quality-tiers

name	quality-tiers
description	Module rigor tier system and uniform coverage thresholds.
paths	["**"]

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. The line threshold applies to every coverage language; the branch threshold applies to languages whose coverage tooling measures branch coverage. 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% for languages whose coverage tooling measures branch coverage. PowerShell (Pester) and bash (kcov) are exempt from this threshold because neither tool measures branch coverage; no branch-coverage gate applies to them.
• 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% applies uniformly across T1–T4 to every coverage language, and branch coverage >= 75% applies uniformly across T1–T4 to every language whose coverage tooling measures branch coverage; tier-specific lower coverage floors are not used in this repository. The branch threshold is not applied to PowerShell or bash because Pester and kcov do not measure branch coverage. That exemption is a capability limit on an unevaluable threshold, not a licence to exclude files from measurement: PowerShell and bash production files remain in the coverage denominator under the Coverage Exclusion Policy in .agents/skills/general-unit-test/SKILL.md.