Example boards

These boards map open source projects at a fixed commit. Open one without signing in, select a component for its explanation and code, and select a connection to see the line it cites.

PostgreSQL: how a query runs and survives a crash

Follows a query from the client through parsing, planning and execution, then shows why committed work survives a crash: WAL reaches disk before the data it protects.

Open the board → · Commit 3168611

OpenObserve: one log line from ingest to search

A log line is searchable before it reaches object storage. Queriers read uploaded files, while ingesters add their in-memory tables and local parquet files.

Open the board → · Commit e6a65bf

MCP TypeScript SDK: one tool call, end to end

Client and server extend the same Protocol class, so stdio and HTTP differ only in their transport.

Open the board → · Commit 1e608ca

umami: how a page view gets stored

One saveEvent call writes to PostgreSQL, ClickHouse or Kafka, depending on environment variables. The board marks the one connection the repository cannot prove.

Open the board → · Commit 559e3c6

Flask: one request through the app

The session opens before URL matching, and a 404 is only raised after before_request hooks have run.

Open the board → · Commit 49943b5

Draw one of your own

Draw how a request moves through this repo: entry point, services, queues and data stores. Cite the line behind every connection. Give each component a short explanation, and distinguish facts from connections you cannot prove.

Connect your agent to try it. For more on this kind of board, see Map an unfamiliar codebase.