Architect Impl Governance

Architect-Impl Governance — the structural-fit bar (impl gate)

The Architect bar at the impl gate: does the implementation fit the existing structure, and is the suite's verification pyramid sound? Loaded by both faces. The SDD default for the architect impl bar; a plugin may bind its own, and this loads when the registry leaves architect/impl unbound.

The bar

• No knowledge duplication. A rule, contract, or piece of logic has one home in the implementation; whatever needs it calls that home. Two copies of one piece of knowledge drift — a change lands in one and misses the other. But coincidental resemblance is not duplication: two units that look alike yet change for different reasons stay separate — a premature shared abstraction couples them, and the wrong abstraction costs more than the repetition. Test: does a change to one force the same change to the other? Only then converge.
• No conflict. The implementation does not contradict conventions, module boundaries, or a spec's contract — including the project's declared layout, judged as declared (sdd:spec-structure-governance). The declaration is not a licence: node <-> capability stays 1:1 under every strategy, because the scheduler cuts one mission per node (ADR-0025).
• Contained complexity. Watch cyclomatic complexity and coupling; a unit hard to test is usually mis-structured — flag it.
• A sound verification pyramid. Across the suite the verification levels form a pyramid — a broad cheap base under a thin e2e cap that keeps the end-to-end path honest. An all-e2e suite is fragile and slow; a capless suite has no honesty check. The per-scenario level is the builder's call (sdd:builder-impl-governance); this bar judges the shape.
• An orthogonal axis. Structural fit judges a property the builder was not optimizing.
• Structural concerns are deferred. A structural problem in another capability spawns a new spec.

Key points (read-check)

1. No knowledge duplication — one home per rule; but coincidental resemblance is not duplication (don't merge units that change for different reasons). No conflict; contained complexity.
2. A sound verification pyramid — cheap base, thin e2e cap; neither all-e2e nor capless.
3. Per-scenario level is the builder's call; this bar judges the shape.
4. Structural concerns in another capability are deferred.