diff --git a/.kiro/specs/learned-decision-engine/tasks.md b/.kiro/specs/learned-decision-engine/tasks.md
index 1d756d1..3eb62ac 100644
--- a/.kiro/specs/learned-decision-engine/tasks.md
+++ b/.kiro/specs/learned-decision-engine/tasks.md
@@ -139,8 +139,18 @@ a model or embedding call.
     on them, so `ousast learn experiment units` could not freeze the candidates.
   - [ ] 7.3 exp-001 run and recorded (~$7.7 expected, ceiling $15) -- an inconclusive result is pre-registered as
     likely; needs the frozen units file first.
-  - [ ] 7.4 exp-002 run and recorded **(budget go-ahead: ~$2 expected, ceiling $4)**; further program variants
-    (`k = 5` vs `k = 1`, the confidence source) as new manifests.
+  - [x] 7.4 exp-002 run and recorded 2026-10-02 (budget go-ahead ~$2 expected, ceiling $4): **reject B**. 160 paired
+    units (injection 119, access_control 41; 56 repositories; 108 units in 54 candidate pairs), both arms, two
+    replicates each, no early stop. Primary: canary agreement A 0.875 -> B 0.906 (diff +0.03, CI [-0.03, +0.10],
+    spans; B meets the 0.90 target), within-pair AUC A 0.815 -> B 0.741 (diff -0.07, CI [-0.13, -0.02], **against B**).
+    Secondary: AUC -0.02 (CI [-0.04, -0.003], against), ADVISORY recall -0.06 (spans; McNemar 7/2, p = 0.18),
+    precision +0.01 (spans), usd per candidate A $0.0021 -> B $0.0051 (CI [+0.0027, +0.0032], against: the five
+    disjoint example sets share only the prompt prefix in DeepSeek's cache). Priced usage A $0.68 (1206 paid calls,
+    395 replayed), B $1.63 (1350 paid, 250 replayed). Result: `benchmarks/experiments/exp-002-retrieval-ensemble/result.json`,
+    `benchmarks/measurements/2026-10-02-exp-002/record.json`. Three repairs on the way (each its own commit): example
+    rows' null plane-only features (1f525ff), the 788 embedding vectors absent from RustFS (copied from the file
+    store), the result row's column-type collision under S3 Select (780caaa). Further program variants (`k = 5` vs
+    `k = 1`, the confidence source) as new manifests.
   - _Requirements: 3.6, 4.1-4.4_
 
 - [ ] 8. Integration
diff --git a/benchmarks/experiments/exp-002-retrieval-ensemble/registration.json b/benchmarks/experiments/exp-002-retrieval-ensemble/registration.json
index 83a148f..09860b1 100644
--- a/benchmarks/experiments/exp-002-retrieval-ensemble/registration.json
+++ b/benchmarks/experiments/exp-002-retrieval-ensemble/registration.json
@@ -19,5 +19,5 @@
     "note": "frozen on the 937-example static memory (slice 2 evaluated 110 + 37 candidates on the 904-example memory of the same day; the recovered negatives of ef6945e moved the seeded compile split and the outer folds). Freezing needed two repairs first: example rows carried the plane-only features as null in x and the renderer refused them (1f525ff), and the RustFS store held none of the 788 embedding vectors the file store had (copied over with put_blob, no embedding call)."
