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+# Contributing to Benefit Decision Toolkit
+
+Thank you for your interest in contributing! BDT is a volunteer-driven open source project run by [Code for Philly](https://codeforphilly.org/projects/dmn_benefit_toolbox-including_the_philly_property_tax_relief_screener). We welcome contributions of all kinds — code, documentation, bug reports, design feedback, and DMN eligibility rules.
+
+## Table of Contents
+
+- [Ways to Contribute](#ways-to-contribute)
+- [Project Structure](#project-structure)
+- [Development Environment Setup](#development-environment-setup)
+- [Running the Project](#running-the-project)
+- [Making Changes](#making-changes)
+- [Testing](#testing)
+- [Code Style](#code-style)
+- [Submitting a Pull Request](#submitting-a-pull-request)
+- [Working with DMN Files](#working-with-dmn-files)
+- [Deployment (Maintainers)](#deployment-maintainers)
+- [Getting Help](#getting-help)
+
+---
+
+## Ways to Contribute
+
+- **Bug reports**: Open a GitHub issue with steps to reproduce
+- **Feature requests**: Open a GitHub issue describing the use case
+- **Code**: Fix bugs, implement features, improve tests
+- **Documentation**: Improve guides, fix typos, add examples
+- **DMN rules**: Add or improve eligibility rules in `library-api`
+- **Testing PRs**: Review and test open pull requests — see the [Codespaces Testing Guide](docs/testing-prs-with-codespaces.md) (no local setup needed!)
+
+---
+
+## Project Structure
+
+This is a monorepo with four distinct applications:
+
+```
+benefit-decision-toolkit/
+├── library-api/          # Quarkus + Kogito: DMN files → REST APIs (Java 17)
+├── builder-api/          # Quarkus: Admin backend, Firebase integration (Java 21)
+├── builder-frontend/     # Solid.js: Admin UI + public screener interface
+├── website/              # Public project website
+├── docs/                 # User and developer documentation
+├── e2e/                  # Playwright end-to-end tests
+├── bin/                  # Developer helper scripts
+├── .github/              # GitHub Actions workflows
+├── devbox.json           # Development environment declaration (Nix)
+└── process-compose.yml   # Multi-service orchestration for local dev
+```
+
+**Important**: `library-api` targets **Java 17 bytecode + Quarkus 2.16.10** (required for Kogito), while `builder-api` uses **Java 21 + Quarkus 3.23.0**. Devbox provides JDK 21 for both — Maven compiles `library-api` with `--release 17` automatically.
+
+---
+
+## Development Environment Setup
+
+See the [README](README.md#development-setup) for full setup instructions covering Codespaces, Devbox, Devcontainer, and DIY options.
+
+---
+
+## Running the Project
+
+### Start All Services
+
+```bash
+# Starts all 5 services in the correct dependency order
+devbox services up
+```
+
+This orchestrates (in order):
+1. **Firebase Emulators** — Auth (9099), Firestore (8080), Storage (9199), UI (4000)
+2. **library-api** — REST API from DMN files at http://localhost:8083
+3. **sync-library-metadata** — Syncs library check metadata to Firebase emulators
+4. **builder-api** — Admin API (port configured via `QUARKUS_HTTP_PORT`)
+5. **builder-frontend** — Vite dev server at http://localhost:5173
+
+> **Do not start services out of order.** `builder-api` depends on Firebase emulators being fully ready, and the metadata sync step must complete before `builder-api` starts.
+
+### Running Individual Services
+
+If you're only working on one part of the stack:
+
+```bash
+# library-api only (no Firebase dependency)
+cd library-api && quarkus dev
+# Swagger UI: http://localhost:8083/q/swagger-ui
+
+# Firebase emulators (required before builder-api)
+firebase emulators:start --project demo-bdt-dev --only auth,firestore,storage
+
+# builder-api (after emulators are running)
+cd builder-api && quarkus dev
+
+# builder-frontend (after builder-api is running)
+cd builder-frontend && npm run dev
+```
+
+### Service URLs
+
+| Service | URL |
+|---|---|
+| builder-frontend | http://localhost:5173 |
+| builder-api | http://localhost:8081 |
+| library-api | http://localhost:8083 |
+| library-api Swagger UI | http://localhost:8083/q/swagger-ui |
+| Firebase Emulator UI | http://localhost:4000 |
+
+---
+
+## Making Changes
+
+### Branching
+
+Create a feature branch from `main`:
+
+```bash
+git checkout main
+git pull
+git checkout -b your-feature-name
+```
+
+Use descriptive branch names, e.g. `fix-dmn-evaluation-edge-case` or `add-snap-eligibility-check`.
