test(server): reproduce checkout RPC timeouts with 200 workspaces

Record the headless Linux slow-request symptom from #7760 without changing production behavior. This is a diagnostic branch; the release-specific event-loop regression and original desktop freeze remain unconfirmed.

Co-authored-by: James Hu <187961+axsuul@users.noreply.github.com>

packages/server/src/server/daemon-e2e/checkout-status-workspace-burst.diagnostic.test.ts

@@ -0,0 +1,104 @@
+import { execFileSync } from "node:child_process";
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { expect, test } from "vitest";
+import { DEFAULT_GIT_PROCESS_POLICY } from "../../utils/git-process-scheduler.js";
+import { DaemonClient } from "../test-utils/daemon-client.js";
+import { createTestPaseoDaemon } from "../test-utils/paseo-daemon.js";
+import {
+  createPersistedProjectRecord,
+  createPersistedWorkspaceRecord,
+} from "../workspace-registry.js";
+
+// Diagnostic for #7760's Linux report. These are small independent checkouts,
+// rather than the reporter's large linked worktrees. No agent turns are needed.
+test("checkout status answers before its client timeout during a 200-workspace observation burst", async () => {
+  // The regular Vitest config raises this cap to avoid fake-timer deadlocks.
+  // This reproduction needs the actual production admission policy.
+  const previousRate = process.env.PASEO_GIT_MAX_PROCESSES_PER_SECOND;
+  process.env.PASEO_GIT_MAX_PROCESSES_PER_SECOND = String(
+    DEFAULT_GIT_PROCESS_POLICY.maxProcessesPerSecond,
+  );
+  const root = mkdtempSync(join(tmpdir(), "paseo-checkout-burst-"));
+  const repo = join(root, "repo");
+  mkdirSync(repo);
+  const git = (cwd: string, args: string[]) => execFileSync("git", args, { cwd, stdio: "pipe" });
+  git(repo, ["init", "-b", "main"]);
+  writeFileSync(join(repo, "a.txt"), "base\n");
+  git(repo, ["add", "."]);
+  git(repo, [
+    "-c",
+    "user.name=Paseo Test",
+    "-c",
+    "user.email=test@example.com",
+    "-c",
+    "commit.gpgsign=false",
+    "commit",
+    "-m",
+    "init",
+  ]);
+  const cwds = Array.from({ length: 200 }, (_, i) => {
+    const cwd = join(root, `repo-${i}`);
+    git(root, ["clone", "--local", "--quiet", repo, cwd]);
+    git(cwd, ["remote", "remove", "origin"]);
+    return cwd;
+  });
+  const registry = join(root, ".paseo", "projects");
+  mkdirSync(registry, { recursive: true });
+  const now = new Date().toISOString();
+  writeFileSync(
+    join(registry, "projects.json"),
+    JSON.stringify(
+      cwds.map((cwd, i) =>
+        createPersistedProjectRecord({
+          projectId: `prj_test_${i}`,
+          rootPath: cwd,
+          kind: "git",
+          displayName: `repo-${i}`,
+          createdAt: now,
+          updatedAt: now,
+        }),
+      ),
+    ),
+  );
+  writeFileSync(
+    join(registry, "workspaces.json"),
+    JSON.stringify(
+      cwds.map((cwd, i) =>
+        createPersistedWorkspaceRecord({
+          workspaceId: `wks_test_${i}`,
+          projectId: `prj_test_${i}`,
+          cwd,
+          kind: "local_checkout",
+          displayName: `repo-${i}`,
+          createdAt: now,
+          updatedAt: now,
+        }),
+      ),
+    ),
+  );
+  const daemon = await createTestPaseoDaemon({
+    paseoHomeRoot: root,
+    cleanup: false,
+    agentClients: {},
+    mcpEnabled: false,
+  });
+  const client = new DaemonClient({
+    url: `ws://127.0.0.1:${daemon.port}/ws`,
+    clientType: "browser",
+  });
+  try {
+    await client.connect();
+    await client.observeEvents(["checkout_status_update"]).ready;
+    const status = await client.getCheckoutStatus(cwds[199]!);
+    expect(status.isGit).toBe(true);
+    expect(status.error).toBeNull();
+  } finally {
+    await client.close();
+    await daemon.close();
+    rmSync(root, { recursive: true, force: true });
+    if (previousRate === undefined) delete process.env.PASEO_GIT_MAX_PROCESSES_PER_SECOND;
+    else process.env.PASEO_GIT_MAX_PROCESSES_PER_SECOND = previousRate;
+  }
+}, 120_000);