[AZ-1133] Cycle 16 closeout — traceability, retro, state

Test-spec sync, doc ripple, retrospective; autodev advances to cycle 17.

Co-authored-by: Cursor <cursoragent@cursor.com>

_docs/06_metrics/retro_2026-06-26_cycle16.md

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+# Retrospective — Cycle 16 (2026-06-26)
+
+**Tasks**: AZ-1133 (perf gate preflight, 1 SP). **1 task, 1 SP, 1 batch.**
+**Mode**: cycle-end. Steps 14–16 **skipped** (shell-harness + docs only; no new attack surface or deploy delta).
+**Previous retro**: `retro_2026-06-26_cycle15.md`
+
+## Implementation Summary
+
+| Metric | Cycle 16 | Δ vs cycle 15 |
+|--------|----------|---------------|
+| Tasks implemented | **1** | unchanged |
+| Total complexity delivered | **1 SP** | unchanged |
+| Blocked tasks | **0** | unchanged |
+| Auto-fix attempts | **0** | unchanged |
+
+## Quality
+
+| Gate | Result |
+|------|--------|
+| Code review | PASS (batch_01_cycle16 — shell + docs) |
+| Step 11 full suite | **PASS** (`run-tests.sh`, 457 unit + integration) |
+| Step 12 traceability | **PASS** — AZ-1133 AC-1..AC-4 rows + Preflight § in `performance-tests.md` |
+| Step 13 docs ripple | **PASS** — `ripple_log_cycle16.md` |
+| Step 14 security | **SKIPPED** (harness-only) |
+| Step 15 perf | **SKIPPED** (preflight is operator guard; PT thresholds unchanged) |
+| Step 16 deploy | **SKIPPED** |
+
+## Cycle 16 delta
+
+- **Perf preflight landed** — Step 15 first-run failure mode (unreachable `API_URL`) now exits **7** with compose-up instructions before PT-01.
+- **Multi-cycle carry-over closed** — cycle 13/14/15 retro Action #1 (perf gate preflight).
+
+## Top 3 Improvement Actions (cycle 17 candidates)
+
+1. **PT-09 shell harness promotion** — optional hardening of inventory perf sub-check (~0.5 SP) — carried from cycle 14
+2. **Full-script AC-2 blackbox** — add a lightweight `scripts/` test or CI doc step that runs preflight-only path without full dotnet build (~0.5 SP)
+3. **Ripple checklist on harness changes** — extend implement batch closure template to always touch `performance-tests.md` when `run-performance-tests.sh` changes (~0 SP process)
+
+## Cycle 16 Verdict
+
+**Successful tooling-hygiene cycle** — perf operator experience improved; full regression green; no production behavior change.