fix(ucca): Cross-Reg 0070 — beide Regelwerk-Domaenen im Router-Top-K (Known Defects 0)

Der einzige offene Retrieval-Haertefall: eine Query mit >=2 genannten Regelwerken
("CRA und Maschinenverordnung") lieferte nur die keyword-dominante Domaene (CRA),
MaschVO fiel raus. Drei zusammenwirkende Ursachen, alle behoben:

1. CodeValues-Mismatch: MaschVO heisst je Collection anders (Slice MASCHVO ·
   gesetze MVO · ce MACHINERY/MASCHINENVO), der Catalog hatte nur ["MASCHVO","MaschVO"]
   → Filter fand MaschVO nur in der Slice. Jetzt alle Varianten als CodeValues.
2. Per-Collection-Truncation: der Router gab perColl=3 → searchMultiRegulation holte
   3+3=6, schnitt auf 3 → konnte eine Domaene je Collection verlieren. Multi-Reg-Queries
   bekommen jetzt perColl = 3*len(regs).
3. Router-Score-Merge starvte die nicht-dominante Domaene. Neue balanceByRegulation()
   gruppiert den gemergten Pool per Regelwerk (exakter regulation_code-Match) und nimmt
   round-robin ueber die genannten Domaenen → jede Domaene mit Treffern ist im Top-K.
   Generisch ueber jede genannte Menge; Single-Domain-Pfad unveraendert.

Validierung: Go-Unit (balanceByRegulation: dominante CRA verdraengt MaschVO NICHT mehr);
0070-e2e gegen dev (Retrieve() → [CRA MVO CRA MVO CRA MVO CRA MASCHINENVO] = beide
Domaenen, vorher nur CRA); CB-100-Stichprobe REGR 0 (Gain-Profil unveraendert).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

ai-compliance-sdk/internal/ucca/authority_router.go

@@ -55,6 +55,15 @@ func (c *LegalRAGClient) Retrieve(ctx context.Context, query string, topK int) (
 		collections = append(collections, c.kbSliceCollection)
 	}
 
+	// Cross-regulation queries (>=2 explicitly named regulations) get a larger per-collection budget
+	// so each collection's multi-regulation search isn't truncated down to the keyword-dominant
+	// domain; the final per-regulation balancing then guarantees every named domain in the top-K.
+	regs := detectRegulations(query)
+	perColl := routerPerCollectionTopK
+	if len(regs) >= 2 {
+		perColl = routerPerCollectionTopK * len(regs)
+	}
+
 	// Warm the full-text indexes sequentially first so the concurrent fan-out below only READS the
 	// shared textIndexEnsured map (the writes happen here, serialized) — closes the cold-start map
 	// race deterministically. Best-effort: a missing collection just stays un-indexed (hybrid then
@@ -71,19 +80,25 @@ func (c *LegalRAGClient) Retrieve(ctx context.Context, query string, topK int) (
 		wg.Add(1)
 		go func(i int, coll string) {
 			defer wg.Done()
-			if res, err := c.searchInternal(ctx, coll, query, nil, routerPerCollectionTopK); err == nil {
+			if res, err := c.searchInternal(ctx, coll, query, nil, perColl); err == nil {
 				out[i] = res
 			}
 		}(i, coll)
 	}
 	wg.Wait()
 
-	merged := make([]LegalSearchResult, 0, len(collections)*routerPerCollectionTopK)
+	merged := make([]LegalSearchResult, 0, len(collections)*perColl)
 	for _, r := range out {
 		merged = append(merged, r...)
 	}
 	merged = dedupResults(merged)
 	sort.SliceStable(merged, func(a, b int) bool { return merged[a].Score > merged[b].Score })
+
+	// Cross-regulation: guarantee every named domain is represented (0070-class fix) instead of
+	// letting a global score-sort starve the non-dominant domain.
+	if len(regs) >= 2 {
+		return balanceByRegulation(merged, regs, topK), nil
+	}
 	if len(merged) > topK {
 		merged = merged[:topK]
 	}

ai-compliance-sdk/internal/ucca/authority_router_e2e_test.go

@@ -60,6 +60,36 @@ func hitDoc(results []LegalSearchResult, toks []string) bool {
 	return false
 }
 
+// TestMultiReg0070E2E (RUN_E2E=1) is the 0070 regression: a cross-regulation query (CRA + MaschVO)
+// must return BOTH domains through the real Retrieve(), not just the keyword-dominant CRA.
+func TestMultiReg0070E2E(t *testing.T) {
+	if os.Getenv("RUN_E2E") != "1" {
+		t.Skip("set RUN_E2E=1 + QDRANT_URL/OLLAMA_URL/QDRANT_API_KEY")
+	}
+	c := NewLegalRAGClient()
+	q := "Wie greifen CRA und Maschinenverordnung bei einer vernetzten Maschine ineinander?"
+	res, err := c.Retrieve(context.Background(), q, 8)
+	if err != nil {
+		t.Fatalf("retrieve: %v", err)
+	}
+	var hasCRA, hasMasch bool
+	var codes []string
+	for _, r := range res {
+		u := strings.ToUpper(r.RegulationCode)
+		codes = append(codes, u)
+		if strings.Contains(u, "CRA") {
+			hasCRA = true
+		}
+		if strings.Contains(u, "MASCH") || strings.Contains(u, "MACHIN") || u == "MVO" {
+			hasMasch = true
+		}
+	}
+	t.Logf("0070 top-8 codes: %v", codes)
+	if !hasCRA || !hasMasch {
+		t.Errorf("0070 must return BOTH domains via Retrieve(): CRA=%v MaschVO=%v", hasCRA, hasMasch)
+	}
+}
+
 // TestAuthorityRouterCB100 (RUN_E2E=1) drives the REAL Retrieve() over the ComplianceBench-100 against
 // the live collections: NEW (scope routing on → slice added for in-scope queries) vs OLD (routing off
 // → broad base only). It is the regression gate that the router actually delivers the proven slice

