The new loop's core: intake, restatement, go-ahead, threads (M2.1, PR B)

nisse_dev.loop runs alongside control.py, chosen with `loop: new`.
Issues assigned to the agent (by an operator, or filed by one) become work
items, each with a Matrix thread. A driver run is one model with tools
until it calls a waiting tool: restate puts rev-N up for a go-ahead, bound
to the revision on screen when the reply arrived; ask_human waits for an
answer; close_item closes the item and its issue. Before the go-ahead the
driver can look but not change or close anything. One item is active at a
time; replies in an item's thread go to it. On boot, an item cut off
mid-run waits on the operator, and waiting points are put up again.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/tests/test_config.py

@@ -367,3 +367,10 @@ def test_no_credential_appears_in_the_config_repr() -> None:
     text = repr(config)
     for secret in SECRETS.values():
         assert secret not in text
+
+
+def test_the_loop_defaults_to_old_and_takes_new() -> None:
+    assert build().loop == "old"
+    assert build(loop="new").loop == "new"
+    with pytest.raises(ConfigError, match="loop: must be old or new"):
+        build(loop="newer")