Several renderers had duplicated logic that made changes error-prone and maintenance harder. The freeze renderer reimplemented the same recursive traversal as the non-unicode text renderer, differing only in the frozen flag and bullet string. The graphviz forward and reverse graph builders each contained their own BFS depth computation with mirrored if/else branches for depth-limited vs unlimited traversal. Edge label derivation (version_spec or "any") was inlined identically across graphviz and mermaid renderers. These duplications meant any bug fix or behavior change had to be applied in multiple places, risking divergence.

♻️ The text/freeze unification extracts _render_text_simple with frozen and bullet parameters, letting freeze.py drop from 40 lines to a single function call. The graphviz cleanup pulls BFS into a shared _compute_reachable_depths helper and collapses each builder's branching into a single iteration that checks visited membership when depth-limiting is active. edge_label properties on DistPackage and ReqPackage replace the repeated inline patterns across graphviz and mermaid. The reverse() methods in PackageDAG and ReversedPackageDAG used next(p for p in m if p.key == v.key) for node deduplication — an O(n) linear scan per edge — replaced with a dict index for O(1) lookups.

⚡ PackageDAG.__getitem__ previously used dict.get(), silently returning None on missing keys and violating the Mapping protocol contract. It now delegates to dict.__getitem__ which raises KeyError, matching what callers expect through Mapping.get(). The type checker has been migrated from mypy to ty, and stale type: ignore comments that ty no longer needs have been cleaned up.