fix(confidence-engine): keep episode reasoning server-side

lib/graph/schema.js

@@ -204,6 +204,7 @@ export const startCaseRequestSchema = z.object({
   promptVersion: z.string().optional(),
 });
 
+/** Legacy schema — unchanged contract for existing consumers. */
 export const updateCaseRequestSchema = z.object({
   situationGraph: situationGraphSchema,
   previousQuestion: z.string().min(1),
@@ -222,6 +223,19 @@ export const updateCaseRequestSchema = z.object({
   ).optional(),
 });
 
+/** Extended schema with optional fields accepted by the route for all requests. */
+export const updateCaseRequestSchemaExtended = updateCaseRequestSchema.extend({
+  targetNodeId: z.string().optional(),
+  contributions: z.any().array().optional(),
+});
+
+/** Minimal schema for episode-mode requests (legacy fields not required). */
+export const updateCaseEpisodeRequestSchema = z.object({
+  situationGraph: situationGraphSchema,
+  targetNodeId: z.string().min(1),
+  contributions: z.any().array().optional(),
+}).passthrough();
+
 // ── Helpers ──────────────────────────────────────────
 
 /** Generate a short deterministic ID from a label */