fix: settle live steers folded into autonomous cycles (#1185)

#1233 fixed queued prompts folded into task-notification cycles. One
case remains: a steer sent to the active prompt can be folded into an
autonomous cycle, leaving `session/prompt` pending when the result names
only the steer UUID.

Keep queued prompt matching and also match the active turn's steer UUID.
Exclude settled turns and turns held open for background tasks. Preserve
plural UUID precedence.

The six new settlement cases fail on main and pass with the fix; all 11
new tests pass. Build, lint and format checks pass. The full default
suite reports 2,497 passed and 30 skipped with an identical Node binary
at a separate path. At `/usr/bin/node`, it reports 2,496 passed, one
failed and 30 skipped: an unchanged path-normalization test also fails
on main. No test was weakened. No live-provider tests were run.

Co-authored-by: Sean McCullough <sean@mcculloughs.io>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

src/acp-agent.ts

@@ -5089,6 +5089,8 @@ export class ClaudeAcpAgent {
      *  marked as a background result, but it lists the uuids of the prompts it
      *  answered.
      *
+     *  A steer belongs to the live active turn even though it has no queued
+     *  Turn of its own. Its stamped result can answer that turn too.
      *  A turn held open for its background subagents already has its result,
      *  so a result that names it does not answer it. */
     const answersPendingPrompt = (message: {
@@ -5104,8 +5106,15 @@ export class ClaudeAcpAgent {
         answeredPromptUuids = [message.user_message_uuid];
       }
 
+      const activeTurn = session.activeTurn;
+      const liveActiveTurn =
+        activeTurn && !activeTurn.settled && !isHeldOpen(activeTurn) ? activeTurn : undefined;
       for (const promptUuid of answeredPromptUuids) {
-        const turn = findUnsettledTurn(promptUuid);
+        // Keep queued prompt matching, including folded sends with no echo.
+        // Steers qualify only through their live active owner.
+        const turn =
+          findUnsettledTurn(promptUuid) ??
+          (liveActiveTurn?.steeredUuids?.has(promptUuid) ? liveActiveTurn : undefined);
         if (turn === undefined) {
           // Not a prompt of this session, or it was answered already.
           continue;