   },
   "first_registration": {"registered": "2026-10-02", "pin": "fbc3220bbe1c8a4f8afa0a724fd41a51b390dd22", "units_status": "pending"},
-  "status": "registered, units frozen; run pending"
+  "status": "run and analysed 2026-10-02: reject (result.json; benchmarks/measurements/2026-10-02-exp-002/record.json)"
 }
diff --git a/benchmarks/experiments/exp-002-retrieval-ensemble/result.json b/benchmarks/experiments/exp-002-retrieval-ensemble/result.json
new file mode 100644
index 0000000..2e8c0ac
--- /dev/null
+++ b/benchmarks/experiments/exp-002-retrieval-ensemble/result.json
@@ -0,0 +1,241 @@
+{
+  "alpha": 0.05,
+  "arms": {
+    "A": {
+      "budget_usd": 1.0,
+      "label": "today's sampling -- k = 5, sample 1 at temperature 0 and samples 2..5 at 0.7, one retrieved example set",
+      "repeats": 2,
+      "replay_only": false
+    },
+    "B": {
+      "budget_usd": 3.0,
+      "label": "retrieval ensemble -- k = 5 at temperature 0, each sample over a disjoint retrieved example set",
+      "repeats": 2,
+      "replay_only": false
+    }
+  },
+  "code_commit": "780caaa558f2cc091fd6b0fd5c618c3b488030c2",
+  "decision": "reject",
+  "experiment": "exp-002-retrieval-ensemble",
+  "hypothesis": "Drawing the k = 5 samples from five disjoint retrieved example sets at temperature 0 (a retrieval ensemble) makes the decision more repeatable than five temperature samples over one example set, without hurting the ranking within a candidate pair, at no higher cost per candidate.\n",
+  "looks": [
+    {
+      "boundary": 2.797,
+      "crossed": false,
+      "estimate": {
+        "a": 0.8611111111111112,
+        "b": 0.8888888888888888,
+        "ci": [
+          -0.08333333333333326,
+          0.1325301204819277
+        ],
+        "diff": 0.02777777777777768,
+        "groups": 28,
+        "metric": "canary_agreement",
+        "resamples": 10000,
+        "se": 0.05449719877526111,
+        "units": 72
+      },
+      "fraction": 0.5,
+      "groups": 28,
+      "z": 0.5097101943226363
+    },
+    {
+      "boundary": 1.977,
+      "crossed": false,
+      "estimate": {
+        "a": 0.875,
+        "b": 0.90625,
+        "ci": [
+          -0.03448275862068961,
+          0.0972972972972973
+        ],
+        "diff": 0.03125,
+        "groups": 56,
+        "metric": "canary_agreement",
+        "resamples": 10000,
+        "se": 0.0337315848833629,
+        "units": 160
+      },
+      "fraction": 1.0,
+      "groups": 56,
+      "z": 0.9264314175588332
+    }
+  ],
+  "manifest_digest": "f5004fb8618b1f7cc7dcf298d42b4ac1b6c0c1aa72a97299c77f937bd6175148",
+  "mde": 0.1,
+  "primary": [
+    {
+      "name": "canary_agreement",
+      "target": 0.9
+    },
+    {
+      "name": "within_pair_auc"
+    }
+  ],
+  "reason": "the CI of within_pair_auc excludes 0 against B",
+  "resamples": 10000,
+  "secondary": [
+    {
+      "name": "usd_per_candidate"
+    },
+    {
+      "name": "auc"
+    },
+    {
+      "name": "advisory_recall"
+    },
+    {
+      "name": "advisory_precision"
+    }
+  ],
+  "spend_usd": {
+    "A": 0.682094,
+    "B": 1.632737
+  },
+  "tests": {
+    "advisory_precision": {
+      "ci_vs_zero": "spans",
+      "direction": 1,
+      "estimate": {
+        "a": 0.8979591836734694,
+        "b": 0.9069767441860465,
+        "ci": [
+          -0.02020202020202022,
+          0.05081826012058566
+        ],
+        "diff": 0.009017560512577072,
+        "groups": 56,
+        "metric": "advisory_precision",
+        "resamples": 10000,
+        "se": 0.018550028052620342,
+        "units": 160
+      },
+      "mcnemar": null,
+      "target": null
+    },
+    "advisory_recall": {
+      "ci_vs_zero": "spans",
+      "direction": 1,
+      "estimate": {
+        "a": 0.5,
+        "b": 0.4431818181818182,
+        "ci": [
+          -0.1235955056179775,
+          0.01010101010101011
+        ],
+        "diff": -0.05681818181818182,
+        "groups": 56,
+        "metric": "advisory_recall",
+        "resamples": 10000,
+        "se": 0.033343898686966876,
