Fix: Send device discovery notifications when contact list is full

[agessaman]

Fix: Send device discovery notifications when contact list is full

Problem

When the contact list reached MAX_CONTACTS, new device discoveries were ignored and the app was not notified. This behavior is particularly frustrating for new users who miss out on mesh discovery because of a full contacts list.

Solution

When the table is full, create a temporary ContactInfo and call onDiscoveredContact() to notify the app, matching manual-add mode behavior and send PUSH_CODE_NEW_ADVERT with the full contact info allowing the Discovery List to continue to populate.

Changes

• BaseChatMesh::onAdvertRecv(): When num_contacts >= MAX_CONTACTS, create a temporary ContactInfo and call onDiscoveredContact() instead of returning early.
• MyMesh::onDiscoveredContact(): Remove check for !isAutoAddEnabled() and send full contact if is_new is true.

Behavior

• Auto-add enabled + table not full: Add contact and notify
• Auto-add enabled + table full: Notify only with temporary ContactInfo using PUSH_CODE_NEW_ADVERT
• Auto-add disabled: Always notify with PUSH_CODE_NEW_ADVERT (existing behavior, unchanged)

Connection checks remain in onDiscoveredContact().

[agessaman]

I just took a look at the potential impacts on meshcore_py for @fdlamotte.

1. Packet parsing: In reader.py (lines 84-112), both CONTACT and PUSH_CODE_NEW_ADVERT packets are parsed identically, and out_path_len = -1 is handled (lines 94-95).
2. Event handling: PUSH_CODE_NEW_ADVERT dispatches EventType.NEW_CONTACT (line 109), which is stored in _pending_contacts. This matches Liam's client pattern.

I don't think there are any code changes necessary to implement.

• No examples directly use NEW_CONTACT events, so no example code breaks.
• The library already distinguishes between permanent contacts (CONTACTS event) which won't be sent after contacts are full and discovered contacts (NEW_CONTACT event) which will continue to fill the discovery list.
• The out_path_len = -1 case is handled correctly.

People writing client code will need to deduplicate NEW_CONTACT events, but I'm guessing that's already implemented to prevent repeated notifications when auto-add is turned off.

[oltaco]

This looks good, I like the refactor. 👌
I just submitted a PR that might supercede it, #1379. I'll look at pinching the refactor!

[oltaco]

I just double checked the logic in my PR and it looks like I already implemented this, you must have telepathic powers or something 😂

MeshCore/src/helpers/BaseChatMesh.cpp

Lines 134 to 139 in b23e622

	from = allocateContactSlot();
	if (from == NULL) {
	ContactInfo ci;
	populateContactFromAdvert(ci, id, parser, timestamp);
	onDiscoveredContact(ci, true, packet->path_len, packet->path);
	onContactsFull();

[agessaman]

Indeed you did. It needed doing, and I'm glad it is getting done. I'll leave this here and close it out when yours gets merged.