measure: claim-24 unfloored semantic leg vs bm25lex baseline - net +0, NOT-SHOWN

gains q14,q25 (gold at global cosine rank 1, previously discarded by the 0.60
floor); losses q15,q28 (the semantic leg was EMPTY on those queries under the
floor, so filling it turns a 2-leg rotation into a 3-leg one and halves the
associative leg's share of the top 5). Guards held: exact_rare 6/6, phrase 7/7,
nonsense 2/3, superseded 2/3 outranks. recall@10 61.8->65.4pp, latency 0.99x.
Baseline reproduced from source (results-bm25base-rerun.json is byte-identical
to the committed results-bm25lex.json), candidate deterministic across 2 runs.

tools/retrieval-eval/sim6b.py

@@ -0,0 +1,32 @@
+exec(open('sim6.py').read().split('if __name__')[0])
+HASSTRUCT=set(adj.keys())
+print("nodes with >=1 structural edge:",len(HASSTRUCT),file=sys.stderr)
+def run2(sfilter, seedout, lim=10):
+    res={}
+    for qid,q in gold.items():
+        v=emb(q['query']); s=M@v; s[~np.isfinite(s)]=-1
+        L,nmatch=lexleg(qid,q['query'])
+        if nmatch==0: res[qid]=[]; continue
+        ordr=np.argsort(-s)
+        cand=[eids[j] for j in ordr[:200] if PRINT.match(eids[j] or '')]
+        S=[x for x in cand if (not sfilter or x in HASSTRUCT)][:10]
+        seeds=[x for x in L[:3] if x in N]
+        semseeds=[eids[j] for j in ordr[:8] if eids[j] in N and eids[j] not in seeds and PRINT.match(eids[j] or '')]
+        seeds=seeds+semseeds
+        A=assoc(seeds,s,False,'cos') if seeds else []
+        if seedout:
+            extra=[(float(s[eidx[x]]),x) for x in semseeds if x in HASSTRUCT and x in eidx]
+            merged=[(float(s[eidx[x]]),x) for x in A if x in eidx]+extra
+            merged.sort(reverse=True)
+            seen=set(); A=[]
+            for c,x in merged:
+                if x in seen: continue
+                seen.add(x); A.append(x)
+            A=A[:ASSOC_MAX]
+        res[qid]=inter([L,S,A])
+    return res
+b,_=run(True,False,False,'cos'); base=score(b,'BASE bm25lex replica')
+a,_=run(False,True,False,'cos'); score(a,'A floor-off+vocabgate',base)
+score(run2(False,True),'E A+struct-seeds-in-graphleg',base)
+score(run2(True,False),'F A+S-restricted-to-graph',base)
+score(run2(True,True),'G  E+F',base)