refactor(aidd-orchestrator): the check zone says when to stop, and reviews its axes in one round #887

Problem

The SDLC Check zone says to re-enter after every corrected candidate but does not distinguish an actionable defect reachable from the repository from a theoretical limitation no supported input can trigger. It can therefore keep extending the loop after the delivered outcome is already trustworthy.

Check also assigns code, contract conformance, and adversarial-input review to one broad checker. These axes are independent and can be assessed by specialized reviewers in the same round.

A measured run on #250 / PR #885 required six review rounds, ten sequential subagents, 2h12 wall-clock, and roughly 1.4M subagent tokens. Rounds 1–4 found reachable defects; rounds 5–6 found only unreachable shapes.

Scope

• Define an actionable finding as one traceable to current repository input, generated output, a supported host contract, or an accepted fixture.
• End Check when no actionable reachable finding remains.
• Record an unreachable limitation in the governing specification or a follow-up issue without re-entering delivery.
• Dispatch three specialized review axes together: code correctness, contract conformance, and adversarial reachable inputs.
• Merge and deduplicate their findings before deciding whether to repair, return to Frame, or finish Check.
• After a repair, run one focused regression pass over the changed behavior and re-enter the full round only when that pass finds a new actionable gap.
• Preserve the current routing of product and contract findings to Frame and implementation findings to Deliver or Todo.

Acceptance criteria

• plugins/aidd-orchestrator/skills/01-sdlc/references/03-check.md defines the reachable-finding exit condition without relying on this incident.
• Every excluded theoretical limitation has an explicit destination and is not silently dropped.
• Code, contract, and adversarial reviewers are dispatched in one parallel round with focused inputs.
• Their outputs are merged and deduplicated before the loop decision.
• A reachable defect still causes repair and a subsequent regression check.
• A regression pass does not automatically repeat all three reviewers unless it exposes a new actionable gap.
• Focused tests or executable fixtures cover exit, re-entry, deduplication, and unreachable-limit handling.

Out of scope

• Acceptance QA and pull-request evidence, owned by feat(aidd-orchestrator): gate draft pull requests with independent QA evidence #909 and feat(aidd-orchestrator): add independent acceptance QA before draft pull requests #919.
• Model selection, owned by refactor(framework): remove provider-specific model pins from portable artifacts #677.
• Cost collection, already owned by aidd-telemetry.