fix(opencode): fail task when child turn ends with an orphaned interrupted tool

packages/opencode/src/tool/task.ts

@@ -196,7 +196,24 @@ export const TaskTool = Tool.define(
  agent: next.name,
  parts,
  })
- return result.parts.findLast((item) => item.type === "text")?.text ?? ""
+ const text = result.parts.findLast((item) => item.type === "text")?.text ?? ""
+ // A severed stream ends the child turn without failing it: cleanup()
+ // marks the never-executed tool_use error/interrupted and the run loop
+ // exits, so the child's mid-work narration would otherwise be returned
+ // as a completed result. Fail the task so the parent knows the work is
+ // unfinished instead of trusting the truncated text.
+ const orphan = result.parts.find(
+ (part): part is SessionV1.ToolPart =>
+ part.type === "tool" && part.state.status === "error" && part.state.metadata?.interrupted === true,
+ )
+ if (orphan) {
+ return yield* Effect.fail(
+ new Error(
+ `Subagent was interrupted mid-turn: its "${orphan.tool}" tool call was cut off before executing, so the task did not finish. Re-run the task to complete it. Partial output before the interruption:\n${text}`,
+ ),
+ )
+ }
+ return text
  })
 
  const inject = Effect.fn("TaskTool.injectBackgroundResult")(function* (

packages/opencode/test/tool/task.test.ts

@@ -3,7 +3,7 @@ import { SessionV1 } from "@opencode-ai/core/v1/session"
 import { Database } from "@opencode-ai/core/database/database"
 import { LayerNode } from "@opencode-ai/core/effect/layer-node"
 import { SessionProjector } from "@opencode-ai/core/session/projector"
-import { Deferred, Effect, Exit, Fiber, Layer } from "effect"
+import { Cause, Deferred, Effect, Exit, Fiber, Layer } from "effect"
 import { Agent } from "../../src/agent/agent"
 import { BackgroundJob } from "@/background/job"
 import { EventV2Bridge } from "@/event-v2-bridge"
@@ -255,6 +255,64 @@ describe("tool.task", () => {
  }),
  )
 
+ it.instance("execute fails when the child turn ends with an orphaned interrupted tool", () =>
+ Effect.gen(function* () {
+ const { chat, assistant } = yield* seed()
+ const tool = yield* TaskTool
+ const def = yield* tool.init()
+ const promptOps: TaskPromptOps = {
+ cancel: () => Effect.void,
+ resolvePromptParts: (template) => Effect.succeed([{ type: "text" as const, text: template }]),
+ prompt: (input) =>
+ Effect.sync(() => {
+ const message = reply(input, "Let me compose the file.")
+ message.parts.push({
+ id: PartID.ascending(),
+ messageID: message.info.id,
+ sessionID: input.sessionID,
+ type: "tool",
+ callID: "call_orphan",
+ tool: "write",
+ state: {
+ status: "error",
+ error: "Tool execution aborted",
+ input: {},
+ metadata: { interrupted: true },
+ time: { start: Date.now(), end: Date.now() },
+ },
+ })
+ return message
+ }),
+ }
+
+ const exit = yield* def
+ .execute(
+ {
+ description: "write file",
+ prompt: "write the briefing file",
+ subagent_type: "general",
+ },
+ {
+ sessionID: chat.id,
+ messageID: assistant.id,
+ agent: "build",
+ abort: new AbortController().signal,
+ extra: { promptOps },
+ messages: [],
+ metadata: () => Effect.void,
+ ask: () => Effect.void,
+ },
+ )
+ .pipe(Effect.exit)
+
+ expect(Exit.isFailure(exit)).toBe(true)
+ const rendered = Exit.isFailure(exit) ? Cause.pretty(exit.cause) : ""
+ expect(rendered).toContain("interrupted mid-turn")
+ expect(rendered).toContain('"write" tool call')
+ expect(rendered).toContain("Let me compose the file.")
+ }),
+ )
+
  it.instance("execute asks by default and skips checks when bypassed", () =>
  Effect.gen(function* () {
  const { chat, assistant } = yield* seed()