diff --git a/.github/copilot-instructions.md b/.github/copilot-instructions.md
new file mode 100644
index 0000000000..0f9a0eead9
--- /dev/null
+++ b/.github/copilot-instructions.md
@@ -0,0 +1,253 @@
+# Pylint Development Instructions
+
+Always follow these instructions first and fallback to additional search and context
+gathering only if the information in these instructions is incomplete or found to be in
+error.
+
+## Issue Label Guidelines
+
+Before attempting to fix any issue, check the GitHub issue labels using the GitHub API:
+
+- If an issue is labeled with "Astroid", "Needs astroid update", "Needs astroid
+  constraint", or "Needs astroid Brain 🧠", **ONLY** create regression tests
+- Do **NOT** attempt to fix astroid-related issues as you cannot modify astroid from
+  this repository
+- For astroid-related issues, focus on creating comprehensive regression tests that
+  reproduce the problem
+- All other issues can be fixed normally following the standard development workflow
+
+## Development Environment Setup
+
+### Basic Installation
+
+Clone and set up pylint development environment:
+
+- `git clone https://github.com/pylint-dev/pylint` -- clone repository
+- `cd pylint` -- enter directory
+- `python3 -m venv venv` -- create virtual environment
+- `source venv/bin/activate` -- activate virtual environment (Linux/Mac)
+- `pip install -r requirements_test_min.txt` -- install test dependencies (~30 seconds)
+- `pip install -e .` -- install pylint in editable mode (~30-60 seconds)
+
+### Optional Setup Steps
+
+- `pre-commit install` -- enable pre-commit hooks for autoformatting
+- `pip install pre-commit` -- install pre-commit separately if needed
+
+### Astroid Development (if needed)
+
+If working on astroid changes:
+
+- `git clone https://github.com/pylint-dev/astroid.git` -- clone astroid
+- `pip install -e astroid/` -- install astroid in editable mode
+- `cd astroid/ && git switch my-astroid-dev-branch` -- switch to development branch
+
+## Running Tests
+
+### Core Test Commands
+
+- `pytest tests/test_functional.py -k test_functional` -- run functional tests (~60
+  seconds, NEVER CANCEL, set timeout to 120+ seconds)
+- `pytest tests/` -- run all tests (several minutes, NEVER CANCEL, set timeout to 300+
+  seconds)
+- `python3 -m pytest` -- run tests with local python
+- `pytest tests/test_check_parallel.py -v` -- quick test file (~2 seconds)
+
+### Specific Test Types
+
+- **Functional tests:**
+  `pytest "tests/test_functional.py::test_functional[missing_kwoa_py3]"` -- single
+  functional test (~1 second)
+- **Unit tests:** Located in `/tests/` directory, test specific pylint functionality
+- **Configuration tests:** In `/tests/config/functional/` for testing configuration
+  loading
+- **Primer tests:** `pytest -m primer_stdlib --primer-stdlib` -- test on stdlib for
+  crashes
+
+### Test with Coverage
+
+- `pytest tests/message/ --cov=pylint.message` -- run with coverage
+- `coverage html` -- generate HTML coverage report
+
+### Tox Usage (Optional)
+
+- `python -m tox` -- run all tox environments
+- `python -m tox -epy313` -- run Python 3.13 suite only
+- `python -m tox -epylint` -- run pylint on pylint's codebase
+- `python -m tox -eformatting` -- run formatting checks
+- `python -m tox --recreate` -- recreate environments (recommended)
+- `python -m tox -e py310 -- -k test_functional` -- run specific tests in tox
+
+## Documentation
+
+### Building Documentation
+
+- `make -C doc/ install-dependencies` -- install doc dependencies (~10 seconds)
+- `make -C doc/ html` -- build documentation (~3 minutes, NEVER CANCEL, set timeout to
+  300+ seconds)
+- `make -C doc/ clean` -- clean build files when starting from scratch
+- `tox -e docs` -- alternative way to build docs
+
+**Network dependency:** Documentation build requires internet access to fetch external
+inventories.
