fix(interactive-subagents): avoid Orca polling fan-out

extensions/interactive-subagents/test/test.ts

@@ -1,6 +1,14 @@
 import { describe, it, before, after, beforeEach } from "node:test";
 import assert from "node:assert/strict";
-import { mkdtempSync, writeFileSync, readFileSync, mkdirSync, rmSync, existsSync } from "node:fs";
+import {
+  chmodSync,
+  existsSync,
+  mkdirSync,
+  mkdtempSync,
+  readFileSync,
+  rmSync,
+  writeFileSync,
+} from "node:fs";
 import { join } from "node:path";
 import { tmpdir } from "node:os";
 import { fileURLToPath } from "node:url";
@@ -32,11 +40,13 @@ import {
 
 import {
   __pollForExitTest__,
+  pollForExit,
   selectMuxBackend,
   shellEscape,
 } from "../pi-extension/subagents/surface.ts";
 import { parseCreatedPane, parseCreatedTab } from "../pi-extension/subagents/herdr.ts";
 import {
+  __orcaTest__,
   parseCreatedSplit,
   parseCreatedTerminal,
   parseReadTail,
@@ -1812,6 +1822,60 @@ describe("subagent-done.ts", () => {
 describe("surface exit signals", () => {
   const { interpretExitSidecar, readCompletionFile } = __pollForExitTest__;
 
+  it("does not poll the terminal while waiting for a filesystem completion signal", async () => {
+    const dir = createTestDir();
+    const completionFile = join(dir, "child.exit-code");
+    let surfaceReads = 0;
+
+    try {
+      const result = await pollForExit(
+        "unused-surface",
+        new AbortController().signal,
+        {
+          interval: 1,
+          completionFile,
+          onTick() {
+            writeFileSync(completionFile, "7\n");
+          },
+        },
+        async () => {
+          surfaceReads += 1;
+          return "__SUBAGENT_DONE_0__";
+        },
+      );
+
+      assert.deepEqual(result, { reason: "sentinel", exitCode: 7 });
+      assert.equal(surfaceReads, 0);
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  it("bounds an asynchronous Orca screen read and kills its CLI process", async () => {
+    const dir = createTestDir();
+    const pidFile = join(dir, "reader.pid");
+    const cli = join(dir, "fake-orca");
+    writeFileSync(
+      cli,
+      `#!/usr/bin/env node\nrequire("node:fs").writeFileSync(${JSON.stringify(pidFile)}, String(process.pid));\nsetInterval(() => {}, 1000);\n`,
+    );
+    chmodSync(cli, 0o755);
+
+    try {
+      await assert.rejects(__orcaTest__.readScreenWithCli(cli, "unused-surface", 5, 500));
+      const pid = Number.parseInt(readFileSync(pidFile, "utf8"), 10);
+      let running = true;
+      try {
+        process.kill(pid, 0);
+      } catch {
+        running = false;
+      }
+      assert.equal(running, false);
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
   it("reads and removes a shell completion file", () => {
     withTempDir((dir) => {
       const completionFile = join(dir, "child.exit-code");