GrowthBook for feature flags, first-party event logging via OpenTelemetry, Datadog for metrics. PII handling enforced at compile time via a never type trick. MCP tool names redacted. File paths NEVER logged.
/api/event_logging/batch. Dynamic sampling via tengu_event_sampling_config. Failed events → ~/.claude/telemetry/ JSONL with quadratic backoff. Retries without auth on 401.CLAUDE_AI_INFERENCE_SCOPE OAuth.Type-level enforcement: AnalyticsMetadata_I_VERIFIED_THIS_IS_NOT_CODE_OR_FILEPATHS = never — compile error if you pass unchecked data. Impossible to accidentally log PII.
MCP tool names → 'mcp_tool' (redacted — reveals user-specific MCP config). Built-in tool names always logged.
File paths NEVER logged. Disabled in: test env, 3P cloud, "no-telemetry" privacy level.