ai-compliance-sdk/internal/ucca/authority_router_test.go

@@ -49,6 +49,38 @@ func TestRouterSliceSelection(t *testing.T) {
 	}
 }
 
+func TestBalanceByRegulation(t *testing.T) {
+	regs := []detectedRegulation{
+		{Canonical: "CRA", CodeValues: []string{"CRA"}},
+		{Canonical: "MaschVO", CodeValues: []string{"MASCHVO", "MVO", "MACHINERY"}},
+	}
+	// CRA dominates by score; without balancing the top-4 would be all CRA + NIST.
+	pool := []LegalSearchResult{
+		{RegulationCode: "CRA", Score: 0.99},
+		{RegulationCode: "CRA", Score: 0.98},
+		{RegulationCode: "CRA", Score: 0.97},
+		{RegulationCode: "NIST", Score: 0.96},
+		{RegulationCode: "MACHINERY", Score: 0.70},
+		{RegulationCode: "MVO", Score: 0.65},
+	}
+	out := balanceByRegulation(pool, regs, 4)
+	var hasCRA, hasMasch bool
+	for _, r := range out {
+		switch r.RegulationCode {
+		case "CRA":
+			hasCRA = true
+		case "MACHINERY", "MVO":
+			hasMasch = true
+		}
+	}
+	if !hasCRA || !hasMasch {
+		t.Errorf("both named domains must be represented: CRA=%v MaschVO=%v out=%v", hasCRA, hasMasch, out)
+	}
+	if out[0].RegulationCode != "CRA" || !(out[1].RegulationCode == "MACHINERY" || out[1].RegulationCode == "MVO") {
+		t.Errorf("round-robin should alternate domains, got %s then %s", out[0].RegulationCode, out[1].RegulationCode)
+	}
+}
+
 func TestDedupResults(t *testing.T) {
 	in := []LegalSearchResult{
 		{RegulationCode: "EDPB WP248", ArticleLabel: "III.B", Text: "lorem", Score: 0.7},

ai-compliance-sdk/internal/ucca/multi_regulation.go

@@ -20,7 +20,9 @@ var regulationCatalog = []struct {
 	CodeValues []string
 }{
 	{"CRA", []string{"cra", "cyber resilience"}, []string{"CRA"}},
-	{"MaschVO", []string{"maschinenverordnung", "maschvo", "machinery regulation"}, []string{"MASCHVO", "MaschVO"}},
+	// MaschVO heisst je Collection anders: Slice MASCHVO · gesetze MVO · ce MACHINERY/MASCHINENVO.
+	// Alle Varianten als CodeValues, sonst findet der per-Reg-Filter MaschVO nur in der Slice (0070).
+	{"MaschVO", []string{"maschinenverordnung", "maschvo", "machinery regulation"}, []string{"MASCHVO", "MaschVO", "MVO", "MASCHINENVO", "MACHINERY"}},
 	{"NIS2", []string{"nis2", "nis-2", "nis 2"}, []string{"NIS2"}},
 	{"DORA", []string{"dora"}, []string{"DORA"}},
 	{"Data Act", []string{"data act", "datengesetz"}, []string{"DATA ACT", "DataAct"}},
@@ -53,6 +55,62 @@ func detectRegulations(query string) []detectedRegulation {
 
 func hitID(h qdrantSearchHit) string { return fmt.Sprintf("%v", h.ID) }
 
+// balanceByRegulation builds the final top-K so EVERY explicitly-named regulation with hits is
+// represented, instead of letting the keyword-dominant domain (e.g. CRA) crowd out the other
+// (e.g. MaschVO) in a cross-regulation query. The input pool must already be score-ordered;
+// results are grouped by exact regulation_code match against each regulation's CodeValues, then
+// taken round-robin across the named domains (highest-scored first within each), with any
+// remaining slots filled by the leftover pool in score order. Generic; no doc-specific logic.
+func balanceByRegulation(pool []LegalSearchResult, regs []detectedRegulation, topK int) []LegalSearchResult {
+	if topK <= 0 {
+		topK = 8
+	}
+	byReg := make([][]LegalSearchResult, len(regs))
+	matched := make([]bool, len(pool))
+	for ri, r := range regs {
+		for pi := range pool {
+			if matched[pi] {
+				continue
+			}
+			code := strings.ToUpper(strings.TrimSpace(pool[pi].RegulationCode))
+			for _, cv := range r.CodeValues {
+				if code == strings.ToUpper(cv) {
+					byReg[ri] = append(byReg[ri], pool[pi])
+					matched[pi] = true
+					break
+				}
+			}
+		}
+	}
+	out := make([]LegalSearchResult, 0, topK)
+	idx := make([]int, len(regs))
+	for len(out) < topK {
+		progressed := false
+		for ri := range regs {
+			if idx[ri] < len(byReg[ri]) {
+				out = append(out, byReg[ri][idx[ri]])
+				idx[ri]++
+				progressed = true
+				if len(out) >= topK {
+					break
+				}
+			}
+		}
+		if !progressed {
+			break
+		}
+	}
+	for pi := range pool {
+		if len(out) >= topK {
+			break
+		}
+		if !matched[pi] {
+			out = append(out, pool[pi])
+		}
+	}
+	return out
+}
+
 // searchMultiRegulation retrieves each explicitly-named regulation SEPARATELY (per-regulation
 // filter) and merges, so a cross-regulation query ("Wie greifen CRA und MaschVO ineinander?")
 // returns BOTH domains in the prompt instead of only the keyword-dominant one. Generic over any