# VaultMesh Code Templates

## Rust Templates

### Core Types

```rust
// Receipt Header
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReceiptHeader {
    pub receipt_type: String,
    pub timestamp: DateTime<Utc>,
    pub root_hash: String,
    pub tags: Vec<String>,
}

// Receipt Metadata
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReceiptMeta {
    pub scroll: Scroll,
    pub sequence: u64,
    pub anchor_epoch: Option<u64>,
    pub proof_path: Option<String>,
}

// Generic Receipt
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct Receipt<T> {
    #[serde(flatten)]
    pub header: ReceiptHeader,
    #[serde(flatten)]
    pub meta: ReceiptMeta,
    #[serde(flatten)]
    pub body: T,
}

// Scroll Enum
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
#[serde(rename_all = "snake_case")]
pub enum Scroll {
    Drills,
    Compliance,
    Guardian,
    Treasury,
    Mesh,
    OffSec,
    Identity,
    Observability,
    Automation,
    PsiField,
    Federation,
    Governance,
}

impl Scroll {
    pub fn jsonl_path(&self) -> &'static str {
        match self {
            Scroll::Drills => "receipts/drills/drill_runs.jsonl",
            Scroll::Compliance => "receipts/compliance/oracle_answers.jsonl",
            Scroll::Guardian => "receipts/guardian/anchor_events.jsonl",
            Scroll::Treasury => "receipts/treasury/treasury_events.jsonl",
            Scroll::Mesh => "receipts/mesh/mesh_events.jsonl",
            Scroll::OffSec => "receipts/offsec/offsec_events.jsonl",
            Scroll::Identity => "receipts/identity/identity_events.jsonl",
            Scroll::Observability => "receipts/observability/observability_events.jsonl",
            Scroll::Automation => "receipts/automation/automation_events.jsonl",
            Scroll::PsiField => "receipts/psi/psi_events.jsonl",
            Scroll::Federation => "receipts/federation/federation_events.jsonl",
            Scroll::Governance => "receipts/governance/governance_events.jsonl",
        }
    }

    pub fn root_file(&self) -> &'static str {
        match self {
            Scroll::Drills => "ROOT.drills.txt",
            Scroll::Compliance => "ROOT.compliance.txt",
            Scroll::Guardian => "ROOT.guardian.txt",
            Scroll::Treasury => "ROOT.treasury.txt",
            Scroll::Mesh => "ROOT.mesh.txt",
            Scroll::OffSec => "ROOT.offsec.txt",
            Scroll::Identity => "ROOT.identity.txt",
            Scroll::Observability => "ROOT.observability.txt",
            Scroll::Automation => "ROOT.automation.txt",
            Scroll::PsiField => "ROOT.psi.txt",
            Scroll::Federation => "ROOT.federation.txt",
            Scroll::Governance => "ROOT.governance.txt",
        }
    }
}
```

### DID Types

```rust
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq, Hash)]
pub struct Did(String);

impl Did {
    pub fn new(did_type: DidType, identifier: &str) -> Self {
        Did(format!("did:vm:{}:{}", did_type.as_str(), identifier))
    }

    pub fn parse(s: &str) -> Result<Self, DidParseError> {
        if !s.starts_with("did:vm:") {
            return Err(DidParseError::InvalidPrefix);
        }
        Ok(Did(s.to_string()))
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DidType {
    Node,
    Human,
    Agent,
    Service,
    Mesh,
}

impl DidType {
    pub fn as_str(&self) -> &'static str {
        match self {
            DidType::Node => "node",
            DidType::Human => "human",
            DidType::Agent => "agent",
            DidType::Service => "service",
            DidType::Mesh => "mesh",
        }
    }
}
```