+        "units": 160
+      },
+      "mcnemar": {
+        "b": 7,
+        "c": 2,
+        "concordant": 79,
+        "p_value": 0.1796875
+      },
+      "target": null
+    },
+    "auc": {
+      "ci_vs_zero": "against",
+      "direction": 1,
+      "estimate": {
+        "a": 0.8012941919191919,
+        "b": 0.7802241161616161,
+        "ci": [
+          -0.04139254385964919,
+          -0.0034279184917158645
+        ],
+        "diff": -0.0210700757575758,
+        "groups": 56,
+        "metric": "auc",
+        "resamples": 10000,
+        "se": 0.009565373841115053,
+        "units": 160
+      },
+      "mcnemar": null,
+      "target": null
+    },
+    "canary_agreement": {
+      "ci_vs_zero": "spans",
+      "direction": 1,
+      "estimate": {
+        "a": 0.875,
+        "b": 0.90625,
+        "ci": [
+          -0.03448275862068961,
+          0.0972972972972973
+        ],
+        "diff": 0.03125,
+        "groups": 56,
+        "metric": "canary_agreement",
+        "resamples": 10000,
+        "se": 0.0337315848833629,
+        "units": 160
+      },
+      "mcnemar": {
+        "b": 10,
+        "c": 15,
+        "concordant": 135,
+        "p_value": 0.42435622215270996
+      },
+      "target": {
+        "b_meets": true,
+        "level": 0.9
+      }
+    },
+    "usd_per_candidate": {
+      "ci_vs_zero": "against",
+      "direction": -1,
+      "estimate": {
+        "a": 0.002131543750000001,
+        "b": 0.005102303125,
+        "ci": [
+          0.002724568181818181,
+          0.00317872222222222
+        ],
+        "diff": 0.002970759374999999,
+        "groups": 56,
+        "metric": "usd_per_candidate",
+        "resamples": 10000,
+        "se": 0.00011577410791736543,
+        "units": 160
+      },
+      "mcnemar": null,
+      "target": null
+    },
+    "within_pair_auc": {
+      "ci_vs_zero": "against",
+      "direction": 1,
+      "estimate": {
+        "a": 0.8148148148148148,
+        "b": 0.7407407407407407,
+        "ci": [
+          -0.12857142857142867,
+          -0.015151515151515138
+        ],
+        "diff": -0.07407407407407407,
+        "groups": 56,
+        "metric": "within_pair_auc",
+        "resamples": 10000,
+        "se": 0.029550669251750233,
+        "units": 160
+      },
+      "mcnemar": null,
+      "target": null
+    }
+  },
+  "tost": null,
+  "units": {
+    "by_label": {
+      "0": 72,
+      "1": 88
+    },
+    "groups": 56,
+    "outcomes": 640,
+    "paired": 160
+  }
+}
diff --git a/benchmarks/measurements/2026-10-02-exp-002/record.json b/benchmarks/measurements/2026-10-02-exp-002/record.json
new file mode 100644
index 0000000..dcdcafa
--- /dev/null
+++ b/benchmarks/measurements/2026-10-02-exp-002/record.json
@@ -0,0 +1,377 @@
+{
+ "created": "2026-10-02",
+ "decision": "reject",
+ "instruments": {
+  "distinct_scores_by_arm": {
+   "A": 72,
+   "B": 57
+  },
+  "outcomes_by_arm_replicate": {
+   "A:r0": 160,
+   "A:r1": 160,
+   "B:r0": 160,
+   "B:r1": 160
+  },
+  "parse_failed_by_arm": {
+   "A": 0,
+   "B": 0
+  }
+ },
+ "looks": [
+  {
+   "boundary": 2.797,
+   "crossed": false,
+   "estimate": {
+    "a": 0.8611111111111112,
+    "b": 0.8888888888888888,
+    "ci": [
+     -0.08333333333333326,
+     0.1325301204819277
+    ],
+    "diff": 0.02777777777777768,
+    "groups": 28,
+    "metric": "canary_agreement",
+    "resamples": 10000,
+    "se": 0.05449719877526111,
+    "units": 72
+   },
+   "fraction": 0.5,
+   "groups": 28,
+   "z": 0.5097101943226363
+  },
+  {
+   "boundary": 1.977,
+   "crossed": false,
+   "estimate": {
+    "a": 0.875,
+    "b": 0.90625,
+    "ci": [
+     -0.03448275862068961,
+     0.0972972972972973
+    ],
+    "diff": 0.03125,
+    "groups": 56,
+    "metric": "canary_agreement",
+    "resamples": 10000,
+    "se": 0.0337315848833629,
+    "units": 160
+   },
+   "fraction": 1.0,
+   "groups": 56,
+   "z": 0.9264314175588332
+  }
+ ],
