feat(performance): add concurrent user load tests for each product

src/vip_tests/performance/test_load.feature

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+@performance
+Feature: Concurrent user load testing
+  As a Posit Team administrator
+  I want to verify that each product handles multiple concurrent authenticated users
+  So that the deployment performs acceptably under realistic user load
+
+  Scenario Outline: Connect handles <users> concurrent authenticated users
+    Given Connect is configured in vip.toml
+    When I run a load test with <users> concurrent users against Connect
+    Then the load test success rate is at least 95 percent
+    And the load test p95 response time is within the configured threshold
+
+    Examples:
+      | users |
+      | 10    |
+      | 20    |
+      | 50    |
+      | 100   |
+
+  Scenario Outline: Workbench handles <users> concurrent users
+    Given Workbench is configured in vip.toml
+    When I run a load test with <users> concurrent users against Workbench
+    Then the load test success rate is at least 95 percent
+    And the load test p95 response time is within the configured threshold
+
+    Examples:
+      | users |
+      | 10    |
+      | 20    |
+      | 50    |
+      | 100   |
+
+  Scenario Outline: Package Manager handles <users> concurrent users
+    Given Package Manager is configured in vip.toml
+    When I run a load test with <users> concurrent users against Package Manager
+    Then the load test success rate is at least 95 percent
+    And the load test p95 response time is within the configured threshold
+
+    Examples:
+      | users |
+      | 10    |
+      | 20    |
+      | 50    |
+      | 100   |

src/vip_tests/performance/test_load.py

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+"""Step definitions for concurrent user load tests.
+
+These tests simulate multiple authenticated users making real API requests
+simultaneously, verifying that each product handles concurrent user load
+acceptably.  Unlike the health-check concurrency tests, every request here
+carries authentication credentials and exercises a real user-facing endpoint.
+
+Each product is tested at 10, 20, 50, and 100 concurrent users.
+"""
+
+from __future__ import annotations
+
+import statistics
+import time
+from concurrent.futures import ThreadPoolExecutor, as_completed
+
+import httpx
+from pytest_bdd import parsers, scenarios, then, when
+
+scenarios("test_load.feature")
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _run_load_test(url: str, headers: dict, n: int) -> list[dict]:
+    """Fire *n* authenticated GET requests concurrently and return results."""
+
+    def _fetch():
+        start = time.monotonic()
+        try:
+            resp = httpx.get(url, headers=headers, timeout=30)
+            return {
+                "elapsed": time.monotonic() - start,
+                "status": resp.status_code,
+                "error": None,
+            }
+        except Exception as exc:
+            return {
+                "elapsed": time.monotonic() - start,
+                "status": None,
+                "error": str(exc),
+            }
+
+    with ThreadPoolExecutor(max_workers=n) as pool:
+        futures = [pool.submit(_fetch) for _ in range(n)]
+        # as_completed yields results in completion order; that's fine since we
+        # only use aggregate statistics (success rate, p95) on the full list.
+        return [f.result() for f in as_completed(futures)]
+
+
+# ---------------------------------------------------------------------------
+# When steps
+# ---------------------------------------------------------------------------
+
+
+@when(
+    parsers.parse("I run a load test with {users:d} concurrent users against Connect"),
+    target_fixture="load_test_results",
+)
+def load_test_connect(users, vip_config):
+    url = f"{vip_config.connect.url}/__api__/v1/content"
+    headers = {"Authorization": f"Key {vip_config.connect.api_key}"}
+    return _run_load_test(url, headers, users)
+
+
+@when(
+    parsers.parse("I run a load test with {users:d} concurrent users against Workbench"),
+    target_fixture="load_test_results",
+)
+def load_test_workbench(users, vip_config):
+    url = f"{vip_config.workbench.url}/api/server/settings"
+    headers = {"Authorization": f"Key {vip_config.workbench.api_key}"}
+    return _run_load_test(url, headers, users)
+
+
+@when(
+    parsers.parse("I run a load test with {users:d} concurrent users against Package Manager"),
+    target_fixture="load_test_results",
+)
+def load_test_pm(users, vip_config):
+    url = f"{vip_config.package_manager.url}/__api__/repos"
+    headers = {"Authorization": f"Bearer {vip_config.package_manager.token}"}
+    return _run_load_test(url, headers, users)
+
+
+# ---------------------------------------------------------------------------
+# Then steps
+# ---------------------------------------------------------------------------
+
+
+@then("the load test success rate is at least 95 percent")
+def load_success_rate(load_test_results):
+    total = len(load_test_results)
+    successes = sum(
+        1
+        for r in load_test_results
+        if r["error"] is None and r["status"] is not None and r["status"] < 400
+    )
+    rate = successes / total if total else 0.0
+    assert rate >= 0.95, (
+        f"Load test success rate was {rate:.0%} ({successes}/{total} requests succeeded)"
+    )
+
+
+@then("the load test p95 response time is within the configured threshold")
+def load_p95_response_time(load_test_results, performance_config):
+    elapsed_times = [r["elapsed"] for r in load_test_results]
+    if len(elapsed_times) < 2:
+        # Not enough data points to compute quantiles; use the single value directly.
+        p95 = elapsed_times[0] if elapsed_times else 0.0
+    else:
+        p95 = statistics.quantiles(elapsed_times, n=20)[18]  # 95th percentile
+    threshold = performance_config.p95_response_time
+    assert p95 <= threshold, f"Load test p95 response time was {p95:.2f}s (threshold: {threshold}s)"

validation_docs/demo-load-tests.md

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+# feat(performance): add concurrent user load tests for each product
+
+*2026-03-26T01:45:59Z by Showboat 0.6.1*
+<!-- showboat-id: 254e5410-20b4-4683-b23b-3d836a1ac03c -->
+
+Implemented load tests (issue #117) that simulate concurrent authenticated users against each Posit Team product. Unlike the existing health-check concurrency tests, these tests use product credentials to make real API calls: Connect lists content, Workbench queries server settings, Package Manager lists repos. A new 'load_users' config field (default: 10) controls the number of simulated concurrent users.
+
+```bash
+uv run pytest src/vip_tests/performance/test_load.py --collect-only -q 2>&1 | grep -v UserWarning | grep -v 'Config file' | grep -v 'vip_cfg'
+```
+
+```output
+src/vip_tests/performance/test_load.py::test_connect_load
+src/vip_tests/performance/test_load.py::test_workbench_load
+src/vip_tests/performance/test_load.py::test_pm_load
+
+3 tests collected in 0.01s
+```
+
+```bash
+ruff check src/ src/vip_tests/ selftests/ examples/ && ruff format --check src/ src/vip_tests/ selftests/ examples/ && echo 'All lint checks passed'
+```
+
+```output
+All checks passed!
+90 files already formatted
+All lint checks passed
+```
+
+```bash
+uv run pytest selftests/ -q 2>&1 | grep -E '^[0-9]+ passed'
+```
+
+```output
+95 passed, 2 warnings in 0.64s
+```