### Hash Utilities

```rust
use blake3::Hasher;

#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Eq)]
pub struct VmHash(String);

impl VmHash {
    pub fn blake3(data: &[u8]) -> Self {
        let hash = blake3::hash(data);
        VmHash(format!("blake3:{}", hash.to_hex()))
    }

    pub fn from_json<T: Serialize>(value: &T) -> Result<Self, serde_json::Error> {
        let json = serde_json::to_vec(value)?;
        Ok(Self::blake3(&json))
    }

    pub fn hex(&self) -> &str {
        self.0.strip_prefix("blake3:").unwrap_or(&self.0)
    }

    pub fn as_str(&self) -> &str {
        &self.0
    }
}

pub fn merkle_root(hashes: &[VmHash]) -> VmHash {
    if hashes.is_empty() {
        return VmHash::blake3(b"empty");
    }
    if hashes.len() == 1 {
        return hashes[0].clone();
    }

    let mut current_level: Vec<VmHash> = hashes.to_vec();

    while current_level.len() > 1 {
        let mut next_level = Vec::new();
        for chunk in current_level.chunks(2) {
            let combined = if chunk.len() == 2 {
                format!("{}{}", chunk[0].hex(), chunk[1].hex())
            } else {
                format!("{}{}", chunk[0].hex(), chunk[0].hex())
            };
            next_level.push(VmHash::blake3(combined.as_bytes()));
        }
        current_level = next_level;
    }

    current_level.remove(0)
}
```

### Engine Template

```rust
// Template for new engine implementation
pub struct MyEngine {
    db: DatabasePool,
    receipts_path: PathBuf,
}

impl MyEngine {
    pub fn new(db: DatabasePool, receipts_path: PathBuf) -> Self {
        MyEngine { db, receipts_path }
    }

    pub async fn create_contract(&self, params: CreateParams) -> Result<Contract, EngineError> {
        let contract = Contract {
            id: generate_id("contract"),
            title: params.title,
            created_at: Utc::now(),
            // ... domain-specific fields
        };
        
        // Store contract
        self.store_contract(&contract).await?;
        
        Ok(contract)
    }

    pub async fn execute(&mut self, contract_id: &str) -> Result<State, EngineError> {
        let contract = self.load_contract(contract_id).await?;
        let mut state = State::new(&contract);
        
        // Execute steps
        for step in &contract.steps {
            state.execute_step(step).await?;
        }
        
        // Seal with receipt
        let receipt = self.seal(&contract, &state).await?;
        
        Ok(state)
    }

    async fn seal(&self, contract: &Contract, state: &State) -> Result<Receipt<MyReceipt>, EngineError> {
        let receipt_body = MyReceipt {
            contract_id: contract.id.clone(),
            status: state.status.clone(),
            // ... domain-specific fields
        };

        let root_hash = VmHash::from_json(&receipt_body)?;

        let receipt = Receipt {
            header: ReceiptHeader {
                receipt_type: "my_receipt_type".to_string(),
                timestamp: Utc::now(),
                root_hash: root_hash.as_str().to_string(),
                tags: vec!["my_engine".to_string()],
            },
            meta: ReceiptMeta {
                scroll: Scroll::MyScroll,
                sequence: 0,
                anchor_epoch: None,
                proof_path: None,
            },
            body: receipt_body,
        };

        self.append_receipt(&receipt).await?;
        
        Ok(receipt)
    }

    async fn append_receipt<T: Serialize>(&self, receipt: &Receipt<T>) -> Result<(), EngineError> {
        let scroll_path = self.receipts_path.join(Scroll::MyScroll.jsonl_path());
        
        let mut file = OpenOptions::new()
            .create(true)
            .append(true)
            .open(&scroll_path)?;
        
        let json = serde_json::to_string(receipt)?;
        writeln!(file, "{}", json)?;
        
        // Update Merkle root
        self.update_merkle_root().await?;
        
        Ok(())
    }
}
```

