fix(rectification): preserve assistant turns in dossier

frontend/tests/rectification-v9-migration.test.ts

@@ -399,3 +399,53 @@ test("birth-context activity migration stays out of the identity migration tree"
     "business migration must not be copied into frontend/db/migrations (BUG-127/BUG-144)",
   );
 });
+
+// ---------------------------------------------------------------------------
+// 20260813030000_rectification_turn_message_projection.sql
+// ---------------------------------------------------------------------------
+
+const turnMessageProjectionMigration = readFileSync(
+  new URL(
+    "../supabase/migrations/20260813030000_rectification_turn_message_projection.sql",
+    import.meta.url,
+  ),
+  "utf8",
+);
+
+const turnMessageProjectionMigrationCopy = fileURLToPath(
+  new URL(
+    "../db/migrations/20260813030000_rectification_turn_message_projection.sql",
+    import.meta.url,
+  ),
+);
+
+test("rectification turn projection migration follows the V9 activity migration", () => {
+  assert.ok(
+    "20260813030000_rectification_turn_message_projection.sql" >
+      "20260813020000_rectification_birth_context_activity.sql",
+  );
+  assert.match(turnMessageProjectionMigration, /^-- Preserve both logical messages[\s\S]*\nbegin;[\s\S]*^commit;$/m);
+});
+
+test("rectification dossier expands each physical turn into user and assistant messages", () => {
+  assert.match(
+    turnMessageProjectionMigration,
+    /cross join lateral \(\s*values\s*\(1, 'user'::text, t\.user_message\),\s*\(2, 'assistant'::text, t\.assistant_message\)\s*\) as message\(ordinal, role, text\)/,
+  );
+  assert.match(turnMessageProjectionMigration, /'role', message\.role/);
+  assert.match(turnMessageProjectionMigration, /'text', message\.text/);
+  assert.match(turnMessageProjectionMigration, /order by t\.created_at, message\.ordinal/);
+  assert.match(turnMessageProjectionMigration, /and message\.text is not null/);
+  assert.doesNotMatch(
+    turnMessageProjectionMigration,
+    /coalesce\(t\.user_message, t\.assistant_message\)/,
+  );
+});
+
+test("rectification turn projection migration stays out of the identity migration tree", () => {
+  assert.equal(
+    existsSync(turnMessageProjectionMigrationCopy),
+    false,
+    "business migration must not be copied into frontend/db/migrations (BUG-127/BUG-144)",
+  );
+});