feat(random): multi-theme groundwork, locked reroll export parity, duplicate export fix, expanded diagnostics and test coverage

code/tests/test_random_performance_p95.py

@@ -0,0 +1,63 @@
+from __future__ import annotations
+
+import os
+from typing import List
+from fastapi.testclient import TestClient
+
+"""Lightweight performance smoke test for Random Modes.
+
+Runs a small number of builds (SURPRISE_COUNT + THEMED_COUNT) using the frozen
+CSV test dataset and asserts that the p95 elapsed_ms is under the configured
+threshold (default 1000ms) unless PERF_SKIP=1 is set.
+
+This is intentionally lenient and should not be treated as a microbenchmark; it
+serves as a regression guard for accidental O(N^2) style slowdowns.
+"""
+
+SURPRISE_COUNT = int(os.getenv("PERF_SURPRISE_COUNT", "15"))
+THEMED_COUNT = int(os.getenv("PERF_THEMED_COUNT", "15"))
+THRESHOLD_MS = int(os.getenv("PERF_P95_THRESHOLD_MS", "1000"))
+SKIP = os.getenv("PERF_SKIP") == "1"
+THEME = os.getenv("PERF_SAMPLE_THEME", "Tokens")
+
+
+def _elapsed(diag: dict) -> int:
+    try:
+        return int(diag.get("elapsed_ms") or 0)
+    except Exception:
+        return 0
+
+
+def test_random_performance_p95(monkeypatch):  # pragma: no cover - performance heuristic
+    if SKIP:
+        return  # allow opt-out in CI or constrained environments
+
+    monkeypatch.setenv("RANDOM_MODES", "1")
+    monkeypatch.setenv("CSV_FILES_DIR", os.path.join("csv_files", "testdata"))
+    from code.web.app import app
+    client = TestClient(app)
+
+    samples: List[int] = []
+
+    # Surprise (no theme)
+    for i in range(SURPRISE_COUNT):
+        r = client.post("/api/random_full_build", json={"seed": 10000 + i})
+        assert r.status_code == 200, r.text
+        samples.append(_elapsed(r.json().get("diagnostics") or {}))
+
+    # Themed
+    for i in range(THEMED_COUNT):
+        r = client.post("/api/random_full_build", json={"seed": 20000 + i, "theme": THEME})
+        assert r.status_code == 200, r.text
+        samples.append(_elapsed(r.json().get("diagnostics") or {}))
+
+    # Basic sanity: no zeros for all entries (some builds may be extremely fast; allow zeros but not all)
+    assert len(samples) == SURPRISE_COUNT + THEMED_COUNT
+    if all(s == 0 for s in samples):  # degenerate path
+        return
+
+    # p95
+    sorted_samples = sorted(samples)
+    idx = max(0, int(round(0.95 * (len(sorted_samples) - 1))))
+    p95 = sorted_samples[idx]
+    assert p95 < THRESHOLD_MS, f"p95 {p95}ms exceeds threshold {THRESHOLD_MS}ms (samples={samples})"