feat(ai-sdk): control-intent result diversity + standard-name classifier override

On an implementation question impl_guidance (ENISA) keeps its earned semantic
Top-1, but the top-K now surfaces the best operational_requirement and
control_standard from the pool (ensureControlDiversity) — so different source
roles are visible instead of one role flooding the list, without forcing the
binding sources to Top-1.

A recognised standard NAME (NIST/OWASP/ISO 27001/CIS/CSA CCM/Grundschutz) now
overrides a mis-applied supervisory_guidance source_class in classifyAuthority,
so those standards classify and rank as technical_standard (control_standard
role). The corpus tags many standards as guidance (weight 70); the name wins.

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

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

@@ -121,3 +121,54 @@ func controlRoleOf(payload map[string]interface{}) string {
 		IsRecital:       getBool(payload, "is_recital"),
 	})
 }
+
+// ensureControlDiversity guarantees that the returned top-K of a control question surfaces at
+// least one operational_requirement and one control_standard WHEN the pool contains them —
+// without forcing them to Top-1. implementation_guidance (e.g. ENISA good practices) keeps its
+// earned semantic lead; the rule only promotes the best hit of a missing control role into the
+// top-K by overwriting the lowest-ranked redundant guidance slot. So an implementation question
+// shows the relevant source ROLES (binding requirement + standard + guidance) side by side
+// instead of one role flooding the list. The promoted hit's original (now duplicate) position
+// stays in the tail and is dropped by the caller's truncation to topK.
+func ensureControlDiversity(results []LegalSearchResult, topK int) []LegalSearchResult {
+	if topK <= 0 || topK >= len(results) {
+		return results // everything is already returned — nothing to promote
+	}
+	roleAt := make([]string, len(results))
+	for i := range results {
+		roleAt[i] = classifyRole(results[i])
+	}
+	present := make(map[string]bool, topK)
+	for i := 0; i < topK; i++ {
+		present[roleAt[i]] = true
+	}
+	for _, want := range []string{roleOperationalReq, roleControlStandard} {
+		if present[want] {
+			continue
+		}
+		src := -1
+		for i := topK; i < len(results); i++ {
+			if roleAt[i] == want {
+				src = i
+				break
+			}
+		}
+		if src < 0 {
+			continue // role absent from the whole pool — nothing to promote
+		}
+		dst := -1
+		for j := topK - 1; j >= 0; j-- {
+			if roleAt[j] == roleImplGuidance {
+				dst = j
+				break
+			}
+		}
+		if dst < 0 {
+			continue // no redundant guidance to sacrifice — leave the head untouched
+		}
+		results[dst] = results[src]
+		roleAt[dst] = want
+		present[want] = true
+	}
+	return results
+}