feat(provider-muse): native subagents open in their own child threads

apps/server/src/orchestration-v2/testkit/fixtures/index.ts

@@ -58,8 +58,13 @@ import { messageSteeringInput } from "./message_steering/input.ts";
 import { assertPiMessageSteeringOutput } from "./message_steering/pi_output.ts";
 import { MUSE_PERMISSION_DECLINED_FILE, musePermissionInput } from "./muse_permission/input.ts";
 import { assertMusePermissionOutput } from "./muse_permission/output.ts";
+import { museSubagentApprovalInput } from "./muse_subagent_approval/input.ts";
+import { assertMuseSubagentApprovalOutput } from "./muse_subagent_approval/output.ts";
+import { museSubagentInterruptInput } from "./muse_subagent_interrupt/input.ts";
+import { assertMuseSubagentInterruptOutput } from "./muse_subagent_interrupt/output.ts";
 import { museWorkflowInput } from "./muse_workflow/input.ts";
 import { assertMuseWorkflowOutput } from "./muse_workflow/output.ts";
+import { assertMuseSubagentV2Output } from "./subagent_v2/muse_output.ts";
 import { assertMuseMultiTurnOutput } from "./multi_turn/muse_output.ts";
 import { assertMuseTurnInterruptOutput } from "./turn_interrupt/muse_output.ts";
 import { piCompactionInput } from "./pi_compaction/input.ts";
@@ -860,6 +865,12 @@ export const ORCHESTRATOR_REPLAY_FIXTURES: ReadonlyArray<OrchestratorReplayFixtu
         modelSelection: CODEX_MODEL_SELECTION,
         assertOutput: assertSubagentV2Output,
       },
+      {
+        driver: ProviderDriverKind.make("muse"),
+        transcriptFile: new URL("./subagent_v2/muse_transcript.ndjson", import.meta.url),
+        modelSelection: MUSE_MODEL_SELECTION,
+        assertOutput: assertMuseSubagentV2Output,
+      },
     ],
   },
   {
@@ -1227,6 +1238,33 @@ export const ORCHESTRATOR_REPLAY_FIXTURES: ReadonlyArray<OrchestratorReplayFixtu
       },
     ],
   },
+  {
+    name: "muse_subagent_approval",
+    buildInput: museSubagentApprovalInput,
+    providers: [
+      {
+        driver: ProviderDriverKind.make("muse"),
+        transcriptFile: new URL("./muse_subagent_approval/muse_transcript.ndjson", import.meta.url),
+        modelSelection: MUSE_MODEL_SELECTION,
+        assertOutput: assertMuseSubagentApprovalOutput,
+      },
+    ],
+  },
+  {
+    name: "muse_subagent_interrupt",
+    buildInput: museSubagentInterruptInput,
+    providers: [
+      {
+        driver: ProviderDriverKind.make("muse"),
+        transcriptFile: new URL(
+          "./muse_subagent_interrupt/muse_transcript.ndjson",
+          import.meta.url,
+        ),
+        modelSelection: MUSE_MODEL_SELECTION,
+        assertOutput: assertMuseSubagentInterruptOutput,
+      },
+    ],
+  },
   {
     name: "muse_workflow",
     buildInput: museWorkflowInput,

apps/server/src/orchestration-v2/testkit/fixtures/muse_subagent_approval/input.ts

@@ -0,0 +1,15 @@
+import { SUBAGENT_V2_APPROVAL_PROMPT, type OrchestratorFixtureInput } from "../shared.ts";
+
+/**
+ * A Supervised Muse thread spawns a native subagent that runs a shell command.
+ * The subagent's approval is asked in its child thread and approved there.
+ */
+export function museSubagentApprovalInput(): OrchestratorFixtureInput {
+  return {
+    runtimeMode: "approval-required",
+    steps: [
+      { type: "message", text: SUBAGENT_V2_APPROVAL_PROMPT },
+      { type: "approve_next_runtime_request" },
+    ],
+  };
+}

apps/server/src/orchestration-v2/testkit/fixtures/muse_subagent_approval/output.ts

@@ -0,0 +1,56 @@
+import { assert } from "@effect/vitest";
+import type { ProviderReplayTranscript } from "@t3tools/contracts";
+
+import type { OrchestratorV2ScenarioResult } from "../../OrchestratorScenario.ts";
+import { assertSemanticProjectionIntegrity, projectionFor } from "../shared.ts";
+
+/**
+ * A native subagent's approval is asked on the parent thread, as Codex and
+ * OpenCode ask theirs: Muse children have no provider session of their own to
+ * answer from. The answer reaches Muse and the subagent finishes its work.
+ */
+export function assertMuseSubagentApprovalOutput(
+  result: OrchestratorV2ScenarioResult,
+  transcript: ProviderReplayTranscript,
+) {
+  const projection = projectionFor(result, transcript.scenario);
+  assertSemanticProjectionIntegrity(projection);
+  assert.deepEqual(
+    projection.runs.map((run) => run.status),
+    ["completed"],
+  );
+
+  const requests = projection.runtimeRequests;
+  assert.lengthOf(requests, 1);
+  assert.equal(requests[0]?.kind, "command");
+  assert.equal(requests[0]?.status, "resolved");
+  assert.equal(requests[0]?.decision, "accept");
+  const outbound = transcript.entries.flatMap((entry) =>
+    entry.type === "expect_outbound" ? [entry.frame] : [],
+  );
+  assert.isTrue(
+    outbound.some(
+      (frame) =>
+        typeof frame === "object" &&
+        frame !== null &&
+        Reflect.get(frame, "method") === "approval/decide",
+    ),
+    "the answer reaches Muse",
+  );
+
+  assert.lengthOf(projection.subagents, 1);
+  const subagent = projection.subagents[0]!;
+  assert.equal(subagent.status, "completed");
+  assert.match(subagent.result ?? "", /^Written\.?$/u);
+  if (subagent.childThreadId === null) throw new Error("The subagent has no child thread");
+  const child = result.projections.get(subagent.childThreadId);
+  if (child === undefined) throw new Error("The child thread has no projection");
+  assert.lengthOf(child.runtimeRequests, 0);
+  assert.deepEqual(
+    child.messages.map((message) => [message.role, message.text]),
+    [
+      ["user", subagent.prompt],
+      ["assistant", subagent.result],
+    ],
+  );
+}

apps/server/src/orchestration-v2/testkit/fixtures/muse_subagent_interrupt/input.ts

@@ -0,0 +1,14 @@
+import type { OrchestratorFixtureInput } from "../shared.ts";
+
+const MUSE_SUBAGENT_INTERRUPT_PROMPT =
+  "Spawn one subagent whose only task is to run the shell command `sleep 30` and then reply with exactly: Done. Wait for it to finish, then reply with exactly what it said.";
+
+/** Stop while a Muse native subagent is still running. */
+export function museSubagentInterruptInput(): OrchestratorFixtureInput {
+  return {
+    steps: [
+      { type: "message", text: MUSE_SUBAGENT_INTERRUPT_PROMPT },
+      { type: "interrupt", targetRunIndex: 1, waitForTurnItemType: "subagent" },
+    ],
+  };
+}