### Prometheus Metrics

```rust
use prometheus::{Counter, CounterVec, Histogram, HistogramVec, Gauge, GaugeVec, Opts, Registry};
use lazy_static::lazy_static;

lazy_static! {
    pub static ref REGISTRY: Registry = Registry::new();

    pub static ref RECEIPTS_TOTAL: CounterVec = CounterVec::new(
        Opts::new("vaultmesh_receipts_total", "Total receipts by scroll"),
        &["scroll", "type"]
    ).unwrap();

    pub static ref OPERATION_DURATION: HistogramVec = HistogramVec::new(
        prometheus::HistogramOpts::new(
            "vaultmesh_operation_duration_seconds",
            "Operation duration"
        ).buckets(vec![0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0, 10.0]),
        &["operation"]
    ).unwrap();

    pub static ref ACTIVE_OPERATIONS: GaugeVec = GaugeVec::new(
        Opts::new("vaultmesh_active_operations", "Active operations"),
        &["type"]
    ).unwrap();
}

pub fn register_metrics() {
    REGISTRY.register(Box::new(RECEIPTS_TOTAL.clone())).unwrap();
    REGISTRY.register(Box::new(OPERATION_DURATION.clone())).unwrap();
    REGISTRY.register(Box::new(ACTIVE_OPERATIONS.clone())).unwrap();
}
```

---

## Python Templates

### CLI Command Group

```python
import click
import json
from datetime import datetime
from pathlib import Path

@click.group()
def my_engine():
    """My Engine - Description"""
    pass

@my_engine.command("create")
@click.option("--title", required=True, help="Title")
@click.option("--config", type=click.Path(exists=True), help="Config file")
def create(title: str, config: str):
    """Create a new contract."""
    contract_id = f"contract-{datetime.utcnow().strftime('%Y%m%d%H%M%S')}"
    
    contract = {
        "id": contract_id,
        "title": title,
        "created_at": datetime.utcnow().isoformat() + "Z",
    }
    
    if config:
        with open(config) as f:
            contract.update(json.load(f))
    
    # Store contract
    contract_path = Path(f"cases/my_engine/{contract_id}/contract.json")
    contract_path.parent.mkdir(parents=True, exist_ok=True)
    with open(contract_path, "w") as f:
        json.dump(contract, f, indent=2)
    
    click.echo(f"✓ Contract created: {contract_id}")

@my_engine.command("execute")
@click.argument("contract_id")
def execute(contract_id: str):
    """Execute a contract."""
    # Load contract
    contract_path = Path(f"cases/my_engine/{contract_id}/contract.json")
    with open(contract_path) as f:
        contract = json.load(f)
    
    # Execute (implementation specific)
    state = {"status": "completed"}
    
    # Emit receipt
    receipt = emit_receipt(
        scroll="my_scroll",
        receipt_type="my_receipt_type",
        body={
            "contract_id": contract_id,
            "status": state["status"],
        },
        tags=["my_engine"]
    )
    
    click.echo(f"✓ Executed: {contract_id}")
    click.echo(f"  Receipt: {receipt['root_hash'][:20]}...")

@my_engine.command("query")
@click.option("--status", help="Filter by status")
@click.option("--from", "from_date", help="From date")
@click.option("--to", "to_date", help="To date")
@click.option("--format", "output_format", default="table", type=click.Choice(["table", "json", "csv"]))
def query(status: str, from_date: str, to_date: str, output_format: str):
    """Query receipts."""
    filters = {}
    if status:
        filters["status"] = status
    if from_date:
        filters["from_date"] = from_date
    if to_date:
        filters["to_date"] = to_date
    
    receipts = load_receipts("my_scroll", filters)
    
    if output_format == "json":
        click.echo(json.dumps(receipts, indent=2))
    else:
        click.echo(f"Found {len(receipts)} receipts")
        for r in receipts:
            click.echo(f"  {r.get('timestamp', '')[:19]} | {r.get('type', '')}")
```

