J-lens workspace reproduction + loop retrofit: lens, band looping, adapters, controls, multi-task evals

Reproduction of the 2026 workspace/J-lens paper on gemma-4 (E2B/12B/26B),
plus the workspace-loop retrofit line: merge adapter, prompt-only latent
planning (MBPP), carry variant, attribution controls (FF/pause/untrained),
band-location ablation, Blocksworld harness, 12B replication scripts.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/eval_plan_baseline.py

@@ -0,0 +1,54 @@
+"""Explicit-planning reference: frozen model, plan-first prompt, MBPP test.
+
+The number latent looping is compared against (equal-or-more FLOPs: ~200-400
+visible plan tokens vs k band passes over the prompt)."""
+
+import json
+import sys
+import time
+from concurrent.futures import ThreadPoolExecutor
+from pathlib import Path
+
+import torch
+
+from prep_mbpp import batch_generate, extract_code, mbpp_prompt, run_tests
+from prep_mbpp_fix import TERSE_PLAN_SUFFIX
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+from jlens.core import load_model  # noqa: E402
+
+OUT = Path(__file__).resolve().parent.parent / "results-loop"
+
+
+def main():
+    model, tok = load_model(dtype=torch.bfloat16)
+    tok.padding_side = "left"
+    items = [it for it in json.load(open(OUT / "mbpp_data.json"))
+             if it["split"] == "test"]
+    t0 = time.time()
+    gens = batch_generate(model, tok,
+                          [mbpp_prompt(tok, it, TERSE_PLAN_SUFFIX)
+                           for it in items], max_new_tokens=700, batch_size=16)
+    codes = [extract_code(g) for g in gens]
+    with ThreadPoolExecutor(8) as ex:
+        oks = list(ex.map(lambda ci: run_tests(ci[0], ci[1]),
+                          zip(codes, items)))
+    by = {}
+    for it, ok in zip(items, oks):
+        d = by.setdefault(it["label"], [0, 0])
+        d[0] += ok
+        d[1] += 1
+    per_item = [{"task_id": it["task_id"], "ok": bool(ok)}
+                for it, ok in zip(items, oks)]
+    res = {"acc": sum(oks) / len(items),
+           "by_label": {l: c / n for l, (c, n) in by.items()},
+           "per_item": per_item}
+    print(f"plan-first pass@1={res['acc']:.3f}  "
+          f"by_label={ {l: round(v,3) for l,v in res['by_label'].items()} }"
+          f"  ({time.time()-t0:.0f}s)", flush=True)
+    json.dump(res, open(OUT / "eval_plan_baseline.json", "w"), indent=1)
+    print("wrote", OUT / "eval_plan_baseline.json")
+
+
+if __name__ == "__main__":
+    main()