PR Blast Radius

A polyglot static analysis tool that computes the "blast radius" of code changes, which downstream symbols could break when you modify a function signature, refactor a class, or update shared utilities. Go performs deterministic AST parsing, dependency resolution and severity scoring; Python builds the diagram from that output (nodes, labels, risk tiers, grouping, edges). The LLM writes short narratives for nodes that are already placed, and Pydantic rejects any narrative that names an unknown node or cites a risk reason Go did not compute.