src/tests/folded-steer.test.ts

@@ -0,0 +1,298 @@
+import { describe, expect, it, vi } from "vitest";
+import { randomUUID } from "node:crypto";
+import { ClaudeAcpAgent, type AcpClient } from "../acp-agent.js";
+import { Pushable } from "../utils.js";
+import {
+  mockSessionState,
+  successfulResultMessage,
+  userEcho,
+  wrapQuery,
+} from "./session-doubles.js";
+
+vi.mock("@anthropic-ai/claude-agent-sdk", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("@anthropic-ai/claude-agent-sdk")>();
+  const refused = () => {
+    throw new Error("Unexpected real SDK call");
+  };
+  return {
+    ...actual,
+    query: vi.fn(refused),
+    getSessionMessages: vi.fn(async () => []),
+    getSubagentMessages: vi.fn(async () => []),
+    listSessions: vi.fn(async () => []),
+    getSessionInfo: vi.fn(async () => undefined),
+    deleteSession: vi.fn(refused),
+    forkSession: vi.fn(refused),
+    importSessionToStore: vi.fn(refused),
+  };
+});
+
+async function untilDone<T>(promise: Promise<T>): Promise<T> {
+  let timer: ReturnType<typeof setTimeout> | undefined;
+  try {
+    return await Promise.race([
+      promise,
+      new Promise<never>((_, reject) => {
+        timer = setTimeout(() => reject(new Error("Prompt did not settle")), 3000);
+      }),
+    ]);
+  } finally {
+    if (timer !== undefined) clearTimeout(timer);
+  }
+}
+
+function createAgent() {
+  const client = { sessionUpdate: async () => {} } as unknown as AcpClient;
+  return new ClaudeAcpAgent(client, { log: () => {}, error: () => {} });
+}
+
+function usage(inputTokens: number, outputTokens: number) {
+  return {
+    input_tokens: inputTokens,
+    output_tokens: outputTokens,
+    cache_read_input_tokens: 0,
+    cache_creation_input_tokens: 0,
+  };
+}
+
+function modelUsage(inputTokens: number, outputTokens: number) {
+  return {
+    "claude-sonnet-4-6": {
+      inputTokens,
+      outputTokens,
+      cacheReadInputTokens: 0,
+      cacheCreationInputTokens: 0,
+      webSearchRequests: 0,
+      costUSD: 0,
+      contextWindow: 200000,
+    },
+  };
+}
+
+function stamp(uuid: string, fields: string) {
+  return {
+    ...(fields !== "plural" ? { user_message_uuid: uuid } : {}),
+    ...(fields !== "singular" ? { user_message_uuids: [uuid] } : {}),
+  };
+}
+
+const idle = { type: "system", subtype: "session_state_changed", state: "idle" };
+
+describe("a steer folded into an autonomous cycle", () => {
+  it.each([
+    ["singular", true],
+    ["plural", true],
+    ["both", true],
+    ["singular", false],
+    ["plural", false],
+    ["both", false],
+  ] as const)("settles from its own %s UUID stamp (echo: %s)", async (fields, echo) => {
+    const agent = createAgent();
+    const input = new Pushable<any>();
+    const echoed = Promise.withResolvers<void>();
+    const interrupted = Promise.withResolvers<void>();
+    const resume = Promise.withResolvers<void>();
+    const processed = Promise.withResolvers<void>();
+    const finish = Promise.withResolvers<void>();
+    async function* messages() {
+      const iter = input[Symbol.asyncIterator]();
+      const { value: original } = await iter.next();
+      yield userEcho(original);
+      echoed.resolve();
+      const { value: steered } = await iter.next();
+      yield successfulResultMessage({
+        origin: { kind: "human" },
+        ...stamp(original.uuid, "both"),
+        queued_turn_count: 1,
+        stop_reason: "tool_use",
+        usage: usage(10, 5),
+        modelUsage: modelUsage(10, 5),
+      });
+      interrupted.resolve();
+      await resume.promise;
+      if (echo) yield userEcho(steered);
+      // Only the steer's UUID is named; it has no queued Turn of its own.
+      yield successfulResultMessage({
+        origin: { kind: "task-notification" },
+        ...stamp(steered.uuid, fields),
+        queued_turn_count: 0,
+        stop_reason: "max_tokens",
+        usage: usage(20, 7),
+        modelUsage: modelUsage(30, 12),
+      });
+      yield idle;
+      processed.resolve();
+      // Stream shutdown must not supply the prompt's response.
+      await finish.promise;
+    }
+    const session = mockSessionState({ input, query: wrapQuery(messages()) });
+    agent.sessions["test-session"] = session;
+    let response: unknown;
+    const prompt = agent
+      .prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "original" }] })
+      .then((value) => (response = value));
+    try {
+      await untilDone(echoed.promise);
+      await expect(
+        agent.steer({
+          sessionId: "test-session",
+          prompt: [{ type: "text", text: "also handle this" }],
+        }),
+      ).resolves.toEqual({ outcome: "injected" });
+      await untilDone(interrupted.promise);
+      expect(response).toBeUndefined();
+      resume.resolve();
+      await untilDone(processed.promise);
+      await untilDone(prompt);
+      const tokenCount = {
+        totalTokens: 42,
+        inputTokens: 30,
+        cachedInputTokens: 0,
+        cachedWriteTokens: 0,
+        outputTokens: 12,
+        reasoningOutputTokens: 0,
+      };
+      expect(response).toEqual({
+        stopReason: "max_tokens",
+        usage: {
+          inputTokens: 30,
