docs: add a contributing guide and a documentation index

CONTRIBUTING.md

@@ -0,0 +1,72 @@
+# Contributing to CodeGraph
+
+Thanks for helping out. Small, focused changes are the easiest to review and land.
+
+**Reporting a bug?** Open an [issue](https://github.com/colbymchenry/codegraph/issues) with your CodeGraph version (`codegraph --version`), Node.js version, operating system, the steps to reproduce it, what you expected, and what happened instead. A small public repository or snippet that shows the problem helps most.
+
+**Asking for a feature?** Describe the use case and why what's there today doesn't cover it.
+
+## Build from source
+
+You need Git, npm, and Node.js 22.5 or later, below 25. Running from source uses Node's built-in `node:sqlite`; the published installers bundle their own Node, so this only matters here.
+
+```bash
+# Fork the repository on GitHub, then:
+git clone https://github.com/<your-username>/codegraph.git
+cd codegraph
+git remote add upstream https://github.com/colbymchenry/codegraph.git
+
+npm ci
+npm run build
+```
+
+A globally installed `codegraph` doesn't run your changes, so run your build directly:
+
+```bash
+node dist/bin/codegraph.js --help    # the build as it stands
+npm run cli -- status                # rebuild first, then run a command
+npm run dev                          # recompile TypeScript on every save
+```
+
+`npm run build` covers the CLI, the SQL schema, the parser grammars and the browser viewer. Two builds are separate:
+
+- `npm run build:kernel` builds the optional native extraction kernel, and needs a Rust toolchain. Tests that need the kernel are skipped without it.
+- `npm run build:lib` builds the viewer's component library.
+
+## Test your change
+
+```bash
+npx vitest run __tests__/extraction.test.ts                   # one file
+npx vitest run __tests__/extraction.test.ts -t "TypeScript"   # tests matching a name
+npm run test:watch                                            # rerun as you edit
+npm test                                                      # everything
+```
+
+Run the focused tests while you work, then `npm test` before opening a pull request. Tests that run the compiled CLI use `dist/`, and the test setup rebuilds it first when it's stale.
+
+- **Tests live in `__tests__/`** and use real files and real SQLite databases, with no database mocking. Create temporary folders with `fs.mkdtempSync` and remove them in `afterEach`.
+- **A bug fix needs a test that fails without the fix.**
+- **Behavior that differs by platform** gets a gated test, such as `it.runIf(process.platform === 'win32')(...)`, and needs checking on the platforms it affects. See [cross-platform validation](AGENTS.md#cross-platform-validation).
+- **New language or framework support** needs validating on real repositories. Start with the `/add-lang` skill in [`.claude/skills/add-lang/SKILL.md`](.claude/skills/add-lang/SKILL.md), then follow the [validation methodology](docs/AGENTS.md#validation-methodology-required-for-every-new-languageframework) and the [coverage playbook](docs/design/dynamic-dispatch-coverage-playbook.md). Before extending a router or web framework, read [framework coverage](docs/design/framework-coverage.md).
+- **A documentation-only change** doesn't need the test suite. Check its examples and links instead.
+
+## Prepare a pull request
+
+- Branch from the latest `main`, and keep to one concern. Unrelated formatting, CI or feature work belongs in its own pull request.
+- Name commits `type(scope): what now works`, such as `fix(go): a constant in a const ( … ) group keeps its own doc comment`. Types in use are `feat`, `fix`, `docs`, `test`, `perf`, `chore` and `ci`.
+- In the description, explain the problem, the resulting behavior, and what you ran, including any failures and any platform you couldn't test.
+- Keep existing CLI commands and the default MCP tools working, unless the pull request exists to change them and says why.
+- Add a line to `CHANGELOG.md` under `## [Unreleased]`, in `### New Features` or `### Fixes`, for anything a user would notice. Write one plain sentence about what changed for them, without internal file names or benchmark numbers. Changes to the `codegraph ui` viewer, which isn't released yet, go in [`docs/viewer-launch-changelog.md`](docs/viewer-launch-changelog.md) instead.
+- Don't bump the version, and change `package-lock.json` only when you add or remove a dependency.
+- Use public or made-up examples. Keep local paths, private code and machine-specific settings out of fixtures.
+
+## What happens next
+
+A maintainer reads every change closely before anything lands, and may ask for changes. Keep your branch up to date by rebasing on `main`.
+
+A maintainer may also land your contribution as their own commit, rewritten where needed, instead of merging your branch. You're credited in the changelog either way.
+
+## Find your way around
+
+- [Documentation index](docs/README.md): guides, design notes and benchmarks.
+- [AGENTS.md](AGENTS.md): the architecture and the development rules, which [CLAUDE.md](CLAUDE.md) imports for Claude Code.

