Principle Sequence Verifiable Units

---
name: principle-sequence-verifiable-units
description: "Apply when multi-step work must end each ordered unit in a verified state."
license: MIT
metadata:
  author: jstack-maintainers
  source: michael-denyer/pstack-claude
  source-version: "0.9.30"
  source-commit: 45f768349a6d7d7e71509fee3f5bccfad54b3bad
  owner: software-factory
  risk: low
  capabilities: jstack,engineering-principle
user-invocable: false
---

# Sequence work into verifiable units

Order work as a sequence of small units, each ending in a state you can check, and don't advance until the current one is green.

**Why:** A break caught at the unit that caused it is cheap to localize. A break caught after a batch is buried, and you have already built further on a broken base. Sequencing those same units into a delivery a reviewer can replay turns "trust me" into "watch it go red, then green."

**Execution.** In a sweep, migration, or any run of similar edits, verify each change before starting the next. Each unit is a before/after bracket: known-good state, one change, run the check, then proceed. Rebase onto clean trunk first so every check measures against the real baseline. When a lever does the edits, the per-unit check is nearly free; run it anyway.

**Delivery.** Stack commits and PRs in the order that proves the work. The canonical shape is the failing test first, then the fix on top. Other story orders are a subtraction before the reshape, a baseline capture before the treatment, the scaffold before the feature. Each commit lands on its own and the sequence reads as an argument.

**Pattern:**
- Pick the smallest unit that ends in a check: an edit plus its test, or a commit that stands alone.
- Verify before advancing. Red to green per unit, never deferred to a final batch.
- Order the units so the sequence builds confidence on its own, for you while executing and for a reviewer reading the stack.

The sequencing complement to the **prove-it-works** principle skill, which keeps each check real, and the **build-the-lever** principle skill, which makes the per-unit check cheap.