+
+## Validation and Quality Checks
+
+### Running Pylint on Code
+
+- `pylint --help` -- verify pylint installation works
+- `pylint --disable=all --enable=E,F pylint/` -- run pylint on itself for errors only
+  (~20 seconds)
+- `pylint --rcfile=pylintrc --fail-on=I path/to/your/changes.py` -- standard pylint run
+- `pylint --disable=all --enable=E,F,W path/to/your/changes.py` -- focus on errors and
+  warnings
+
+### Pre-commit and Formatting
+
+- `pre-commit run --all-files` -- run all formatting checks (requires network for
+  initial setup)
+- **Network dependency:** pre-commit may fail in isolated environments due to hook
+  downloads
+
+### Validation Test Scenarios
+
+Always test your changes with these validation scenarios:
+
+- `echo "def badFunction(): pass" > /tmp/test_sample.py && pylint --enable=C0103 /tmp/test_sample.py`
+  -- should find naming issues
+- `pylint --help` and `pylint --list-msgs | head -10` -- verify CLI functionality
+- `pylint --help-msg=C0103` -- should show invalid-name help
+- `pylint --rcfile=pylintrc --fail-on=I pylint/__init__.py` -- should get 10.00/10
+  rating
+
+## Writing Tests
+
+### Functional Tests
+
+Located in `/tests/functional/`, consists of `.py` test files with corresponding `.txt`
+expected output files:
+
+- Annotate lines where messages are expected:
+  `a, b, c = 1 # [unbalanced-tuple-unpacking]`
+- Multiple messages on same line:
+  `a, b, c = 1.test # [unbalanced-tuple-unpacking, no-member]`
+- Use offset syntax for special cases: `# +1: [singleton-comparison]`
+- **Run and update:**
+  `python tests/test_functional.py --update-functional-output -k "test_functional[test_name]"`
+
+### Test File Organization
+
+- **New checkers:** Create `new_checker_message.py` in `/tests/functional/n/`
+- **Extensions:** Place in `/tests/functional/ext/extension_name/`
+- **Regression tests:** Place in `/tests/r/regression/` with `regression_` prefix
+- **Configuration tests:** Place in `/tests/config/functional/`
+
+### Configuration Test Files
+
+Create `.result.json` files with configuration differences from standard config:
+
+```json
+{
+  "functional_append": {
+    "disable": [["a-message-to-be-added"]]
+  },
+  "jobs": 10
+}
+```
+
+## Codebase Structure
+
+```
+pylint/                    # Main package
+├── checkers/             # All pylint checkers (rules implementation)
+├── config/               # Configuration handling and parsing
+├── message/              # Message system and formatting
+├── reporters/            # Output formatters (text, json, etc.)
+├── testutils/            # Testing utilities and helpers
+└── extensions/           # Optional extensions and plugins
+
+tests/                     # Test suite
+├── functional/           # Functional test files (.py + .txt expected output)
+├── config/functional/    # Configuration functional tests
+├── r/regression/         # Regression tests
+├── test_*.py            # Unit tests
+└── regrtest_data/       # Test data files
+
+doc/                      # Documentation
+├── user_guide/          # User documentation
+├── development_guide/   # Developer and contributor documentation
+│   ├── contributor_guide/    # Setup, testing, contribution guidelines
+│   ├── technical_reference/  # Technical implementation details
+│   └── how_tos/             # Guides for custom checkers, plugins
+└── additional_tools/    # Tools documentation
+
+script/                   # Development utility scripts
+```
+
+### Key Files
+
+- `pyproject.toml` -- Main configuration (dependencies, build, tools)
+- `tox.ini` -- Multi-environment testing configuration
+- `.pre-commit-config.yaml` -- Code quality checks configuration
+- `pylintrc` -- Pylint's own configuration
+- `requirements_test_min.txt` -- Minimal test dependencies
+
+## Creating New Checkers
+
+### Getting Started
+
+- `python script/get_unused_message_id_category.py` -- get next available message ID
+- Study existing checkers in `pylint/checkers/` for patterns
+- Read technical reference documentation in `doc/development_guide/technical_reference/`
