bench(learn): slice 2 -- six families out-of-repo

Decision-engine task 6.7 (partial). After the advisory-fix harvest (memory 724 -> 904 static examples),
one compile per evaluable family and an outer grouped 5-fold evaluation of that family's own candidates,
input profile v1, priors off, k = 5, cross-fitted Platt, nested operating points (repository-cluster
bootstrap 95%):

  family                 n   AUC(s)              ADVISORY R / P   'vulnerable' P / R   ECE    canary
  injection            110   0.77 [0.67, 0.88]   0.88 / 0.57      0.84 / 0.36          0.093  0.77
  untrusted_dest.       62   0.85 [0.76, 0.94]   0.84 / 0.73      0.96 / 0.66          0.071  0.87
  path                  35   0.89 [0.79, 0.97]   0.86 / 0.69      0.89 / 0.76          0.119  0.90
  output_encoding       44   0.91 [0.82, 0.97]   0.86 / 0.81      0.94 / 0.55          0.045  0.90
  deserialization       46   0.90 [0.82, 0.97]   0.83 / 0.76      0.93 / 0.83          0.095  0.93
  access_control        37   0.96 [0.90, 1.00]   0.91 / 0.91      1.00 / 0.61          0.076  0.83

BLOCK offered for none: calibration fails everywhere except output_encoding, where no fold reaches a
Wilson lower bound of 0.95. Within paired groups (a function and its own fix) AUC is lower, 0.72-0.93:
every single-label group in the new families holds positives only. Injection learning-curve point,
paired (same program, candidates, folds): memory 724 -> 904, AUC 0.76 -> 0.77 (no injection example
was added). $2.88 metered DeepSeek (ceiling $8; balance 17.73 -> 16.73), $0.0009 embeddings.

Instrument fix: compiled demonstrations now follow the near-duplicate rule (cos >= 0.98) that retrieval
and the pre-call assertion apply; the assertion had stopped the untrusted_destination evaluation.

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01EmM1j46qgKMh3zqD1QMwEo

tests/test_learn_retrieve.py

@@ -136,6 +136,24 @@ def test_near_duplicates_drop_in_evaluation_and_stay_in_deployment() -> None:
     assert kept.near_duplicates == 0 and twin.id in {e.id for e in kept.examples}
 
 
+def test_a_near_duplicate_demonstration_is_swapped_in_evaluation_and_kept_in_deployment() -> None:
+    """A compiled demonstration whose excerpt is a near-duplicate of the target's (cos >= 0.98) is ineligible in
+    evaluation, like a retrieved one: swapped for its alternate, or dropped. Before 2026-10-02 only the pre-call
+    assertion checked it, and the advisory-fix slice stopped there (BoundaryViolation: near duplicate)."""
+    twin = example("demo-twin", group="fork/repo", label=1)
+    alt = example("demo-alt", group="a/b", label=1)
+    vectors = {twin.excerpt_sha: [1.0, 0.0], alt.excerpt_sha: [0.0, 1.0]}
+    target = replace(_target(), vector=[1.0, 0.0])
+    evaluation = replace(outer_folds([twin], k=1)[0], eval_groups=frozenset())
+    demos = [{"example_id": twin.id, "alternate": {"example_id": alt.id}}]
+    usable = demonstrations_for(demos, by_id([twin, alt]), target, evaluation, vectors=vectors)
+    assert [d["example_id"] for d in usable] == [alt.id]
+    assert_boundary([d["example_id"] for d in usable], by_id([twin, alt]), target, evaluation, vectors=vectors)
+    assert demonstrations_for([{"example_id": twin.id, "alternate": None}], by_id([twin]), target, evaluation, vectors=vectors) == []
+    deployed, _ = deployment_fold("https://github.com/someone/else", ["fork/repo"])
+    assert [d["example_id"] for d in demonstrations_for(demos, by_id([twin, alt]), target, deployed, vectors=vectors)] == [twin.id]
+
+
 def test_deployment_excludes_the_scanned_repository_when_it_is_a_corpus_group() -> None:
     own = example("own", group="acme/webapp", label=1)
     fold, note = deployment_fold("https://github.com/Acme/WebApp.git", ["acme/webapp", "x/y"])