Add contributor workflow guide

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

CONTRIBUTING.md

@@ -0,0 +1,83 @@
+# Contributing to Hyperbrowser Python SDK
+
+Thanks for contributing! This guide keeps local development and CI behavior aligned.
+
+## Prerequisites
+
+- Python `>=3.9`
+- `pip`
+
+## Local setup
+
+```bash
+python -m pip install -e . pytest ruff build
+```
+
+Or with Make:
+
+```bash
+make install
+```
+
+## Development workflow
+
+1. Create a focused branch.
+2. Make a single logical change.
+3. Run relevant tests first (targeted), then full checks before opening a PR.
+4. Keep commits small and descriptive.
+
+## Commands
+
+### Linting and formatting
+
+```bash
+python -m ruff check .
+python -m ruff format --check .
+```
+
+Or:
+
+```bash
+make lint
+make format-check
+```
+
+### Tests
+
+```bash
+python -m pytest -q
+```
+
+Or:
+
+```bash
+make test
+```
+
+### Full local CI parity
+
+```bash
+make ci
+```
+
+This runs lint, format checks, compile checks, tests, and package build.
+
+## Testing guidance
+
+- Add tests for any bug fix or behavior change.
+- Keep sync/async behavior in parity where applicable.
+- Prefer deterministic unit tests over network-dependent tests.
+
+## Code quality conventions
+
+- Prefer explicit error messages with `HyperbrowserError`.
+- Preserve `original_error` for wrapped runtime failures.
+- Avoid mutating user-provided input payloads.
+- Keep sync and async manager APIs aligned.
+
+## Pull request checklist
+
+- [ ] Lint and format checks pass.
+- [ ] Tests pass locally.
+- [ ] New behavior is covered by tests.
+- [ ] Public API changes are documented in `README.md` (if applicable).

README.md

@@ -247,6 +247,8 @@ make check
 make ci
 ```
 
+Contributor workflow details are available in [CONTRIBUTING.md](CONTRIBUTING.md).
+
 ## Examples
 
 Ready-to-run examples are available in `examples/`: