`todo` NEVER takes a turn of its own: emit it in the same response as your next real tool call (parallel tool calls), `init` beside the first read or action, `done`/`start` beside the next action or check. A response whose only call is `todo` wastes a full model round trip.
Tasks identified by verbatim content, NEVER generated IDs (task-1). Unique, stable task/phase names; lost text: view, NEVER guess.
`append` requires `items`; omitted `phase` uses the in-progress task's phase, else the first pending task's phase, else the last phase, else a new `Tasks` phase. Supply `phase` to target another phase; an empty name is invalid.
Before work, init for 3+ steps, requested task sets, or new instructions. MUST list EVERY user item separately (phased/numbered/bulleted/N); NEVER omit or remember leftovers.
After successful mutation: no active means earliest pending starts (phase order); multiple active means only earliest stays. Blocked NEVER starts automatically; unblock returns pending. Done out of order may rewind pointer but NEVER reopen completed. Mark done immediately; follow phase order.
External waits (user/agent/service): block with optional reason suppresses stop reminder, starts next pending. Unblock when actionable; append a clearing task for agent-actionable blocker.