/onBob

Problem Large codebases are opaque. When a new engineer joins a team, or a senior engineer moves to an unfamiliar service, there is no fast path to understanding how the system is actually structured, which components own which concerns, how a user request travels through the stack, and what breaks if a given module changes. Documentation rots. Architecture diagrams live in stale Confluence pages. Reading code file by file takes weeks. Solution: onBob onBob is a native IBM Bob skill that turns any repository into a living, interactive Architectural Atlas in seconds. The engineer simply types /onBob inside Bob. Bob scans the repo using its built-in file tools, no shell scripts, no external dependencies, identifies architectural pillars (logical groupings of files by ownership and responsibility), maps directed dependencies between them, traces real execution paths for key features, calculates blast radius scores for every node, and surfaces annotated notes (risks, TODOs, performance hotspots). It then injects a structured window.__ONBOB_DATA__ payload into a self-contained HTML template and writes a single onbob-output/architecture-atlas.html file. The Atlas UI The output file opens directly in any browser: no server, no install. It renders a D3.js force-graph of all architectural pillars with animated feature-flow playback, step-by-step execution trace drawers, a blast simulator modal, a node inspector panel, and a full pillars list view. Engineers can toggle light/dark theme (T), fit the graph (F), and close any panel (Escape) via keyboard. Every element is sourced exclusively from the injected data, the template contains zero hardcoded repo knowledge. It all learns from the current repository and guides the final dashboard UI. Target Users + Engineers onboarding to an unfamiliar codebase + Tech leads preparing architecture reviews + SREs assessing blast radius before a high-risk change + CTOs who want a shareable, always-current architecture one-pager What makes it unique Unlike long README files, static diagram tools or AI chat summaries, onBob produces a living document, re-run it after any major refactor and get a fresh atlas in seconds. The skill is repo-agnostic: it has been designed and validated against a 3,000+ file C++ monorepo (DuckDB) and the FastAPI full-stack templates. The output is a single portable HTML file anyone can open, bookmark, or email. Business Impact Engineering onboarding time at large enterprises typically costs 3–6 weeks of lost productivity per hire. onBob compresses the "understand the architecture" phase from days to minutes, directly reducing that cost. For platform teams managing dozens of microservices, the blast radius simulator turns a subjective gut-check into a data-backed risk assessment before every deployment, reducing incident rates and accelerating change velocity. Because the output is a single portable HTML file, it integrates into existing processes (PR reviews, architecture review boards, runbooks) with zero tooling adoption friction.