feat(agent): ship cloud agent logs to PostHog Logs via OTEL

[pauldambra]

Problem

The cloud AgentServer (the process that runs each task in a sandbox) shipped no telemetry to PostHog — its logs only went to stdout and S3. When something goes wrong with a cloud run (e.g. the recent Slack reports), there's no way to query what happened by run_id / task_id. The OtelLogWriter and otelTransport config existed but were never wired to anything.

This makes the desktop's existing pattern (logs → PostHog Logs via OTEL, indexed by service/run) work for the cloud agent too.

Changes

• OtelLogWriter.emitLog(level, scope, message, data) — maps the agent log level to an OTEL severity and stores the scope as a log.scope attribute, mirroring the desktop electron-log OTEL transport. Adds service.version to the resource attributes and defaults the endpoint to /i/v1/logs (matches desktop + the existing OtelTransportConfig; the old /i/v1/agent-logs default was never used).
• AgentServer routes every server log line through one onLog choke point that emits to OTEL and still mirrors to the SSE console stream; flushes on fatal error and shuts down on stop.
• New optional POSTHOG_OTEL_LOGS_HOST / POSTHOG_OTEL_LOGS_API_KEY / POSTHOG_OTEL_LOGS_PATH env vars (plumbed via bin.ts → AgentServerConfig.otelLogs).

Export is disabled (no-op) unless the sandbox injects the host + key — same behavior as the desktop transport. This is deliberate: the sandbox only has the customer's API URL + personal key, so exporting there would dump customer task logs into customer projects (and a personal key may not even authorize log ingest). A follow-up on the infra side needs to inject a dedicated PostHog-internal logs host + ingest key to turn this on.

Scope note: this is logs-only. Errors land in PostHog Logs as ERROR-severity records; wiring exceptions into the dedicated Error Tracking product (posthog-node) is a deliberate follow-up.

How did you test this?

• pnpm --filter @posthog/agent typecheck — passes.
• pnpm --filter @posthog/agent test otel-log-writer — 5/5 pass (added tests for emitLog severity/scope/body mapping and the /i/v1/logs default endpoint).
• biome check on all changed files — clean.
• Note: agent-server.test.ts has 55 pre-existing failures in this environment (msw beforeAll cascade) — identical on a clean main checkout, unrelated to this change.

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

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Created with PostHog Code from a Slack thread

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 08c21cf.}

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 1
packages/agent/src/otel-log-writer.test.ts:49-72
**Non-parameterised severity/body tests**

The two new `emitLog` tests only exercise `warn` (with data) and `error` (without data), leaving `debug` and `info` untested. The team's convention is to prefer parameterised tests: an `it.each` over all four levels (`debug`/`info`/`warn`/`error`) would cover the mapping table exhaustively in a single block, and a second `it.each` for the body-formatting cases (data present vs. absent) would remove the duplication between the two tests.

_{Reviews (1): Last reviewed commit: "feat(agent): ship cloud agent logs to Po..." | Re-trigger Greptile}