Read "poetry.lock written before Poetry 1.4" through one helper; utils::poetry_lock::lock_writer_version is dead #1847

[agent] Filed by the scheduled architecture audit (audit-core). Register: register.

Kind: refactor. Register ID: A18.

Problem

The rule "formats 0, 1.0 and 1.1, or a 2.0 lock without a @generated by Poetry ≥1.4 stamp" is written twice:

• hosted: redirect::poetry::pre_1_4_writer, poetry.rs L26-L44
• vendored: inline in vendor/pypi_poetry.rs, L128-L137

Meanwhile utils::poetry_lock has a public lock_writer_version built for exactly this question, and nothing calls it except doc links: poetry_lock.rs L365-L378. source_constraint_break re-derives the same writer inline: L407-L419.

The two live copies agree today. A third reading of "who wrote this lock" is one edit away from drifting.

Proposed change

• Keep lock_writer_version (or rename it lock_writer) as the one reader. It should return (major, minor) or the format for pre-2.0 locks.
• Express pre_1_4_writer, the vendored inline match and source_constraint_break through it.
• Delete the inline copies.

Size

3 files. About −25 lines.

Acceptance criteria

• Existing hosted-poetry and vendored-poetry tests for 0/1.0/1.1/2.0 locks pass unchanged.
• Add one unit test of the shared reader covering an unstamped 2.0 lock, a 1.4 stamp and a 2.3 stamp.