feat(ucca): Blue-Green „authoritative slice promotion" — KB-2026.1 Scope-Routing

Additiv (KEIN CE-Ersatz): faellt eine Query in den KB-2026.1-Scope (DP/CRA/MaschVO/
NIS2/DataAct/DORA/AIAct + EDPB/DSK-Guidance), wird die hochwertige Slice-Collection
`kb_2026_1_build` abgefragt; sonst bleibt der breite Default `bp_compliance_ce`.
Damit werden die Guidance-Intent- + Multi-Reg-Fixes (PR #42/#43) fuer den Slice LIVE,
Broad-Corpus (OWASP/NIST/ENISA/IFRS/ISO) unangetastet -> 0 Regressionen by construction.

- resolveCollection(query, requested): explizit angefragte Collection unveraendert;
  Default-Request -> Slice bei inKBScope, sonst CE. Env RAG_KB_SCOPE_ROUTING=false = Rollback
  ohne Redeploy; RAG_KB_SLICE_COLLECTION ueberschreibt den Slice-Namen.
- inKBScope: detectRegulations (in-Slice-Regelwerke) + DP-Guidance-Marker (edpb/dsk/wp/gl) +
  DP/Compliance-Topics. Bewusst NICHT die generischen Verben aus guidanceIntentSignals
  (sagt/laut) und NICHT enisa/bsi/nist/owasp (die liegen in CE) -> konservativ, in-scope->Slice.

Validierung: Unit (Scoping + resolveCollection); dev-e2e (RUN_E2E, geroutetes Search() gegen
dev): WP248/MaschVO/CRA+MaschVO -> Slice (Treffer da, fehlen in dev-ce); NIST -> CE (NIST-Treffer).

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

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

@@ -21,6 +21,12 @@ type LegalRAGClient struct {
 	textIndexEnsured map[string]bool
 	hybridEnabled    bool
 	graphEnabled     bool
+
+	// Blue-Green „authoritative slice promotion" (additiv, KEIN CE-Ersatz): faellt eine Query
+	// in den KB-2026.1-Scope (DP/CRA/MaschVO/NIS2/DataAct/DORA/AIAct + EDPB/DSK-Guidance), wird
+	// die hochwertige Slice-Collection abgefragt; sonst bleibt der breite Default (bp_compliance_ce).
+	kbSliceCollection     string
+	kbScopeRoutingEnabled bool
 }
 
 // NewLegalRAGClient creates a new Legal RAG client using Ollama bge-m3 embeddings.
@@ -45,15 +51,25 @@ func NewLegalRAGClient() *LegalRAGClient {
 	// zur Begruendung/Vollstaendigkeit genutzt, nicht zur Pool-Expansion (Default).
 	graphEnabled := os.Getenv("RAG_GRAPH_EXPANSION") == "true"
 
+	// KB-2026.1 authoritative slice (Blue-Green, additiv). Routing default AN; Rollback ohne
+	// Redeploy ueber RAG_KB_SCOPE_ROUTING=false (dann faellt alles auf den CE-Default zurueck).
+	kbSlice := os.Getenv("RAG_KB_SLICE_COLLECTION")
+	if kbSlice == "" {
+		kbSlice = "kb_2026_1_build"
+	}
+	kbScopeRouting := os.Getenv("RAG_KB_SCOPE_ROUTING") != "false"
+
 	return &LegalRAGClient{
-		qdrantURL:        qdrantURL,
-		qdrantAPIKey:     qdrantAPIKey,
-		ollamaURL:        ollamaURL,
-		embeddingModel:   "bge-m3",
-		collection:       "bp_compliance_ce",
-		textIndexEnsured: make(map[string]bool),
-		hybridEnabled:    hybridEnabled,
-		graphEnabled:     graphEnabled,
+		qdrantURL:             qdrantURL,
+		qdrantAPIKey:          qdrantAPIKey,
+		ollamaURL:             ollamaURL,
+		embeddingModel:        "bge-m3",
+		collection:            "bp_compliance_ce",
+		textIndexEnsured:      make(map[string]bool),
+		hybridEnabled:         hybridEnabled,
+		graphEnabled:          graphEnabled,
+		kbSliceCollection:     kbSlice,
+		kbScopeRoutingEnabled: kbScopeRouting,
 		httpClient: &http.Client{
 			Timeout: 60 * time.Second,
 		},
@@ -63,15 +79,13 @@ func NewLegalRAGClient() *LegalRAGClient {
 // SearchCollection queries a specific Qdrant collection for relevant passages.
 // If collection is empty, it falls back to the default collection (bp_compliance_ce).
 func (c *LegalRAGClient) SearchCollection(ctx context.Context, collection string, query string, regulationIDs []string, topK int) ([]LegalSearchResult, error) {
-	if collection == "" {
-		collection = c.collection
-	}
-	return c.searchInternal(ctx, collection, query, regulationIDs, topK)
+	return c.searchInternal(ctx, c.resolveCollection(query, collection), query, regulationIDs, topK)
 }
 
-// Search queries the compliance CE corpus for relevant passages.
+// Search queries the compliance corpus for relevant passages. The target collection is resolved by
+// the Blue-Green slice routing: the KB-2026.1 slice for in-scope queries, else the broad CE default.
 func (c *LegalRAGClient) Search(ctx context.Context, query string, regulationIDs []string, topK int) ([]LegalSearchResult, error) {
-	return c.searchInternal(ctx, c.collection, query, regulationIDs, topK)
+	return c.searchInternal(ctx, c.resolveCollection(query, ""), query, regulationIDs, topK)
 }
 
 // searchInternal performs the actual search against a given collection.