GTM API / Search mass-action items

Per-target drill-down of a mass action: one row per target with current_step, the object cursor (object_type / object_sid, on a generative run what the row created) and step_log[], one entry per plan step with status (running / deferred / succeeded / failed / skipped), executor_ref (the key a send step went out under, next to its doubt fields), created_object_sid for steps that minted one, and error_message. The last step_log entry says what failed and why, earlier ones what completed: a failed item keeps the effects of its finished steps (fail-forward), created_object_sid is the cleanup surface. Filter by mass_action_sid, then narrow by status / current_step / wait_reason; object_sid is parent-scoped, so always pair it with mass_action_sid (unpaired it degrades to a full team scan). Sort defaults to position asc (insertion order; position 1 is the canary); page_size 0 returns pagination.total_count alone. No include[] and no counts block; run-level aggregation lives on the parent, mass-actions metrics. Contract: - MCP tool search_mass_action_items, registry package mcp.orchestration/mass_action_items, mount orchestration.mass_actions. - Operation search, response envelope search. - Flags: read only.