        if (active is null)
+        var result = new List<ContractInstanceState>();
+        using var reader = cmd.ExecuteReader();
+        while (reader.Read())
         {
-            return completed;
+            result.Add(ReadSnapshot(reader));
         }
 
-        var result = new List<ContractInstanceState>(1 + completed.Count) { active };
-        result.AddRange(completed);
         return result;
     }