SAFETY-107 review: test a writer that turns round on a dead pack; say when rule 3 applies

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/DECISIONS/SAFETY-107-refusal-under-another-writer.md

@@ -37,7 +37,10 @@ probe, exactly as before the change. Then:
    while another writer is;
 2. it does not: the refusal ends, logged "another writer", or "the battery
    gives power" when the reading shows it (it was "another writer" before);
-3. it finds the other direction: end, then a new start, as before.
+3. it finds the other direction: end, then a new start, as before. In
+   practice 2 comes first: SAFETY-94's evidence restarts when the ask changes
+   sign, so a writer that turns round ends the refusal at once and the other
+   way is learned ~12 cycles later (`test_safety107.py` part 3e).
 
 **Why this rule.** The end now means what SAFETY-52 meant by it: the refusal no
 longer describes what is on the wire, judged by the same test that learns it.

goodwe_controller/test_safety107.py

@@ -272,6 +272,17 @@ check("the refusal carries over to the loop with no line",
 check("the first probe after the writer left comes PROBE_EVERY_S later",
       close[0] is not None and bool(probes)
       and probes[0] >= close[0] + control.PROBE_EVERY_S - 10.0)
+# e. A writer turns round on a dead pack with no gap. The evidence restarts
+#    on the new sign (SAFETY-94), so the old refusal ends at once and the
+#    other way is learned once, ~12 cycles later.
+rows, log, _ = run(1, plant=lambda u, t, cmd: (
+    -2.0 - int(t) % 3 if u == "a" else round(cmd)), house=lambda t: 2000.0,
+    maint=False, trade=lambda t: 2000.0 if t < 300.0 else -2000.0)
+e = ends(log)
+print("    " + " / ".join(f"{x[0]:.0f} s {x[1][:45]}" for x in lines(log)))
+check("a writer turns round on a dead pack: one end, then the other way",
+      len(lines(log)) == 3 and len(e) == 1 and 300.0 < e[0][0] < 400.0
+      and present(nth(rows, -1)) and nth(rows, -1)[4] == -1)
 
 # ==============================================================================
 print("\n4. not covered: a perfectly flat reading under a writer")