fix(plan): show plan content as markdown in exit prompt, guard empty plan

Author: BYK

packages/opencode/src/tool/plan.ts

@@ -30,12 +30,24 @@ export const PlanExitTool = Tool.define(
       execute: (_params: {}, ctx: Tool.Context) =>
         Effect.gen(function* () {
           const info = yield* session.get(ctx.sessionID)
-          const plan = path.relative(Instance.worktree, Session.plan(info))
+          const abs = Session.plan(info)
+          const plan = path.relative(Instance.worktree, abs)
+          const content = yield* Effect.promise(() =>
+            Bun.file(abs)
+              .text()
+              .catch(() => ""),
+          )
+          if (!content.trim())
+            return {
+              title: "Plan is empty",
+              output: "The plan file is empty. Write the plan first before calling plan_exit.",
+              metadata: {},
+            }
           const answers = yield* question.ask({
             sessionID: ctx.sessionID,
             questions: [
               {
-                question: `Plan at ${plan} is complete. Would you like to switch to the build agent and start implementing?`,
+                question: `Plan at ${plan} is complete. Would you like to switch to the build agent and start implementing?\n\n---\n\n${content}`,
                 header: "Build Agent",
                 custom: false,
                 options: [