Preserve active subagents across reload

test/integration/subagent-lifecycle.test.ts

@@ -30,6 +30,7 @@ import {
   uniqueId,
   trackTempFile,
   readScreen,
+  sendCommand,
   PI_TIMEOUT,
   type TestEnv,
 } from "./harness.ts";
@@ -103,6 +104,57 @@ for (const backend of backends) {
       }
     });
 
+    // ── Reload preservation ──
+
+    it("keeps a running subagent and fresh tool wrappers across parent extension reload", async () => {
+      const id = uniqueId();
+      const startedFile = `/tmp/pi-integ-reload-start-${id}.txt`;
+      const completedFile = `/tmp/pi-integ-reload-done-${id}.txt`;
+      const followupFile = `/tmp/pi-integ-reload-followup-${id}.txt`;
+      trackTempFile(env, startedFile);
+      trackTempFile(env, completedFile);
+      trackTempFile(env, followupFile);
+
+      const surface = createTrackedSurface(env, `reload-${id}`);
+      await sleep(1000);
+
+      const task = [
+        `Call the subagent tool once with these EXACT parameters:`,
+        `  name: "Reload-${id}"`,
+        `  agent: "test-echo"`,
+        `  task: "Run: echo 'START_${id}' > '${startedFile}'; sleep 10; echo 'DONE_${id}' > '${completedFile}'"`,
+        `Do not run the command yourself.`,
+        `After that subagent result arrives, call the subagent tool once more with these EXACT parameters:`,
+        `  name: "Reload-followup-${id}"`,
+        `  agent: "test-echo"`,
+        `  task: "Write 'FOLLOWUP_${id}' to '${followupFile}'"`,
+        `After the second subagent result arrives, say RELOAD_SURVIVED_${id}.`,
+      ].join("\n");
+
+      startPi(surface, env.dir, task);
+      await waitForFile(startedFile, PI_TIMEOUT, /START_/);
+
+      sendCommand(surface, "/reload");
+
+      const completed = await waitForFile(completedFile, PI_TIMEOUT, /DONE_/);
+      assert.ok(completed.includes(`DONE_${id}`), "child should finish after parent reload");
+      const followup = await waitForFile(followupFile, PI_TIMEOUT, /FOLLOWUP_/);
+      assert.ok(
+        followup.includes(`FOLLOWUP_${id}`),
+        "the result-triggered turn should spawn through the fresh tool wrapper",
+      );
+
+      const resultMarker = `RELOAD_SURVIVED_${id}`;
+      const responseLine = new RegExp(`^ ${resultMarker}\\s*$`, "m");
+      const screen = await waitForScreen(surface, responseLine, PI_TIMEOUT, 300);
+      assert.equal(
+        screen.match(new RegExp(`^ ${resultMarker}\\s*$`, "gm"))?.length,
+        1,
+        "the fresh runtime should receive the completion exactly once",
+      );
+      assert.doesNotMatch(screen, /Subagent cancelled|ctx is stale after session replacement or reload/i);
+    });
+
     // ── In-progress activity snapshots ──
 
     it("keeps a long active tool call from surfacing false stalled status", async () => {