diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
new file mode 100644
index 000000000000..40430cc5bce8
--- /dev/null
+++ b/.github/copilot-instructions.md
@@ -0,0 +1,337 @@
+# OpenProject Coding Agent Instructions
+
+## Repository Overview
+
+**OpenProject** is a web-based, open-source project management software written in Ruby on Rails. It uses PostgreSQL for data persistence and supports features like project planning, task management, Agile/Scrum, time tracking, wikis, and forums.
+
+- **Size**: Large monorepo (~840MB, ~1M+ lines of code)
+- **History**: Originally forked from Redmine over a decade ago, evolved significantly as an independent project
+- **Backend**: Ruby 3.4.5, Rails ~8.0.3
+- **Frontend**: Node.js 22.15.0, npm 10.1.0+, TypeScript
+- **Database**: PostgreSQL (required)
+- **Architecture**: Server-rendered HTML with Hotwire (Turbo + Stimulus). Legacy Angular components exist and are being migrated to custom elements. Uses GitHub's Primer Design System via ViewComponent.
+- **Editions**: OpenProject comes in Community and Enterprise editions
+  - **Enterprise Edition**: Includes additional features like Single sign-on (OIDC & SAML), LDAP, Nextcloud integration, SCIM API, and more (requires token for development)
+  - **BIM Edition**: Tailored for construction industry needs. Code in `modules/bim/`, docs in `docs/bim-guide/`. Existing instances can be switched to BIM edition.
+
+## Critical Setup Requirements
+
+### Ruby and Node Versions
+**ALWAYS verify versions before building:**
+- Ruby: `3.4.5` (see `.ruby-version`)
+- Node: `^22.15.0` (see `package.json` engines)
+- Bundler: Latest 2.x
+
+### Development Environment Options
+
+**Docker (Recommended for Quick Start)**
+```bash
+# ALWAYS run these commands in sequence:
+cp .env.example .env
+cp docker-compose.override.example.yml docker-compose.override.yml
+docker compose run --rm backend setup
+docker compose run --rm frontend npm install
+docker compose up -d backend
+# Access at http://localhost:3000
+```
+
+**Local Development Setup**
+```bash
+# Install dependencies (ALWAYS run in this order):
+bundle install                    # Install Ruby gems
+cd frontend && npm ci && cd ..   # Install Node packages (use 'ci' not 'install' for reproducibility)
+bundle exec rake db:migrate      # Setup database
+bundle exec rails openproject:plugins:register_frontend assets:export_locales
+
+# Start services (use bin/dev for all-in-one):
+bin/dev                          # Starts Rails, frontend dev server, and Good Job worker
+# OR manually:
+# Terminal 1: bundle exec rails server
+# Terminal 2: npm run serve
+# Terminal 3: bundle exec good_job start
+```
+
+**Important**: The `config/database.yml` file MUST NOT exist when using Docker. Delete or rename it if present.
+
+## Building and Testing
+
+### Linting (Run Before Committing)
+
+**Ruby (Rubocop)**
+```bash
+bundle exec rubocop                          # Check all files
+bin/dirty-rubocop --uncommitted              # Check only uncommitted changes
+bin/dirty-rubocop --uncommitted --force-exclusion {files}  # Check specific files
+```
+
+**JavaScript/TypeScript (ESLint)**
+```bash
+cd frontend
+npx eslint src/                              # Lint all frontend code
+cd ..
+```
+
+**ERB Templates (erb_lint)**
+```bash
+erb_lint {files}                             # Lint ERB template files
+```
+
+**Install Git Hooks** (optional but recommended):
+```bash
+bundle exec lefthook install                 # Sets up pre-commit hooks for linting
+```
+
+### Running Tests
+
+**Backend Tests (RSpec)**
+```bash
+# Run specific tests (ALWAYS preferred over running all tests):
+bundle exec rspec spec/models/user_spec.rb              # Single file
+bundle exec rspec spec/models/user_spec.rb:42           # Single line
+bundle exec rspec spec/features                         # Directory
+
+# Run all tests (slow, ~40 minutes on CI):
+bundle exec rspec
+
+# Parallel execution (faster):
+bundle exec rake parallel:spec
+
+# With Docker:
+docker compose run --rm backend-test "bundle exec rspec spec/features/work_package_show_spec.rb"
+```
+
+**Frontend Tests (Jasmine/Karma)**
+```bash
+cd frontend
+npm test                                     # Run all frontend unit tests
+npm run test:ci                             # Run in CI mode (single run)
+cd ..
