# Architecture Decision Records

We record every significant architectural decision as an ADR following the
[Michael Nygard format](https://cognitect.com/blog/2011/11/15/documenting-architecture-decisions):
**Context → Decision → Consequences**, plus a status line.

Statuses: `Proposed` → `Accepted` → (`Deprecated` | `Superseded by ADR-XXXX`).
ADRs are immutable once accepted; to change course, write a new ADR that
supersedes the old one. New ADRs are proposed via pull request and accepted by
maintainer consensus.

## Index

| ADR | Title | Status |
|---|---|---|
| [0001](0001-monorepo-layout.md) | Monorepo with separate backend and frontend apps | Accepted |
| [0002](0002-django-backend.md) | Django 5.2 LTS + DRF over FastAPI for the backend | Accepted |
| [0003](0003-nextjs-frontend.md) | Next.js + TypeScript + Tailwind + shadcn/ui for the frontend | Accepted |
| [0004](0004-postgresql-primary-store.md) | PostgreSQL as the single primary datastore | Accepted |
| [0005](0005-structured-json-content.md) | Structured JSON block content over raw HTML or MDX source files | Accepted |
| [0006](0006-immutable-version-snapshots.md) | Immutable full-snapshot versioning with fork lineage | Accepted |
| [0007](0007-meilisearch.md) | Meilisearch for MVP search | Accepted |
| [0008](0008-redis-celery.md) | Redis + Celery for cache and background jobs | Accepted |
| [0009](0009-iframe-widget-sandbox.md) | Sandboxed cross-origin iframes + postMessage for widgets | Accepted |
| [0010](0010-code-execution-sandbox.md) | Dedicated judge service with container isolation for code challenges | Accepted |
| [0011](0011-auth-strategy.md) | Django session auth + django-allauth OAuth; token auth for the public API | Accepted |
| [0012](0012-agplv3-platform-license.md) | AGPLv3 for platform code | Accepted |
| [0013](0013-cc-by-sa-content-license.md) | CC BY-SA 4.0 as the default content license | Accepted |
| [0014](0014-katex-math-rendering.md) | KaTeX over MathJax for math rendering | Accepted |
| [0015](0015-s3-compatible-storage.md) | S3-compatible object storage (MinIO dev / R2 or S3 prod) | Accepted |
| [0016](0016-i18n-strategy.md) | Translations as sibling content versions; UI catalogs via standard i18n tooling | Accepted |
| [0017](0017-audit-log-postgres.md) | Append-only audit log in partitioned PostgreSQL tables | Accepted |
| [0018](0018-rest-over-graphql.md) | REST + OpenAPI over GraphQL for the public API | Accepted |
| [0019](0019-spaced-repetition-sm2.md) | SM-2 variant for spaced repetition scheduling | Accepted |
| [0020](0020-docker-compose-deployment.md) | Docker Compose for dev; single-host Docker prod first, Kubernetes optional | Accepted |

## Template

```markdown
# ADR-NNNN: Title

- Status: Proposed | Accepted | Superseded by ADR-XXXX
- Date: YYYY-MM-DD
- Deciders: <names/handles>

## Context
## Decision
## Consequences
### Positive
### Negative / risks
### Alternatives considered
```