Mentions

A feed of notifications: who, what, whether you were mentioned. Nothing is ever sent back to the chat, not even a canned reply – there is no way to reply from here, on purpose.

How a message becomes a notification

1. Someone mentions you, or sends you a direct message, in whatever chat client you run in the COMMS tab.
2. That client’s own notification hook runs phosphor mention-hook, piping one JSON object on stdin: {"from": ..., "message": ..., "mention": bool}. It has to return at once and print nothing – most chat clients show any output as an error, which is why mention-hook never does, whatever goes wrong on its end (a crash there is logged, never printed; see troubleshooting).
3. The notification is appended to a small file (~/.local/share/phosphor/mentions.jsonl, trimmed to the last 300) and to the events file the SYS adjutant reads, so it can announce who and what without you looking anywhere. It also reaches you off the deck the same way phosphor notify does: pushed to your phone if [push] is on, spoken if [tts] is on.
4. fleet’s always-on marker loop notices the feed has something unseen and renames the COMMS tab (or whichever tab is named COMMS or runs matterhorn, iamb or gomuks) to COMMS ●N.

5. Tapping that tab, or the marker loop simply seeing a client has arrived there, clears the count – there’s nothing to mark “read” by hand.

You can feed this from anywhere, not just a chat client: a script, a cron job, a CI webhook – anything that can shape a notification as that one JSON object and pipe it in:

echo '{"from": "ci", "message": "nightly build failed", "mention": true}' | phosphor mention-hook

For matterhorn specifically, phosphor mentions --setup does step 2 for you: it writes the hook and points Mattermost’s activityNotifyCommand at it, so from then on every notification your own Mattermost preferences allow (usually mentions and direct messages) lands here without you doing anything per-message.

Reading the feed

phosphor mentions (or + → mentions) lists what came in, newest first:

A notification doesn’t carry which channel it came from – your chat client still owns that; this feed only tells you that something arrived and what it said. j/k (or a tap) move between them; q leaves.

Prepare notes

With prepare set in [mentions] (see profile), pick a notification and press p (or tap “prepare notes”): the command you named gets a briefing prompt on its stdin, and whatever it prints on stdout lands in WORK NOTES (phosphor notes --book work) – only when you actually press it, never automatically. Keep that command read-only, since it’s about to read the notification and act on its own:

prepare = 'cd ~/work-docs && claude -p --disallowedTools Bash Edit Write NotebookEdit WebFetch WebSearch'

The built-in prompt (replace it with your own via prompt in [mentions]) asks whatever you point prepare at to read the folder’s GEMINI.md / AGENTS.md / CLAUDE.md / README first, summarize what’s relevant to the notification, and never reply to anyone – it’s preparing your own reading material, not answering on your behalf. The message and whatever documents that command reads go to that assistant’s own provider, same as any other call you make to it.