arthai-marketplace

/marker

Drop a timeline marker into the current session for later A/B comparison.

Synopsis

/marker "<label>"

When to use it

Annotating meaningful moments during an A/B experiment — “starting refactor”, “bug repro confirmed”, “baseline recorded” — so the Arth dashboard can display them in the compare view
Bookmarking a point in a long session you’ll want to find later on the timeline
Not for: configuring telemetry itself — that’s /otel-setup

Quickstart

/marker "starting refactor"

What you’ll see: marker recorded: starting refactor — the marker is attached to the current session’s timeline. If the Arth engine isn’t reachable, you’ll see marker queued (engine unreachable): starting refactor instead and the marker is saved locally.

Examples

/marker "starting refactor"      # annotate the start of an experiment arm
/marker "baseline recorded"      # mark the comparison point
/marker "bug repro confirmed"    # pin the moment a hypothesis was verified

What it does

Reads the current Claude Code session ID to identify which session the marker belongs to.
Captures a nanosecond-precision timestamp.
Sends {label, timestamp_ns, session_id} to the Arth engine’s markers API.
If the engine is unreachable, appends the marker to a local fallback file (/tmp/claude-agents-otel/<session>/markers.jsonl) instead — markers are never lost, and the skill never blocks your session.

Each invocation appends a new marker — running the same label twice records two distinct markers, so you can mark repeated checkpoints (e.g. each retry of an experiment) without overwriting earlier ones. The whole operation is inline shell with no agent spawns, so it adds effectively zero cost or latency to your session.

Output & artifacts

A timeline marker on your session in the Arth dashboard — see Arth Intelligence for how markers appear in the session compare view
Fallback file /tmp/claude-agents-otel/<session>/markers.jsonl when the engine is unreachable (append-only)

Troubleshooting

Problem	Fix
`no active session — run inside Claude Code`	The skill needs a live session ID; invoke `/marker` from within a Claude Code session
`usage: /marker "<label>"`	A label is required — quote it if it contains spaces
`marker queued (engine unreachable): <label>`	The Arth engine isn’t responding; the marker was saved locally. Check the engine is running (default `http://localhost:3333`, override with `ARTH_BASE_URL`)

Arth Intelligence — the dashboard where markers show up in A/B compare views
/otel-setup — configure the observability pipeline that feeds the dashboard