A buffer is four pointers dividing one memory range into three slices: PAST (consumed), DATA (live), and IDLE (free). Feeding appends to DATA out of IDLE; draining consumes DATA into PAST; each move grows the adjoining slice, so a buffer tracks its own fill level and no length ever travels beside it. A buffer owns its backing memory — heap, mmap, arena, or stack — and the verb that created it decides who frees it. Pass a buffer down the call stack by pointer; never copy one.
buf[0..3] bound PAST [0,1), DATA [1,2), and IDLE [2,3). Reads and writes move the inner borders, so the buffer always knows what is live and what is free.
u8bData / u8bDataC, the free span with u8bIdle; sizes via u8bDataLen / u8bIdleLen.u8bFeed / u8bFeed1; clear with u8bReset; trim the DATA end with u8bShed.A buffer's backing comes from exactly one source, and you release it with the matching verb. Provenance lives in the caller's head, not the buffer's type — match create to release at every site.
u8bAllocate ↔ u8bFree (heap); u8bMap ↔ u8bUnMap (mmap, files).u8bAcquire from an arena ↔ arena rewind (no per-buffer free); a_pad ↔ scope exit (stack).A buffer can dispense slices to other code, LIFO along the call tree. This removed most need for malloc: build records in place, then rewind to reclaim them all at once.
u8aMark / u8aRewind bracket a borrow; u8bAcquire rents a whole sub-buffer for the duration.a_lign then a_cquire to build incrementally, a_ren for a one-shot copy.