Split forgelm/cli/subcommands/_purge.py into a sub-package (_row_id, _run_id, _check_policy, _shared) — deferred until Phase 16 S9 has landed #908

Deferred work · F-PR29-A1-06 / A1-07 / A1-08: _purge.py · severity Low · cost ~4-8 h · recorded in docs/roadmap/risks-and-decisions.md:80

Summary

forgelm/cli/subcommands/_purge.py is a deferred module split: row-id erasure, run-id erasure, the retention-policy check and their shared helpers live in one file. The module-size guard holds it to a fatal no-growth budget, but nothing pays the debt down until someone takes the split.

Condition or budget

Phase 16 S9 has landed (it rewrites _artefact_targets_for_run, one of the candidate seams); S9 is #895

State today (re-checked 2026-10-09)

1216 code lines against a budget of 1216 at 08f2426 (raised once from 1215).

Related

#667 and #668 track how the module-size guard counts lines and accepts budget raises; decide them before relying on a module's budget.

Acceptance criteria

• The module becomes a sub-package along the recorded seams, behaviour-neutral, with every public name still importable from its current path.
• Its _DEFERRED_SPLITS entry is removed from tools/check_module_size.py and every resulting module is under the normal ceiling.
• Test patch targets that named the old module are retargeted to the module that resolves the name at call time (the forgelm/verify.py split found five that silently moved).
• The row is removed from the deferral table and the CHANGELOG names its ID (the table's removal contract).

_{Recorded in docs/roadmap/risks-and-decisions.md (read at f94595f) and re-checked against the code on 2026-10-09. The row leaves that table only when the fix is on main, the CHANGELOG names its ID and any promised guard exists.}