Rust Core — briefcase-core

The Rust core (briefcase-core) is the high-performance foundation of the Briefcase platform. All language bindings and the HTTP server are built on top of it.

Modules

Decision Models

Core data structures for recording AI decisions:

• DecisionSnapshot — Complete record of an AI decision (inputs, outputs, model parameters, execution context)
• Input / Output — Typed data with confidence scores
• ModelParameters — Model name, version, provider, and configuration
• ExecutionContext — Environment and runtime metadata

Replay Engine

Deterministic replay of recorded decisions with three modes:

Mode	Behavior
Strict	Byte-for-byte output match required
Tolerant	Allow formatting/whitespace differences
ValidationOnly	Validate context without re-execution

The engine uses the ModelExecutor trait, which consumers implement to re-run their model during replay.

Drift Detection

Identifies when model behavior changes over time:

• String Similarity — Levenshtein distance comparison
• Consensus Analysis — Detect output divergence across runs
• Outlier Detection — Flag anomalous outputs

Cost Tracking

Model pricing, cost estimation, and budget enforcement.

PII Sanitizer

Detects and redacts sensitive data: SSN, credit card numbers, email addresses, phone numbers, API keys, and IP addresses.

Storage Backends

All backends implement the StorageBackend trait:

trait StorageBackend {
    async fn save(&self, snapshot: DecisionSnapshot) -> Result<String>;
    async fn load(&self, id: &str) -> Result<DecisionSnapshot>;
    async fn query(&self, query: SnapshotQuery) -> Result<Vec<DecisionSnapshot>>;
    async fn delete(&self, id: &str) -> Result<bool>;
    async fn health_check(&self) -> Result<bool>;
}

Backend	Description	Use Case
SqliteBackend	File or in-memory SQLite with compression	Production (single-node)
LakeFSBackend	Versioned storage with branching and commits	Production (versioned)
MemoryBackend	In-memory HashMap	Testing

Feature Flags

[features]
default = ["async", "storage", "networking", "compression"]
async = ["tokio"]
storage = ["rusqlite"]
networking = ["reqwest"]
compression = ["flate2", "zstd"]
parallel = ["rayon"]
wasm = []
sync-only = []

Crate Dependencies

Core runtime, storage, and analysis dependencies used by briefcase-core.

Dependency groups:

• serialization: serde, serde_json
• runtime and I/O: tokio, reqwest, rusqlite
• model metadata: chrono, uuid
• analysis and validation: regex, strsim, sha2
• performance: flate2, zstd, optional rayon