Crate dpp_calc 

EU-methodology compliance calculators for Odal Node.

Pure, stateless calculation of regulatory metrics from typed inputs. No I/O, no infrastructure — every function is deterministic and side-effect free.

Placement: these compute EU methodology (cradle-to-gate CO₂e, battery CFB stub) plus a non-regulatory repairability heuristic, so they change when a regulation changes and therefore live in dpp-core under Apache-2.0 — not in the platform. The licensing split: the methodology is open; licensed LCI datasets are never bundled here and are injected at runtime via factor::FactorProvider.

Architecture

┌──────────────────────────────────────────────────────────────────────┐
│  dpp-calc (Apache-2.0, open)                                         │
│                                                                      │
│  co2e::calculate()          — cradle-to-gate, operator-supplied EFs  │
│  repairability::calculate() — non-regulatory heuristic → A–E band    │
│  co2e::cfb::calculate_cfb() — STUB → CalcError::NotImplemented       │
│                                                                      │
│  ruleset_registry           — date-based ruleset resolution          │
│  Ruleset / RegulatoryBasis  — legal citation in every ruleset        │
│  FactorProvider             — runtime injection point for LCI data   │
│  CalculationReceipt         — proof-of-calculation envelope          │
└──────────────────────────────────────────────────────────────────────┘

Every calculator emits a receipt::CalculationReceipt that records the input hash, ruleset id + version, factor dataset version and table hash — ready to be stored in the proof-bound store for notified-body audit.

Adding a new sector calculator

New methodology (algorithm not yet in dpp-calc)

1. Add src/{methodology}/ with four files (see co2e/ or repairability/):
   • mod.rs — pub fn calculate(inputs, ruleset) -> Result<...> + output types
   • parameters.rs — typed input struct (derives Serialize for receipt hashing)
   • thresholds.rs — pub trait {Methodology}Ruleset: Ruleset { ... } + concrete impls
   • golden_vectors.rs — #[cfg(test)] regression tests
2. Every impl RepairabilityRuleset / Co2eRuleset / CfbRuleset must also impl Ruleset and fill regulatory_basis() with the EU citation.
3. Add a resolve_{methodology}() function to ruleset_registry/resolve.rs and a &NewRuleset row to all_rulesets().
4. Write golden vectors, including the all_concrete_rulesets_have_non_empty_regulatory_basis pattern.
5. Register the module in lib.rs.

New product category on an existing methodology

1. Add impl Ruleset + impl {Methodology}Ruleset for the new struct in thresholds.rs. Fill regulatory_basis from the product-specific delegated act.
2. Add a row to the resolver table in ruleset_registry/resolve.rs and to all_rulesets() (one-liner each).
3. Add golden vectors. Run cargo test -p dpp-calc.

Effective dates

How a governing ruleset is selected, why Pending has no date, and the conditional max(floor, entry-into-force + N months) arithmetic that is deliberately not built yet: see docs/architecture/EFFECTIVE-DATES.md.

Pending delegated act (stub)

Use Effectivity::pending(empowerment, adoption_deadline) and regulatory_basis.regulation = "pending — {PEFCR title}".

There is no date sentinel. A pending ruleset has no application date, so it resolves for no date at all and ensure_active_on returns CalcError::RulesetUndetermined naming the instrument being waited on. The type stays compile-visible for future wiring. A far-future from date would assert something the regulation does not say — EU staged obligations are written as “from <date> or N months after entry into force, whichever is the latest”, so until the act lands the date is unknown, not distant.

Superseded ruleset

• Set the ruleset’s Effectivity to closed(from, last_valid_day).
• Set regulatory_basis.superseded_by to the new ruleset’s ID string.
• Keep the row in ruleset_registry — receipts reference rulesets by ID + version, so removing a row makes old receipts unverifiable.

Modules

assessability

Why a metric has a value, or why it does not.

clock

The two dates a compliance computation needs.

co2e

Cradle-to-gate CO₂e calculator and Battery CFB stub.

error

Error type for all calculator operations in dpp-calc.

factor

FactorProvider trait for injecting licensed LCI emission factor datasets at runtime.

receipt

Proof-of-calculation receipt — auditable envelope for every calculator result.

repairability

Simplified repairability heuristic — six-parameter, 0–2 each, A–E band.

repairability_index

The enacted EU repairability index — Regulation (EU) 2023/1669.

ruleset

Ruleset identity and validity period types used across all dpp-calc calculators.

ruleset_registry

Date-based ruleset resolution for all registered methodologies.