Claude Code Telemetry v0.0.15

Fixed

• Headless runs (claude -p) emitted nothing at all. The hook was registered only on Stop with async: true, and Claude Code registers an async Stop hook but exits before spawning it in headless mode — verified with a probe hook that never executed once, while the same hook registered synchronously ran and received its full payload. Since headless is how another harness drives Claude Code, every non-interactive session was invisible. The installer now also registers a synchronous SessionEnd hook, which does fire there. Stop stays async, so interactive turns are unaffected. SessionEnd additionally fires on interactive quit and on Ctrl-C, so it catches a final turn whose async Stop hook died with the process; only SIGKILL escapes both. The two never double-count — emission is incremental behind a byte offset and a state lock. Both hand their work to a detached worker (detached: true, so setsid moves it out of the session's process group), which keeps the synchronous SessionEnd from delaying session teardown: 0.03s rather than the 0.32s an npx-resolved inline run costs. LATITUDE_CLAUDE_CODE_DETACH=0 forces the inline path. The SessionEnd entry carries an explicit timeout, because Claude Code kills those hooks on a shared ~1.5s budget that a cold npx resolve can exceed on its own. Existing installs need install re-run to pick up the SessionEnd entry.

Added

• Cross-harness trace correlation. When another harness launches Claude Code — a Hermes tool call, a CI job, a subprocess agent — it can hand over its active span through the standard TRACEPARENT variable. The hook then joins that trace instead of deriving one from sessionId:turnNumber, and parents its turns on the supplied span, so a Claude Code session appears nested under the tool call that launched it rather than beside it. LATITUDE_SESSION_ID joins the parent's Latitude session and LATITUDE_PROJECT keeps both halves in one project (ingest is project-scoped, so a mismatch would split the trace with no error). LATITUDE_TRACEPARENT takes precedence for setups where TRACEPARENT already belongs to something else, and LATITUDE_CLAUDE_CODE_INHERIT_CONTEXT=0 opts out. A session launched on its own is unaffected: with no valid header the hook generates ids exactly as before, and a malformed header is ignored rather than failing the turn. Claude's own session id stays available as claude_code.session.id. Joining is capped per session so one long-lived session cannot grow a trace it does not own without bound. Contract: dev-docs/trace-correlation.md.