# Quality Tiers

> Converted rule

- Skill: `drmoisan/quality-tiers` (Agent Skill)
- Install (CLI): `npx skillmds@latest add drmoisan/quality-tiers`
- Raw SKILL.md: https://api.skillmd.com/api/skills/drmoisan/quality-tiers/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: drmoisan (https://skillmd.com/u/drmoisan)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/drmoisan/quality-tiers

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# Converted rule

Source: legacy Claude rule `quality-tiers`.

# Module Rigor Tiers

This rule defines the T1–T4 module rigor tier system used by all CI gates in this repository. The tier system source of truth is `docs/ci.research.md` section 1; the file `quality-tiers.yml` at the repository root maps every project to a tier. Adding a project without a tier classification fails CI.

## Tiers

- **T1 — Critical.** Behavior bugs cause silent data loss, model drift, or security holes. Examples (No-COM architecture): classifier engines (SpamBayes, Triage), ToDo ID allocator and hierarchy operations, Graph extended-properties adapter, auth/token handling, host-agnostic command bus.
- **T2 — Core.** Bugs cause feature regressions but not data loss. Examples: `TaskMaster.Domain`, `TaskMaster.Application`, mail-item DTOs, settings store abstraction, schema definitions.
- **T3 — Adapters & UI.** Glue around APIs the team does not own. Examples: Outlook task pane UI, Office.js wrappers, Microsoft Graph SDK wrappers, persistence I/O.
- **T4 — Scaffolding.** Examples: DI wiring, bootstrap, build scripts, dev tooling, generated code, manifests.

## Source of Truth

- `quality-tiers.yml` at repo root maps every project to one tier.
- The CI pipeline's `tier-classification` stage validates that every project entry has a tier and that no unclassified project exists. Adding a project without a tier classification fails CI.

## Uniform-vs-Tier-Dependent Gate Matrix

Per Authoritative Decision #2, line and branch coverage thresholds are uniform across all tiers. Other gates remain tier-dependent.

### Uniform across all tiers (T1–T4)

- Format check: 100% pass.
- Lint errors: 0.
- Type errors: 0.
- Architecture violations: 0.
- Line coverage: >= 85%.
- Branch coverage: >= 75%.
- No regression on changed lines.

### Tier-dependent

| Gate | T1 | T2 | T3 | T4 |
|---|---|---|---|---|
| Untyped escape hatches (`any`/`dynamic`) | 0 | 0 | <= 5 per file, justified | unlimited |
| Property test density | >= 1 per pure function | >= 1 per pure function | none | none |
| Mutation score | >= 75% | trend-only | none | none |
| Contract breaking changes | major bump required | major bump required | n/a | n/a |
| Determinism (retry rate) | < 0.5% | < 1% | < 2% | n/a |
| Golden tests | required for classifier-output modules | optional | none | none |
| Full E2E suite scope | all critical paths | core paths | adapter smoke | none |

## Rationale (uniform coverage thresholds)

High test coverage is a fundamental quality-control design choice that enables autonomous agentic development and trust in the work product. For that reason, line coverage >= 85% and branch coverage >= 75% apply uniformly across T1–T4; tier-specific lower coverage floors are not used in this repository.