Task Harness

Open, structure, and resume the durable log of a multi-session run: a .claude/binnacle.md file at the root of the run's worktree, created from a bundled template, ignored through the repo's local exclude file, and written as an immutable reverse-chronological changelog with a line-count cursor (read_until_line) so a cold session restores the run with one bounded Read. Invoke when task-planning opens a run, and whenever a fresh session finds a binnacle in its worktree and must resume the run it describes. Session-closing entries are written by the log-binnacle skill, not here.

Write the closing entry of a work session into the run's binnacle (.claude/binnacle.md): insert an immutable entry at the top of the changelog, advance the session checkbox and current_session, update status and last_updated, and recalculate the read_until_line cursor. Invoke when the task titled "invoke log-binnacle" is reached — the explicit last task of every session in a task-harness run — when a resume detects the previous session died without closing and needs a recovery entry, or whenever the user asks to close, log, or checkpoint the current session before a /clear.

Turn an approved plan into a multi-session run: create a dedicated worktree, decompose the work into sessions of letter-group blocks sized by friction, open the binnacle that carries the run's state across /clear boundaries, and register only the current session's tasks with TaskCreate. Invoke this skill immediately when the user gives a substantial request — one that touches 2+ files, involves 3+ sequential steps, requires executing an approved plan, or comes right after exiting plan mode with ExitPlanMode. Trigger on signals like "let's do it", "go ahead and implement", "execute the plan", "make it so", "start working", "implement this", or any multi-part request where the user is clearly kicking off real implementation work. When in doubt about whether the scope is large enough, invoke it — the overhead is small and the structure it provides prevents skipped steps and messy commit history.

User-invoked shortcut to resume a multi-session run from its binnacle: locates .claude/binnacle.md at the current worktree root, delegates to the binnacle skill's resume procedure in full, optionally warms context with read-only explorers when the latest entry points at code it does not explain, and continues the work. Invoked manually as /resume-from-binnacle at the start of a cold session, to avoid retyping the resume prompt every time.