diff --git a/packages/bus/tests/session-compactions.test.mjs b/packages/bus/tests/session-compactions.test.mjs
index bde15c282..4493d1d70 100644
--- a/packages/bus/tests/session-compactions.test.mjs
+++ b/packages/bus/tests/session-compactions.test.mjs
@@ -1,14 +1,18 @@
 import test from 'node:test';
 import assert from 'node:assert/strict';
-import { mkdtempSync, rmSync } from 'node:fs';
+import { randomUUID } from 'node:crypto';
+import { mkdtempSync, readFileSync, rmSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join } from 'node:path';
+import { fileURLToPath } from 'node:url';
 import { Store } from '../src/store.mjs';
 import { Broker } from '../src/broker.mjs';
 
 // Row 270 (264c, #1775, T1 item 7 D6): session.list's `compactions` key, from the host's ledger
 // reader (runtime.mjs gives the seat's compactionCount). The reader itself is
 // packages/seat/tests/compactions.test.mjs's.
+const shipped = (name) =>
+  JSON.parse(readFileSync(fileURLToPath(new URL(`../../../roles/${name}.json`, import.meta.url)), 'utf8'));
 const businesses = {
   demo: {
     id: 'demo',
@@ -16,9 +20,10 @@ const businesses = {
     arbiters: { technical: 'pm', delivery: 'chief' },
     roles: {
       chief: { definition: 'chief-of-staff', authority: { withinRole: ['message.send'], crossRole: [] } },
+      assistant: { definition: 'assistant', authority: { withinRole: ['message.send'], crossRole: [] } },
       pm: { definition: 'pm', authority: { withinRole: ['message.send'], crossRole: [] } },
     },
-    definitions: { 'chief-of-staff': {}, pm: {} },
+    definitions: { 'chief-of-staff': {}, assistant: { messaging: shipped('assistant').messaging }, pm: {} },
     projects: { stack: { root: '/nonexistent' } },
   },
 };
@@ -35,7 +40,7 @@ function setup(t, options = {}) {
   const call = (verb, args = {}) => b.request(human, { verb, args });
   const project = call('project.create', { name: 'stack work', repo: 'stack' }).id;
   const A = call('thread.create', { project, name: 'alpha' }).id;
-  return { store, call, A };
+  return { store, call, project, A };
 }
 
 test('session.list rows carry the reader count for each session, with its store identity', (t) => {
@@ -56,13 +61,19 @@ test('session.list rows carry the reader count for each session, with its store
   assert.ok(rows.every((r) => !('op' in r)));
 });
 
-// A legacy session (op legacy-3l, from the 3k-3l migration) keeps the thread's store.
+// A legacy session (op legacy-3l, from the 3k-3l migration, its id the thread's) keeps the
+// thread's store. The thread is made by hand with the session the migration gives it, as
+// message-filter.test.mjs does; sessions is append-only.
 test('a legacy session is asked for with legacy true', (t) => {
   const asked = [];
   const f = setup(t, { compactions: (q) => (asked.push(q), { count: 0, known: true, reason: null, at: null }) });
-  f.store.run("UPDATE sessions SET op='legacy-3l' WHERE thread=?", f.A);
-  f.call('session.list', { thread: f.A });
-  assert.deepEqual(asked.map((q) => q.legacy), [true]);
+  const L = randomUUID();
+  const at = '2026-10-21T00:00:00.000Z';
+  f.store.run('INSERT INTO threads(id,at,business,project,instance,owner,name) VALUES(?,?,?,?,?,?,?)', L, at, 'demo', f.project, 'assistant', 'jason', 'legacy');
+  f.store.run("INSERT INTO sessions(at,business,thread,id,instance,owner,name,op) SELECT at,business,id,id,instance,owner,'default','legacy-3l' FROM threads WHERE id=?", L);
+  f.store.run("INSERT INTO session_defaults(at,thread,session,by) SELECT at,id,id,'migration-3l' FROM threads WHERE id=?", L);
+  f.call('session.list', { thread: L });
+  assert.deepEqual(asked, [{ business: 'demo', thread: L, session: L, legacy: true }]);
 });
 
 test('without a reader the count is unknown, never 0; a reader that throws is store-unreadable', (t) => {