diff --git a/frontend/package.json b/frontend/package.json
index b70a5c1..6799fbb 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -12,7 +12,9 @@
     "check:a11y": "node scripts/check-accessible-controls.mjs",
     "test:ws-outbox": "node scripts/test-ws-outbox.mjs",
     "test:dds-history": "node scripts/test-dds-history.mjs",
-    "test:dds-ack": "node scripts/test-dds-ack.mjs"
+    "test:dds-ack": "node scripts/test-dds-ack.mjs",
+    "test:session-report": "node scripts/test-session-report.mjs",
+    "test:scenario-start": "node scripts/test-scenario-start.mjs"
   },
   "dependencies": {
     "@tanstack/react-query": "^5.103.1",
diff --git a/frontend/scripts/test-scenario-start.mjs b/frontend/scripts/test-scenario-start.mjs
new file mode 100644
index 0000000..70c9764
--- /dev/null
+++ b/frontend/scripts/test-scenario-start.mjs
@@ -0,0 +1,31 @@
+import assert from "node:assert/strict";
+
+import { scenarioStartMessage } from "../src/features/instructor/start.mjs";
+
+const minimal = JSON.parse(JSON.stringify(scenarioStartMessage({
+  scenarioId: "s1", mode: "exam", trainee: "Иванов",
+})));
+assert.deepEqual(minimal, {
+  type: "scenario.start", scenario_id: "s1", mode: "exam", trainee: "Иванов",
+  group_id: null, trainee_id: null, dds_service: null, exercise: "dds", handoff_to_dds: false,
+  dds_arrival_interval_seconds: 60, dds_max_waiting: 3,
+}, "умолчания прежние, пустые списки и критерии в сокет не уходят");
+
+const criteria = { allowed_errors: 2 };
+const full = scenarioStartMessage({
+  scenarioId: "s1", mode: "training", trainee: "Петров", exercise: "call", groupId: "g1",
+  traineeId: "t1", ddsService: "01", scenarioIds: ["s1", "s2"], randomScenarioIds: ["s3"],
+  ddsArrivalIntervalSeconds: 30, ddsMaxWaiting: 5, handoffToDds: true, criteria,
+});
+assert.deepEqual(full, {
+  type: "scenario.start", scenario_id: "s1", mode: "training", trainee: "Петров",
+  group_id: "g1", trainee_id: "t1", dds_service: "01", exercise: "call", handoff_to_dds: true,
+  scenario_ids: ["s1", "s2"], random_scenario_ids: ["s3"],
+  dds_arrival_interval_seconds: 30, dds_max_waiting: 5, criteria,
+});
+
+const empty = scenarioStartMessage({ scenarioId: "s1", mode: "exam", trainee: "И", scenarioIds: [], randomScenarioIds: [] });
+assert.equal(empty.scenario_ids, undefined, "пустой список не отправляется");
+assert.equal(empty.random_scenario_ids, undefined);
+
+console.log("scenario.start: named options build the same socket message.");
diff --git a/frontend/src/features/instructor/start.d.mts b/frontend/src/features/instructor/start.d.mts
new file mode 100644
index 0000000..35f1cad
--- /dev/null
+++ b/frontend/src/features/instructor/start.d.mts
@@ -0,0 +1,36 @@
+import type { LessonCriteria, SessionMode } from "@/shared/types/generated";
+
+export interface ScenarioStartOptions {
+  scenarioId: string;
+  mode: SessionMode;
+  trainee: string;
+  exercise?: "dds" | "call" | "card";
+  groupId?: string;
+  traineeId?: string;
+  ddsService?: string;
+  scenarioIds?: string[];
+  randomScenarioIds?: string[];
+  ddsArrivalIntervalSeconds?: number;
+  ddsMaxWaiting?: number;
+  handoffToDds?: boolean;
+  criteria?: LessonCriteria;
+}
+
+export interface ScenarioStartMessage {
+  type: "scenario.start";
+  scenario_id: string;
+  mode: SessionMode;
+  trainee: string;
+  group_id: string | null;
+  trainee_id: string | null;
+  dds_service: string | null;
+  exercise: "dds" | "call" | "card";
+  handoff_to_dds: boolean;
+  scenario_ids: string[] | undefined;
+  random_scenario_ids: string[] | undefined;
+  dds_arrival_interval_seconds: number;
+  dds_max_waiting: number;
+  criteria: LessonCriteria | undefined;
+}
+
+export function scenarioStartMessage(options: ScenarioStartOptions): ScenarioStartMessage;
diff --git a/frontend/src/features/instructor/start.mjs b/frontend/src/features/instructor/start.mjs
new file mode 100644
index 0000000..488e62a
--- /dev/null
+++ b/frontend/src/features/instructor/start.mjs
@@ -0,0 +1,26 @@
+// Сборка `scenario.start` из именованных параметров консоли преподавателя.
+// Отдельный .mjs, чтобы состав сообщения проверялся node-скриптом без сборки.
+
+/** @param {import("./start.d.mts").ScenarioStartOptions} options */
+export function scenarioStartMessage({
+  scenarioId, mode, trainee, exercise = "dds", groupId, traineeId, ddsService,
+  scenarioIds, randomScenarioIds, ddsArrivalIntervalSeconds = 60, ddsMaxWaiting = 3,
+  handoffToDds = false, criteria,
+}) {
+  return {
+    type: "scenario.start",
+    scenario_id: scenarioId,
+    mode,
+    trainee,
+    group_id: groupId || null,
+    trainee_id: traineeId || null,
+    dds_service: ddsService || null,
+    exercise,
+    handoff_to_dds: handoffToDds,
+    scenario_ids: scenarioIds?.length ? scenarioIds : undefined,
+    random_scenario_ids: randomScenarioIds?.length ? randomScenarioIds : undefined,
+    dds_arrival_interval_seconds: ddsArrivalIntervalSeconds,
+    dds_max_waiting: ddsMaxWaiting,
+    criteria,
+  };
+}
diff --git a/frontend/src/features/instructor/useControl.ts b/frontend/src/features/instructor/useControl.ts
index 92e7496..02b16d3 100644
--- a/frontend/src/features/instructor/useControl.ts
+++ b/frontend/src/features/instructor/useControl.ts
@@ -8,7 +8,8 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 
 import { controlChannel, type ChannelStatus } from "@/shared/api/ws";
-import type { LessonCriteria, SessionMode } from "@/shared/types/generated";
+
+import { scenarioStartMessage, type ScenarioStartOptions } from "./start.mjs";
 
