liquidraverandClaude Opus 5.5
9fc1eaf18a
DESIGN.md is the reconciled high-level design after the 2026-09 restructure: system context, roles, build-time composition, layers and dependency rules (with the known exceptions), threading and event loop, end-to-end flows, cross-cutting concerns and the upstream alignment policy. docs/adr/ holds the nine decision records (ESP32 boot layout, S3 native USB, overlay precedence, BLE privacy, Zephyr main pin, SX126x duty cycle and RX-busy gating, adaptive contention window, storage backend, WiFi companion boards). ARCHITECTURE.md stays the detailed component reference and links both. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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ADR 0004 — BLE privacy: off on nRF/MG24, on for ESP32-S3 (with identity advertising)
Status: accepted (recorded 2026-09-25)
Context
BLE privacy (CONFIG_BT_PRIVACY): keep disabled on nRF / MG24 (they already advertise the identity address,
so both iOS and Android work). ESP32-S3 enables privacy (boards/common/esp32_common.conf) because the
Espressif controller's privacy-OFF Secure-Connections path MIC-fails against iOS (HCI disconnect 0x3d at
encryption start; root cause captured 2026-06-15). Privacy ON keeps the
controller on its working SC path. Android "connect from app" is preserved despite privacy ON because
advertising uses BT_LE_ADV_OPT_USE_IDENTITY (adapters/ble/ZephyrBLE.cpp start_adv) — we expose the stable
identity address, never an RPA.
Decision
Privacy per platform as above; advertising always uses the identity address.
Consequences
Do not drop USE_IDENTITY while ESP32 privacy is on, or Android connect-from-app regresses. If Espressif ever
fixes the privacy-OFF controller path, the ESP32 privacy override can be dropped (USE_IDENTITY stays harmless
everywhere). Never send an SMP Security Request proactively: pairing is triggered reactively via ATT error 0x05
(Apple §55).