Part 2 — Composing Sandcastles with Crossplane

Part 2 will develop how the Crossplane composition layer requests engineering work from the Sandcastle construction layer. The intended learning arc is:

• A learner authors a Crossplane Composite Resource asking for a new Open Engineering artifact (for example, a new Pico kind).
• The Composition turns that request into an EngineeringTask (or equivalent) — a declarative record of the construction work the cluster wants done.
• A Sandcastle picks up the EngineeringTask, spins up an isolated workspace with the right tools and permissions, runs an engineering agent through the Part 1 agent inner loop, and returns durable Git artifacts.
• Crossplane then reconciles those artifacts back onto the cluster, closing the compose → construct → behave loop.

Lessons

• 01 Composing a Sandcastle request — the first Part 2 lesson. Covers the compose → construct boundary: how a Crossplane XR becomes an EngineeringTask, how a Sandcastle consumes the task (never the XR), and how the construction stage stays parametric on the request. Runnable end-to-end via the reusable Compose a Sandcastle request lab.

NoteStatus — Part 2 lesson 01 runnable; further lessons scaffolded

Lesson 01 is runnable end-to-end via the reusable Compose a Sandcastle request lab, whose verify.sh asserts the four hand-off rules programmatically. Further Part 2 lessons (for example, a cluster-backed variant using a real Crossplane Composition emitting a real EngineeringTask CR) remain intentionally scaffolded for this wave.