This page explains Settings › Diagnostics › Performance.
You never need this screen. Nothing on it is a setting, and none of it changes how CHANNEL behaves. It exists because "it didn't arrive" and "it arrived late" have several different causes that look identical from the outside, and these counts tell them apart.
Everything here is counted on this device, held in memory, and never sent anywhere.
The page is the same text Copy for support puts on the clipboard, grouped the same way, and it is in English on every phone because it is written to be read by support. Copy for support is at the top, with the buttons that share the text and reset the counts beside it.
Under DELIVERY, each path has its own lines. saw them counts the times that path reported the other phone reachable; anything short of delivered is a send that failed after that point. The percentage at the end of the line is the share of those that were delivered.
A path that sees the other phone often and delivers rarely is a path whose timeout is too short for your surroundings. A path that never sees them at all is one that is not available here — Bluetooth in a steel building, Wi-Fi Aware on a phone that does not have it.
When Bluetooth is not running, a line under Bluetooth radio at rest says why: Bluetooth not started: switched off for this profile, Bluetooth is off or permission missing, with the time since. On Android, CHANNEL tries to start it again every minute while the reason may have cleared.
A second tick on a message means the other phone said it got it. Read the Receipts line under RECEIPTS on both phones after sending one message:
Counts only. No names, no times, and nothing leaves the phone.
A photo, a video or a voice note travels as many slices, and appears only once every one of them has arrived. Read the Attachments line under ATTACHMENTS on the phone that was meant to receive it:
Carried for others appears on a device that carries sealed mail for other people: how many it took, how many it handed on, and how many tries to hand one on were refused, with the reason for the last one: the relay's answer, no connection, or no way out switched on. A refused envelope stays carried and is tried again.
Encounters counts the meetings with nearby phones in which mail was carried: how many began, how many were refused with the reason for the last one, how many envelopes were received in them, and how many of your own messages a nearby phone took. A meeting held back to keep a single phone from using it up, and a repeat envelope that was not moved again, are counted beside them.
The Filing line under SECURITY AND FILING says which card a message was filed on, and why.
sender disagreed counts the times a message arrived naming a sender this device had filed under a different key. It is nearly always a card here that had gone stale, and reading the message is what corrected it. The number keeps rising because it is a running total, not a list of anything still wrong.
CROSSED CARDS is the one to watch, and it appears only when there is something in it. It names two cards this device could not choose between: the app cannot currently tell which of two contacts you are writing to. When that happens, the conversation itself says so above the message box. Pair again in person with the card you mean, and delete the other.
Cards belong to a profile, not to this device, so the card table at the bottom of the page lists each profile separately with its own identity.
Within a profile, Card and Session should always match, and no two cards should show the same four bytes. Compare a profile's identity here with the card another device holds for it: if they differ, that card is wearing the wrong name.
Last wake-up, under CALLS AND WAKING, is what Apple or Google answered the last time the relay asked them to wake this device. A refusal means messages still arrive when the app looks for them, but nothing wakes it in between. See Waking your device.
Copy for support puts the page on the clipboard as plain text, and the share button beside it hands the same text to another app. It carries the kind of phone and its system version, which millions of phones share, and nothing that identifies you or your particular phone: no name, no contact, no phone number or address, no device name or identifier; a profile's published values appear only as their kinds, and contacts and profiles only by number. Read it before you send it to anybody. On the main Settings page, Copy Diagnostics puts the same text on the clipboard.
The reset button starts the measurement window again. It changes nothing about how messages are sent.
English is the reference text; any translation is a convenience.
CHANNEL