What
SDK host integrations can now emit custom telemetry events into Claude Code's OTLP pipeline using a host.* namespace. The system includes rate limiting and deduplication of error messages to avoid log spam.
Details
- Events must follow the naming pattern
host.<lowercase.dotted.name> - Attributes must use
snake_casekeys with string values - Payload is validated and rejected if it uses reserved namespaces (
claude_code.*) or has invalid shapes - Rate cap: 240 tokens, refilling over time
- Error categories:
bad_envelope,bad_event_name,bad_attributes_shape,too_many_attributes,bad_attribute_key,bad_attribute_value,payload_too_large,emit_failed
Evidence
OTLP routing implementation (search for "host OTLP event dropped", "host OTLP event route error", "host OTLP event emit failed")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.