Runs that go in circles end (M7.8)

Driver.run checks each turn with nisse_core.loop.circles and ends the run
as "circling" when the same calls get much the same back, one harness
correction is given again and again, or the model apologises, for
circle_repeats turns in a row (default 3). Near-identical calls (git add
a.py, b.py) and scattered apologies stay flags on the status page. A
fact in the transcript says why the run ended.

nisse-dev calls in a helper as for a stuck run, then asks the operator;
nisse-review counts a failed run and posts none of its drafts. Tuning:
tuning.driver / tuning.review circle_repeats (0 off) and circle_similar.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01J5Utyfzw7gF7UhjRDEtjTk

nisse-dev/tests/test_config.py

@@ -182,6 +182,23 @@ def test_tuning_is_read() -> None:
     assert (tuning.build_vm.retry_s, tuning.build_vm.settle_s) == (60.0, 180.0)
 
 
+def test_circles_are_tuned_and_checked() -> None:
+    # L2, M7.8: when a driver run going in circles ends.
+    assert (
+        build().tuning.driver.circle_repeats,
+        build().tuning.driver.circle_similar,
+    ) == (3, 0.9)
+    tuned = build(tuning={"driver": {"circle_repeats": 0, "circle_similar": 0.8}})
+    assert (tuned.tuning.driver.circle_repeats, tuned.tuning.driver.circle_similar) == (
+        0,
+        0.8,
+    )
+    with pytest.raises(ConfigError, match=r"circle_repeats: must be 0 \(off\) or 2"):
+        build(tuning={"driver": {"circle_repeats": 1}})
+    with pytest.raises(ConfigError, match="circle_similar: must be at most 1"):
+        build(tuning={"driver": {"circle_similar": 2}})
+
+
 def test_a_partly_given_tuning_section_keeps_the_other_defaults() -> None:
     tuning = build(tuning={"driver": {"max_turns": 40}}).tuning
     assert tuning.driver.failure_limit == 2