Add copilot instructions for team review

Author: PasiVuohijoki

.github/copilot-instructions.md

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+# Copilot Instructions for jore4-ui
+
+These instructions define how AI coding assistants should work in this repository.
+Follow them for all code edits unless the user explicitly asks otherwise.
+
+## 1) Repository context
+
+- Monorepo with Yarn workspaces.
+- Main workspaces:
+  - `ui` (main application)
+  - `cypress` (e2e tests)
+  - `codegen` (GraphQL code generation)
+  - `test-db-manager` (test DB tooling)
+  - `timetables-data-inserter` (submodule)
+- Prefer workspace-scoped commands (`yarn ws:...`) when possible.
+
+## 2) Default development workflow
+
+- Prefer day-to-day development flow:
+  - `yarn ws:ui dev`
+  - Run GraphQL generation manually when needed: `yarn ws:codegen generate`
+- Avoid defaulting to `yarn dev` for normal edits because continuous codegen can heavily degrade IDE performance.
+- If test-db seed data is changed, rebuild with `yarn ws:db build`.
+
+## 3) Environment and dependencies
+
+- For local backend dependencies, use `./scripts/development.sh` commands (for example `start:deps`, `setup:env`, `setup:test`, `stop`).
+- Do not introduce alternative local orchestration scripts if existing script targets are sufficient.
+- Assume UI runs on `http://localhost:3300` when using local dev server.
+
+## 4) Quality gates and verification
+
+Before finalizing a non-trivial change, run the smallest relevant checks first, then broaden only as needed:
+
+1. Targeted checks for changed area (tests/lint where applicable)
+2. Type checking: `yarn ts:check`
+3. Linting: `yarn lint` (or `yarn lint --fix` when safe)
+4. Formatting: `yarn prettier:check` (or `yarn prettier` when formatting is required)
+
+Use `yarn qa` for full local validation when appropriate.
+Use `yarn qa:fix` for automatic eslint/prettier fixes.
+
+## 5) Testing guidance
+
+- Unit/local tests: `yarn test`
+- Integration tests (require Hasura/deps running): `yarn test:integration`
+- E2E tests:
+  - Open mode: `yarn test:e2e:open`
+  - Headless: `yarn test:e2e`
+  - Tag filtering example: `yarn test:e2e --env grepTags=@routes`
+- For map-related Cypress reliability/speed, optionally set `CYPRESS_DISABLE_MAP_TILES=true`.
+- When adding or changing user-interactive UI elements, include stable `data-testid` attributes.
+
+## 6) GraphQL codegen rules
+
+- GraphQL typings are generated from Hasura schema and `gql` definitions.
+- Because generation is heavy in this repo, prefer manual generation after finishing query edits:
+  - `yarn ws:codegen generate`
+- Do not set up automatic codegen watch flows unless explicitly requested.
+
+## 7) Code style conventions
+
+### General
+
+- Keep changes minimal and scoped to the task.
+- Follow existing TypeScript/React patterns in the touched area.
+- Prefer editor/CI-aligned formatting and lint behavior over custom style choices.
+
+### Components
+
+- Avoid inline child components unless necessary; prefer extracted components.
+- Keep components composable and loosely coupled.
+
+### Imports
+
+- Prefer namespaced/barrel imports where available instead of fragmented deep imports.
+
+### Test IDs
+
+- Use `data-testid` for important interaction elements.
+- Follow naming convention: `ComponentName::camelCaseElementName`.
+- Define test IDs via a top-level `const testIds = { ... }` object instead of inline string literals where practical.
+
+### Tailwind class composition
+
+- Use `twJoin` for simple class concatenation and pass-through patterns.
+- Use `twMerge` as final composition step when conflicting utility classes are possible.
+- Do not rely on raw class order alone for override behavior.
+
+## 8) Workspace dependency management
+
+- Install workspace-specific dependencies into the correct workspace.
+- Install shared dependencies in repository root only when truly shared.
+- Do not move lint/prettier config out of root without explicit request.
+
+## 9) Git workflow
+
+- The user always makes git commits themselves. Never commit or offer to commit on behalf of the user.
+
+## 10) Operational guardrails for AI edits
+
+- Do not refactor unrelated areas.
+- Do not add new frameworks, state libraries, or architectural patterns without request.
+- Do not rewrite existing scripts when existing `yarn` and `development.sh` flows solve the task.
+- Keep generated-file churn minimal; regenerate only when required by changes.
+- When uncertain about behavior that depends on running services (Hasura, Docker stack, db seeds), state assumptions and choose the safest minimal change.
+- Avoid writing unnecessary comments. Explain your changes in chat instead of code comments.
+- Comments should be added only if they provide value beyond what the code itself can express. If you think a comment is needed, consider whether the code can be refactored to be more self-explanatory instead.
+
+## 11) Helpful commands reference
+
+- Dev UI only: `yarn ws:ui dev`
+- Full dev (heavy): `yarn dev`
+- GraphQL codegen: `yarn ws:codegen generate`
+- Build test DB manager: `yarn ws:db build`
+- Type check: `yarn ts:check`
+- Lint: `yarn lint`
+- Format check: `yarn prettier:check`
+- Full QA: `yarn qa`
+- Unit tests: `yarn test`
+- Integration tests: `yarn test:integration`
+- E2E tests: `yarn test:e2e`
+- Start dependencies: `./scripts/development.sh start:deps`
+- Stop dependencies: `./scripts/development.sh stop`