refactor(server): share the question card's multi-select answer splitting

OpenCode v2 and OMP both read the question card's comma-joined
multi-select answer back into option labels. Keep that in one helper
next to the providers so the two cannot drift.

Co-authored-by: Grant Ammons <grant@grant.dev>

packages/server/src/server/agent/providers/omp/question-ui.ts

@@ -3,6 +3,7 @@ import type {
   AgentPermissionResponse,
   AgentProvider,
 } from "../../agent-sdk-types.js";
+import { splitMultiSelectAnswer } from "../question-card-answer.js";
 import type { OmpAgentMessage, OmpRuntimeEvent } from "./rpc-types.js";
 
 type UiRequest = Extract<OmpRuntimeEvent, { type: "extension_ui_request" }>;
@@ -176,21 +177,7 @@ function selectedAnswer(
     return labels.includes(answer)
       ? { selected: [answer], custom: null }
       : { selected: [], custom: answer };
-
-  // The shared question UI sends a comma-joined answer in click order. Consume
-  // exact option labels from the front; any remaining text is the Other answer.
-  let remaining = answer;
-  const selected: string[] = [];
-  while (remaining.length > 0) {
-    const label = labels
-      .filter((candidate) => !selected.includes(candidate))
-      .sort((left, right) => right.length - left.length)
-      .find((candidate) => remaining === candidate || remaining.startsWith(`${candidate}, `));
-    if (!label) break;
-    selected.push(label);
-    remaining = remaining === label ? "" : remaining.slice(label.length + 2);
-  }
-  return { selected, custom: remaining || null };
+  return splitMultiSelectAnswer(answer, labels);
 }
 
 /** Owns OMP question mapping and the ask tool's multi-RPC answer sequence. */

packages/server/src/server/agent/providers/opencode/v2/permissions.ts

@@ -7,6 +7,7 @@ import type {
   AgentSessionConfig,
   AgentStreamEvent,
 } from "../../../agent-sdk-types.js";
+import { splitMultiSelectAnswer } from "../../question-card-answer.js";
 
 export class SessionPermissions {
   private readonly pending = new Map<string, AgentPermissionRequest>();
@@ -163,31 +164,10 @@ function multiSelectAnswer(field: MultiSelectField, value: unknown): string[] |
   if (Array.isArray(value) && value.every((item: unknown) => typeof item === "string"))
     return value;
   if (typeof value !== "string") return undefined;
-  const { selected, custom } = splitJoinedLabels(
+  const { selected, custom } = splitMultiSelectAnswer(
     value,
     field.options.map((option) => option.label),
   );
   if (custom === null) return selected;
   return field.custom === true ? [...selected, custom] : undefined;
 }
-
-// The shared question card sends a multi-select answer as one comma-joined string in
-// click order. Consume exact option labels from the front, longest first so a label
-// containing ", " wins over its prefix; any remaining text is the typed answer.
-function splitJoinedLabels(
-  answer: string,
-  labels: string[],
-): { selected: string[]; custom: string | null } {
-  let remaining = answer;
-  const selected: string[] = [];
-  while (remaining.length > 0) {
-    const label = labels
-      .filter((candidate) => !selected.includes(candidate))
-      .sort((left, right) => right.length - left.length)
-      .find((candidate) => remaining === candidate || remaining.startsWith(`${candidate}, `));
-    if (!label) break;
-    selected.push(label);
-    remaining = remaining === label ? "" : remaining.slice(label.length + 2);
-  }
-  return { selected, custom: remaining || null };
-}

packages/server/src/server/agent/providers/question-card-answer.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, test } from "vitest";
+
+import { splitMultiSelectAnswer } from "./question-card-answer.js";
+
+describe("splitMultiSelectAnswer", () => {
+  const labels = ["Delete both", "Delete both, fix code", "Email the user"];
+
+  test("splits checked labels in click order", () => {
+    expect(splitMultiSelectAnswer("Email the user, Delete both", labels)).toEqual({
+      selected: ["Email the user", "Delete both"],
+      custom: null,
+    });
+  });
+
+  test("keeps a label that contains a comma as one selection", () => {
+    expect(splitMultiSelectAnswer("Delete both, fix code, Email the user", labels)).toEqual({
+      selected: ["Delete both, fix code", "Email the user"],
+      custom: null,
+    });
+  });
+
+  test("returns trailing text as the typed answer", () => {
+    expect(splitMultiSelectAnswer("Delete both, Also check the logs", labels)).toEqual({
+      selected: ["Delete both"],
+      custom: "Also check the logs",
+    });
+    expect(splitMultiSelectAnswer("Only typed text", labels)).toEqual({
+      selected: [],
+      custom: "Only typed text",
+    });
+  });
+});

packages/server/src/server/agent/providers/question-card-answer.ts

@@ -0,0 +1,23 @@
+/**
+ * The shared question card sends a multi-select answer as one string: the checked option
+ * labels in click order, then any typed answer, joined with ", ". Consume exact option
+ * labels from the front, longest first so a label containing ", " wins over its prefix;
+ * any remaining text is the typed answer.
+ */
+export function splitMultiSelectAnswer(
+  answer: string,
+  labels: string[],
+): { selected: string[]; custom: string | null } {
+  let remaining = answer;
+  const selected: string[] = [];
+  while (remaining.length > 0) {
+    const label = labels
+      .filter((candidate) => !selected.includes(candidate))
+      .sort((left, right) => right.length - left.length)
+      .find((candidate) => remaining === candidate || remaining.startsWith(`${candidate}, `));
+    if (!label) break;
+    selected.push(label);
+    remaining = remaining === label ? "" : remaining.slice(label.length + 2);
+  }
+  return { selected, custom: remaining || null };
+}