EdgeSummary

The parent-facing view of one edge — everything a parent needs to schedule a child, and deliberately nothing more. It exposes how much entitlement was issued down the edge, how much was returned, and how much service was spent through it; the child's queues, identities, placement, and leaf receipts are simply not in this projection. Information hiding here is a hard interface boundary, not a convention (design §4.5).

spent is the total service charged through the edge — the sum of service charged where the edge is a path's final edge and where it is a strict prefix.

Every figure is an effective value: the grow-only base counter plus any relocation recorded against it (see EntitlementLedger's "relocation counters"). So an edge that received a re-homed generation reports the credit it now carries, and one whose generation was moved away reports itself drained — without any counter ever having been decremented.

The projection is a merge homomorphism: because the ledger merges per-edge, componentwise, reading one edge's summary from a merged ledger equals merging the two edges' summaries (design §10.8).