 export function useControl(sessionId: string | null) {
   const [status, setStatus] = useState<ChannelStatus>("closed");
@@ -37,30 +38,11 @@ export function useControl(sessionId: string | null) {
     };
   }, [sessionId]);
 
-  const start = useCallback(
-    (targetSessionId: string, scenarioId: string, mode: SessionMode, trainee: string, exercise: "dds" | "call" | "card" = "dds", group?: string, traineeId?: string, ddsService?: string, scenarioIds?: string[], ddsArrivalIntervalSeconds = 60, ddsMaxWaiting = 3, handoffToDds = false, criteria?: LessonCriteria, randomScenarioIds?: string[]) => {
-      const message = {
-        type: "scenario.start",
-        scenario_id: scenarioId,
-        mode,
-        trainee,
-        group_id: group || null,
-        trainee_id: traineeId || null,
-        dds_service: ddsService || null,
-        exercise,
-        handoff_to_dds: handoffToDds,
-        scenario_ids: scenarioIds?.length ? scenarioIds : undefined,
-        random_scenario_ids: randomScenarioIds?.length ? randomScenarioIds : undefined,
-        dds_arrival_interval_seconds: ddsArrivalIntervalSeconds,
-        dds_max_waiting: ddsMaxWaiting,
-        criteria,
-      } as const;
-      const current = channel.current;
-      if (!current || current.sessionId !== targetSessionId) return false;
-      return current.socket.send(message);
-    },
-    [],
-  );
+  const start = useCallback((targetSessionId: string, options: ScenarioStartOptions) => {
+    const current = channel.current;
+    if (!current || current.sessionId !== targetSessionId) return false;
+    return current.socket.send(scenarioStartMessage(options));
+  }, []);
 
   const note = useCallback(
     (transcriptRef: string, text: string) =>
diff --git a/frontend/src/pages/instructor/Instructor.tsx b/frontend/src/pages/instructor/Instructor.tsx
index 481eac9..3c1f435 100644
--- a/frontend/src/pages/instructor/Instructor.tsx
+++ b/frontend/src/pages/instructor/Instructor.tsx
@@ -283,19 +283,27 @@ export function Instructor() {
       && !(exercise === "dds" && wholeTicket)
       ? visibleScenarios.filter((item) => item.outcome === "card").map((item) => item.id)
       : undefined;
-    const sent = control.start(sessionId, primaryScenarioId, mode, selected?.name || trainee || "Демо-курсант",
-      exercise === "card_dds" ? "card" : exercise,
-      undefined, selected?.id, selected?.service ?? undefined,
-      scenarioIds && scenarioIds.length > 1 ? scenarioIds : undefined,
-      ddsArrivalIntervalSeconds, ddsMaxWaiting,
-      exercise === "card_dds", {
+    const sent = control.start(sessionId, {
+      scenarioId: primaryScenarioId,
+      mode,
+      trainee: selected?.name || trainee || "Демо-курсант",
+      exercise: exercise === "card_dds" ? "card" : exercise,
+      traineeId: selected?.id,
+      ddsService: selected?.service ?? undefined,
+      scenarioIds: scenarioIds && scenarioIds.length > 1 ? scenarioIds : undefined,
+      randomScenarioIds,
+      ddsArrivalIntervalSeconds,
+      ddsMaxWaiting,
+      handoffToDds: exercise === "card_dds",
+      criteria: {
         decision_time_limit_seconds: decisionTimeLimit,
         card_fill_time_limit_seconds: cardFillTimeLimit,
         dds_card_work_time_limit_seconds: ddsCardWorkTimeLimit,
         allowed_errors: allowedErrors,
         require_correct_grammar: requireCorrectGrammar,
         score_weights: lessonScoreWeights,
-      }, randomScenarioIds);
+      },
+    });
     if (sent) toStart.current = null;
   }, [sessionId, control, scenarioId, extraScenarioIds, mode, trainee, traineeId, trainees.data,
     exercise, decisionTimeLimit, cardFillTimeLimit, ddsCardWorkTimeLimit, allowedErrors, requireCorrectGrammar, wholeTicket, selectedTicketScenarios,