diff --git a/packages/shared/src/issue-thread-interactions.test.ts b/packages/shared/src/issue-thread-interactions.test.ts
index a4406e924fd..9610acc750d 100644
--- a/packages/shared/src/issue-thread-interactions.test.ts
+++ b/packages/shared/src/issue-thread-interactions.test.ts
@@ -313,6 +313,22 @@ describe("issue thread interaction schemas", () => {
     expect(createIssueThreadInteractionSchema.parse({ kind: "ask_user_questions", payload: complete }).payload).toMatchObject({ questionSet: { questions: expect.any(Array) } });
   });
 
+  it.each([
+    ["required", { required: false }],
+    ["answer mode", { answerMode: "multi_select" }],
+    ["option IDs", { options: [{ id: "different", label: "Blue" }] }],
+    ["option labels", { options: [{ id: "blue", label: "Red" }] }],
+    ["prompt", { prompt: "A different question?" }],
+  ])("rejects conflicting canonical %s at creation", (_name, changes) => {
+    const payload = {
+      version: 1,
+      questions: [{ id: "color", prompt: "Color?", required: true, selectionMode: "single", options: [{ id: "blue", label: "Blue" }] }],
+      questionSet: { schema: "paperclip.question_set.v1", questions: [{ id: "color", prompt: "Color?", required: true, answerMode: "single_select", options: [{ id: "blue", label: "Blue" }], ...changes }] },
+    };
+    expect(() => createIssueThreadInteractionSchema.parse({ kind: "ask_user_questions", payload })).toThrow("must match");
+    expect(askUserQuestionsPayloadSchema.parse(payload).questions).toHaveLength(1);
+  });
+
   it("rejects unsafe request_confirmation target hrefs", () => {
     const base = {
       kind: "request_confirmation",
diff --git a/packages/shared/src/validators/issue.ts b/packages/shared/src/validators/issue.ts
index 3c49460a118..5501c1258f5 100644
--- a/packages/shared/src/validators/issue.ts
+++ b/packages/shared/src/validators/issue.ts
@@ -1879,6 +1879,29 @@ const createAskUserQuestionsPayloadSchema = askUserQuestionsPayloadSchema.superR
       message: "questionSet must present every questions entry with the same question IDs. Include choice questions as well as text questions; a partial form hides required answers.",
     });
   }
+  const storedById = new Map(value.questions.map((question) => [question.id, question]));
+  for (const [index, question] of value.questionSet.questions.entries()) {
+    const storage = storedById.get(question.id);
+    if (!storage) continue;
+    const mismatch = (field: string) => ctx.addIssue({
+      code: z.ZodIssueCode.custom,
+      path: ["questionSet", "questions", index, field],
+      message: `questionSet ${field} must match the corresponding questions entry.`,
+    });
+    if (question.prompt !== storage.prompt) mismatch("prompt");
+    // An omitted storage flag adds no constraint; an explicit flag must agree.
+    if (storage.required !== undefined && question.required !== storage.required) mismatch("required");
+    const mode = question.answerMode === "multi_select" ? "multi" : "single";
+    if (storage.selectionMode !== mode) mismatch("answerMode");
+    if (question.answerMode === "text") {
+      if (storage.options.length !== 1 || !storage.options[0].freeText) mismatch("answerMode");
+    } else {
+      // Text/custom-answer sentinels are storage compatibility, not visible choices.
+      const choices = storage.options.filter((option) => !option.freeText);
+      const canonical = new Map((question.options ?? []).map((option) => [option.id, option.label]));
+      if (choices.length !== canonical.size || choices.some((option) => canonical.get(option.id) !== option.label)) mismatch("options");
+    }
+  }
 });
 
 export const createIssueThreadInteractionSchema = z.discriminatedUnion("kind", [