feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/core/src/tool/question.ts

@@ -0,0 +1,76 @@
+export * as QuestionTool from "./question"
+
+import { Tool, toolText } from "@opencode-ai/llm"
+import { Effect, Layer, Schema } from "effect"
+import { QuestionV2 } from "../question"
+import { ToolRegistry } from "../tool-registry"
+
+export const name = "question"
+
+export const description = `Use this tool when you need to ask the user questions during execution. This allows you to:
+1. Gather user preferences or requirements
+2. Clarify ambiguous instructions
+3. Get decisions on implementation choices as you work
+4. Offer choices to the user about what direction to take.
+
+Usage notes:
+- When \`custom\` is enabled (default), a "Type your own answer" option is added automatically; don't include "Other" or catch-all options
+- Answers are returned as arrays of labels; set \`multiple: true\` to allow selecting more than one
+- If you recommend a specific option, make that the first option in the list and add "(Recommended)" at the end of the label`
+
+export const Parameters = Schema.Struct({
+  questions: Schema.Array(QuestionV2.Prompt).annotate({ description: "Questions to ask" }),
+})
+
+export const Success = Schema.Struct({
+  answers: Schema.Array(QuestionV2.Answer),
+})
+export type Success = typeof Success.Type
+
+export const toModelOutput = (
+  questions: ReadonlyArray<QuestionV2.Prompt>,
+  answers: ReadonlyArray<QuestionV2.Answer>,
+) => {
+  const formatted = questions
+    .map(
+      (question, index) =>
+        `"${question.question}"="${answers[index]?.length ? answers[index].join(", ") : "Unanswered"}"`,
+    )
+    .join(", ")
+  return `User has answered your questions: ${formatted}. You can now continue with the user's answers in mind.`
+}
+
+const definition = Tool.make({
+  description,
+  parameters: Parameters,
+  success: Success,
+  toModelOutput: ({ parameters, output }) => [
+    toolText({ type: "text", text: toModelOutput(parameters.questions, output.answers) }),
+  ],
+})
+
+export const layer = Layer.effectDiscard(
+  Effect.gen(function* () {
+    const registry = yield* ToolRegistry.Service
+    const question = yield* QuestionV2.Service
+
+    yield* registry.contribute((editor) =>
+      editor.set(name, {
+        tool: definition,
+        execute: ({ parameters, sessionID, source }) =>
+          question
+            .ask({
+              sessionID,
+              questions: parameters.questions,
+              // The registry intentionally leaves source absent until it owns the durable assistant message ID.
+              tool: source?.type === "tool" ? { messageID: source.messageID, callID: source.callID } : undefined,
+            })
+            .pipe(
+              Effect.map((answers) => ({ answers })),
+              // V1 treats a dismissed question as an interrupted tool invocation rather than model-facing text.
+              Effect.orDie,
+            ),
+      }),
+    )
+  }),
+)