Adds tests/native/test_lexer_scaling.el, the regression gate for el #132.
Both directions are proven on LIVE workloads, not synthetic series:
healthy per-character scan 1821 3251 6007 10422 us -> O(n) PASS
rescan-from-zero (the #132 shape) 922 3667 13524 44792 -> O(n^2) FAIL
A gate only proven to pass is decoration. The quadratic specimen exists so
the gate is proven to FIRE.
Also fixes elb_spread_ok to judge the ASYMPTOTIC TAIL (last three ratios)
rather than the whole sweep. Measured on a genuinely linear scan the ratios
ran 3.37 2.92 1.76 1.65 -- the head looks quadratic because it is cold
cache, the tail is the truth. Whole-sweep spread rejected correct data. A
complexity bound is an asymptotic claim and must be judged asymptotically.
That fix came from the classifier refusing to rubber-stamp my own bad
measurement: it reported INDETERMINATE on an unwarmed sweep rather than
passing it. Warmup is now taken and discarded at every sweep point.
Reverts the == workarounds in test_elbench.el now that el #137 has landed;
the natural form generates no str_eq and all 13 fitter tests stay green.
The workaround remains -- the Plus arm is still open.
Adds el_black_box (inline asm, +r constraint, memory clobber) and
runtime/elbench.el: a growth-curve classifier that gates time AND
allocation-count AND allocation-bytes, failing if any exceeds its
declared curve.
Refusal is a first-class verdict. The classifier REFUSES rather than
classifying when the largest measurement is below the floor, or when a
series is hard-flat across an 8x input range -- the shape produced when
the optimiser deletes the work. Reporting O(1) there would be a
confident answer with nothing behind it. Disagreeing ratios report
INDETERMINATE rather than a guess.
Deviation from DESIGN.md 6.2, stated in the source: uses consecutive
ratios on a mandated geometric sweep rather than least-squares over
candidate curves. Ratios are directly interpretable on a doubling sweep
and need no floating point; the cost is weaker O(n) vs O(n log n)
separation, reported as an ambiguous band rather than guessed.
Documents the counter scope limit: engram_*.c and libcurl malloc are
NOT tracked, so a flat curve over engram/HTTP-dominated work is not
evidence of anything.
13 tests prove the classifier against real measured series from
fitprobe.el -- including that an accumulator's allocation COUNT is
linear while its bytes are quadratic, and that el #132's pure-CPU shape
reads FLAT on both allocation signals and is caught only by time.
Neuron