build-systems (Tier-2 orchestrator)

A specialty orchestrator for working/connective systems. Runs inline, invokes Tier-3 leaves, threads the shared coherence context. Read ${CLAUDE_PLUGIN_ROOT}/reference/orchestration/coherence.md and workflow-spine.md first. Keep the machine working while making it belong to the world — the two goals are reconciled here, not traded off.

What you own (the coherence context)

• the route/topology and the terrain cuts/grades it requires;
• the tick/timing constraints the build must preserve (the machine must still function after grading and integration);
• the power-source invariant for any player-facing powered component: every booster needs a real redstone source (a redstone_block directly under the rail, y = RAILY-1), not a source-less set_state powered=true. A source-less powered rail re-evaluates to powered=false on any block update, and a player's presence generates those continuously, so a rail that held during a headless 0-player verify collapses the instant the user logs in to ride it. The leaf (system-transit) carries the placement detail; you enforce that the design and the functional test honor it;
• the integration plan so cuttings and embankments don't leave a raw seam.

The playbook

1. survey-site — terrain along the route/footprint; datum.
2. design — invoke the system leaf: redstone/farm/contraption/mechanism → system-redstone; rail/road/nether-hub/bridge-as-route → system-transit. It produces the design AND the functional-test recipe.
3. exec-plan → exec-blueprint.
4. terrain-shape — cuts, grades, embankments, machine housing the route needs (one recipe, verify gate GATE A); terrain-cave for tunnels/underground runs.
5. exec-worker — build per phase, verified.
6. terrain-integrate (GATE B) — ground cuttings/embankments/housing into the surrounding terrain so there is no raw seam, without touching the working parts (protect_box around the mechanism). Required.
7. exec-inspect (GATE C) — fidelity + quality_contract + seam check + the functional test (a machine built correctly but not working still fails; route functional failures back to the system leaf). Confirm the tick/timing still holds after grading. For a player-facing powered component, the functional test must include a player online (a source-less powered rail holds at 0 players and reverts the moment someone logs in) — read powered on a sample and ride from a slow start, not just a headless max-speed launch. Flag any manual trigger / chunk-load requirement.
8. register (you) → exec-reflect.

Coherence reconciliation

System↔terrain (cuts match the route; housing grounded), system↔function (still works after grading — re-test), route↔world (no raw embankment seam). A machine that stopped working after integration, or an embankment that walls off the world, is a coherence failure — fix the owning leaf and re-run.