> ## Documentation Index > Fetch the complete documentation index at: https://docs.asymptotelabs.ai/llms.txt > Use this file to discover all available pages before exploring further. # beacon endpoint fx > Collect endpoint telemetry from fx (vercel-labs/fx) session records ## Command overview `beacon endpoint fx` collects telemetry from [fx](/runtimes/vercel-fx), Vercel Labs' native coding agent, by reading the session records fx commits under `~/.fx/sessions` and converting them into Beacon [endpoint events](/concepts/core-concepts#endpoint-event). ```bash title="Command syntax" theme={null} beacon endpoint fx [command] ``` It is a command rather than an install step because fx has nothing to install into. Every other supported runtime exposes a hook config, a plugin directory, or an OTLP endpoint, so Beacon writes something once and the runtime calls it. fx has none of those: what it has is a durable session log, so collecting from it is an action rather than a configuration. Every event is marked `harness.collection_method=poll`. Beacon sees what a turn did once fx committed it, rather than observing the agent as it works, so nothing here can hold or deny a tool call. Reading is local and offline. Nothing this command does reaches the network. ## Commands | Command | Description | | --------------------------- | ------------------------------------------------------------------------ | | `beacon endpoint fx sync` | Read new fx session records into the runtime log | | `beacon endpoint fx status` | Show fx sessions on this machine and how much of each has been collected | ## Flags Both subcommands accept: | Flag | Description | | ----------------------- | ------------------------------------------------------------------------- | | `--sessions-dir ` | fx session directory. Defaults to `~/.fx/sessions` | | `--state ` | Collector cursor file. Defaults to `~/.beacon/endpoint/state/fx.json` | | `--json` | Print the result as JSON | | `--user` | Use per-user endpoint paths. Enabled by default | | `--system` | Use system endpoint paths. The cursor moves beside the system runtime log | `sync` also accepts: | Flag | Description | | ----------------------- | ------------------------------------------------------------------------ | | `--log-path ` | Runtime JSONL log path. Defaults to the resolved endpoint log | | `--print` | Print mapped events as JSON without writing them or advancing the cursor | | `--watch` | Sweep continuously on `--interval` instead of sweeping once and exiting | | `--interval ` | Sweep interval for `--watch`. Defaults to `1m`, with a 5-second floor | ## Sweeping ```bash title="Sweep once" theme={null} beacon endpoint fx sync ``` ```bash title="Preview without writing anything" theme={null} beacon endpoint fx sync --print ``` `--print` is a dry run in both directions: it neither writes the runtime log nor advances the cursor, so running it twice shows the same events and running it does not quietly consume the work a later real sweep would do. ```bash title="Sweep continuously" theme={null} beacon endpoint fx sync --watch --interval 5m ``` Nothing sweeps on its own. Run `sync` under whatever scheduler the platform already uses, or leave `--watch` running. A sweep prints what it did, and says out loud the two conditions a counter would hide: ```text theme={null} fx sync: 4 sessions, 2 changed, 37 events, 0 errors 1 unreadable line(s) in fx session logs 1 session(s) had a partly written record; it will be read on the next sweep ``` A damaged session log and an empty one produce the same event count, and only one of them is a reason to look at the machine. The summary is reported even when the sweep hit an error, because a sweep that collected nine sessions and failed on the tenth did nine sessions' worth of work. ## Status ```bash title="Show fx sessions and collection progress" theme={null} beacon endpoint fx status ``` ```text theme={null} fx sessions: 2 in /Users/you/.fx/sessions 1788051418424-... collected seq 41/41 /Users/you/src/app 1788139022101-... pending seq 0/12 /Users/you/src/api ``` `collected` means the cursor is level with what fx's own manifest says it has committed, in the same log generation. A session whose manifest cannot be read is reported as pending rather than assumed collected, because it cannot say how far fx has committed. ## Cursor behavior The cursor is what keeps a scheduled sweep from re-appending every session's whole history. It stores both the sequence number and fx's log generation, because fx restarts sequence numbers when it compacts a session log; without the generation a compaction would look like a rewind. | Mode | Default cursor path | | ------ | --------------------------------------------- | | User | `~/.beacon/endpoint/state/fx.json` | | System | `fx-state.json` beside the system runtime log | A sweep reads each session's log only as far as the manifest's committed watermark, so a frame fx is still writing is left for the next sweep rather than counted as corruption. Re-reading is safe: each event's dedup id comes from the record's own coordinates rather than its content, so the same fx record maps to the same event every time. ## Related Telemetry coverage, discovery, and known gaps for the runtime. Check whether fx is detected and how much has been collected.