mizu 0.1.0

Initial release.

• mizu_channel(): lock-free SPSC channels between R processes — or between R and a Python peer — over POSIX shared memory or Win32 file mappings, with sentinel outcomes for a full ring, timeout, close, or peer death.
• mizu_pool(): work-stealing task pools over spawned workers — mizu_submit() / mizu_collect(), batch submission, mizu_collect_any() / mizu_collect_all(), worker retirement and respawn, nested submission, and classed remote errors.
• mizu_map(): a parallel map — streaming and prepared maps, .template output areas with a zero-copy .collect = "view", and reproducible per-element random streams (.seed).
• Zero-copy vectors and data frames — received as ALTREP views, and a view sent on again crosses by reference.
• Zero-copy Arrow interchange — 'arrow' tables and record batches travel without copying, converting back with mizu_as_arrow().
• Python interop — channels and pools mix with Python processes running pymizu: mizu_py_launcher() spawns peers and workers, mizu_call() task specs drive them, and data frames cross with full type fidelity.
• Event-driven async — mizu_recv_async(), mizu_recv_handler(), mizu_collect_async(), and as.promise() methods for channels, tasks, and maps over later and promises, ready for Shiny.
• Agent skill — an agent skill for AI coding assistants ships in the installed package at skills/mizu, picked up automatically by btw and similar tools.
• Housekeeping — mizu_prune() reclaims shared memory orphaned by dead processes; mizu_pool_dump() introspects a running or hung pool.