Buglyst
Explore Practice
Codebase Navigator

Practice building a mental map of unfamiliar codebases.

Work through three guided repo-navigation missions: trace a request, find a config source of truth, and map module ownership. Read the structure, inspect one file at a time, and save a scored mental map.

explore3 guided codebase mapsschedule~19 min totalscoreboardScored out of 100saveProgress saved on this device
Curated practice snapshots. No uploads. No private repo scanning. Not official, and not affiliated with any company, GitHub/Bitbucket, or upstream project — the repositories and code are fictional, anonymized engineering snapshots.

Navigation drills

ND-001 · Entrypoint traceTrace the request entrypoint
easy

A new developer must find where a GET /orders/:id request actually begins and follow it through to the database.

server.tsroutes/index.tsorders.routes.tsorders.handler.ts
folder_open
orders-service
code
6 excerpts
psychology
request-flow navigation
schedule
~6 min
mapA request-flow map: entrypoint → handler → service → repository → database.Start
ND-002 · Config sourceFind the config source
medium

A feature toggles on in staging but stays off in production. Find where config is actually resolved and where the fallback lives.

env/load.tsconfig/defaults.tsconfig/index.tsfeatures/invoices.ts
folder_open
billing-api
code
4 excerpts
psychology
source-of-truth tracing
schedule
~6 min
mapA config-resolution note: env is read and merged over defaults in one place.Start
ND-003 · Ownership mapMap the cache owner
medium

After a cache key change, stale product data appears across the app. Find the module that owns key construction and the callers that depend on it.

cacheKeys.tsproduct.repo.tssearch.service.tspricing.service.ts
folder_open
catalog-service
code
6 excerpts
psychology
ownership / dependency mapping
schedule
~7 min
mapAn ownership map: the key owner and the three callers that depend on it.Start
scoreboard

How a drill is scored

Each drill is graded objectively out of 100: pick the right target file (the entrypoint, the config source, or the owner), order the flow correctly where the drill asks for it, and select the true observations about how the code fits together. After you submit, the expected answer lights up in the map and a Buglyst reference trace is revealed so you can compare your read of the system.