Milestone D.1.2 — Cursor rules + EditorConfig

Status: Planned
Goal: D.1
Phase: 1.5 — Docs Site
Wave: 1
Estimated effort: 30 minutes
ADR required: None (tooling only)

Spec detail: MASTER_BRIEF.md Part D (D.1.2).

Why This Milestone Exists

AI-assisted development on the docs site without explicit design constraints produces generic UI (gradients, blur, pill buttons) that violates the Matte Graphite system.

Cursor project rules must be in place before any Fumadocs UI code lands so every edit session inherits the non-negotiable visual rules from MASTER_BRIEF §0.1.

EditorConfig and .nvmrc keep LF, 2-space indent, and Node 20 aligned with Vercel and GitHub Actions.

Non-Goals

Fumadocs bootstrap (D.2.1)
Copying rules into ibexdepo landing repo

D.1.1 merged

Deliverables

.cursor/rules/docs-site.mdc (MASTER_BRIEF §0.1 content)
.editorconfig — 2-space, LF, trim trailing whitespace
.nvmrc — 20.18.0
docs/app/CONTRIBUTING.md — branch naming, anti-patterns, pnpm docs:dev

See MASTER_BRIEF Part D (D.1.2) for full acceptance detail.

Files Affected

File Path	Action	Notes
`.cursor/rules/docs-site.mdc`	Add	Matte Graphite Cursor rules
`.editorconfig`	Add	Editor formatting
`.nvmrc`	Add	Node version pin
`docs/app/CONTRIBUTING.md`	Add	Contributor guide for docs app

Testing Requirements

verifyCursorRules_ActiveForAppsDocs: Editing docs/app/** shows docs-site rule active
verifyNvmrc_MatchesCI: .nvmrc matches docs-checks Node version (D.4.2)

Acceptance Criteria

Cursor status shows project rules active under docs/app/
.editorconfig present at repo root
docs/app/CONTRIBUTING.md documents no-gradient / no-blur rules

Risks

Risk	Probability	Impact	Mitigation
Rules ignored on non-`docs/app` paths	Medium	Low	Scope globs to `docs/app/**` only
Duplicate rules in parent `.cursor` mirror	Low	Low	Keep repo-local rule canonical; sync mirror if needed
CONTRIBUTING drift from MASTER_BRIEF	Low	Medium	Link to MASTER_BRIEF.md in CONTRIBUTING