Events

Goose uses EventFormat::Goose. It is run with goose run --output-format stream-json, which emits a line-delimited JSON stream on standard output: each non-empty line is a complete JSON object carrying a top-level type. The harness layer parses that stream and maps each record onto the normalized harness events.

Raw event stream

The stream is made up of four record types:

Goose record	Handling
message	A serialized conversation message whose content is an array of blocks (text, thinking/redactedThinking, toolRequest, toolResponse) processed in order.
notification	Surfaced verbatim as an unknown event rather than parsed from prose.
error	Becomes an error event.
complete	The run boundary. It carries usage (consumed for metrics) and flushes any pending assistant span.

Within a message, assistant text blocks are agent progress and assistant thinking blocks are the model’s reasoning; user text is the echoed prompt and is ignored, and redactedThinking blocks carry no readable text. Goose streams each fragment as cumulative-or-delta records sharing a message id, so fragments of the same kind and id are accumulated into one pending span: a record that restates the pending text replaces it (a cumulative update), and any other same-kind, same-id record is appended (a delta). A pending span is flushed when activity of a different kind or id follows, or when the run completes — so a message’s reasoning is reported just ahead of its agent message.

A toolRequest block is recorded against its call id and resolved when the matching toolResponse arrives; the two are correlated by id. The response’s toolResult.status (success/error) sets the event’s success field. A toolRequest that cannot be parsed becomes an unknown event.

Normalized mapping

Raw	Normalized
assistant text block	agent (accumulated across same-id fragments, then flushed)
assistant thinking block	reasoning (accumulated across same-id fragments, then flushed)
user text, redactedThinking	consumed — no event
toolRequest + matching toolResponse	the tool event for the tool, or unknown
complete	consumed for usage; flushes pending text — no event of its own
error	error
notification	unknown
unrecognized record / block type	unknown

The harness layer does not capture a session id from Goose’s stream, so harness events from a Goose run carry no session ID.

Tool mapping

Goose and MCP servers prefix tool names with an extension id (such as developer__shell); the name is split on __ and the extension prefix is stripped before classification. Tools from the todo extension are consumed as internal session state. The remaining base names map as follows:

Goose tool	Event
read, read_image	read (an image’s path comes from its source field)
write, edit	write
text_editor	read or write, by its command (view/read read; write/create/overwrite/edit/str_replace/insert/move/rename/delete write; anything else unknown)
shell	command, or a recognized file operation
grep, glob	search
list, tree	list
load_skill, skill	skill
todo__*	consumed — internal session state, no event
any other tool	unknown

See Harness Events for the normalized event contract.