feat(rules): model the Art. 8(1) declaration duty

[LKSNDRTMLKV]

Item 2 of the six left open by the citation audit. Art. 8(1) is a separate obligation from the Art. 8(2)/(3) minimums already modelled, with its own date ladder and its own granularity.

Two ladders, not one

	Duty	Dates
Art. 8(1)	Document the actual shares, no minimum	18 Aug 2028 (industrial > 2 kWh / EV / SLI), 18 Aug 2033 (LMT)
Art. 8(2)/(3)	Meet minimum shares	18 Aug 2031, 18 Aug 2036

A battery can owe the declaration without yet owing a minimum. Conflating them would report a shortfall against a duty that does not exist yet.

The date is conditional, and that changes the answer

Unlike 8(2)/(3), which state their dates outright, Art. 8(1) applies from the floor "or 24 months after the date of entry into force of the delegated act …, whichever is the latest" — and that act (due 18 Aug 2026) is unadopted.

So art8_declaration_duty_for returns three outcomes rather than a boolean:

• NotYetDue below the floor — certain, because the real date can only be the floor or later. This is the part that remains knowable while the act is pending.
• Undetermined on or after the floor, naming the empowerment being waited on. Reporting "due" here would assert a date the regulation does not set.
• NotCovered outside scope.

This is the EFFECTIVE-DATES.md §4 principle applied to a concrete rule without building the full arithmetic: the floor is a lower bound, so a lower bound is what we answer with.

A share without its year is not the declaration

Art. 8(1) requires the shares "for each battery model per year and per manufacturing plant". The model carried a bare percentage — an unattributed number that no reader can tie to a production run.

Schema v2.3.0 adds recycledContentReportingYear to pair with the existing manufacturingPlace, and the battery plugin flags shares declared without it. Same principle already applied to the carbon-footprint class (needs its ruleset) and state of health (needs its parameter set): a number without its provenance is not a declaration.

Disclosure

Verified, no change needed: Annex XIII point 1(e) makes Art. 8(1) documentation public passport content, and the recycled-content fields correctly fall through to the public default.

Verification

just check green: 818 tests, plugin suites included. just build-plugins green.

Eight new tests, including one asserting the two ladders stay independent — a battery placed on the market in 2029 is past the declaration floor but years short of the minimums.

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 18 complexity · 2 duplication

Metric	Results
Complexity	18
Duplication	2

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AI Reviewer: first review requested successfully. AI can make mistakes. Always validate suggestions.

_{TIP This summary will be updated as you push new changes.}

[codacy-production]

Pull Request Overview

The PR successfully models the core state machine for Art. 8(1) declaration duties (NotYetDue, Undetermined, NotCovered), but there is a significant implementation gap in the battery plugin's validation logic. While the documentation and regulatory notes correctly identify that a declaration must be anchored to both a reporting year and a manufacturing plant, the current implementation only checks for the presence of the reporting year. This renders the validation insufficient for full Art. 8(1) compliance.

Codacy analysis indicates the PR is up to standards, though it identified code duplication between the benchmark suite and the domain test support. Beyond the validation logic gap, the remaining findings are primarily nits regarding string literal formatting and missing structural type-checking for the new schema field. These issues should be resolved to ensure the reliability of the declaration duty reporting.

About this PR

• The valid_battery() function in benches/src/validation.rs is a duplicate of sample_battery_data() in crates/dpp-domain/src/test_support.rs. This increases maintenance overhead as changes to the battery schema now require manual updates in multiple locations. Consider exposing the test support utilities via a test-support feature flag for reuse in benchmarks.

1 comment outside of the diff

benches/src/validation.rs

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This test data setup is duplicated from crates/dpp-domain/src/test_support.rs. Refactoring this into a shared utility would eliminate the need for manual synchronization across crates.

Test suggestions

• art8_declaration_duty_for returns NotYetDue for dates preceding the category floor
• art8_declaration_duty_for returns Undetermined for dates on or after the floor while the delegated act is unadopted
• LMT batteries correctly trigger the 2033 duty floor instead of the 2028 floor
• Battery plugin emits a 'reporting_year_missing' warning when recycled content shares are present but the year is null
• Battery plugin remains silent if no recycled content shares are declared, regardless of the reporting year
• Verify that a battery can be in the Undetermined declaration state while still being in the NotYetBinding state for minimum shares (independent ladders)

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[codacy-production]

_{🟡 MEDIUM RISK}

The Art. 8(1) declaration check is incomplete. According to the regulatory requirements cited in your documentation, shares must be anchored to both a reporting year AND a manufacturing plant to constitute a valid declaration. Currently, the check only verifies the year. Additionally, using .is_none() on the raw JSON input will fail to catch explicit null values which are permitted by the schema but invalid for the reporting duty.

Update the logic to ensure both recycledContentReportingYear and manufacturingPlace are present and non-null when shares are declared.

[codacy-production]

_{⚪ LOW RISK}

Nitpick: The constant ART8_DECLARATION_EMPOWERMENT contains an unintentional sequence of six spaces between 'calculation,' and 'verification'. Remove the excessive whitespace.

[codacy-production]

_{⚪ LOW RISK}

Nitpick: This multi-line string literal includes the leading indentation as literal spaces, which will corrupt the formatting of the user-facing warning message. Use backslashes to escape the newline and indentation.

Suggested change

	"Recycled-content shares are declared without a reporting year. EU 2023/1542 Art. 8(1) requires them per battery model, per year and per manufacturing plant, so a share without its year is not the Art. 8(1) declaration.",
	"Recycled-content shares are declared without a reporting year. \
	EU 2023/1542 Art. 8(1) requires them per battery model, per year \
	and per manufacturing plant, so a share without its year is not \
	the Art. 8(1) declaration.",