Work Package
A work package is the lowest-level node of a WBS — the smallest unit at which cost and duration are estimated and progress is measured.
Where decomposition stops
A WBS does not decompose forever. It stops where a single owner can be named, effort can be estimated, and "done" can be judged. That last node is the work package. The 8/80 rule — between 8 and 80 hours — is a common starting heuristic, not a law.
Why it matters
Progress, schedule, and cost all aggregate from here. A parent's progress is the weighted sum of its work packages. When "backend 60% done" feels untrustworthy, the usual cause is a work package too large to see inside. Split it into "payment API implementation" and "payment API unit tests," and the 60% suddenly has evidence.
Common misconceptions
A work package is not a personal task. It is a management unit; the team can run the actual to-dos beneath it however it likes. The reverse confusion also happens: treating every node as a work package. A node with children is a summary — its progress is computed, never typed in.
wbsgantt accepts progress input only on leaf nodes and rolls parents up as weighted sums automatically.