Task 3.1. A teacher is a vendored pair, at a review tier a maintainer stands
behind, on the train split, and scorable. Every learning path now asks the same
module that one question, so the split cannot be enforced in one place and
forgotten in another. A refusal is data rather than an exception: the path
records which holdout pairs a candidate touched and moves on, so a leak is
visible in the run instead of silently accepted.
The exporter refuses to seed from a holdout pair, leave-one-out teaches from the
train split while still scoring every pair, and the mechanism lever refuses a
candidate a holdout pair taught, because such a shape can only recover the pair
that produced it.
Measured and committed: on the vibe-py holdout the lever's own number falls from
seven detected and a Youden of +0.059 to five detected and -0.059 once holdout
pairs stop teaching, and the candidate set shrinks from ten shapes to six. That
gap is the inflation this rule removes.
Two existing tests encoded the leak and now encode the truth. The documented
export-to-improve flow had a single holdout pair teaching itself, and now needs
a train pair to teach and a holdout pair to recover. The obligation export
claimed the corpus seeds at least one obligation shape, which was true only
because holdout pairs were teaching: every vibe-py absence pair that yields an
obligation lesson sits on the holdout side, so the honest number today is zero.
The derivation stays covered by fixtures; the corpus gap belongs to the absence
re-harvest and to a maintainer pass over the splits.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
Task 1.3. An expected row may carry a family label, stored opaquely because the
classifier owns the taxonomy and the corpus module never imports the learning
package. Every pair carries a computed reason when it cannot be scored: a
declared known limit wins, otherwise identical twin when the two excerpts are
the same code once the provenance header is stripped. No row is ever dropped.
Two corpus defects the new accounting surfaces, committed as an artifact beside
the numbers they cap. Nineteen repositories sit on both sides of the split, so a
learning path could be taught by one file of a repository and evaluated on
another. Ten groups of pairs share a vulnerable excerpt byte for byte, mostly
the same fix harvested twice at different granularity.
The split helper keeps every declared split, lets rows that named none inherit
their repository's side, and otherwise assigns a whole repository at once,
oldest first, so nothing straddles by our doing. Pair signals can now be
restricted to one split, which is what lets a learning path teach from train
rows only.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
Measured 2026-09-06 on the vibe-py holdout: the existing tool hunter, with no
learning, scores 12/14 pair-correct (Youden +0.857, no leaks) once detection
and silence are keyed on the labeled class and function and the byte-identical
twins are excluded; the overlay scores 5/14 on the same rows. The published
hunter number (0/17, Youden -0.588) was a scoring artifact: the scorer wanted
the literal CWE id in the finding text and the prompt never asked for it.
The brief proposes an auto-classifier as the routing key, one evolved hunter
configuration per class, a class-aware scorer with unscorable denominators,
the split enforced by construction, and the HarnessX evolve loop with per-class
attribution as the round primitive. Raw measurements are committed under
reports/measurements.
Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01T7XD7x5KonMdmGRkp63EQG
