fix(2): plausible install overlay — assert /api/health subsystems, not / (auth_controller 500s under headless DISABLE_AUTH; / is not a valid readiness probe)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/plausible/test_install.py

@@ -1,13 +1,32 @@
-"""plausible — INSTALL overlay (Phase 1d): reuse generic serving, then assert the SPA shell serves."""
+"""plausible — INSTALL overlay (Phase 1d): reuse generic serving, then assert plausible's own
+/api/health reports BOTH datastores + the sites_cache as ready.
+
+We do NOT probe `/`: under the headless CI config (DISABLE_AUTH=true, no user) plausible's `/`
+auth_controller 500s (it tries to render a dashboard for a non-existent session/user), so `/` is not
+a valid readiness signal. /api/health is plausible's dedicated readiness endpoint and is a STRONGER
+assertion than a bare status code — it confirms the postgres metadata store, the ClickHouse events
+store, and the in-memory sites_cache are all reachable, which is exactly what "installed and serving"
+means for an analytics app."""
 
 import os
 import sys
 
 sys.path.insert(0, os.path.join(os.path.dirname(__file__), "..", "..", "runner"))
-from harness import generic, lifecycle  # noqa: E402
+from harness import generic  # noqa: E402
+from harness import http as harness_http  # noqa: E402
 
 
 def test_serving(live_app, meta):
     generic.assert_serving(live_app, meta)
-    status = lifecycle.http_get(live_app, "/")
+
-    assert status in (200, 301, 302), f"expected 2xx/3xx from {live_app}, got {status}"
+    # plausible-specific readiness: /api/health -> 200 with every subsystem "ok".
+    status, body = harness_http.retry_http_get(
+        f"https://{live_app}/api/health", expect_status=(200,), max_wait=60, interval=3
+    )
+    assert status == 200, f"/api/health on {live_app} returned HTTP {status} (expected 200)"
+    assert isinstance(body, dict), f"/api/health body is not JSON object: {body!r}"
+    for subsystem in ("clickhouse", "postgres", "sites_cache"):
+        assert body.get(subsystem) == "ok", (
+            f"/api/health subsystem {subsystem!r} = {body.get(subsystem)!r} (expected 'ok'); "
+            f"full body: {body!r}"
+        )