Imported from Fantastic-Computing-Machine/atlantis (AGENTS.md). Install upstream with npx skills add Fantastic-Computing-Machine/atlantis. Copyright stays with the author.

Atlantis AGENTS Guide

Purpose: concise, high-signal defaults for this Next.js 16 + TypeScript + Tailwind app. Keep scope tight, stay type-safe, avoid regressions.

Quick Facts

• Framework: Next.js 16 App Router, TypeScript strict, moduleResolution bundler.
• Styling: Tailwind v4 + Shadcn UI primitives in src/components/ui.
• State: Zustand (src/lib/store.ts) for persisted settings.
• Diagrams: Mermaid editor; persisted to Prisma SQLite or JSON backup.
• Notes: see src/app/notes, server layouts fetch data and render client shells.
• Icons/Fonts/Themes: lucide-react, next/font, next-themes (light/dark toggle).
• Code map: plan/code-map.md is the required map-first index for file ownership and task routing.
• Editors: no Cursor rules (.cursor/ missing); no Copilot instructions (.github/copilot-instructions.md missing). This file is authoritative.

Mandatory Code Map Workflow

• Always read plan/code-map.md before searching or editing code.
• Use map-first navigation: start with the intent map and open those files before broad searching.
• Avoid blind repo-wide searches unless the code map does not cover the task.
• If you add/move/rename files, routes, folders, or exported functions, update plan/code-map.md in the same change.
• Treat stale code-map entries as bugs; fix them as part of the task.

Commands (npm)

• Install deps: npm install (first step before any command).
• Dev server: npm run dev (runs node scripts/bootstrap.js then next dev, http://localhost:3000).
• Build (type-safety gate): npm run build (runs bootstrap then Next build).
• Start prod: npm run start (after build).
• Lint: npm run lint (ESLint via Next config).
• Prisma helpers: npm run prisma:prepare, prisma:generate, prisma:push, prisma:migrate, migrate:json-to-db.

Testing Guidance

• No test runner configured. If tests are requested, add Vitest + @testing-library/react for Next 16.
• Suggested scripts once added: "test": "vitest", "test:watch": "vitest watch", "test:ui": "vitest --ui".
• Run single test (after setup): npm run test -- path/to/file.test.tsx or npx vitest path -t "case".
• Co-locate tests near components or under tests/; mock browser-only APIs (Clipboard, window) in Node.
• Prefer behavioral assertions over snapshotting large Mermaid/notes content.

Project Map

• src/app/: routes/layout. src/app/page.tsx uses ISR 30s.
• src/app/diagram/[id]/: diagram editor (client-heavy); gate browser libs with mounted checks.
• src/app/notes/: notes layout + list; dynamic fetch with getNotePage; entry page shows empty-state; [id]/page loads note with getNoteById and renders NoteWorkspace; dynamic = 'force-dynamic' on layout and page to avoid caching.
• src/app/api/: API routes; keep server-only.
• src/components/: feature/layout components. Avoid touching src/components/ui unless fixing a shared UI bug.
• src/lib/: utilities, data access (notes-data), types, Zustand store.
• data/: SQLite db/backups; public/: static assets; scripts/: bootstrap + Prisma helpers (bootstrap must run before dev/build).
• docs/: repo docs; update this file and docs/AI.md if conventions change.
• plan/: planning docs; plan/code-map.md must stay current with structure and ownership.

Styling

• Tailwind utilities; compose with cn from src/lib/utils.ts.
• Class order: layout → spacing → typography → colors → effects; keep classes readable.
• Respect design system: use Shadcn primitives and override via className rather than editing primitives.
• Support dark mode using semantic tokens (bg-background, text-foreground, border-border).
• Avoid generic purple/white defaults; pick intentional palettes when adding UI.

State

• Use Zustand store setters; avoid direct mutation; prefer functional updates.
• Derive filtered/sorted arrays near usage to limit re-renders; supply stable keys (diagram id).

React/Next Conventions

• Default to server components; add 'use client' only when using state/effects/browser APIs.
• Gate browser-only libs (Mermaid, CodeMirror, react-resizable-panels, react-zoom-pan-pinch) with mounted checks (useEffect).
• Use async/await for data fetching; API routes return NextResponse with status codes; avoid accessing window/document in route handlers.
• Keep route handlers side-effect minimal; validate input; avoid long blocking writes; ensure directories exist before file writes (fs.mkdir recursive).
• Preserve revalidate settings (e.g., home uses ISR 30s) unless requirements change.
• Follow App Router naming (page.tsx, layout.tsx, route.ts).
• Type params/searchParams objects; avoid dynamic any route params.
• Notes routes: NotesLayout fetches first page server-side; NotePage awaits params via params: Promise<{ id: string }>; ensure types match this shape.

