PREREG_flat_creep outcome: NOT accepted. Unkept promise AND creep under the projection: APS 2806 -> 2878 (V2 fails), CHA 3220 -> 3354 (V1 fails), flat fun3-6 1823 -> 1991 (V4 fails), guarantee holds (V3). With G2: 2782 -> 2842, 3169 -> 3318. Under safe CHA 3390 -> 3149, weaker than the single flag (3037). None of the three flat-regime gates pays under the projection: its budget already does their work. Server regression x2: 952 passed, 1 failed = the expected paper-number check (46 numbers after the signfix, pending the paper decision).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_flat_gate.py

@@ -58,6 +58,31 @@ def test_the_twice_gate_is_silent_where_the_model_is_exact_and_fires_on_a_power(
     assert st["pre_refused"] > 0
 
 
+@pytest.mark.parametrize("f,a,b", PROBS)
+@pytest.mark.parametrize("guard", ("project", "credit"))
+@pytest.mark.parametrize("ext", ("none", "pattern"))
+def test_the_guarantee_holds_with_the_creep_gate(f, a, b, guard, ext):
+    x, n, ok = pure_root(f, a, b, XTOL, MAXFEV, similarity="ratio", scale="derived3",
+                         guard=guard, prestep="flatcreep", extrapolate=ext)
+    assert ok and min(a, b) <= x <= max(a, b)
+    half = math.ceil(math.log2(abs(b - a) / XTOL))
+    assert n <= (2 * half + 3 if guard == "project" else half + 4), n
+
+
+def test_the_creep_gate_is_silent_on_a_line_fires_on_a_power_and_spares_a_simple_root():
+    """Measured before pinning: silent where the model is exact, fires on x^9, and does
+    NOT fire on x^3 - 2x - 5 over [1, 4], where the single flag fired once."""
+    runs = {}
+    for name, f, a, b in (("line", lambda t: 3.0 * t - 1.0, -2.0, 5.0),
+                          ("x9", lambda t: t ** 9, -1.0, 2.0),
+                          ("cubic", lambda t: t ** 3 - 2.0 * t - 5.0, 1.0, 4.0)):
+        st = {}
+        pure_root(f, a, b, XTOL, MAXFEV, similarity="ratio", scale="derived3",
+                  guard="project", prestep="flatcreep", stats=st)
+        runs[name] = st["pre_refused"]
+    assert runs["line"] == 0 and runs["x9"] > 0 and runs["cubic"] == 0, runs
+
+
 def test_the_gate_never_fires_where_the_model_is_exact():
     """On a straight line the model's step lands on the root: r = 0, never >= 1/4."""
     st = {}