feat: harden errors, recovery, and resource usage

PLANS.md

@@ -823,7 +823,7 @@ If all criteria pass, set this milestone to `DONE`, append its execution record,
 
 ## Milestone 016 — Harden errors, recovery, and resource usage
 
-**Status:** `READY`
+**Status:** `DONE`
 **Depends on:** Milestone 015
 
 ### Objective
@@ -851,11 +851,22 @@ Make the integrated application resilient to malformed traffic, connection churn
 
 If all criteria pass, set this milestone to `DONE`, append its execution record, and change Milestone 017 from `BLOCKED` to `READY`.
 
+### Execution record
+
+- Date: 2026-08-29
+- Board model and revision: ESP32-C6FH4 QFN32, revision v0.2.
+- Toolchain and library versions: PlatformIO Core 6.1.19; `espressif32` 7.0.1; ESP-IDF 6.0.1; `esp_littlefs` 1.20.4.
+- Result: PASS for automated hardening verification; pending on-device soak and recovery confirmation.
+- Evidence: Rejection diagnostics are now saturating and protected against concurrent callback updates. `GET /api/health` includes the platform reset reason alongside uptime, heap, minimum heap, largest free block, connection count, and rejected-input count. Added bounded malformed-traffic coverage that repeatedly exercises all HTTP command parsers and 600 randomized WebSocket frames with open/close churn; invalid traffic produces bounded errors without lifecycle mutation. Existing fixed session, WebSocket hello timeout, delivery failure removal, reconnect/polling, and queue limits remain in effect.
+- Measurements: `make -C test/host run` passed command queue, domain, bot strategy, lifecycle, presenter, HTTP API, synchronization, human-game integration, bot-game integration, and robustness suites. The robustness suite covers 400 malformed HTTP requests, oversized bodies, 600 randomized WebSocket frames, oversized WebSocket frames, and repeated connection-slot reuse. `node --check data/app.js`, gzip integrity checks, and compressed JavaScript syntax checks passed. `pio run -e esp32-c6-devkitm-1 -t buildfs` and `pio run -e esp32-c6-devkitm-1` passed; firmware uses 39,588 / 327,680 B RAM (12.1%) and 1,018,786 / 2,097,152 B flash (48.6%), both within final budget limits.
+- Issues or deviations: No firmware upload, Wi-Fi interruption, 30-minute soak, or live heap/latency measurement was performed. Those remain mandatory physical-device checks before release acceptance.
+- Next action: Milestone 017 is ready. Do not start it unless explicitly requested.
+
 ---
 
 ## Milestone 017 — Execute final MVP acceptance and create the release baseline
 
-**Status:** `BLOCKED`  
+**Status:** `READY`
 **Depends on:** Milestone 016
 
 ### Objective