Cartographer is a structural intelligence engine that maps a codebase's architecture, monitors its health, and predicts the ripple effects of changes before they're made. Where CKB handles deep semantic analysis at the symbol level, Cartographer operates at the module and dependency graph level — answering questions like "what are the architectural bottlenecks?" and "what breaks if I change this?"
The dependency graph maps files and modules as nodes with import relationships as edges, annotated with language, complexity estimates, and bridge flags. Bridge detection uses Bridgeness Centrality (betweenness centrality filtered to exclude noisy utility hubs) to find files that genuinely connect disparate subsystems — the ones where a change propagates furthest. Layer enforcement is config-driven via `layers.toml`, detecting back-calls and skip-calls before they land in main. Health scoring runs on a 0–100 formula accounting for cycles, bridges, god modules, and violations.
The predictive simulation feature is the most useful part in practice: before writing a single line, you run `cartographer simulate` to see whether a proposed signature change will create a cycle, which modules will be affected, what layer rules it violates, and what the net health impact is. Historical evolution tracking surfaces architectural debt trends over time. Ships as a Rust binary with an MCP server for AI tool integration and BM25 search over the codebase map.