Cancellation-token control channel checked at every step boundary lets a
coordinator PAUSE/RESUME/REDIRECT/KILL a running worker mid-task instead of
waiting for the whole (possibly wrong) plan to finish. Bounded purviews
mean no half-committed state to unwind on interrupt. Includes a proof
harness (proof.el, run.sh) comparing a broken non-interruptible worker
against the new one under identical kill/redirect/pause timing.
Distinct from the already-preserved swarm-ccr orchestrator (fan-out/
converge dispatch): this is single-worker interruptibility, a
complementary mechanism, not a duplicate.
bigmerge