Summary: design, build, defend

The capstone contains no new machinery. It is the track exercised at once: you design a small agentic system, build it in Claude Code, and then write the one-page defense that separates an architect from an assembler. The defense, not the demo, is the deliverable.

Core ideas

• The assignment has six required parts: one clear job with a beginning and an end; a project memory file that makes standards durable; one custom tool (a small MCP server) with a five-part description; structured output whose schema keeps the truth legal; one must-hold rule enforced in structure; one escalation path with an explicit criterion.
• Small is a requirement. The capstone measures judgment, not surface area. Anything with “platform” in the name is too big.
• Two agents are allowed only if the work genuinely splits. A single well-configured agent is often the stronger design, and saying so in the defense earns more respect than an unnecessary seam.
• Phase one is a one-page design with five sections: the job, the path (workflow or agent, and why), the rules (must-hold versus should-usually), the seams, and the desk (carry versus fetch). A section that is hard to fill is the design talking.
• Phase two builds in a deliberate order: configuration first (the newest teammate’s rules before their first day), then the tool, the schema, the guarantee, the escalation, and finally one unattended run.
• Test where the system is weakest: feed the schema a document with a real gap; try to break your own must-hold rule three ways; construct the exact situation the escalation exists for; read the unattended run’s output as if you were not the author.
• Phase three is the defense, one page, four headings: where judgment lives; what I traded away; what breaks first; what I did not build. A defense with no admitted costs is a sales pitch.
• The ten-point rubric is weighted toward failure handling, because products are judged on their worst day, and demos never show it.
• The closing assessment is a comparison: your lesson 1 paper sketch read against the finished design. The distance between them is what the track taught you.
• The defense format is portable. It is the shape of a real design review, and it works on systems of every size, long after the tools in this track have been replaced.

What changes for you

You leave the track with three things: a working reference system where every decision was deliberate, a defense document you can reuse as a design-review template, and the standing habit of asking the architect’s questions before the first line of code. The next system worth designing is the real one at your work.