aecbff0de81f6e69a367cbb0e726f754f77eab13
Driven by a retail FIFA 17 capture: the client sends the WHOLE squad on
every save (~2KB, every slot/item/kit number), and a user swapping two
players produced nine changed slots across two saves. Slot deltas
therefore do not describe intent, so the only honest semantic operation
is "this is the squad now".
replace_squad, and why save_squad no longer has its own write path
------------------------------------------------------------------
save_squad UPDATEd the squad, DELETEd every squad_players row, then
INSERTed the new ones one at a time -- all outside a transaction. A
failure part-way through left a squad with some old players deleted and
only some new ones written: a state nobody asked for and no client can
detect. It also never checked that the cards being placed belonged to the
club, and accepted the same card in two slots.
replace_squad validates BEFORE any write (so a rejection leaves the
stored squad untouched) and performs every write in one transaction:
- card must exist AND belong to this club
- a card may occupy at most one slot
- a slot may hold at most one card
- slot indices must not be negative
- the squad being replaced must belong to this club
save_squad is now a thin wrapper over it. That deliberately tightens the
existing Core REST route -- it now validates ownership and rejects
duplicates. Those were bugs, and two write paths with different
guarantees is how the stricter one gets bypassed.
A cross-club card is reported as NotFound, not Forbidden: whether a card
exists in someone else's club is not the caller's business.
Game-rules boundary
-------------------
Core contained calculate_chemistry -- a full FUT-style link-scoring
formula. Chemistry is game-specific and changed between FIFA
generations, so a formula compiled into generic Core quietly makes Core a
FIFA-something server.
It now sits behind SquadRules, with the existing implementation preserved
byte-for-byte in behaviour as DefaultSquadRules ("openfut-default-v2").
Rules take a resolved SquadSnapshot of pure data rather than a pool and a
card database, so they are synchronous, testable without fixtures, and
cannot reach Core's storage. Fifa17SquadRules is deliberately NOT
written: the algorithm is unproven and inventing one is worse than having
none.
Client-reported values
----------------------
FIFA sends its own chemistry/rating/starRating. ClientReportedEvaluation
is a DIFFERENT TYPE from SquadEvaluation, so assigning one where the
other belongs does not compile. Disagreement is reported through
EvaluationComparison and never reconciled in either direction -- the
server's value stands and the mismatch is surfaced for investigation
against the exact squad that produced it.
Evidence
--------
17 unit tests, 113 in the crate, 7/7 mutations killed including
"ownership check removed", "replacement becomes a merge" and
"client-reported chemistry becomes the server value".
Scope note: `cargo fmt` without -p reformatted ~27 unrelated files; those
were reverted so this commit touches only the squad path.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
OpenFUT Core
Offline Ultimate Team backend — game-independent.
OpenFUT Core is the heart of the OpenFUT project: a fully offline, single-player FUT-style backend written in Rust. It is deliberately decoupled from any specific game, though it is designed to power a FIFA 23 offline experience.
What it does
- Creates and manages local player profiles and clubs
- Manages coins, XP, and progression
- Generates packs from weighted JSON definitions
- Tracks your full card collection
- Squad builder with formations and chemistry (chemistry calculations: WIP)
- Objectives engine (daily, weekly, lifetime, milestone)
- SBC (Squad Building Challenge) engine with JSON-defined challenges
- Match result processing with coin and XP rewards
- NPC transfer market with daily refreshes
- Statistics tracking
- Fully moddable via JSON data files
Tech Stack
- Rust + Axum (HTTP framework)
- Tokio (async runtime)
- SQLite + SQLx (database + migrations)
- Serde (JSON data layer)
- tower-http (middleware: CORS, tracing)
Quick Start
# Build
cargo build --release
# Run (creates openfut.db in current directory)
./target/release/openfut-core
# Or with custom config
DATABASE_URL=sqlite://./myclub.db LISTEN_ADDR=127.0.0.1:8080 ./target/release/openfut-core
Environment Variables
| Variable | Default | Description |
|---|---|---|
LISTEN_ADDR |
127.0.0.1:8080 |
Address to listen on |
DATABASE_URL |
sqlite://openfut.db |
SQLite database path |
DATA_DIR |
data |
Path to JSON data files |
API Routes
| Method | Path | Description |
|---|---|---|
GET |
/health |
Health check |
POST |
/auth/local |
Create first-run profile + club |
GET |
/profile |
Get active profile |
GET |
/club |
Get active club with coins |
GET |
/cards |
Browse all card definitions |
GET |
/collection |
Get owned cards |
GET |
/packs |
List unopened packs |
POST |
/packs/open/:pack_id |
Open a pack |
GET |
/squad |
Get active squad |
POST |
/squad |
Save squad |
GET |
/objectives |
List objectives with progress |
POST |
/matches/result |
Submit match result + receive rewards |
GET |
/sbc |
List SBC definitions |
POST |
/sbc/submit |
Submit SBC solution |
GET |
/market |
Browse NPC transfer market |
POST |
/market/buy |
Buy listing |
POST |
/market/sell |
Quick-sell card |
POST |
/market/refresh |
Refresh NPC listings |
GET |
/statistics |
Get match/pack/SBC stats |
First Run
# Create your profile
curl -X POST http://localhost:8080/auth/local \
-H 'Content-Type: application/json' \
-d '{"username": "Player 1"}'
# Check your club (5000 coins + a gold pack waiting)
curl http://localhost:8080/club
# Open your starter pack
curl -X POST http://localhost:8080/packs/open/<pack_id>
# Submit a match win
curl -X POST http://localhost:8080/matches/result \
-H 'Content-Type: application/json' \
-d '{"squad_id":"any","opponent_name":"Beginner AI","goals_for":3,"goals_against":0,"mode":"squad_battles"}'
Modding
All game content lives in data/. Drop JSON files into the appropriate folder and restart.
data/
cards/ ← CardDefinition[]
packs/ ← PackDefinition[]
objectives/ ← ObjectiveDefinition[]
sbcs/ ← SbcDefinition[]
events/ ← (future)
See docs/modding.md for schema reference.
Development
cargo fmt
cargo clippy -- -D warnings
cargo test
License
MIT — see LICENSE
Description
Languages
Rust
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