improvement: some files replaced, lots of them i shall say. AGENT.MD file created. some rules and skills added for cursor agent.

.cursor/rules/api-errors-i18n.mdc

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+---
+description: Error codes backend ↔ frontend and i18n message keys
+globs: backend/src/common/errors/**,frontend/src/components/shared/formatApiError.ts,frontend/messages/**
+alwaysApply: false
+---
+
+# API errors & translations
+
+## Adding a new error
+
+1. Add code to `backend/src/common/errors/error-codes.ts`
+2. Throw via `AppException` (or validation DTO with that code)
+3. Add matching key under `errors` in **all three** message files:
+   - `frontend/messages/en.json`
+   - `frontend/messages/fa.json`
+   - `frontend/messages/nl.json`
+4. Frontend catch: `getUserFacingError(err, tErrors, t('fallbackKey'))`
+
+## Validation field errors
+
+Backend returns `{ success: false, error: { code, details: [{ field, code }] } }`.
+
+Frontend maps `details[].code` through the `errors` namespace.
+
+## Do not
+
+- Show raw `error.message` or stack traces to users.
+- Add English-only strings inline in components.

.cursor/rules/backend-nestjs.mdc

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+---
+description: Backend NestJS modules, Prisma, permissions, guards
+globs: backend/src/**
+alwaysApply: false
+---
+
+# Backend conventions
+
+## Module layout
+
+`backend/src/modules/{feature}/` → `{feature}.module.ts`, `.controller.ts`, `.service.ts`, `dto/`.
+
+Register new modules in `app.module.ts`.
+
+## Errors
+
+Use coded errors — not raw user-facing strings:
+
+```typescript
+throw new AppException(ErrorCode.PERMISSION_DENIED, HttpStatus.FORBIDDEN);
+```
+
+- Codes: `backend/src/common/errors/error-codes.ts`
+- DTO validation: `{ message: ErrorCode.VALIDATION_* }` on class-validator decorators
+- Global filter: `HttpExceptionFilter` in `main.ts`
+
+## Permissions
+
+- Check access with `hasEffectivePermission(membership, 'TAB_*')` from `common/membership-permissions.ts`.
+- Clinic-only routes: `ClinicOrgGuard`. Lab-only: `LabOrgGuard`.
+- Feature-specific checks belong in the **service**, not only the controller.
+
+## Prisma
+
+- Schema: `backend/prisma/schema.prisma`
+- Always add a migration for schema changes (`npm run prisma:migrate` in backend).
+- Seed permissions stay in sync with `ALL_TAB_PERMISSIONS` in `common/permissions.ts`.
+
+## API responses
+
+Prefer `{ success: true, data: ... }` shape consistent with existing modules.

.cursor/rules/dyolink-overview.mdc

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+---
+description: Dyolink project context — stack, org types, git safety, verification
+alwaysApply: true
+---
+
+# Dyolink overview
+
+Monorepo: `backend/` (NestJS + Prisma), `frontend/` (Next.js + next-intl), `infrastructure/` (Docker).
+
+## Domain
+
+- **CLINIC** orgs: patients, appointments, treatment, staff.
+- **LAB** orgs: cases, tasks, lab workflows.
+- Tab access: `TAB_*_READ` / `TAB_*_EDIT` in `backend/src/common/permissions.ts`. EDIT implies READ.
+
+## Agent behavior
+
+- Read `AGENTS.md` and file-scoped rules before large changes.
+- **Never commit or push** unless the user explicitly asks.
+- Prefer minimal diffs; reuse existing components and API patterns.
+- After cross-cutting changes: `backend` → `npm run build`; `frontend` → `npx tsc --noEmit`.
+
+## i18n
+
+All user-visible strings: `frontend/messages/en.json`, `fa.json`, `nl.json` — add keys to **all three**.
+
+## Treatment / appointment colors
+
+Treatment-type colors and labels: `components/shared/treatmentTypeDisplay.ts` + `catalog-type-colors.ts`. UI badges: `components/ui/treatment/TreatmentTypeBadge.tsx`.

.cursor/rules/frontend-components.mdc

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+---
+description: Frontend folder structure — ui vs non-ui, thin pages, feature layout
+globs: frontend/src/**
+alwaysApply: false
+---
+
+# Frontend component structure
+
+## Rules
+
+| Kind | Location |
+|------|----------|
+| Cross-feature UI | `components/ui/shared/` |
+| Feature UI | `components/ui/{feature}/` |
+| Cross-feature non-UI | `components/shared/` |
+| Feature non-UI | `components/{feature}/` |
+| Route logic | `components/ui/{feature}/{Feature}Page.tsx` |
+| App routes | `app/**/page.tsx` — **thin wrapper only** |
+
+## Thin page pattern
+
+```tsx
+'use client';
+import { PatientsPage } from '@/components/ui/patient/PatientsPage';
+export default function Page() {
+  return <PatientsPage />;
+}
+```
+
+Reference: `app/.../treatment/page.tsx` + `components/ui/treatment/TreatmentWorkspace.tsx`.
+
+## Do not
+
+- Put React components (`.tsx` with JSX) in `components/` outside `ui/`.
+- Put pure helpers (`.ts`, no JSX) inside `components/ui/`.
+- Put business logic, API calls, or large forms directly in `app/**/page.tsx`.
+
+## API & errors
+
+- API clients: `lib/api/`.
+- Catch blocks: `getUserFacingError(err, tErrors, fallback)` from `components/shared/formatApiError.ts`.
+
+## When adding UI
+
+1. Check `components/ui/shared/` for an existing primitive.
+2. Check the feature's `ui/{feature}/` folder for an existing pattern.
+3. Add i18n keys to en, fa, and nl.

.cursor/rules/maintain-agent-docs.mdc

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+---
+description: When and how to update AGENTS.md, rules, and skills after new conventions
+alwaysApply: true
+---
+
+# Maintaining agent docs
+
+Rules and skills **load automatically** but **do not self-update**. Update them when the user establishes a durable convention.
+
+## Update when the user says (or clearly means)
+
+- "Remember this" / "Save as convention" / "Add to project rules"
+- "Document this for future agents"
+- "We always do X in this project" (and it is not already in rules/skills)
+
+## Where to put new knowledge
+
+| Kind of knowledge | Update |
+|-------------------|--------|
+| Always true, 1–5 bullets | `.cursor/rules/*.mdc` (pick existing file or create new, <50 lines) |
+| Multi-step workflow | `.cursor/skills/{name}/SKILL.md` |
+| Project map / onboarding | `AGENTS.md` (index only — link to rules/skills) |
+
+## Do not auto-update when
+
+- One-off task instructions ("fix this bug today")
+- Experimental code not yet agreed as standard
+- User did not ask to persist the pattern
+
+## After updating
+
+- Keep rules concise; split if a file grows past ~50 lines.
+- Tell the user which file(s) changed in one sentence.
+
+Use skill `.cursor/skills/capture-convention/` for the full workflow.