README.md

@@ -68,6 +68,7 @@ Follow [@getcodegraph](https://x.com/getcodegraph) on X for updates.
 - [Supported Languages](#supported-languages)
 - [Measured cross-file coverage](#measured-cross-file-coverage)
 - [Troubleshooting](#troubleshooting)
+- [Contributing](#contributing)
 - [License](#license)
 
 ## Get Started
@@ -903,6 +904,10 @@ Framework routing is validated the same way, on a canonical app per framework: E
 
 **Very large repositories (hundreds of thousands of files), or a large `.codegraph/codegraph.db-wal` file** — The `-wal` file is SQLite's write-ahead log: writes waiting to be folded into `codegraph.db`. While a big index is being built, CodeGraph lets it grow in proportion to the index (soft threshold = the larger of 256 MB and a quarter of the index size, up to 2 GB) before folding it back, because folding too often is what made large indexes slow on ordinary disks. At rest it is trimmed to 64 MB, and a leftover from a killed session is folded and trimmed the next time the project opens — the index itself has no size limit. Two environment variables tune this: `CODEGRAPH_WAL_VALVE_MB` (the soft threshold during indexing) and `CODEGRAPH_WAL_HEAL_MB` (the resting size and the trim threshold). `CODEGRAPH_WAL_VALVE_DEBUG=1` prints every decision to stderr.
 
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md) to build from source, test a change and prepare a pull request. The [documentation index](docs/README.md) links to the project's guides and design notes.
+
 ## License
 
 MIT

docs/README.md

@@ -0,0 +1,26 @@
+# Documentation
+
+To install and use CodeGraph, start with the [project README](../README.md). To build it and send a change, see [Contributing](../CONTRIBUTING.md).
+
+## Guides
+
+| Topic | Where to start |
+|-------|----------------|
+| Architecture, build rules and platform validation | [Project guide](../AGENTS.md) |
+| Distribution and release packaging | [Bundling](../BUNDLING.md) |
+| What telemetry collects, and how to turn it off | [Telemetry](../TELEMETRY.md) |
+| Release history | [Changelog](../CHANGELOG.md) |
+| Entries held for the viewer's launch | [Viewer changelog](viewer-launch-changelog.md) |
+| What languages and frameworks cover, and what's left | [Framework coverage](design/framework-coverage.md) |
+| Validating a language or framework on real repositories | [Validation guide](AGENTS.md) and [coverage playbook](design/dynamic-dispatch-coverage-playbook.md) |
+| Checking a language by hand | [Language verification guide](SEARCH_QUALITY_LOOP.md) |
+| The browser viewer's design | [Viewer design spec](design/codegraph-ui-design-spec.md) |
+| The native extraction kernel | [Kernel design](design/native-extraction-kernel.md) |
+
+## Supporting material
+
+- [Design](design/): architecture notes and feature proposals. Some describe planned work rather than what has shipped.
+- [Benchmarks](benchmarks/): measurements and how they were taken. Read each against the revision and setup it records.
+- [Grammars](grammars/): notes and patches for the parser grammars CodeGraph builds itself.
+- [Plans](plans/): implementation plans.
+- [Discussion notes](from-chat/): supporting notes from design discussions.