Making-of

Mercator was first written in Ruby on Rails with Hobo, between 2013 and 2017. This version is a port to Elixir, Phoenix and Ash, made by one developer working with an AI coding assistant, Claude Code.

The sessions below are the actual conversations from the port, from the first look at the old repositories to the deployment of this demo. Only the conversation is kept: thinking, tool calls and tool output are left out, and personal details (names, addresses, infrastructure) are replaced.

The metrics show the size of the result and how long it took.

Project metrics

Code size, tests, commits and working time, compared with the Rails original.

The sessions

Session 2026-10-13 (2a53ba5b)

159 messages

Session 2026-10-13 (87be7c65)

8 messages

Session 2026-10-14 (3c7d3d68)

131 messages

Session 2026-10-15 (4c06f629)

50 messages

Session 2026-10-15 (5090fc35)

61 messages

Session 2026-10-15 (fafce14e)

118 messages

Session 2026-10-16 (d377cff1)

82 messages