Phase 5 of PLAN-IO-UNIFY retired the bespoke fiber-task API (Task/go/wait/cancel)
and re-homed race onto *Future. Prepend SUPERSEDED banners to the three historical
planning docs (PLAN-FIBERS, CHECKPOINT-FIBERS, PLAN-RACE) pointing readers to
PLAN-IO-UNIFY for the current design, noting that the Scheduler engine primitives
+ the race type-machinery they document remain accurate. Bodies kept as the
historical record. Completes the plan's 'update roadmap/checkpoints' item.
Verified by parallel agents: a completeness pass (no retired API in compilable
code; sched.sx surface fully retired; migrated examples meaningful; readme on the
unified API) and an adversarial memory-safety pass over the heap reclamation (no
UAF/double-free; await/worker orderings, cancel timings, 8-way double-free+deinit,
blocking impl all reclaim cleanly with exact values).
Plan the `race` async deliverable (roadmap A1): a structured first-wins over
the M:1 `Task` layer, returning a comptime-synthesized tagged-union mirroring
the input named tuple's labels. Identifies the one net-new compiler primitive
needed — `pointee($P: Type) -> Type` (project `*Task(A)` → `A`); everything else
(tuple reflection, union synthesis, the suspending runtime) is already in place.
Issue 0196: a named-tuple type ALIAS (`NT :: Tuple(a: i64, b: bool)`) loses its
structure — field access and reflection both fail on the alias, while the inline
and `$T`-type-parameter forms work. Not on the race critical path (race reflects
a tuple type parameter), filed for tracking.
