Add CODEOWNERS, branch protection, and updated contributor guide with dev branch flow

Author: vignesh2027

.github/CODEOWNERS

@@ -0,0 +1,2 @@
+# All changes must be reviewed by the project author
+* @vignesh2027

CONTRIBUTING.md

@@ -1,51 +1,71 @@
 # Contributing to VORTEXRAG
 
-Thank you for your interest in contributing! Every improvement helps make RAG systems more faithful.
+Thanks for wanting to contribute! Here's everything you need to know.
 
-## Ways to contribute
+## Branch structure
 
-- **Bug reports** — open an issue with the bug report template
-- **Feature requests** — open an issue with the feature request template
-- **Code contributions** — fork the repo, make changes, open a PR
-- **Documentation** — improve README, examples, or docstrings
-- **Benchmarks** — run VORTEXRAG on new datasets and share results
+```
+main          ← stable, protected — only reviewed PRs merge here
+dev           ← integration branch — your PR targets this
+feat/*        ← feature branches (e.g. feat/beir-benchmark)
+fix/*         ← bug fix branches (e.g. fix/sdc-threshold)
+```
+
+**Always open your PR against `dev`, not `main`.** Once reviewed and merged into `dev`, it gets merged into `main` from there.
+
+If you're working on an open issue:
+1. Fork the repo
+2. Create a branch: `git checkout -b feat/your-feature`
+3. Make your changes + add tests
+4. Open a PR targeting the `dev` branch
+5. Comment on the issue so it gets assigned to you
 
 ## Getting started
 
 ```bash
 git clone https://github.com/vignesh2027/VORTEXRAG
 cd VORTEXRAG
 pip install -r requirements.txt
-python3 -m pytest tests/ -q   # all 229 should pass
+python3 -m pytest tests/ -q   # 247 tests should pass
 ```
 
 ## Before submitting a PR
 
-1. **Tests must pass**: `python3 -m pytest tests/ -q`
-2. **Lint must be clean**: `ruff check core/ vortexrag.py --select=E,F --ignore=E501,F401`
-3. **Add tests** for any new behaviour
-4. **Keep the math correct** — any change to a layer formula must match the paper (DOI: 10.5281/zenodo.20579702)
+1. Tests must pass: `python3 -m pytest tests/ -q`
+2. Lint must be clean: `ruff check core/ vortexrag.py --select=E,F --ignore=E501,F401`
+3. Add tests for any new behaviour
+4. If you change a layer formula, it must match the paper (DOI: [10.5281/zenodo.20579702](https://doi.org/10.5281/zenodo.20579702))
 
 ## Project structure
 
 ```
 core/
-  tve.py   # Layer 1 — Tri-Vector Encoding
-  vrc.py   # Layer 2 — Vortex Retrieval Cone
-  sdc.py   # Layer 3 — Semantic Drift Corrector
-  cpg.py   # Layer 4 — Context Poison Guard
-  rfg.py   # Layer 5 — Rank Fusion Gate
-  ccb.py   # Layer 6 — Causal Context Builder
-  fv.py    # Layer 7 — Faithfulness Verifier
-vortexrag.py   # Top-level pipeline
-tests/         # 229 unit + integration tests
-paper/         # LaTeX source + compiled PDF
+  tve.py        # Layer 1 — Tri-Vector Encoding
+  vrc.py        # Layer 2 — Vortex Retrieval Cone
+  sdc.py        # Layer 3 — Semantic Drift Corrector
+  cpg.py        # Layer 4 — Context Poison Guard
+  rfg.py        # Layer 5 — Rank Fusion Gate
+  ccb.py        # Layer 6 — Causal Context Builder
+  fv.py         # Layer 7 — Faithfulness Verifier
+vortexrag.py    # Top-level pipeline
+integrations/   # LangChain, LlamaIndex wrappers
+benchmarks/     # BEIR and other eval scripts
+tests/          # 247 unit + integration tests
+paper/          # LaTeX source + PDF
 ```
 
+## Open issues for new contributors
+
+| Issue | Branch to target | Difficulty |
+|-------|-----------------|-----------|
+| [BEIR benchmark script](https://github.com/vignesh2027/VORTEXRAG/issues/3) | `feat/beir-benchmark` | Good first issue |
+| [LangChain integration](https://github.com/vignesh2027/VORTEXRAG/issues/4) | `feat/langchain-integration` | Good first issue |
+| [Biomedical domain preset](https://github.com/vignesh2027/VORTEXRAG/issues/5) | `dev` | Easy |
+
 ## Recognition
 
-All contributors are listed in the GitHub contributors graph. Significant contributions will be acknowledged in the project README.
+Every merged contributor shows up in the [GitHub contributors graph](https://github.com/vignesh2027/VORTEXRAG/graphs/contributors).
 
 ## Questions?
 
-Open a [Question issue](https://github.com/vignesh2027/VORTEXRAG/issues/new?template=question.md) — happy to help.
+Open a [Question issue](https://github.com/vignesh2027/VORTEXRAG/issues/new?template=question.md).