feat(session): add cross-session references

packages/ui/tui/tests/tui.snapshot.ts

@@ -44,6 +44,10 @@ const CHECKPOINTS = [
   'disposed-terminal',
 ] as const
 
+// Real-loop scenarios own their assertions in separate snapshot suites but
+// share this directory, whose inventory remains exact.
+const STANDALONE_CHECKPOINTS = ['session-reference'] as const
+
 type Checkpoint = typeof CHECKPOINTS[number]
 type SnapshotHarness = TuiHarness<HeadlessTerminal, (code: number) => void>
 
@@ -576,5 +580,5 @@ afterAll(async () => {
   const files = (await readdir(SNAPSHOTS_DIR))
     .filter(file => file.endsWith('.expected.txt'))
     .sort()
-  expect(files).toEqual(CHECKPOINTS.map(name => `${name}.expected.txt`).sort())
+  expect(files).toEqual([...CHECKPOINTS, ...STANDALONE_CHECKPOINTS].map(name => `${name}.expected.txt`).sort())
 })