LangWatch from a coding session

LangWatch stores the traces your application and your coding agent emit. The langwatch CLI reads them back. Every lookup below is read-only; the one command that writes anything is langwatch login, which stores credentials on this machine.

Check the CLI is there and signed in

langwatch --version
langwatch whoami

whoami prints the identity langwatch login persisted. If it reports nobody, run langwatch login and let the user complete it in the browser. Do not guess credentials.

Find a trace

Search the last 24 hours by default. Widen with --start-date / --end-date.

langwatch trace search -q "checkout agent" --limit 10 -o json

Useful flags: --limit <n>, --origin <origins> (comma-separated, e.g. application,evaluation,simulation).

Read one trace

langwatch trace get <traceId> -o json

For a coding-agent trace, the transcript is the readable form: what the agent did, in order.

langwatch trace transcript <traceId>

Add -o json to either when you want to parse the result rather than read it.

Read one coding-agent session

langwatch session events <sessionId>

Lists the session's model calls, compactions, rate limits and tool runs in time order. --kinds model_call,compaction narrows it.

How sessions get captured

langwatch ingest hook <tool> is the command a coding agent runs at the start and end of a session. It reports the repository, branch and worktree the session is working in, so the agent's traces can be joined to the code they touched. This plugin ships that hook, so an installed plugin needs nothing on PATH for the capture to happen.

Nothing here sends the user's code anywhere. The hook reports repository identity, not file contents.

When a command fails

Read the error. A missing trace id, an expired session and a self-hosted endpoint the CLI was never pointed at all fail differently, and the CLI says which. Do not retry a failed read in a loop.