chore: import upstream snapshot with attribution

tests/repro/repro_issue363.c

@@ -0,0 +1,72 @@
+/*
+ * repro_issue363.c — Regression guard for bug #363 (both axes now FIXED).
+ *
+ * Issue: #363 — "Linux: cbm_system_info / cbm_default_worker_count don't
+ *               respect cgroup CPU/memory limits"
+ *
+ * Both axes of #363 have shipped; this case is now a permanent GREEN guard:
+ *
+ *   CPU axis — FIXED in v0.8.0 (commit a5a3d1d).
+ *     cbm_detect_cgroup_cpus() reads /sys/fs/cgroup/cpu.max (v2) or
+ *     .../cpu/cpu.cfs_quota_us + .../cpu/cpu.cfs_period_us (v1); the result
+ *     feeds detect_system_linux(). cbm_default_worker_count() also honours the
+ *     CBM_WORKERS env override (commit d952238). Both tested in test_platform.c.
+ *
+ *   Memory axis — FIXED.
+ *     cbm_detect_cgroup_mem() reads /sys/fs/cgroup/memory.max (v2) or
+ *     .../memory/memory.limit_in_bytes (v1); detect_system_linux() applies
+ *     min(cgroup, host). The missing env knob — the "EXACT OPEN GAP" this
+ *     repro was filed for — now exists: cbm_mem_init() reads CBM_MEM_BUDGET_MB
+ *     and routes it through the pure cbm_mem_resolve_budget() (explicit
+ *     override > implicit detection, mirroring CBM_WORKERS).
+ *
+ * IMPORTANT — clamp semantics:
+ *   cbm_mem_resolve_budget() clamps the override to effective (cgroup/host) RAM
+ *   so it can never claim more than the box has. So a *large* override is NOT
+ *   honoured verbatim on a small host — it clamps to total_ram. This guard
+ *   therefore uses a small budget (REPRO363_BUDGET_MB) that is at/below any
+ *   realistic host's RAM, so it is honoured exactly and the assertion is stable
+ *   on every runner. The clamp behaviour itself is unit-tested separately in
+ *   tests/test_mem.c (resolve_budget_override_clamped_to_total).
+ *
+ * NOTE on cbm_mem_init() caching:
+ *   g_budget is initialised once via atomic_compare_exchange_strong, so this
+ *   guard relies on running before any suite that calls cbm_mem_init(); the
+ *   repro runner does not init the budget before this suite.
+ */
+
+#include "test_framework.h"
+#include <foundation/mem.h>
+#include <foundation/compat.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/* Deliberately small so the resolver honours it exactly (never clamps) on any
+ * host — see the clamp-semantics note above. */
+#define REPRO363_BUDGET_MB 128UL
+#define REPRO363_BUDGET_BYTES (REPRO363_BUDGET_MB * 1024UL * 1024UL)
+
+/*
+ * repro_issue363_mem_budget_env_override
+ *
+ * Precondition: CBM_MEM_BUDGET_MB is set before the process's first
+ * cbm_mem_init(). The budget must equal the override (honoured exactly, since
+ * it is below any host's effective RAM), proving the env knob is wired.
+ */
+TEST(repro_issue363_mem_budget_env_override) {
+    cbm_setenv("CBM_MEM_BUDGET_MB", "128", 1);
+
+    cbm_mem_init(0.5);
+
+    size_t budget = cbm_mem_budget();
+
+    cbm_unsetenv("CBM_MEM_BUDGET_MB");
+
+    ASSERT_EQ((long long)budget, (long long)REPRO363_BUDGET_BYTES);
+
+    PASS();
+}
+
+SUITE(repro_issue363) {
+    RUN_TEST(repro_issue363_mem_budget_env_override);
+}