julian
7649b897c4
"ALL 740 / 3h 2m" gave no derivation. explainFee in @parking/shared runs the EXACT computeFee walk with an optional trace collector — one code path, so Σ line items ≡ the amount by construction (golden V1 regression byte-identical; instrumentation changes no fee). Items: contiguous same-price increment runs (time window · N × unit · tier-card name), window-package occurrences, stepped day totals (top-tier repeat flagged), daily-cap clamps as NEGATIVE adjustments, entry grace. /api/tariff/simulate returns `breakdown` (null when settled); the lab's Outcome panel renders the lined table with a rounding note (raw min → billed min at the increment — answers "why does 3h 2m bill as 4h") and a total row. Works against active/historical versions and drafts alike, so a night-package draft can be verified line by line before publish. Largely delivers the wiki's open "composer price preview" item. 4 new engine tests pin the sum invariant + item shapes (97 shared green). Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V