test(docs): pin docs/redos-sweep.py under test.py's contract

It was the only docs/ measurement script without a row here, and this
repo just made it load-bearing for two published LIMITATIONS.md numbers
(the 1.5 ms floor, the 2.6 flag ratio). Pins structure only, per the
sweep's own docstring: the suite clock (not a reimplemented wall clock),
the constants against the doc's prose, and the 152-pattern/11-table
collector count. Never pins a timing outcome -- that would be red
several runs in twenty.

tests/test_docs_measurement_scripts.py

@@ -28,10 +28,12 @@ from pathlib import Path
 
 import pytest
 
+import redos_clock
 from llm_ingestion_guard import Disposition, PRESET_USER_UPLOAD, Risk, screen_output
 from llm_ingestion_guard import active_content as ac
 
 _DOCS = Path(__file__).resolve().parent.parent / "docs"
+_LIMITATIONS = _DOCS / "LIMITATIONS.md"
 
 
 def _load(filename: str):
@@ -41,6 +43,7 @@ def _load(filename: str):
     spec = importlib.util.spec_from_file_location(name, path)
     assert spec and spec.loader, f"cannot load {path}"
     module = importlib.util.module_from_spec(spec)
+    sys.modules[name] = module  # @dataclass resolves its own module via sys.modules
     spec.loader.exec_module(module)
     return module
 
@@ -49,6 +52,7 @@ def _load(filename: str):
 # script's import list fails the whole file loudly instead of one quiet test.
 fp_sweep = _load("fp-sweep.py")
 census = _load("rawhtml-census.py")
+redos_sweep = _load("redos-sweep.py")
 
 
 # --- docs/fp-sweep.py --------------------------------------------------------
@@ -245,6 +249,38 @@ def test_census_production_row_equals_its_shipped_candidate(name, attrs):
     assert candidate(name, attrs) == ac.active_tag_class(name, attrs)
 
 
+# --- docs/redos-sweep.py ------------------------------------------------------
+
+
+def test_redos_sweep_times_on_the_suite_clock_not_a_reimplementation():
+    # Until 1.1.0 this script timed on `time.monotonic()`, a different instrument
+    # than every ReDoS bound in the suite. `t()` must call the shared
+    # `scan_seconds` — imported, not restated — and the module must not import
+    # `time` itself, else a drift back to a wall clock would go unnoticed here.
+    assert redos_sweep.scan_seconds is redos_clock.scan_seconds
+    assert not hasattr(redos_sweep, "time"), "module must not import time itself"
+
+
+def test_redos_sweep_floor_and_flag_match_the_published_numbers():
+    # docs/LIMITATIONS.md publishes the 1.5 ms floor and the 2.6 flag ratio this
+    # script derives from twelve full runs. Pin both sides: the constants, and
+    # that the doc still states the same numbers — either drifting alone is a bug.
+    assert redos_sweep.NOISE_FLOOR == 0.0015
+    assert redos_sweep.RATIO_FLAG == 2.6
+    text = _LIMITATIONS.read_text(encoding="utf-8")
+    assert "1.5 ms noise floor" in text
+    assert "2.6 flag threshold" in text
+
+
+def test_redos_sweep_collector_covers_152_patterns_across_11_tables():
+    # The count docs/LIMITATIONS.md carries as "all 152 compiled patterns across
+    # all eleven regex-bearing modules". A pattern added or removed in `src/`
+    # without re-measuring would drift the doc's claim silently otherwise.
+    assert len(redos_sweep.TABLES) == 11
+    total = sum(len(collect()) for collect in redos_sweep.TABLES.values())
+    assert total == 152
+
+
 # --- both scripts: the argument-less contract --------------------------------