fix(server): offer ACP array enum form fields as multi-select questions

Generic ACP form elicitation only read a property's top-level enum, so a field declared as type array with items.enum became a question with no options and no multiSelect. The mapping now lives in elicitationFormQuestion, which reads items.enum for array fields and marks them multiSelect.

Fixes #30851

Author: HoneyPaptan

packages/provider-acp/src/server/adapter.ts

@@ -1308,6 +1308,39 @@ function elicitationContent(
   return content;
 }
 
+function stringEnum(schema: Record<string, unknown> | undefined): ReadonlyArray<string> {
+  return Array.isArray(schema?.enum)
+    ? schema.enum.filter((value): value is string => typeof value === "string")
+    : [];
+}
+
+export function elicitationFormQuestion(
+  id: string,
+  property: unknown,
+  index: number,
+  message: string,
+): OrchestrationV2UserInputQuestion {
+  const record = unknownRecord(property);
+  const isArray = record?.type === "array";
+  const enumValues = stringEnum(isArray ? unknownRecord(record.items) : record);
+  const options =
+    enumValues.length > 0
+      ? enumValues.map((value) => ({ label: value, description: value }))
+      : record?.type === "boolean"
+        ? [
+            { label: "true", description: "Yes" },
+            { label: "false", description: "No" },
+          ]
+        : [];
+  return {
+    id,
+    header: nonEmptyText(record?.title, `Question ${index + 1}`),
+    question: nonEmptyText(record?.description, message),
+    options,
+    ...(isArray && options.length > 0 ? { multiSelect: true } : {}),
+  };
+}
+
 interface ActiveTextSegment {
   readonly nativeItemId: string;
   readonly startedAt: DateTime.Utc;
@@ -6625,28 +6658,8 @@ export const makeAcpAdapterV2 = Effect.fn("makeAcpAdapterV2")(function* (
                 "sessionId" in params ? params.sessionId : `request:${params.requestId}`;
               const questions =
                 nativeForm?.questions ??
-                Object.entries(properties).map(
-                  ([id, property], index): OrchestrationV2UserInputQuestion => {
-                    const record = unknownRecord(property);
-                    const enumValues = Array.isArray(record?.enum)
-                      ? record.enum.filter((value): value is string => typeof value === "string")
-                      : [];
-                    const options =
-                      enumValues.length > 0
-                        ? enumValues.map((value) => ({ label: value, description: value }))
-                        : record?.type === "boolean"
-                          ? [
-                              { label: "true", description: "Yes" },
-                              { label: "false", description: "No" },
-                            ]
-                          : [];
-                    return {
-                      id,
-                      header: nonEmptyText(record?.title, `Question ${index + 1}`),
-                      question: nonEmptyText(record?.description, params.message),
-                      options,
-                    };
-                  },
+                Object.entries(properties).map(([id, property], index) =>
+                  elicitationFormQuestion(id, property, index, params.message),
                 );
               const userInput = yield* requestUserInputWithAdmission(
                 handlerGeneration,

packages/provider-acp/src/server/elicitationForm.test.ts

@@ -0,0 +1,54 @@
+import { assert, describe, it } from "@effect/vitest";
+
+import { elicitationFormQuestion } from "./adapter.ts";
+
+describe("elicitationFormQuestion", () => {
+  it("offers an array property's items.enum as a multi-select question", () => {
+    const question = elicitationFormQuestion(
+      "answer",
+      { type: "array", items: { type: "string", enum: ["PostgreSQL", "SQLite"] } },
+      0,
+      "Choose databases",
+    );
+    assert.deepStrictEqual(question, {
+      id: "answer",
+      header: "Question 1",
+      question: "Choose databases",
+      options: [
+        { label: "PostgreSQL", description: "PostgreSQL" },
+        { label: "SQLite", description: "SQLite" },
+      ],
+      multiSelect: true,
+    });
+  });
+
+  it("keeps single-choice enums, booleans and free text as before", () => {
+    const single = elicitationFormQuestion("db", { type: "string", enum: ["a", "b"] }, 0, "Pick");
+    assert.deepStrictEqual(single.options, [
+      { label: "a", description: "a" },
+      { label: "b", description: "b" },
+    ]);
+    assert.isUndefined(single.multiSelect);
+    const yesNo = elicitationFormQuestion("ok", { type: "boolean" }, 1, "Continue?");
+    assert.deepStrictEqual(
+      yesNo.options.map((option) => option.label),
+      ["true", "false"],
+    );
+    assert.isUndefined(yesNo.multiSelect);
+    const text = elicitationFormQuestion("name", { type: "string", title: "Name" }, 2, "Name?");
+    assert.deepStrictEqual(text.options, []);
+    assert.strictEqual(text.header, "Name");
+    assert.isUndefined(text.multiSelect);
+  });
+
+  it("leaves an array without enum items as free text", () => {
+    const question = elicitationFormQuestion(
+      "tags",
+      { type: "array", items: { type: "string" } },
+      0,
+      "Tags",
+    );
+    assert.deepStrictEqual(question.options, []);
+    assert.isUndefined(question.multiSelect);
+  });
+});