nx_apm_collect_gate.nx

nx_apm_collect_gate.nx -- SOVEREIGN gate for the internal-HTTP APM collector. Spawns real mock daemons (nx_apm_mock, self-terminating) on loopback and proves ac_burst's four verdicts against ground truth -- each test prints its MEASURED numbers (no overclaim: the operator reads the raw stats, not a curated "GREEN"): T1 NEGATIVE CONTROL -- a healthy fast daemon must be GREEN, fully served, nothing flagged. T2 DETECTION -- a daemon that SERIALIZES (300ms/req) must, under 8 concurrent probes, show a stall and max >= ~2400ms = the "tabs don't load" wedge, caught. T3 LIAR-KILL -- an ABSENT daemon (no listener) must be DOWN with oks=0, never GREEN. T4 GRACEFUL DEGRADE -- a daemon slower than the probe timeout must time out (~1s) not hang forever. T5 ARTIFACT-IMMUNITY -- a daemon that sends FAST then HOLDS the socket open (keep-alive/idle) must be GREEN (ttfb fast) with slowclose>0 -- NOT a false wedge. This is THE fix: the live :8791/vroom "20s" was exactly this (ttfb~0, total~20-25s), an artifact. Requires /tmp/nx_apm_mock.sov.elf built first. Per-test reap; no kill primitive needed. license_tier: ORIGINAL