To Be Played – Core Service

Business service of To Be Played, a Steam backlog tracker. It syncs the user's Steam library, stores the backlog (status, rating, notes, priority), tracks playtime per day, syncs the wishlist and adds time-to-beat data from IGDB.

To Be Played is split into three repositories:

Repository	Role
ToBePlayed-Auth	Users, login, settings, signs JWTs
ToBePlayed-Core (this one)	Steam library, backlog, wishlist, stats; verifies JWTs
ToBePlayed-Frontend	React single-page app

Features

• Steam sync: owned games, playtime and achievements through the Steam Web API. Manual sync plus a nightly sync. Resilience4j retries and rate-limits every Steam call; Caffeine caches game counts and player summaries.
• Backlog: status (BACKLOG, PLAYING, FINISHED, COMPLETED = 100 %, DROPPED), rating 1–5, notes, priority, filters and sorting. "Pile of Shame" summary with a random suggestion of what to play.
• Picker: up to 10 random backlog games for a time budget (IGDB normal time to beat), HIGH priority first, then MEDIUM, then the rest. Games already shown can be excluded for a reroll.
• Achievements: after every library sync a background job fetches the achievement schema of each owned game and the user's unlocks of each game whose playtime changed. One Steam call per second, so user requests keep half of the rate limit; it stops after 3 Steam errors in a row or when Steam hides the achievements. A Steam error never overwrites stored data. Summary: unlocked total, perfect games, average completion over started games, the 5 games closest to 100 %.
• Playtime history: one row per game and day, for the activity view and the "most played in the last two weeks" dashboard banner.
• Wishlist: synced from Steam with store price and discount.
• Time to beat: story, extras and completionist hours from the IGDB API. Optional: without credentials the feature is off and the rest works.
• Public profile data: totals, status counts, games in progress and finished games with rating, perfect games and average completion. Readable only with a profile ticket issued by Auth. Never returns notes, priority or the Steam ID.

Authentication

Core never issues tokens. It verifies Auth's EdDSA (Ed25519) JWTs with public keys only. It loads them from Auth's JWKS by the token's kid and loads again when a new kid shows up (at most every 10 seconds). Loaded keys stay until Core restarts. JWT_PUBLIC_KEY is used only until the first JWKS load works. Core reads userId and steamId from the claims. A token with a typ claim (for example a profile ticket) is rejected on normal endpoints; the profile ticket is accepted only by GET /api/public/profiles/library in the X-Profile-Ticket header.

API

Method	Path	Auth
GET	/api/library/games, /api/library/games/{appid}	JWT
PUT	/api/library/games/{appid}/backlog	JWT
PUT	/api/library/games/{appid}/status (status only, keeps rating, notes, priority)	JWT
POST	/api/library/sync	JWT
GET	/api/library/picker?maxMinutes=&count=&exclude=	JWT
GET	/api/library/achievements/summary	JWT
GET	/api/library/sync-status, /summary, /activity, /wishlist, /steam-profile, /games-count	JWT
GET	/api/public/profiles/library	profile ticket
GET	/api/stats/public	public

Tech stack

• Java 25, Spring Boot 4.1 (Web MVC, Security, Data JPA, Validation, Cache with Caffeine), virtual threads
• PostgreSQL 17, Flyway migrations
• Resilience4j: retry and rate limiter for Steam, rate limiter for IGDB
• JJWT with Ed25519 public key
• Spring Boot Actuator + Micrometer (Prometheus)
• Tests: JUnit 5, Testcontainers (PostgreSQL), ArchUnit
• CI: Forgejo Actions, multi-stage Docker image

Architecture

A modular monolith. Each module under core_service.modules is a vertical slice that could move to its own service later:

Module	Content
library	Sync, backlog, playtime history, wishlist, public profile data
stats	Public numbers for the landing page
steam_adapter	Steam Web API client
igdb_adapter	IGDB client (Twitch OAuth)

Inside a module: api (controllers, DTOs), service (business logic), domain (JPA entities) and repo (Spring Data repositories). ArchUnit enforces cycle freedom, controller-to-repository direction, naming and module isolation in src/test/java/core_service/architecture/ArchitectureTest.java.

Run locally

Needs Java 25 and Docker.

./mvnw spring-boot:run -Dspring-boot.run.profiles=dev

Spring Boot's Docker Compose support starts PostgreSQL from compose.yaml, Flyway applies the migrations, and the service listens on http://localhost:8090. Health: /actuator/health, metrics: /actuator/prometheus.

In the dev profile a request without an Authorization header gets a dummy user, so the API is usable without a running Auth service.

Configuration comes from environment variables:

Variable	Purpose
JWT_JWKS_URL	Auth's /.well-known/jwks.json
JWT_PUBLIC_KEY	Ed25519 public key (Base64 of the X.509 DER bytes), used until the first JWKS load. Set this, JWT_JWKS_URL, or both
STEAM_API_KEY	Steam Web API key
IGDB_CLIENT_ID, IGDB_CLIENT_SECRET	Twitch app for IGDB (optional)
DB_PASSWORD	Local PostgreSQL password

Tests

./mvnw clean verify

Runs unit, WebMvc, persistence and integration tests plus the ArchUnit rules. Needs Docker for Testcontainers.

Roadmap

• Mood filter for the picker (needs genres or themes from IGDB).
• Sale alerts for wishlist games.
• Move steam_adapter DTOs out of api, then turn on strict module independence in ArchUnit.

License

All rights reserved. The source is public for reading only.