docs(arch): tighten door-type framing — reversal cost, not deferral

ADR-009, open-questions.md, and the architect agent spec all had the same
conflation: 'two-way door' was phrased as 'can be decided during
implementation,' which reads as 'defer the decision.' That's not what it
means. A two-way door is a decision you make now and can revert later if
wrong — it's about reversal cost, not urgency.

ADR-009: add §'What this framework is NOT' — explicitly separates door
type (reversal cost) from deferral (scope management). State that
architecture decisions are the architect's regardless of door type.
Reword the two-way-door process from 'can be decided during
implementation' to 'pick the simplest option that works, implement it,
revert if needed.'

open-questions.md: reword the header to clarify door type describes
reversal cost, not urgency. Add 'Door type is separate from whether a
decision is made.'

architect.md: add Key Principle #8 (decisions are made, not deferred),
a new 'Door Types and Decision Urgency' section, and two new anti-patterns
(#8: door type as deferral, #9: hedging language in resolved decisions).
This commit is contained in:
2026-06-28 09:19:10 +00:00
parent 7d812af8f4
commit 3f011cbb82
3 changed files with 74 additions and 13 deletions

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@@ -7,9 +7,11 @@ last_updated: 2026-06-27
Questions are organized by theme. Each question has a stable OQ-ID for cross-referencing from spec documents.
Door type classifications follow ADR-009:
- **One-way door**: Reversal requires rewriting significant code or permanently closes a capability. Requires ADR before implementation.
- **Two-way door**: Reversal is cheap or additive. Can be decided during implementation.
Door type classifications follow ADR-009 — they describe **reversal cost** (how expensive it is to undo), not urgency:
- **One-way door**: Reversal requires rewriting significant code or permanently closes a capability. Getting it wrong is expensive — requires ADR before implementation.
- **Two-way door**: Reversal is cheap or additive. Getting it wrong is recoverable — decide, implement, revert if needed.
Door type is separate from whether a decision is made. A two-way door is a decision you make now and can revert later, not a decision to defer. See ADR-009 §"What this framework is NOT."
## Theme: Core Types