BlastRadius — PR Impact Analysis

Paste a GitHub PR URL. BlastRadius fetches the diff, loads the repository, and runs a two-stage reasoning pipeline powered by IBM Bob. Stage 1 — TraceAgent sends Bob the full priority-ranked repository context with a mandatory chain-of-thought reasoning block. Bob traces every transitive call chain from the changed symbols outward, up to 5 hops deep, assigning risk levels and confidence scores. Each edge is then statically verified using Python AST analysis or JavaScript regex matching and labeled VERIFIED, INFERRED, or UNVERIFIABLE. Stage 2 — RemediationAgent takes every CRITICAL chain with no test coverage and sends Bob a focused second call. Bob generates a complete runnable test stub for each gap plus a one-sentence fix summary. If the verdict is BLOCK, the system computes an estimated incident cost using DORA 2023 benchmark figures and shows it in the UI. The pipeline streams live stage events over SSE so engineers watch the reasoning happen in real time. The final report renders as a D3 force-directed graph — nodes are files, edges are call relationships, colors encode risk, dashed borders mean missing test coverage. Every report gets a shareable URL that survives server restarts via on-disk persistence. IBM Bob was used across five documented sessions during development — improving the prompt engineering strategy, adding TypeScript interface detection, validating AST edge cases, generating additional test cases, and hardening the GitHub Actions workflow. All sessions are exported and committed with verifiable commit references. A GitHub Actions bot posts an automatic impact report as a PR comment on every pull request, making blast radius analysis part of the standard review workflow.