Carry-forward slack let a file spend what the files ABOVE it left on the
table. Nothing held back what was promised BELOW it. The whole-file BUY arm
has always refused that trade (`owedBelow`); the cluster path read `headroom`
— what is left before the hard ceiling — instead of what is still owed, so
`fileBudget` and `SPINE_CEILING` could pay a 1.5x overshoot out of another
file's reservation.
`fundedHeadroom` is the same inequality in the units the cluster path spends
in: source PLUS the per-section overhead each unreached file will charge.
Floored at the file's own reservation — a kept promise is not a displacement —
and it is <= `headroom` by construction, so it is the only bound the three
render sites need. The skeleton path's `bodyCap` takes it too.
Measured on `__tests__/fixtures/displacement-ts` (a 4-stage pipeline padded
past 500 files, where the 24K envelope genuinely saturates the 24.4K render
ceiling):
before ingest.ts emitted 9,301 on a 6,289 spendable, then lost the whole
section to the final ceiling — 0 delivered. types.ts and sink.ts
skipped `budget-whole-file`. 3 of 6 admitted files delivered.
after ingest.ts bounded to the 4,913 actually free. 6 of 6 delivered,
envelope 14,908 -> 22,066.
The self-query allocation fixture flips back to PASS with it, on a clean full
rebuild of this repo's index (CG-33). Its `afterCG30` verdict blamed an
over-RESERVED incidental file; the reservation was identical in both arms —
the file was over-SPENDING. Recorded honestly in `afterCG31`.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Colby McHenry
089dcc276f