pikuri-tasks 0.0.4

pikuri-tasks gives a pikuri-core agent an in-memory task list it can use to plan and track multi-step work. A +Pikuri::Tasks::List+ holds the per-Agent state; four tools (+task_create+, +task_in_progress+, +task_completed+, +task_delete+) mutate it via content-as-identifier (no item IDs to hallucinate). +Pikuri::Tasks::Extension+ wires the list and tools onto an +Pikuri::Agent+ via +c.add_extension(...)+ inside the +Agent.new+ block. The list lives in process memory only — nothing is written to disk. Sub-agents do not inherit the parent's list (consistent with the "sub-agents do not inherit extensions" rule).