+
+### Commits
+
+Write clear, descriptive commit messages. Focus on *what* changed and *why*:
+
+```
+# Good
+fix: handle null income value in eligibility check
+
+# Good
+feat: add SNAP benefit eligibility check for Philadelphia
+
+# Avoid
+fix stuff
+update
+```
+
+### Syncing Library Metadata After library-api Changes
+
+If you modify DMN files in `library-api`, re-sync metadata so `builder-api` picks up the changes:
+
+```bash
+# Re-sync metadata
+./bin/library/sync-metadata
+
+# Then restart builder-api (in the process-compose UI, restart the process)
+```
+
+---
+
+## Testing
+
+### Java Unit Tests
+
+```bash
+# builder-api
+cd builder-api && mvn test
+
+# library-api
+cd library-api && mvn test
+```
+
+These run automatically in CI on every push and pull request that touches `builder-api/` or `library-api/`.
+
+### Bruno API Tests (library-api)
+
+[Bruno](https://www.usebruno.com/) is used to test the DMN-generated REST endpoints in `library-api`. The test suite lives in `library-api/test/bdt/` and mirrors the DMN file structure.
+
+```bash
+# Run all Bruno tests
+cd library-api/test/bdt && bru run
+```
+
+**When adding a new benefit or check to `library-api`, add Bruno tests first** (test-driven development). Bruno tests validate DMN logic, while Java tests validate internal application behavior.
+
+### End-to-End Tests (Playwright)
+
+```bash
+# Run e2e tests (requires all services to be running)
+cd e2e && npx playwright test
+```
+
+E2E tests run automatically in CI. They start all services via `devbox services up` and run against them.
+
+### Before Submitting a PR
+
+- [ ] Run Java unit tests for any service you modified
+- [ ] Run Bruno tests if you modified `library-api` DMN files
+- [ ] Verify your changes work end-to-end with all services running
+- [ ] Run Prettier on changed frontend files (see [Code Style](#code-style))
+
+---
+
+## Code Style
+
+### JavaScript / TypeScript (builder-frontend)
+
+The project uses [Prettier](https://prettier.io/) for formatting. Configuration is in `.prettierrc`:
+
+```json
+{
+  "semi": true,
+  "singleQuote": false,
+  "trailingComma": "all",
+  "tabWidth": 2
+}
+```
+
+Format changed files before committing:
+
+```bash
+# Format a specific file
+npx prettier --write path/to/file.tsx
+
+# Format all frontend files
+cd builder-frontend && npx prettier --write "src/**/*.{ts,tsx,js,jsx}"
+```
+
+### Java (builder-api, library-api)
+
+Follow standard Java conventions. The project includes a VS Code Java formatter config at `.vscode/java.format.xml` — if you use VS Code with the Java extension, this will be picked up automatically. Otherwise, match the style of the surrounding code.
+
+### DMN Files
+
+- File names: `kebab-case.dmn`
+- Decision Service names: `{ModelName}Service` (e.g., a file named `snap-benefit.dmn` → Decision Service named `SnapBenefitService`)
+- Model names must be **globally unique** across the entire `library-api` — check existing names before adding a new DMN file
+- Imported decision services cannot share names even if in different models
+
+---
+
+## Submitting a Pull Request
+
+1. Push your branch and open a PR against `main`
+2. Write a clear PR description: what changed, why, and how to test it
+3. All PRs require review from at least one maintainer (@Michael-Dratch or @prestoncabe — see [CODEOWNERS](.github/CODEOWNERS))
+4. CI runs API unit tests and E2E tests automatically — check that they pass
+5. For changes to `library-api` DMN files, include Bruno test results or a description of manual testing
+
+**For non-technical contributors** testing a PR: follow the [Codespaces Testing Guide](docs/testing-prs-with-codespaces.md) — no local setup needed.
