rseng-code-review

# Code and project review Most review attention goes to new diffs; most risk lives in the code nobody has looked at for a year. This skill covers the retrospective forms: reviewing the EXISTING codebase with findings ranked and then implemented, and reviewing the PROJECT on a cadence - after milestones, before releases and submissions. Division of labor: rseng-pair-programming owns diff-time pre-review of new work; rseng-version-control-review owns the review process and rules; this skill owns review as an undertaking on what is already there. Review-then-implement is a two-phase contract: findings first, agreement second, changes third - never silent rewriting under the review's flag. ## The codebase review Scope before depth - review the code that matters most: 1. Map risk: recently churned complex modules (rseng-software-metrics' hotspot map), result-bearing code paths (what feeds published numbers), security surfaces (rseng-security), and anything the tests do not reach (rseng-testing's coverage). Review THOSE deeply; skim the rest. 2. Sweep with the pack's lenses, each producing findings with file:line evidence: correctness and silent-failure modes (rseng-defensive-coding), numerical practice (rseng-numerical-accuracy), design and coupling (rseng-software-design), performance red flags on hot paths (rseng-performance-profiling), hygiene and dead code (rseng-code-quality), reproducibility hazards - unseeded randomness, unpinned environ...