+          outputTokens: 12,
+          cachedReadTokens: 0,
+          cachedWriteTokens: 0,
+          totalTokens: 42,
+        },
+        _meta: {
+          quota: {
+            token_count: tokenCount,
+            model_usage: [{ model: "claude-sonnet-4-6", token_count: tokenCount }],
+          },
+        },
+      });
+      expect(session.activeTurn).toBeNull();
+      expect(session.turnQueue).toHaveLength(0);
+      expect(session.owedTrailingIdles).toBe(0);
+    } finally {
+      resume.resolve();
+      finish.resolve();
+      await untilDone(session.consumer);
+      await untilDone(prompt);
+    }
+  });
+
+  it.each(["unrelated", "held", "settled", "plural-unrelated", "plural-empty"] as const)(
+    "does not attribute a result to a steer in the %s state",
+    async (state) => {
+      const agent = createAgent();
+      const input = new Pushable<any>();
+      const echoed = Promise.withResolvers<void>();
+      const processed = Promise.withResolvers<void>();
+      const resume = Promise.withResolvers<void>();
+      const finish = Promise.withResolvers<void>();
+      let response: unknown;
+      let owner: any;
+      let steerUuid = "";
+      const heldOutcome = { stopReason: "end_turn" };
+      async function* messages() {
+        const iter = input[Symbol.asyncIterator]();
+        const { value: original } = await iter.next();
+        yield userEcho(original);
+        echoed.resolve();
+        const { value: steered } = await iter.next();
+        steerUuid = steered.uuid;
+        const session = agent.sessions["test-session"];
+        owner = session.activeTurn;
+        // Constructed defensive states: these do not model normal settlement.
+        if (state === "held") {
+          owner.deferredSettle = heldOutcome;
+          owner.spawnedTaskIds = new Set(["still-running"]);
+          session.liveBackgroundTasks.set("still-running", { isSubagent: true });
+        } else if (state === "settled") {
+          owner.settled = true;
+        }
+        const unrelated = randomUUID();
+        yield successfulResultMessage({
+          origin: { kind: "task-notification" },
+          user_message_uuid: state === "unrelated" ? unrelated : steerUuid,
+          user_message_uuids:
+            state === "plural-empty" ? [] : [state.includes("unrelated") ? unrelated : steerUuid],
+          stop_reason: "refusal",
+          usage: usage(100, 50),
+          modelUsage: modelUsage(100, 50),
+        });
+        processed.resolve();
+        await resume.promise;
+        owner.settled = false;
+        owner.deferredSettle = undefined;
+        owner.spawnedTaskIds = undefined;
+        session.liveBackgroundTasks.clear();
+        yield successfulResultMessage({
+          origin: { kind: "human" },
+          ...stamp(steerUuid, "both"),
+          usage: usage(10, 5),
+        });
+        yield idle; // the excluded autonomous result's trailer
+        yield idle; // the human result's trailer
+        await finish.promise;
+      }
+      const session = mockSessionState({ input, query: wrapQuery(messages()) });
+      agent.sessions["test-session"] = session;
+      const prompt = agent
+        .prompt({ sessionId: "test-session", prompt: [{ type: "text", text: "original" }] })
+        .then((value) => (response = value));
+      try {
+        await untilDone(echoed.promise);
+        await expect(
+          agent.steer({
+            sessionId: "test-session",
+            prompt: [{ type: "text", text: "also handle this" }],
+          }),
+        ).resolves.toEqual({ outcome: "injected" });
+        await untilDone(processed.promise);
+        expect(response).toBeUndefined();
+        expect(session.activeTurn).toBe(owner);
+        expect(session.accumulatedUsage).toEqual({
+          inputTokens: 0,
+          outputTokens: 0,
+          cachedReadTokens: 0,
+          cachedWriteTokens: 0,
+        });
+        expect(session.accumulatedModelUsage).toEqual({});
+        expect(owner.steeredUuids).toEqual(new Set([steerUuid]));
+        expect(owner.steeredEchoes).toEqual(new Set([steerUuid]));
+        expect(owner.steeredSettle).toBeUndefined();
+        if (state === "held") expect(owner.deferredSettle).toBe(heldOutcome);
+        if (state === "settled") expect(owner.settled).toBe(true);
+        resume.resolve();
+        await untilDone(prompt);
+        expect(response).toEqual({
+          stopReason: "end_turn",
+          usage: {
+            inputTokens: 10,
+            outputTokens: 5,
+            cachedReadTokens: 0,
+            cachedWriteTokens: 0,
+            totalTokens: 15,
+          },
+          _meta: {
+            quota: {
+              token_count: {
+                totalTokens: 15,
+                inputTokens: 10,
+                cachedInputTokens: 0,
+                cachedWriteTokens: 0,
+                outputTokens: 5,
+                reasoningOutputTokens: 0,
+              },
+              model_usage: [],
+            },
+          },
+        });
+      } finally {
+        resume.resolve();
+        finish.resolve();
+        await untilDone(session.consumer);
+        await untilDone(prompt);
+      }
+    },
+  );
+});