fix(gateway): isolate qualification evidence

2026-07-30 15:06:23 +07:00
parent c0aabf2a72
commit b5aaff9e39
10 changed files with 1004 additions and 160 deletions
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+## Context
+
+The qualification driver already reaches the production Apollo-to-QUIC path, but its source shaper reorders jitter even when reorder is disabled, its packet accounting cannot identify unexplained loss, and in-process resource counters include the provider/client driver.
+
+## Goals / Non-Goals
+
+**Goals:**
+
+- Attribute every source unit to one bounded production-path outcome.
+- Keep impairment axes independently configured and observed.
+- Sample CPU, heap, allocation, and goroutine use from the gateway process only.
+- Record measured monotonic-clock overhead.
+
+**Non-Goals:**
+
+- No second simulator, profiling service, production dependency, or expanded impairment matrix.
+- No larger queues or relaxed acceptance limits without measured need.
+
+## Decisions
+
+- Reuse the existing source-boundary shaper, preserve source order unless explicit reorder is enabled, and limit catch-up to one media serialization interval. Record the fixed-seed applied-delay standard deviation separately from the jitter observed after ordered traversal.
+- Assign stable source sequence identifiers and retain per-stage counts so injected loss, provider/FEC drop, queue replacement, QUIC failure, and client miss are disjoint.
+- Reuse the established gateway child-test pattern for the actual gateway server; the Apollo fixture and QUIC client remain in the parent driver. A token-protected loopback test control endpoint starts and stops bounded child-owned recording and returns aggregate stage state.
+- Stream queue, processing, and pacing samples from the production `sendMedia` boundary to child-owned raw evidence. Sample child `RUSAGE_SELF`, Go heap, allocations, and goroutines once per second with independent per-run baselines.
+- Measure clock overhead as the median elapsed time per read across 1,000 batches of 100 monotonic reads and record that method.
+
+## Risks / Trade-offs
+
+- [Ordered release suppresses some delivered jitter] → Retain both the applied fixed-seed delay distribution and the separately observed ordered-traversal jitter.
+- [Stage attribution double-counts a unit] → Record one terminal outcome per source sequence and validate accounting equality.
+- [Process sampling perturbs qualification] → Use bounded low-rate samples and include the sampling method in evidence.