+ "note": "COUNTS ONLY. Experiment exp-002 (learned-decision-engine task 7.4): arm A = the slice-2 compiled programs as they are (k = 5, sample 1 at temperature 0, samples 2..5 at 0.7, one retrieved example set); arm B = the same programs with ProgramSpec.sampling = retrieval_ensemble (k = 5 at temperature 0, each sample over a disjoint retrieved example set). Paired on the frozen units (every unit in both arms, two replicates per arm under different response-cache salts; replicate 1 is the canary), seeded repository order and a seeded per-unit coin for which arm goes first, the incumbent folds' seed on the 937-example static memory, 788 embedding vectors. Intervals: repository-cluster paired bootstrap 95% (10,000 resamples); exact McNemar on discordant units for binary metrics; two looks (O'Brien-Fleming 2.797 / 1.977). The overall table is the runner's result.json; the per-family table here uses the same estimator on each family's pairs. Driver: `ousast learn experiment run|analyse` (learn/experiments.py). No candidate, path, function or repository name.",
+ "overall": {
+  "advisory_precision": {
+   "A": 0.8979591836734694,
+   "B": 0.9069767441860465,
+   "ci95": [
+    -0.02020202020202022,
+    0.05081826012058566
+   ],
+   "ci_vs_zero": "spans",
+   "diff_B_minus_A": 0.009017560512577072,
+   "mcnemar": null,
+   "target": null
+  },
+  "advisory_recall": {
+   "A": 0.5,
+   "B": 0.4431818181818182,
+   "ci95": [
+    -0.1235955056179775,
+    0.01010101010101011
+   ],
+   "ci_vs_zero": "spans",
+   "diff_B_minus_A": -0.05681818181818182,
+   "mcnemar": {
+    "b": 7,
+    "c": 2,
+    "concordant": 79,
+    "p_value": 0.1796875
+   },
+   "target": null
+  },
+  "auc": {
+   "A": 0.8012941919191919,
+   "B": 0.7802241161616161,
+   "ci95": [
+    -0.04139254385964919,
+    -0.0034279184917158645
+   ],
+   "ci_vs_zero": "against",
+   "diff_B_minus_A": -0.0210700757575758,
+   "mcnemar": null,
+   "target": null
+  },
+  "canary_agreement": {
+   "A": 0.875,
+   "B": 0.90625,
+   "ci95": [
+    -0.03448275862068961,
+    0.0972972972972973
+   ],
+   "ci_vs_zero": "spans",
+   "diff_B_minus_A": 0.03125,
+   "mcnemar": {
+    "b": 10,
+    "c": 15,
+    "concordant": 135,
+    "p_value": 0.42435622215270996
+   },
+   "target": {
+    "b_meets": true,
+    "level": 0.9
+   }
+  },
+  "usd_per_candidate": {
+   "A": 0.002131543750000001,
+   "B": 0.005102303125,
+   "ci95": [
+    0.002724568181818181,
+    0.00317872222222222
+   ],
+   "ci_vs_zero": "against",
+   "diff_B_minus_A": 0.002970759374999999,
+   "mcnemar": null,
+   "target": null
+  },
+  "within_pair_auc": {
+   "A": 0.8148148148148148,
+   "B": 0.7407407407407407,
+   "ci95": [
+    -0.12857142857142867,
+    -0.015151515151515138
+   ],
+   "ci_vs_zero": "against",
+   "diff_B_minus_A": -0.07407407407407407,
+   "mcnemar": null,
+   "target": null
+  }
+ },
+ "per_family": {
+  "access_control": {
+   "groups": 24,
+   "metrics": {
+    "advisory_precision": {
+     "A": 1.0,
+     "B": 1.0,
+     "ci95": [
+      0.0,
+      0.0
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": 0.0,
+     "mcnemar": null
+    },
+    "advisory_recall": {
+     "A": 0.72,
+     "B": 0.68,
+     "ci95": [
+      -0.16666666666666674,
+      0.08333333333333337
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": -0.039999999999999925,
+     "mcnemar": {
+      "b": 2,
+      "c": 1,
+      "concordant": 22,
+      "p_value": 1.0
+     }
+    },
+    "auc": {
+     "A": 0.94625,
+     "B": 0.95125,
+     "ci95": [
+      -0.023157894736842155,
+      0.02941176470588236
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": 0.0050000000000000044,
+     "mcnemar": null
+    },
+    "canary_agreement": {
+     "A": 0.926829268292683,
+     "B": 0.8780487804878049,
+     "ci95": [
+      -0.18421052631578938,
+      0.08108108108108103
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": -0.04878048780487809,
+     "mcnemar": {
+      "b": 5,
+      "c": 3,
+      "concordant": 33,
+      "p_value": 0.7265625
+     }
+    },
+    "usd_per_candidate": {
+     "A": 0.0019149512195121951,
+     "B": 0.0043439878048780484,
+     "ci95": [