Imports & Formatting

• Order imports: external libs, then @/ absolute, then relative; separate groups with a blank line when edits are sizable.
• Use named exports; default exports only when Next requires (pages, route handlers).
• Type-only imports use type modifier (import type { Diagram } from '@/lib/types';).
• Formatting via ESLint; 2-space indent; minimal semicolons to match existing style; keep quotes consistent per file.
• Keep files ASCII unless the file already uses non-ASCII and it is necessary.
• Avoid auto-reformatting whole files; keep diffs focused.

TypeScript Rules

• strict: true; avoid any; provide explicit return types and generics.
• Prefer type aliases for props/DTOs; use interface when extension is expected.
• Narrow optional fields before access; avoid non-null assertions unless unavoidable.
• Use Readonly/readonly where appropriate; keep immutability in Zustand setters.

Naming & Structure

• Components/files: PascalCase (DiagramGrid.tsx, NoteWorkspace.tsx).
• Functions/vars: camelCase (handleSave, currentDiagram).
• Types/interfaces: PascalCase (Diagram, Note, DiagramStore).
• API route folders: kebab-case (api/diagrams/[id]/route.ts).
• Descriptive prop names; avoid single-letter vars outside loops.

Data & Persistence

• Default persistence via Prisma + SQLite at data/atlantis.db; switch provider with env (PRISMA_PROVIDER, DATABASE_URL).
• Backup/restore via /api/backup; data/diagrams.json created on demand for file-based flows.
• Diagram shape: { id, title, content, emoji, createdAt, updatedAt, isFavorite }; extend types, defaults, serializers, and UI together; id generation uses 6-char random with collision retry.
• Notes data access lives in src/lib/notes-data; keep dates as ISO strings; format for UI with formatDate to avoid hydration mismatch.
• Validate API inputs; keep route handlers side-effect minimal and ensure directories exist before file writes.

Error Handling & UX

• Use sonner toasts for user feedback; avoid silent failures.
• Validate API inputs; respond with clear 400/500 messages without leaking internals.
• Confirm destructive actions via Radix/AlertDialog patterns (see DiagramGrid).
• Handle hydration mismatches by gating client-only logic with mounted flags.
• For notes/diagrams, ensure missing entities call notFound().

Accessibility

• Maintain focus states; add aria-label for icon-only controls.
• Provide text alternatives for emoji/logo buttons; keep color contrast via tokens.

Assets & Icons

• Import lucide icons individually (import { Star, Trash2 } from 'lucide-react';).
• Keep SVG/data URIs lightweight; favicon already referenced in src/app/layout.tsx.

Performance

• Memoize only when profiling indicates benefit; keep components simple first.
• Avoid unnecessary re-renders; ensure dependency arrays are accurate.

Logging & Debugging

• Avoid console.log in production code; remove temporary logs.
• Prefer toasts or error boundaries for user-visible messaging.

Tooling Notes

• No Cursor rules (.cursor/ absent) and no Copilot instructions (.github/copilot-instructions.md missing). This file is authoritative.
• Editors: do not auto-reformat; follow existing style.

Git & Workflow

• Read files before editing; keep changes minimal and scoped.
• Do not revert user changes; avoid drive-by refactors.
• Avoid modifying src/components/ui unless fixing a shared UI bug.
• Follow existing commit style (check git log); concise messages focus on why.
• No force-push unless explicitly allowed; no amend unless requested.
• Run npm run build after changes to catch type/route errors (acts as tests when no test runner).

Notes Feature

• Layout: NotesLayoutClient wraps children with initialNotes; respect existing sidebar/list interactions.
• Empty state: src/app/notes/page.tsx shows centered prompt with FileText icon; keep copy concise.
• Note page: NoteWorkspace receives initialNote; missing note triggers notFound().
• When extending notes, keep server fetches fast and cache-safe (dynamic rendering already configured).

Documentation

• Docs live in docs/; see docs/AI.md for AI/agent usage guidance.
• Update this file when commands, tooling, or conventions change.
• Update plan/code-map.md whenever code structure, directory ownership, routes, or exported responsibilities change.

Extension Checklist

• Add new dependencies to package.json only when necessary; prefer existing patterns.
• When adding tests, wire scripts and ensure Vitest config respects Next 16 (jsdom where needed).
• Update types, serializers, and UI together for new diagram/note fields.
• Keep dark mode support intact; preserve hydration safety checks.

When in Doubt

• Prefer explicitness over cleverness; ask for clarification on persistence/UX-sensitive work.
• Preserve existing UX patterns (toasts, dialogs, theme toggle, grid layout, notes empty state).
• Keep changes incremental; avoid broad refactors unless requested.
• Maintain ASCII output unless justified by existing content.
• Deliver small, reviewable diffs with rationale.