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02

The Playbook

Eight principles. Everything we build is downstream of them.

Document
The QAISS Playbook
Revision
Rev. 1
Issued
2026-08-15

  1. § 1

    Engineering First

    Technology selection happens after the problem is understood, and every selection is written down with the constraint that motivated it. A choice nobody can justify later is a choice that will be re-litigated in every subsequent decision.

  2. § 2

    Measure. Reason. Engineer.

    Discovery is not a phase that precedes the work; it is the first third of it. A proposal that arrives without the constraints it was reasoned against is an opinion, and it is treated as one.

  3. § 3

    Evidence over Opinion

    When a question is settleable by measurement, it gets measured rather than argued. When it is not, the assumption is written down as an assumption so it can be revisited when evidence arrives.

  4. § 4

    Architecture before Implementation

    Boundaries, data ownership, and failure behavior are settled before feature work scales up. Decisions that are cheap to change are deliberately deferred, so that attention goes to the ones that are not.

  5. § 5

    Complexity Must Earn Its Place

    A new dependency, service boundary, or layer of indirection is argued for on the record, against the simpler option it replaces. The default answer is the smaller system.

  6. § 6

    AI as Engineering

    An AI feature ships with an evaluation method, a defined behavior when the model is wrong or unavailable, and a boundary describing what it is permitted to act on. Use the smallest sufficient intelligence, and escalate complexity only when the problem earns it.

  7. § 7

    Security by Design

    Trust boundaries and data handling are named while the architecture is still being reasoned about. Secure defaults are the starting position, and relaxing one is a decision with a reason attached.

  8. § 8

    Build Once. Learn Forever.

    Decisions are recorded with their reasoning, so that a future change can tell whether the constraint still holds. Methods that prove themselves are written into the way the next project starts, which is what makes this Playbook a document that changes.

Revision history

  1. Rev. 12026-08-15First published. Eight principles.

The Playbook is versioned because it changes. When a principle is added or strengthened it is because something happened that made the previous version insufficient, and the revision note says so.

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