Remote comms: Cross-incarnation wake detection

[sirtimid]

Problem

The current wake detector (installWakeDetector in @metamask/kernel-utils) only works within a single running process. If the kernel restarts while the system was asleep, we don't detect the time discontinuity and don't reset reconnection backoffs, causing unnecessary delays.

Expected Behavior

• Store last known timestamp in persistent storage on shutdown
• On kernel startup, compare stored timestamp with current time
• If gap exceeds threshold (e.g., > 1 hour), treat as wake event and reset all reconnection backoffs
• Complement the existing runtime wake detector

Implementation

Files to Modify

File	Changes
platform/transport.ts	Check timestamp on initTransport() startup, reset backoffs if needed
platform/reconnection.ts	Use existing resetAllBackoffs() method
kernel/remote-comms.ts	Persist timestamp on stop, pass to transport
Kernel store	Add lastNetworkActivityTimestamp storage

Approach

1. Add timestamp storage to kernel store

   • New key: lastNetworkActivityTimestamp
   • Write timestamp periodically during operation (e.g., every 5 minutes)
   • Write timestamp on initTransport stop

2. Check timestamp on startup (in initTransport or initRemoteComms)

   • Read lastNetworkActivityTimestamp from store
   • Compare with current time
   • If gap > threshold (configurable, default 1 hour), call reconnectionManager.resetAllBackoffs()

3. Handle edge cases

   • Clock changes / timezone issues
   • First startup (no previous timestamp)
   • Timestamp in the future (clock was adjusted backward)

Acceptance Criteria

• Last timestamp stored on shutdown
• Timestamp updated periodically during operation
• Time discontinuity detected on startup
• Backoffs reset when discontinuity exceeds threshold
• Works alongside runtime wake detector (installWakeDetector)
• Unit tests verify cross-restart detection
• Handles clock adjustment edge cases gracefully