+
+---
+
+## Working with DMN Files
+
+DMN (Decision Model and Notation) is the core technology used for eligibility logic in this project. If you're new to DMN, start here:
+- [Learn DMN in 15 minutes](https://learn-dmn-in-15-minutes.com/)
+- [DMN Editor for VS Code](https://marketplace.visualstudio.com/items?itemName=kie-group.dmn-vscode-extension) (strongly recommended)
+
+### Adding a Benefit to library-api
+
+Benefits represent specific programs (e.g., SNAP, property tax relief). They define eligibility logic using DMN and automatically become REST endpoints.
+
+1. **Write Bruno tests first** in `library-api/test/bdt/benefits/{jurisdiction}/{benefit-name}/`
+2. Create a DMN file: `library-api/src/main/resources/benefits/{jurisdiction}/{benefit-name}.dmn`
+3. Define a Decision Service named `{BenefitName}Service`
+4. Include a `checks` context and an `isEligible` boolean decision
+5. Save — Quarkus dev mode hot-reloads and the endpoint appears at `POST /api/v1/benefits/{jurisdiction}/{benefit-name}`
+6. Verify in Swagger UI: http://localhost:8083/q/swagger-ui
+7. Run your Bruno tests: `cd library-api/test/bdt && bru run`
+
+### Adding a Reusable Check
+
+Checks are reusable decision logic that can be shared across multiple benefits.
+
+> **Tip**: Use the `/new-dmn-check` Claude Code (CC) command to generate the boilerplate DMN file and Bruno test stubs automatically.
+
+1. Create a DMN file: `library-api/src/main/resources/checks/{category}/{check-name}.dmn`
+2. Define a Decision Service named `{CheckName}Service`
+3. Standard inputs: `situation` (tSituation type), `parameters` (check-specific context)
+4. Standard output: `result` (boolean)
+5. Endpoint: `POST /api/v1/checks/{category}/{check-name}`
+
+### Key DMN Constraints
+
+- **Decision Service name must be `{ModelName}Service`** — this is required for automatic endpoint generation
+- **Model names are globally unique** — if two DMN files have the same model name, things break
+- Imported decision services cannot share names even across different files
+- Import `BDT.dmn` for shared types like `tSituation`
+
+### Editing DMN Files
+
+- Use the VS Code DMN Editor extension for visual editing
+- To see raw XML: right-click the file → "Reopen with Text Editor"
+- Changes are hot-reloaded in `quarkus dev` mode — no restart needed
+
+---
+
+## Deployment (Maintainers)
+
+### library-api
+
+Deployments are triggered by pushing a git tag matching `library-api-v*`. Use the provided script to create a release atomically:
+
+```bash
+cd library-api
+
+# Update pom.xml version and create git tag in one step
+./bin/tag-release 0.3.0
+
+# Review the changes
+git show
+
+# Push the commit and the tag (triggers GitHub Actions deployment)
+git push origin <your-branch>
+git push origin library-api-v0.3.0
+```
+
+The GitHub Actions workflow validates that the tag version matches `pom.xml`, builds the Docker image, pushes to Google Artifact Registry, deploys to Cloud Run, and syncs library metadata automatically.
+
+**Version source of truth**: `pom.xml`. The git tag, Docker image tag, and Cloud Run revision name all derive from it.
+
+### builder-api
+
+Deploys automatically to Cloud Run on every push to `main` that touches `builder-api/` files. No manual versioning needed.
+
+### builder-frontend and docs
+
+Deploy automatically to Firebase Hosting on push to `main`.
+
+### Production Library Metadata Sync (Manual)
+
+If you need to sync library metadata to production outside of a `library-api` deployment, trigger the **"Load Library API Metadata"** GitHub Actions workflow manually:
+
+1. Go to [Actions → Load Library API Metadata](../../actions/workflows/load-library-metadata.yml)
+2. Click **Run workflow** → **Run workflow**
+
+This is the recommended approach — it handles GCP authentication, runs the sync script against the production library-api, and automatically restarts `builder-api` to pick up the new metadata.
+
+---
+
+## Getting Help
+
+- **GitHub Issues**: For bugs and feature requests
+- **Code for Philly**: Join [codeforphilly.org](https://codeforphilly.org) to connect with the team
+- **Project maintainers**: @Michael-Dratch and @prestoncabe
+
+If you're stuck on setup, open an issue — improving the onboarding experience is itself a valuable contribution.