feat: orchestration harness, selective install, observer improvements

tests/lib/orchestration-session.test.js

@@ -7,6 +7,7 @@ const path = require('path');
 
 const {
   buildSessionSnapshot,
+  listTmuxPanes,
   loadWorkerSnapshots,
   parseWorkerHandoff,
   parseWorkerStatus,
@@ -186,6 +187,16 @@ test('buildSessionSnapshot merges tmux panes with worker metadata', () => {
   }
 });
 
+test('listTmuxPanes returns an empty array when tmux is unavailable', () => {
+  const panes = listTmuxPanes('workflow-visual-proof', {
+    spawnSyncImpl: () => ({
+      error: Object.assign(new Error('tmux not found'), { code: 'ENOENT' })
+    })
+  });
+
+  assert.deepStrictEqual(panes, []);
+});
+
 test('resolveSnapshotTarget handles plan files and direct session names', () => {
   const tempRoot = fs.mkdtempSync(path.join(os.tmpdir(), 'ecc-orch-target-'));
   const repoRoot = path.join(tempRoot, 'repo');