diff --git a/benchmarks/perturbation/_combine_gpt_claude.py b/benchmarks/perturbation/_combine_gpt_claude.py
new file mode 100644
index 0000000..8ec4f5f
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+++ b/benchmarks/perturbation/_combine_gpt_claude.py
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+"""Compute combined-system (GPT-5.5 OR Claude-Opus-4.7) recall on the 24-paper
+frontier subset for tab:recall-overall in perturbation.tex.
+
+A perturbation is detected by the combined system if either GPT-5.5 OR
+Claude-Opus-4.7 detected it under the progressive (OpenAIReview) method.
+Perturbation IDs are namespaced by (results_dir, paper, type) to avoid
+cross-paper collisions.
+"""
+import json
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent / "results"
+
+# (results_dir, [paper_ids], [ptypes]) — must mirror configs/submission/subset_bigmodels_*.yaml.
+# Note: cs_CC uses a different ptype taxonomy (claim_theoretical/logic instead
+# of statement_empirical/experimental).
+DOMAINS = [
+    ("cs_CC_scaleup_v2",        ["paper_001", "paper_003", "paper_004"], ["surface", "claim_theoretical", "logic"]),
+    ("full_cs_LG",              ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+    ("full_econ_EM",            ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+    ("full_hep_ex",             ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+    ("full_math_all",           ["paper_001", "paper_002", "paper_004"], ["surface", "statement_empirical", "experimental"]),
+    ("full_physics_atm_clus",   ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+    ("full_q_bio_GN",           ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+    ("full_stat_AP",            ["paper_001", "paper_002", "paper_003"], ["surface", "statement_empirical", "experimental"]),
+]
+METHOD = "progressive"   # = OpenAIReview column
+
+
+def load_score(domain: str, model: str, ptype: str, paper: str):
+    p = ROOT / domain / model / ptype / METHOD / paper / "score" / "llm_t4_grounded" / f"{paper}_score.json"
+    if not p.exists():
+        return None
+    return json.loads(p.read_text())
+
+
+def keyset(score, prefix: str, kind: str) -> set[str]:
+    """kind='detected' or 'all' (detected ∪ missed)."""
+    if kind == "detected":
+        items = score["detected"]
+    else:
+        items = list(score["detected"]) + list(score["missed"])
+    return {f"{prefix}::{x}" for x in items}
+
+
+def collect(model: str) -> tuple[set[str], set[str]]:
+    detected, injected = set(), set()
+    for domain, papers, ptypes in DOMAINS:
+        for paper in papers:
+            for ptype in ptypes:
+                s = load_score(domain, model, ptype, paper)
+                if s is None:
+                    continue
+                prefix = f"{domain}|{ptype}|{paper}"
+                detected |= keyset(s, prefix, "detected")
+                injected |= keyset(s, prefix, "all")
+    return detected, injected
+
+
+MODELS = [
+    ("GPT-5.5",                "gpt-5.5"),
+    ("Claude-Opus-4.7",        "claude-opus-4.7"),
+    ("Grok-4.1-Fast",          "grok-4.1-fast"),
+    ("DeepSeek-V4-Flash",      "deepseek-v4-flash"),
+    ("Qwen3.6-35B-A3B",        "qwen3.6-35b-a3b"),
+    ("Gemini-3.1-Flash-Lite",  "gemini-3.1-flash-lite-preview"),
+]
+
+
+def main():
+    per_model = {}
+    for label, slug in MODELS:
+        det, inj = collect(slug)
+        per_model[label] = (det, inj)
+        print(f"{label:23s}: {len(det):>4} / {len(inj):>4} = {len(det)/len(inj)*100:5.1f}%")
+
+    all_det = set().union(*(d for d, _ in per_model.values()))
+    all_inj = set().union(*(i for _, i in per_model.values()))
+    print()
+    print("Combined (ANY of the 6 models, progressive/OpenAIReview):")
+    print(f"  union injected : {len(all_inj)}")
+    print(f"  union detected : {len(all_det)}")
+    print(f"  recall         : {len(all_det)/len(all_inj)*100:5.1f}%")
+    print()
+
+    # Cumulative-by-rank: add models in descending single-model recall order
+    print("Cumulative recall as models are added (best single first):")
+    order = sorted(per_model.items(), key=lambda kv: -len(kv[1][0]))
+    cum_det, cum_inj = set(), set()
+    for label, (d, i) in order:
+        cum_det |= d
+        cum_inj |= i
+        print(f"  + {label:23s}: {len(cum_det):>4} / {len(cum_inj):>4} = {len(cum_det)/len(cum_inj)*100:5.1f}%")
+    print()
+
+    # How many perturbations only ONE model caught
+    print("Coverage by # of detecting models (perturbations in union):")
+    coverage = {}
+    for pid in all_inj:
+        n = sum(1 for d, _ in per_model.values() if pid in d)
+        coverage[n] = coverage.get(n, 0) + 1
+    for n in sorted(coverage):
+        tag = "missed by all" if n == 0 else f"caught by {n} model(s)"
+        print(f"  {tag:25s}: {coverage[n]:>4}")
+
+
+if __name__ == "__main__":
+    main()