Measured this session, the reason the bound was flaky at all:
size-matched ordinary prose 3.50-4.20s (cold up to ~4.2s)
the "pathological" blob 3.35-3.86s warm, 4.70s cold
ratio patho/ordinary 0.93x, and 0.96x with the order swapped
The blob is the FASTER side. The test therefore never proved what its comment
claimed -- it measured throughput on 1MB of text, not catastrophic backtracking,
and could only fail when the process was cold or the machine loaded. That is
exactly how it failed: 4.39 / 4.46 / 4.92s against a 5.0s bound.
Catastrophic backtracking IS covered, elsewhere and properly, by
test_lexicon.py::test_redos_pathological_subagent_input_returns_fast, which
crafts against a known-bad nested `.*?` pattern (0.137s against a 2.0s bound --
14x headroom, measured, left untouched).
So: raise the bound rather than make it relative. A relative bound was the other
option on the table and the measurement killed it -- with a ratio below 1.0 you
would need k >= 3 to clear the noise, and an assertion with 3x headroom over a
case already under 1.0 can never fire. Vacuous, plus it would add a second
cold-start asymmetry and double the wall clock.
10.0s is ~2.4x the slowest observed legitimate run (ordinary prose, cold). The
comment now carries the measurements, says the name overstates the payload, and
warns that the 1_000_200-char size is deliberate -- 200 over the max_scan_chars
default, so the test also exercises the truncate-and-flag oversize path.
No production code changed. 642 passed.
Kjell Tore Guttormsen
f74245f01f