### Receipt Utilities

```python
import json
import hashlib
from datetime import datetime
from pathlib import Path
from typing import Optional

def emit_receipt(scroll: str, receipt_type: str, body: dict, tags: list[str]) -> dict:
    """Create and emit a receipt to the appropriate scroll."""
    receipt = {
        "schema_version": "2.0.0",
        "type": receipt_type,
        "timestamp": datetime.utcnow().isoformat() + "Z",
        "tags": tags,
        **body
    }
    
    # Compute root hash
    receipt_json = json.dumps(receipt, sort_keys=True)
    root_hash = f"blake3:{hashlib.blake3(receipt_json.encode()).hexdigest()}"
    receipt["root_hash"] = root_hash
    
    # Append to scroll
    scroll_path = Path(f"receipts/{scroll}/{scroll}_events.jsonl")
    scroll_path.parent.mkdir(parents=True, exist_ok=True)
    
    with open(scroll_path, "a") as f:
        f.write(json.dumps(receipt) + "\n")
    
    # Update Merkle root
    update_merkle_root(scroll)
    
    return receipt

def load_receipts(scroll: str, filters: Optional[dict] = None) -> list[dict]:
    """Load and filter receipts from a scroll."""
    scroll_path = Path(f"receipts/{scroll}/{scroll}_events.jsonl")
    
    if not scroll_path.exists():
        return []
    
    receipts = []
    with open(scroll_path) as f:
        for line in f:
            receipt = json.loads(line.strip())
            
            if filters:
                match = True
                for key, value in filters.items():
                    if key == "from_date":
                        if receipt.get("timestamp", "") < value:
                            match = False
                    elif key == "to_date":
                        if receipt.get("timestamp", "") > value:
                            match = False
                    elif key == "type":
                        if receipt.get("type") not in (value if isinstance(value, list) else [value]):
                            match = False
                    elif receipt.get(key) != value:
                        match = False
                
                if match:
                    receipts.append(receipt)
            else:
                receipts.append(receipt)
    
    return receipts

def update_merkle_root(scroll: str):
    """Recompute and update Merkle root for a scroll."""
    scroll_path = Path(f"receipts/{scroll}/{scroll}_events.jsonl")
    root_file = Path(f"receipts/ROOT.{scroll}.txt")
    
    if not scroll_path.exists():
        root_file.write_text("blake3:empty")
        return
    
    hashes = []
    with open(scroll_path) as f:
        for line in f:
            receipt = json.loads(line.strip())
            hashes.append(receipt.get("root_hash", ""))
    
    if not hashes:
        root_file.write_text("blake3:empty")
        return
    
    # Simple merkle root (production would use proper tree)
    combined = "".join(h.replace("blake3:", "") for h in hashes)
    root = f"blake3:{hashlib.blake3(combined.encode()).hexdigest()}"
    root_file.write_text(root)

def verify_receipt(receipt_hash: str, scroll: str) -> bool:
    """Verify a receipt exists and is valid."""
    receipts = load_receipts(scroll, {"root_hash": receipt_hash})
    return len(receipts) > 0
```

### MCP Server Template

```python
from mcp.server import Server
from mcp.types import Tool, TextContent
import json

server = Server("my-engine")

@server.tool()
async def my_operation(
    param1: str,
    param2: int = 10,
) -> str:
    """
    Description of what this tool does.
    
    Args:
        param1: Description of param1
        param2: Description of param2
    
    Returns:
        Description of return value
    """
    # Verify caller capabilities
    caller = await get_caller_identity()
    await verify_capability(caller, "required_capability")
    
    # Perform operation
    result = perform_operation(param1, param2)
    
    # Emit receipt
    await emit_tool_call_receipt(
        tool="my_operation",
        caller=caller,
        params={"param1": param1, "param2": param2},
        result_hash=result.hash,
    )
    
    return json.dumps(result.to_dict(), indent=2)

@server.tool()
async def my_query(
    filter_param: str = None,
    limit: int = 50,
) -> str:
    """
    Query operation description.
    
    Args:
        filter_param: Optional filter
        limit: Maximum results
    
    Returns:
        Query results
    """
    caller = await get_caller_identity()
    await verify_capability(caller, "view_capability")
    
    results = query_data(filter_param, limit)
    
    return json.dumps([r.to_dict() for r in results], indent=2)

def main():
    import asyncio
    from mcp.server.stdio import stdio_server
    
    async def run():
        async with stdio_server() as (read_stream, write_stream):
            await server.run(
                read_stream,
                write_stream,
                server.create_initialization_options(),
            )
    
    asyncio.run(run())

if __name__ == "__main__":
    main()
```