+```
+
+**Debugging Failed GitHub Actions Tests**
+```bash
+# Extract and run all failed tests from CI:
+./script/github_pr_errors
+./script/github_pr_errors | xargs bundle exec rspec
+
+# Run flaky tests multiple times:
+./script/bulk_run_rspec spec/path/to/flaky_spec.rb
+```
+
+### Running the Application Locally
+
+**Development Mode**
+```bash
+bin/dev                                      # Uses Overmind or Foreman to start all services
+# Access at http://localhost:3000
+```
+
+**Individual Services**
+```bash
+bundle exec rails server                    # Rails backend (port 3000)
+npm run serve                               # Frontend dev server (proxied through Rails)
+bundle exec good_job start                  # Background job worker
+```
+
+## Project Structure
+
+### Key Directories
+- `app/` - Rails application code (models, controllers, services, views, components)
+  - `app/components/` - ViewComponent-based UI components (Ruby + ERB)
+  - `app/contracts/` - Validation and authorization contracts
+  - `app/controllers/` - Rails controllers
+  - `app/models/` - ActiveRecord models
+  - `app/services/` - Service objects (business logic)
+  - `app/workers/` - Background job workers
+- `config/` - Rails configuration
+  - `config/application.rb` - Application configuration
+  - `config/locales/` - I18n translations
+  - `config/routes.rb` - Rails routes
+- `db/` - Database migrations and seeds
+- `docker/` - Docker build contexts
+- `frontend/src/` - Frontend
+  - `frontend/src/app/` - Angular modules, components, services (legacy Angular code)
+  - `frontend/src/main.ts` - Angular Application bootstrap entry point
+  - `frontend/src/react` - React components (currently only used for experimental BlockNote integration)
+  - `frontend/src/stimulus` - Stimulus controllers, helpers
+  - `frontend/src/turbo` - Turbo integration (e.g. custom Turbo Stream actions)
+- `lib/` - Ruby libraries and extensions
+- `lookbook/` - Lookbook component previews for ViewComponents (see https://github.com/lookbook-hq/lookbook)
+- `modules/` - OpenProject plugin modules
+- `spec/` - RSpec test suite
+  - `spec/features/` - System/feature tests (Capybara)
+  - `spec/models/` - Model unit tests
+  - `spec/requests/` - API/integration tests
+  - `spec/services/` - Service tests
+
+### Configuration Files
+- `.erb_lint.yml` - ERB template linting
+- `.rubocop.yml` - Ruby linting rules
+- `.ruby-version` - Ruby version (check this file for current version)
+- `docker-compose.yml` - Docker development environment
+- `frontend/eslint.config.mjs` - JavaScript/TypeScript linting
+- `Gemfile` / `Gemfile.lock` - Ruby dependencies
+- `lefthook.yml` - Git hooks configuration
+- `package.json` / `frontend/package.json` - Node.js dependencies
+- `Procfile.dev` - Services for `bin/dev`
+
+## GitHub Actions CI/CD
+
+### Main Workflows
+- **test-core.yml** - Main test suite (units + features, ~40 min, runs on all PRs)
+- **rubocop-core.yml** - Ruby linting (runs on all PRs with Ruby changes)
+- **eslint-core.yml** - JS/TS linting (runs on all PRs with JS/TS changes)
+- **test-frontend-unit.yml** - Frontend unit tests
+- **brakeman-scan-core.yml** - Security scanning
+- **codeql-scan-core.yml** - Code quality/security analysis
+
+### CI Requirements for Merge
+- All linting checks must pass (Rubocop, ESLint, erb_lint)
+- Test suite must be green
+- No security vulnerabilities introduced (Brakeman, CodeQL)
+
+**Skip CI**: Add `[ci skip]` to commit message to skip CI (use sparingly).
+
+## Common Issues and Workarounds
+
+### Database Configuration
+- **Issue**: Docker fails with "database.yml exists"
+- **Fix**: Delete or rename `config/database.yml` when using Docker
+
+### Memory Issues in Docker
+- **Issue**: Frontend container exits with status 137
+- **Fix**: Increase Docker memory limit to at least 4GB
+
+### Test Failures on CI but Passing Locally
+- Run with `CI=true` environment variable (eager loads app)
+- Check for `OPENPROJECT_*` environment variables
+- Match the random seed: `bundle exec rspec --seed 18352`
+- Use `--bisect` to find order-dependent failures
+- View browser tests with `OPENPROJECT_TESTING_NO_HEADLESS=1`
+
+### Frontend Build Issues
+- **Issue**: "jQuery not defined", frontend asset errors, or blank page
+- **Fix**: Run `bin/setup_dev` to rebuild frontend completely
+
+### Parallel Test Failures
+- Tests run in parallel on CI with different random seeds per group
+- Check `tmp/parallel_runtime.log` for execution times
+- **Flaky specs**: Some tests may fail randomly; see `docs/development/running-tests/` for handling flaky tests
+  - Use `script/bulk_run_rspec` to run tests multiple times to identify flaky behavior
+
+## Code Style Guidelines
+
+### Ruby
+- Follow [Ruby community style guide](https://github.com/bbatsov/ruby-style-guide)
+- Use service objects for complex business logic
+  - Return results using the `ServiceResult` class (well-documented in codebase)
+  - Some services use monads via [dry-monads](https://github.com/dry-rb/dry-monads) for result modeling
+- Use contracts for validation and authorization
+- Keep controllers thin, models focused
+- Document code units and patterns with [YARD](https://yardoc.org/)
+- Write tests for all new features (RSpec)
+  - Unit tests for models, services, and other components