+- Use `astroid.extract_node` for AST manipulation
+
+### Workflow
+
+1. Create checker class in appropriate `pylint/checkers/` file
+2. Add functional tests in `tests/functional/`
+3. Search existing code for warning message to find where logic exists
+4. Test with sample code to ensure functionality works
+
+## Pull Request Guidelines
+
+### Before Submitting
+
+- Use Python 3.8+ for development (required for latest AST parser and pre-commit hooks)
+- Write comprehensive commit messages relating to tracker issues
+- Keep changes small and separate consensual from opinionated changes
+- Add news fragment: `towncrier create <IssueNumber>.<type>`
+- Always launch `pre-commit run -a` before committing
+
+### Documentation Changes
+
+- Document non-trivial changes
+- Generate docs with `tox -e docs`
+- Maintainers may label issues `skip-news` if no changelog needed
+
+### Contribution Credits
+
+- Add emails/names to `script/.contributors_aliases.json` if using multiple identities
+
+## Critical Timing Information
+
+- **NEVER CANCEL:** All operations that show "NEVER CANCEL" may take significant time
+- **Full test suite:** 60+ seconds (set timeout to 120+ seconds)
+- **Documentation build:** 180 seconds (set timeout to 300+ seconds)
+- **Functional tests:** 60 seconds (set timeout to 120+ seconds)
+- **Pylint self-check:** 20 seconds (set timeout to 60+ seconds)
+- **Individual test files:** 1-15 seconds
+- **Installation steps:** 30-60 seconds each
+
+## Environment Limitations and Workarounds
+
+- **Network connectivity required:** Documentation build and pre-commit setup require
+  internet access
+- **Tox failures:** In isolated environments, use direct pytest and pip commands instead
+  of tox
+- **Import errors in self-check:** Some import errors when running pylint on itself are
+  expected (git dependencies not installed)
+- **Build environments:** Use direct pip/pytest commands when tox environments fail to
+  build
+
+Always validate your changes by running pylint on sample code to ensure functionality
+works correctly.
diff --git a/pyproject.toml b/pyproject.toml
index d16b274573..39293df7f4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -33,7 +33,8 @@ classifiers = [
   "Typing :: Typed",
 ]
 dynamic = [ "version" ]
-
+# All the dependencies of the project will be configured here, once pip fully supports PEP735
+# TODO: Remove all requirements.txt files and use this section instead once pip supports PEP735
 dependencies = [
   # Also upgrade requirements_test_min.txt.
   # Pinned to dev of second minor update to allow editable installs and fix primer issues,
@@ -50,8 +51,10 @@ dependencies = [
   "tomlkit>=0.10.1",
   "typing-extensions>=3.10; python_version<'3.10'",
 ]
+
 optional-dependencies.spelling = [ "pyenchant~=3.2" ]
 optional-dependencies.testutils = [ "gitpython>3" ]
+
 urls."Bug Tracker" = "https://github.com/pylint-dev/pylint/issues"
 urls."Discord Server" = "https://discord.com/invite/Egy6P8AMB5"
 urls."Docs: Contributor Guide" = "https://pylint.readthedocs.io/en/latest/development_guide/contributor_guide/index.html"
@@ -64,6 +67,44 @@ scripts.pylint-config = "pylint:_run_pylint_config"
 scripts.pyreverse = "pylint:run_pyreverse"
 scripts.symilar = "pylint:run_symilar"
 
+[dependency-groups]
+dev = [
+  "contributors-txt>=1",
+  "pre-commit",
+  "tbump~=6.11.0",
+]
+
+test = [
+  "coverage~=7.8",
+  "pytest-cov~=6.0",
+  "pytest-xdist~=3.6",
+  "six",
+  "tox>=3",
+  "types-setuptools==78.1.0.20250329",
+  { include-group = "test-min" },
+]
+
+docs = [
+  "furo==2024.8.6",
+  "sphinx==8.2.3",
+  "sphinx-reredirects<1",
+  "towncrier~=24.8",
+]
+
+# Configuration for the build system
+test-min = [
+  # Base test dependencies
+  "astroid==4.0.0a0",                   # Pinned to a specific version for tests
+  "py~=1.11.0",
+  "pytest~=8.3",
+  "pytest-benchmark~=5.1",
+  "pytest-timeout~=2.3",
+  "requests",
+  "setuptools; python_version>='3.12'",
+  "towncrier~=24.8",
+  "typing-extensions~=4.12",
+]
+
 [tool.setuptools.packages.find]
 include = [ "pylint*" ]