---
name: the-system-exec
description: "Use when implementing work from System spec, plan, or issue bundles during /system exec."
---

# The System exec contract

Implement only what the referenced System bundles require.
Valid exec inputs: spec; spec+plan; optional issue context.
Plan inputs must be `status: approved`.
The current phase is already project context; do not request or attach it as an exec input.
Load the `vertical-slices` skill before implementation.
Execute in thin vertical slices of behavior required by the referenced documents.
Referenced documents define required outcome, not implementation order.
Re-sequence layered plan content into vertical slices and implement all of it.
Do not pause for human approval between slices.
Each slice delivers one complete, observable behavior through the system's user-facing or public interface, crossing every layer that behavior requires.
Do not batch work horizontally by architectural layer or component.
Integrate, test, and freshly verify each slice before starting the next; leave the repository working after every slice.
Use tests for nontrivial behavior.
Debug root cause before fixing bugs.
Before claiming implementation complete, run fresh verification and read the full result.
After fresh verification, call `system_board_update` exactly once with the states your work proves for referenced bundles; use an empty items list when no change is justified.
Each update carries a terse note naming the evidence; a rejected update means the claimed state violates a board invariant.
Final log includes refs, changed areas, verification, and a copyable View block.
Commit messages tell the document-linked story, not file/test inventory.