+  - Feature specs use Capybara (with Cuprite and Selenium WebDriver)
+  - Feature specs can use A11y selectors ([capybara_accessible_selectors](https://github.com/citizensadvice/capybara_accessible_selectors)), test IDs, or page objects (in `spec/support/pages/`)
+
+### Database Migrations
+- Follow Rails migration conventions
+- OpenProject implements migration "squashing" between major releases
+- See `docs/development/migrations/` for details on the squashing process
+- Migrations are consolidated to manage database changes across major versions
+- OpenProject does not currently aim for zero downtime migrations
+
+### JavaScript/TypeScript
+- **New development**: Use Hotwire (Turbo + Stimulus) with server-rendered HTML
+- **Legacy code**: Follow ESLint recommended rules (eslint, typescript-eslint, Angular ESLint)
+- Prefer TypeScript over JavaScript
+- **Design system**: Use GitHub's [Primer Design System](https://primer.style/product/) via ViewComponent
+  - [primer_view_components](https://github.com/opf/primer_view_components) - OpenProject's fork of Primer Rails/ViewComponent
+  - [openproject-octicons](https://github.com/opf/openproject-octicons) - OpenProject's fork of Primer Octicons
+  - [commonmark-ckeditor-build](https://github.com/opf/commonmark-ckeditor-build) - Custom CKEditor build with CommonMark Markdown support
+- Write unit tests for components (Jasmine for legacy Angular, RSpec for ViewComponents)
+
+### Templates
+- Use ERB for server-rendered views
+- Use ViewComponents for reusable UI components
+  - Document new ViewComponents with API/Yard docs and Lookbook previews
+  - Lookbook deployed at: https://qa.openproject-edge.com/lookbook/
+  - See https://github.com/lookbook-hq/lookbook for Lookbook documentation
+- Lint with erb_lint before committing
+
+### Commit Messages
+- First line: < 72 characters
+- Blank line
+- Detailed description wrapped to 72 characters
+- Reference work packages when applicable
+- See [code review guidelines](docs/development/code-review-guidelines/) for more details
+- **Merge strategy**: Use "Merge pull request" (not squash) to retain commit history, except for single-commit PRs which can use "Rebase and merge"
+
+### Translations
+- OpenProject is a multilingual product with officially supported and community-supported languages
+- UI translations are managed via [Crowdin](https://crowdin.com/)
+- Don't modify translation files directly; contributions should go through Crowdin
+  - Exception: Source translations in `**/config/locales/en.yml` can be modified directly
+- UI strings should never be hard-coded; always use translation keys for accessibility and internationalization
+
+## Performance Considerations
+
+### CI Timeouts
+- Main test suite: 40 minutes timeout
+- Individual jobs: varies by type
+- Use parallel execution when available
+
+### Build Times
+- Full Docker build: ~10-15 minutes (first time)
+- Bundle install: ~2-5 minutes
+- npm install: ~3-7 minutes
+- Database setup: ~1-2 minutes
+- Asset compilation: ~30-40 seconds
+
+## Important Commands Reference
+
+```bash
+# Setup
+bin/setup              # Initial Rails setup (creates DB, runs migrations)
+bin/setup_dev          # Full dev environment setup (backend + frontend)
+
+# Database
+bundle exec rake db:migrate              # Run pending migrations
+bundle exec rake db:rollback             # Rollback last migration
+bundle exec rake db:seed                 # Seed database with sample data
+bundle exec rake db:migrate:status       # Check migration status
+
+# Testing
+bundle exec rspec                        # Run RSpec tests
+bundle exec rake parallel:spec           # Run tests in parallel
+cd frontend && npm test                  # Run frontend tests
+
+# Linting
+bundle exec rubocop                      # Ruby linting
+cd frontend && npx eslint src/           # JavaScript/TypeScript linting
+erb_lint {files}                         # ERB template linting
+
+# Development
+bin/dev                                  # Start all services
+bundle exec rails console                # Rails console
+bundle exec rails routes                 # List all routes
+
+# Docker
+bin/compose setup                        # Setup Docker environment
+bin/compose start                        # Start Docker services
+bin/compose run                          # Run with backend in foreground
+bin/compose rspec {test_file}            # Run tests in Docker
+```
+
+## Trust These Instructions
+
+These instructions are comprehensive and validated. Only search for additional information if:
+1. You encounter an error not documented here
+2. You need specific implementation details for a feature
+3. The instructions appear outdated (e.g., version mismatches)
+
+For any issues, consult:
+- `docs/development/` - Development documentation
+- `docs/development/running-tests/` - Testing guide
+- `docs/development/code-review-guidelines/` - Code review standards
+- `CONTRIBUTING.md` - Contribution workflow
diff --git a/.github/workflows/cla.yml b/.github/workflows/cla.yml
index bcd0ac1255c9..ff84b013a785 100644
--- a/.github/workflows/cla.yml
+++ b/.github/workflows/cla.yml
@@ -45,6 +45,7 @@ jobs:
             brunopagno,
             bsatarnejad,
             cbliard,
+            copilot[bot],
             corinnaguenther,
             crohr,
             dependabot[bot],