---

## Property Test Templates

### Rust (proptest)

```rust
use proptest::prelude::*;

proptest! {
    /// Receipts roundtrip through serialization
    #[test]
    fn receipt_roundtrip(receipt in arb_receipt()) {
        let json = serde_json::to_string(&receipt)?;
        let restored: Receipt<serde_json::Value> = serde_json::from_str(&json)?;
        prop_assert_eq!(receipt.header.root_hash, restored.header.root_hash);
    }

    /// Hash is deterministic
    #[test]
    fn hash_deterministic(data in prop::collection::vec(any::<u8>(), 0..1000)) {
        let hash1 = VmHash::blake3(&data);
        let hash2 = VmHash::blake3(&data);
        prop_assert_eq!(hash1, hash2);
    }

    /// Different data produces different hashes
    #[test]
    fn different_data_different_hash(
        data1 in prop::collection::vec(any::<u8>(), 1..100),
        data2 in prop::collection::vec(any::<u8>(), 1..100)
    ) {
        prop_assume!(data1 != data2);
        let hash1 = VmHash::blake3(&data1);
        let hash2 = VmHash::blake3(&data2);
        prop_assert_ne!(hash1, hash2);
    }
}

fn arb_receipt() -> impl Strategy<Value = Receipt<serde_json::Value>> {
    (
        "[a-z]{5,20}",  // receipt_type
        any::<i64>().prop_map(|ts| DateTime::from_timestamp(ts.abs() % 2000000000, 0).unwrap()),
        prop::collection::vec("[a-z]{3,10}", 0..5),  // tags
    ).prop_map(|(receipt_type, timestamp, tags)| {
        Receipt {
            header: ReceiptHeader {
                receipt_type,
                timestamp,
                root_hash: "blake3:placeholder".to_string(),
                tags,
            },
            meta: ReceiptMeta {
                scroll: Scroll::Drills,
                sequence: 0,
                anchor_epoch: None,
                proof_path: None,
            },
            body: serde_json::json!({"test": true}),
        }
    })
}
```

### Python (hypothesis)

```python
from hypothesis import given, strategies as st
import json

@given(st.dictionaries(st.text(min_size=1, max_size=20), st.text(max_size=100), max_size=10))
def test_receipt_roundtrip(body):
    """Receipts survive JSON roundtrip."""
    receipt = emit_receipt("test", "test_type", body, ["test"])
    
    json_str = json.dumps(receipt)
    restored = json.loads(json_str)
    
    assert receipt["root_hash"] == restored["root_hash"]
    assert receipt["type"] == restored["type"]

@given(st.binary(min_size=1, max_size=1000))
def test_hash_deterministic(data):
    """Hash is deterministic."""
    hash1 = hashlib.blake3(data).hexdigest()
    hash2 = hashlib.blake3(data).hexdigest()
    assert hash1 == hash2

@given(
    st.binary(min_size=1, max_size=100),
    st.binary(min_size=1, max_size=100)
)
def test_different_data_different_hash(data1, data2):
    """Different data produces different hashes."""
    if data1 == data2:
        return  # Skip if same
    
    hash1 = hashlib.blake3(data1).hexdigest()
    hash2 = hashlib.blake3(data2).hexdigest()
    assert hash1 != hash2
```