BLE Protocol Stack

Step 1: Define the protocol contract

1. DEFINE advertising/discovery | connection lifecycle | GATT database | client procedure | notification/indication | caching/versioning | ATT bearer/EATT | L2CAP CoC | interoperability defect.
2. IDENTIFY GAP roles, Link Layer central/peripheral, GATT client/server per procedure, service owner, peer/platform/controller/stack/Core/profile versions, UUID namespace, value schemas, permissions/security levels, cache policy, ATT bearers, L2CAP channels, failure/reconnect behavior, and compatibility matrix.
3. READ references/layers-roles.md, then the current Core 6.2 GAP/GATT/ATT/L2CAP sections it identifies for the change.
4. SEPARATE roles: central/peripheral controls link establishment; client/server controls each GATT procedure. Either connected peer can be client, server, or both.
5. ROUTE Apple platform mechanics to corebluetooth, Android GATT client/platform mechanics to android-ble, Android local GATT server mechanics to android-ble-gatt-server, Android RFCOMM/LE CoC socket mechanics to android-bluetooth-sockets, PHY/DLE/interval/throughput tuning to ble-throughput, and application cryptographic handshakes to noise-protocol.

Completion: roles, discovery/connection flow, logical schema, wire procedures, security/cache/channel ownership, and target matrix are explicit.

Step 2: Model and validate the logical schema