fix: shows live sessions for pty view

tests/test_backend.py

@@ -234,6 +234,48 @@ async def test_complete_fresh_session_yields_events(tmp_path: Path) -> None:
     assert harness.seed_files == []
 
 
+@pytest.mark.asyncio
+async def test_live_sessions_visible_during_turn_and_after(tmp_path: Path) -> None:
+    """A session must appear in ``live_sessions`` *while* its turn runs — so
+    the admin terminal viewer can attach mid-flight, not only once the turn
+    is done — and must stay visible as an idle pooled session afterwards so
+    snapshots / interaction with a quiet terminal keep working.
+
+    Regression guard: the session is popped from the fingerprint pool (or
+    not yet pooled, on a fresh spawn) for the duration of the turn, so
+    without the in-flight ``_active`` registry an active session is
+    invisible to ``live_sessions``.
+    """
+    scripts_per_session = [
+        [
+            [_user_rec("hi", "S0"), _assistant_rec("hello there", "S0")],
+        ],
+    ]
+    harness = FakeFactoryHarness(scripts_per_session)
+    backend = ClaudeCodeBackend(
+        BackendOptions(cwd=str(tmp_path)),
+        _session_factory=harness,
+    )
+
+    seen_live_mid = False
+    async for _event in backend.complete([{"role": "user", "content": "hi"}]):
+        live = backend.live_sessions
+        if live:
+            seen_live_mid = True
+            # The only live pty is the one the harness spawned for this turn.
+            assert list(live.values()) == [harness.spawned[0]]
+
+    # The regression we're guarding against: visible *during* the turn.
+    assert seen_live_mid
+    # Still visible once the turn finishes — repooled idle session, so the
+    # viewer can snapshot / interact exactly as before.
+    assert list(backend.live_sessions.values()) == [harness.spawned[0]]
+
+    await backend.aclose()
+    # Teardown clears the pool.
+    assert backend.live_sessions == {}
+
+
 # --- multi-turn fingerprint reuse ----------------------------------------