community-plugins/claude-companion/PROTOCOL.md

The Pulse Protocol

An agent-agnostic contract for driving the pulse bar widget (and everything downstream of it: the presence orb, tooltips, claude.pulse subscribers). The widget knows nothing about Claude Code — it consumes events and an optional telemetry payload over noctalia's plugin IPC. Any coding agent that can run a shell command on its lifecycle hooks (gemini-cli, codex, opencode, aider, a CI job, a cron script) can light up the same bar dot.

Two adapters ship in hooks/:

Adapter	For	Telemetry
pulse.py	Claude Code (reads hook JSON on stdin, parses the session transcript)	live token burn, O(delta)
pulse-emit	anything else (plain POSIX sh, args only)	whatever you pass, or none

Transport

noctalia msg plugin <target> all <event> [payload]

• <target> is the plugin dispatch id: <plugin-id>:<widget-entry> — lowcache/claude-companion:pulse for this install. Adapters must treat it as configurable (pulse-emit reads $PULSE_TARGET).
• all addresses every monitor's widget instance. (focused or a bare connector errors when the widget sits on multiple bars.)
• [payload] is a single positional token — noctalia's msg CLI splits on whitespace, so the payload must be space-free. That's why it's a CSV, not JSON.
• Fire-and-forget. The dispatch returns ok: dispatched N or an error string; adapters ignore both (see the fail-open contract below).

Event vocabulary

Eight events. Priority decides which session the bar shows when several are active; "resting" matters for the default-slot rule below.

Event	Meaning	Priority	Resting
needs_attention	agent is blocked on the human (permission prompt, question)	6	no
error	hard failure	5	yes
tool_start	executing a tool / command	4	no
turn_start	thinking — a turn has begun	3	no
text	streaming a response	3	no
turn_end	turn finished — output ready for the human	2	yes
idle	session alive, nothing happening	1	yes
session_end	session is over — retires its slot	—	—

Unknown events render as idle-with-the-event-kept-as-state-word; stick to the vocabulary. Glyph, accent color, and breath tempo are widget-side concerns (see VISUAL in pulse.luau) — the protocol only fixes the semantics.

Payload

model,in,out,cacheCreate,cacheRead,session

• session (field 6) is the only field that changes behavior: it keys the per-session slot, so every event from the same agent session must carry the same short id (Claude's adapter uses the first - segment of the session UUID; any stable [A-Za-z0-9_-]+ token works).
• model is a display string; use ? when unknown.
• Token fields are lifetime-cumulative for the session, not per-turn deltas. The widget displays input as in + cacheCreate (full-rate work) and shows cacheRead separately. All-zero telemetry is fine — the burn line is simply omitted (model of ? or zero in+out hides it).
• No commas or whitespace inside fields.

Minimum viable adapter: fire bare events with just a session id — ?,0,0,0,0,<sid>. State tracking, urgency priority, multi-session tooltip all work; you only lose the burn readout.

Session semantics (what the widget guarantees)

• One slot per session id; re-sending updates the slot in place.
• The bar renders the most urgent state across all live slots (priority table above); the tooltip lists every session, most recent first, with a Σ burn total.
• session_end retires the slot. Nothing else does — a real session may sit at idle or turn_end indefinitely and stays listed.
• Payload-less events (no CSV at all — e.g. a manual noctalia msg plugin … all needs_attention poke from a terminal) land in a single shared default slot. To keep CLI pokes from leaving a phantom session, any resting event (idle, turn_end, error) retires the default slot instead of updating it. Consequence for adapters: always send a session id; the default slot is a test surface, not a home.

Adapter contract

1. Fail-open, always. Exit 0 no matter what — noctalia offline, binary missing, malformed input. An adapter runs inside an agent's hook path and must never block or error the agent. Swallow stdout/stderr, cap the dispatch with a timeout (~3 s).
2. Tag everything with the session id (see above).
3. Send cumulative telemetry or none — don't send per-turn deltas.
4. Don't invent events; map your agent's lifecycle onto the eight above.

Lifecycle mapping guide

The Claude Code mapping (from hooks/settings.snippet.json) doubles as the template for any agent:

Agent moment	Event
session starts / process launches	idle
prompt submitted / turn begins	turn_start
about to run a tool or shell command	tool_start
tool finished, agent resumes thinking	turn_start
response streaming to the user	text
waiting on permission / a question for the human	needs_attention
turn complete, output delivered	turn_end
unrecoverable failure	error
session exits (however it exits)	session_end

If your agent only exposes a subset (say, just "done" notifications), map what you have — a session that only ever sends turn_end/session_end still renders correctly.

The generic emitter

hooks/pulse-emit <event> [session] [model] [in] [out] [cacheCreate] [cacheRead]

POSIX sh, no dependencies beyond noctalia on PATH. Omitted fields default to ?/0; omitting session sends a bare (default-slot) event. Env: PULSE_TARGET overrides the dispatch id, PULSE_DRYRUN=1 prints the command instead of running it. Examples:

pulse-emit turn_start mysess                 # state only
pulse-emit turn_end mysess gpt-5 12000 800   # with burn figures
pulse-emit session_end mysess                # retire the slot
long_build && pulse-emit needs_attention ci  # non-agent uses work too

Downstream: the claude.pulse state mirror

The widget is the single aggregator; subscribers (the orb, or any future surface) never parse events themselves. On every event — never from the animation timer — it publishes a rollup snapshot to noctalia shared state under claude.pulse:

{ state = <most-urgent event name>,   -- "idle" when no sessions
  count = <live session count>,
  model = <model or "?">,             -- single-session only
  tin   = <in + cacheCreate>,         -- one session's, or the Σ across all
  tout  = <output tokens>,
  cr    = <cacheRead; 0 when count > 1> }

Desktop widgets receive it via noctalia.state.watch("claude.pulse", cb); bar widgets must poll state.get (watch doesn't fire on bars in noctalia 5.0.0).

Deployment invariant

The aggregator lives in the pulse bar widget — bar widgets only run when placed on a bar. If pulse isn't in a bar layout, every event is silently dropped and all subscribers freeze. Noctalia 5.0.0 has no headless plugin entry kind, so "pulse on a bar" is a hard install requirement.