Module Presence

ArmorLink tracks whether paired modules are online or offline.

Presence is managed by the Gateway and surfaced to the App through events and snapshots.

Activity-Based Detection

Whenever a paired module sends valid traffic to the Gateway, ArmorLink updates the module's last-seen timestamp.

Examples:

• Commands
• Logs
• Telemetry
• Configuration traffic
• Pairing-related messages

A module is considered offline once it remains silent longer than moduleTimeoutMs.

Options

ArmorLinkOptions options;
options.modulePresenceCheckIntervalMs = 5000;
options.moduleTimeoutMs = 900000;

Option	Description
modulePresenceCheckIntervalMs	How often the Gateway checks paired module state.
moduleTimeoutMs	How long a paired module may stay silent before it is considered offline.

App Events

The Gateway emits:

Event	Description
module_presence_snapshot	Full paired-module snapshot sent on connect/request.
module_presence	Online/offline update for one module.
module_unpaired	Module was removed from the Gateway.
module_pairing_required	Module talks to this Gateway but must be paired again.

Example snapshot:

{
  "type": "module_presence_snapshot",
  "pairedModuleCount": 1,
  "modules": [
    {
      "name": "Helmet",
      "type": "Helmet",
      "mac": "E4:B3:23:C4:74:3C",
      "moduleVersion": "1.0",
      "armorLinkVersion": "0.4.0"
    }
  ]
}

Apps should treat the snapshot as authoritative for the connected Gateway and remove local modules that are not present in it.

Runtime Hook

ArmorLink.setModuleTimeoutHook(
    [](const ArmorLinkStoredPairedModule& module, uint32_t silentMs) {
        ArmorLink.warn(String(module.name) + " went offline");
    });

Summary

Presence is Gateway-managed and App-visible. Snapshots are used to keep local UI state aligned with the Gateway's actual paired module list.