+      0.0021030595238095253,
+      0.00275970731707317
+     ],
+     "ci_vs_zero": "against",
+     "diff_B_minus_A": 0.0024290365853658533,
+     "mcnemar": null
+    },
+    "within_pair_auc": {
+     "A": 0.9375,
+     "B": 0.875,
+     "ci95": [
+      -0.125,
+      0.0
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": -0.0625,
+     "mcnemar": null
+    }
+   },
+   "paired_units": 41
+  },
+  "injection": {
+   "groups": 34,
+   "metrics": {
+    "advisory_precision": {
+     "A": 0.8387096774193549,
+     "B": 0.8461538461538461,
+     "ci95": [
+      -0.043269230769230727,
+      0.06763285024154597
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": 0.007444168734491274,
+     "mcnemar": null
+    },
+    "advisory_recall": {
+     "A": 0.4126984126984127,
+     "B": 0.3492063492063492,
+     "ci95": [
+      -0.140625,
+      0.0
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": -0.06349206349206349,
+     "mcnemar": {
+      "b": 5,
+      "c": 1,
+      "concordant": 57,
+      "p_value": 0.21875
+     }
+    },
+    "auc": {
+     "A": 0.7475907029478458,
+     "B": 0.7140022675736961,
+     "ci95": [
+      -0.061038961038961004,
+      -0.011363636363636465
+     ],
+     "ci_vs_zero": "against",
+     "diff_B_minus_A": -0.03358843537414968,
+     "mcnemar": null
+    },
+    "canary_agreement": {
+     "A": 0.8571428571428571,
+     "B": 0.9159663865546218,
+     "ci95": [
+      -0.016129032258064502,
+      0.1322314049586777
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": 0.05882352941176472,
+     "mcnemar": {
+      "b": 5,
+      "c": 12,
+      "concordant": 102,
+      "p_value": 0.143463134765625
+     }
+    },
+    "usd_per_candidate": {
+     "A": 0.002206168067226891,
+     "B": 0.005363571428571428,
+     "ci95": [
+      0.0028887247706422007,
+      0.0033776267605633826
+     ],
+     "ci_vs_zero": "against",
+     "diff_B_minus_A": 0.003157403361344537,
+     "mcnemar": null
+    },
+    "within_pair_auc": {
+     "A": 0.7631578947368421,
+     "B": 0.6842105263157895,
+     "ci95": [
+      -0.15384615384615385,
+      0.0
+     ],
+     "ci_vs_zero": "spans",
+     "diff_B_minus_A": -0.07894736842105265,
+     "mcnemar": null
+    }
+   },
+   "paired_units": 119
+  }
+ },
+ "reason": "the CI of within_pair_auc excludes 0 against B",
+ "registration": "benchmarks/experiments/exp-002-retrieval-ensemble/registration.json",
+ "result": "benchmarks/experiments/exp-002-retrieval-ensemble/result.json",
+ "run": {
+  "decided": {
+   "A": 320,
+   "B": 320
+  },
+  "folds_digest": "a1f78e141a572a4adcc9cd57eb8a784c440c177f0b60d5ef5bed9e94c8753c5f",
+  "reason": "",
+  "skipped": {
+   "A": 0,
+   "B": 0
+  },
+  "status": "done",
+  "stopped_at_look": null,
+  "units": 160
+ },
+ "spend": {
+  "caller": {
+   "A": {
+    "cache_digest": "39ba875897ccbc9dee39b07029d26e1fee84392d230776b63bb6f8aa2189d7b9",
+    "client_calls": 1206,
+    "replayed": 395,
+    "usd": 0.682094
+   },
+   "B": {
+    "cache_digest": "5f6187e9445f180fe234b2f48a984eb8fbecf0000552a4acc0a412780c6e628a",
+    "client_calls": 1350,
+    "replayed": 250,
+    "usd": 1.632737
+   }
+  },
+  "deepseek_balance_usd": {
+   "after": 16.04,
+   "before": 16.72,
+   "metered_delta": 0.68
+  },
+  "note": "priced usage prices every response a decision used, a replayed one the same as a paid one (Caller.usd); client_calls are the paid calls and replayed the response-cache hits (arm A: 33 units whose slice-2 sample-0 request was still cached, plus identical prompts across identical-twin candidates and retries; arm B: twins and retries only). The provider balance is read at the run's end and lags; the metered spend is bounded by the arm meters (A $1, B $3).",
+  "priced_usage_usd_by_arm": {
+   "A": 0.6821,
+   "B": 1.6327
+  },
+  "priced_usage_usd_by_arm_replicate": {
+   "A:r0": 0.4299,
+   "A:r1": 0.2522,
+   "B:r0": 1.3797,
+   "B:r1": 0.253
+  }
+ },
+ "units": {
+  "by_label": {
+   "0": 72,
+   "1": 88
+  },
+  "groups": 56,
+  "outcomes": 640,
+  "paired": 160
+ }
+}