How much of each line item is already claimed by tasks, and by which tasks.

Feeds the picker's inventory breakdown — the pool a new claim is measured against. excludeTaskId leaves the task being edited out of its own sum.

claimants names the holders so a fully-allocated line can say who has the units rather than only that there are none; totals stay a separate key so a caller that only wants the sums is unaffected.

A claimant also carries what it would take to work out WHO LOSES UNITS to a new claim, because that is decided by the allocation queue and not by the totals:

task_id, task_title, work_stream_id, work_stream_title,
project_id, project_title, project_number,   # lineage — project may be null
quantity,                                    # what it asked for
start_date, computed_start,                  # queue key 1 (typed, then engine)
link_created_at, link_id,                    # queue keys 2 and 3
allocated_quantity                           # what it holds today, or null

allocated_quantity is the shop-wide share from the same allocator the truth pass runs, so it agrees with /tasks/material-allocation-shares by construction rather than by coincidence. Unlike the rest of the payload it does NOT honour excludeTaskId: the excluded task still consumes units, so removing it from the split would inflate everybody else's share.

Purely additive — every field the picker read before is untouched and in place.