207. A new mechanism is admitted only with the measured problem it removes
Context
Self-assessments on 2026-09-11, 10-02, 10-08, 10-13 and 10-16 found the same pattern: a local problem answered by a registry, doctrine, schema, API, MCP tool, Cockpit panel, gate and ADR at once. Rules project.no-new-nouns and project.optional-complexity bound the vocabulary and the ordinary path, but neither asks a new subsystem what it removes, so the question is argued per review.
Decision
A milestone or issue that adds a subsystem, capability family, record kind or surface names, in its why, the measured problem it removes: a manual step, a regression class, context or token cost, or a lower probability of reaching a verified merge, with the evidence of that problem. A proposal without one is recorded as an open question, not planned.
Alternatives rejected
- A permanent freeze
- Leaving it to reviewer judgement case by case
Consequences
The critique of an intent gains one question. Lumen, notifications, federation and similar proposals start from their measured problem. The rule is advisory until a plan validator can read the why for a cited measurement.
Sources
Promoted on 2026-10-18 from the owner's ChatGPT project (workspace chatgpt-majordomus, issue I3100). The owner has not accepted it; it is proposed for the owner's decision.
chatgpt-majordomus:c119#3chatgpt-majordomus:c277#1chatgpt-majordomus:c256#0chatgpt-majordomus:c256#2chatgpt-majordomus:c269#2