# CI Parallelization Design

## Overview

Parallelize GitHub Actions workflows to reduce total CI time by running independent tasks concurrently and sharing build artifacts between jobs.

## Scope

- ci.yml
- release.yml
- staging.yml
- nightly.yml

## Approach

Use artifact sharing to avoid redundant builds. Frontend build artifacts are uploaded once and downloaded by dependent jobs.

## Design

### ci.yml

1. **Remove lighthouse dependency** - currently waits for frontend unnecessarily
2. **Upload frontend artifact** - `frontend` job uploads `dist/`
3. **Download artifact in test jobs** - `integration`, `e2e`, `regression` download instead of rebuilding
4. **Split quality job** into 3 parallel jobs:
   - `coverage` - runs tests with coverage, uploads to Codecov
   - `bundle-size` - checks bundle size limits
   - `security` - runs npm audit

Job graph:
```
commitlint ──────┐
frontend ────────┼──► integration
backend ─────────┤
                 ├──► e2e
                 ├──► regression
                 │
lighthouse ──────┘ (parallel, no deps)

coverage ──────── (parallel)
bundle-size ───── (parallel)
security ──────── (parallel)
```

### release.yml

Split monolithic job into parallel jobs:

1. **lint** - runs npm run lint
2. **frontend-test** - runs npm run test:run
3. **backend-test** - runs backend npm test
4. **build** - waits for lint + tests, uploads dist artifact
5. **release** - semantic-release (waits for build)
6. **docker** - unchanged, waits for release

Job graph:
```
lint ──────────┐
frontend-test ─┼──► build ──► release ──► docker
backend-test ──┘
```

### staging.yml

Split into 2 jobs:

1. **test** - lint + frontend tests + backend tests in parallel steps
2. **deploy** - waits for test, builds and pushes docker

Job graph:
```
test ──► deploy
```

### nightly.yml

Split into 2 jobs:

1. **build** - builds frontend, uploads artifact
2. **docker** - waits for build, pushes docker image

Job graph:
```
build ──► docker
```

## Implementation Notes

- Use `actions/upload-artifact@v4` and `actions/download-artifact@v4`
- Artifact retention: 1 day (sufficient for workflow duration)
- No changes to actual test/build logic, only workflow structure

## Implementation Complete

- [x] Task 1: ci.yml lighthouse parallelization and artifact sharing
- [x] Task 2: ci.yml quality job split into parallel jobs
- [x] Task 3: release.yml parallel lint, frontend-test, backend-test, build, release
- [x] Task 4: staging.yml split into test and deploy jobs
- [x] Task 5: nightly.yml split into build and docker jobs