feat: add process runner for subagents

src/process-runner.test.ts

@@ -0,0 +1,113 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { EventEmitter } from "node:events";
+import { mkdtemp, readFile, writeFile } from "node:fs/promises";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+import { createRunArtifacts } from "./artifacts.ts";
+import { monitorRun } from "./monitor.ts";
+import { createProcessSingleRunner } from "./process-runner.ts";
+
+class FakeChild extends EventEmitter {}
+
+test("createProcessSingleRunner launches wrapper without tmux and returns monitored result", async () => {
+  const cwd = await mkdtemp(join(tmpdir(), "pi-subagents-process-"));
+  let metaPathSeen = "";
+
+  const runSingleTask = createProcessSingleRunner({
+    createArtifacts: createRunArtifacts,
+    buildWrapperSpawn(metaPath: string) {
+      metaPathSeen = metaPath;
+      return { command: process.execPath, args: ["-e", "process.exit(0)"] };
+    },
+    spawnChild() {
+      const child = new FakeChild() as any;
+      process.nextTick(async () => {
+        const meta = JSON.parse(await readFile(metaPathSeen, "utf8"));
+        await writeFile(
+          meta.resultPath,
+          JSON.stringify(
+            {
+              runId: meta.runId,
+              mode: meta.mode,
+              agent: meta.agent,
+              agentSource: meta.agentSource,
+              task: meta.task,
+              requestedModel: meta.requestedModel,
+              resolvedModel: meta.resolvedModel,
+              sessionPath: meta.sessionPath,
+              exitCode: 0,
+              finalText: "done",
+              stdoutPath: meta.stdoutPath,
+              stderrPath: meta.stderrPath,
+              transcriptPath: meta.transcriptPath,
+              resultPath: meta.resultPath,
+              eventsPath: meta.eventsPath,
+            },
+            null,
+            2,
+          ),
+          "utf8",
+        );
+        child.emit("close", 0);
+      });
+      return child;
+    },
+    monitorRun: (input) => monitorRun({ ...input, pollMs: 1 }),
+  });
+
+  const result = await runSingleTask({
+    cwd,
+    meta: {
+      mode: "single",
+      agent: "scout",
+      agentSource: "builtin",
+      task: "inspect auth",
+      requestedModel: "openai/gpt-5",
+      resolvedModel: "openai/gpt-5",
+    },
+  });
+
+  assert.equal(result.finalText, "done");
+  assert.equal(result.exitCode, 0);
+  assert.match(result.resultPath ?? "", /\.pi\/subagents\/runs\//);
+});
+
+test("createProcessSingleRunner writes error result.json when wrapper launch fails", async () => {
+  const cwd = await mkdtemp(join(tmpdir(), "pi-subagents-process-"));
+
+  const runSingleTask = createProcessSingleRunner({
+    createArtifacts: createRunArtifacts,
+    buildWrapperSpawn() {
+      return { command: process.execPath, args: ["-e", "process.exit(0)"] };
+    },
+    spawnChild() {
+      const child = new FakeChild() as any;
+      process.nextTick(() => {
+        child.emit("error", new Error("spawn boom"));
+      });
+      return child;
+    },
+    monitorRun: (input) => monitorRun({ ...input, pollMs: 1 }),
+  });
+
+  const result = await runSingleTask({
+    cwd,
+    meta: {
+      mode: "single",
+      agent: "scout",
+      agentSource: "builtin",
+      task: "inspect auth",
+      requestedModel: "openai/gpt-5",
+      resolvedModel: "openai/gpt-5",
+    },
+  });
+
+  assert.equal(result.exitCode, 1);
+  assert.equal(result.stopReason, "error");
+  assert.match(result.errorMessage ?? "", /spawn boom/);
+
+  const saved = JSON.parse(await readFile(result.resultPath!, "utf8"));
+  assert.equal(saved.exitCode, 1);
+  assert.match(saved.errorMessage ?? "", /spawn boom/);
+});