typed_use_cases 0.1.2

# Verification Report

## ✅ All Tests Pass

### Library Tests
```
running 3 tests
test tests::system_is_zero_sized ... ok
test tests::use_case_execution_works ... ok
test tests::use_case_metadata_is_accessible_at_compile_time ... ok

test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```

### Integration Tests
```
running 1 test
test integration_test_passes ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```

### Example Tests
```
running 6 tests
test tests::add_item_to_cart_works ... ok
test tests::browse_catalog_works ... ok
test tests::checkout_works ... ok
test tests::print_use_case_metadata ... ok
test tests::system_is_zero_sized ... ok
test tests::checkout_fails_with_empty_cart - should panic ... ok

test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```

### Doctests
```
running 1 test
test src/macros.rs - macros::implement_all_use_cases (line 7) - compile ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```

## ✅ Zero Runtime Overhead

System is a Zero-Sized Type:
```rust
assert_eq!(std::mem::size_of::<System>(), 0);
```

## ✅ No Warnings on Build

```
cargo build
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.06s
```

```
cargo build --release
    Finished `release` profile [optimized] target(s) in 3.34s
```

## ✅ static_assertions Only in Dev Dependencies

Normal dependency tree (no static_assertions):
```
typed_use_cases v0.1.0
└── typed_use_cases_derive v0.1.0 (proc-macro)
    ├── proc-macro2 v1.0.106
    ├── quote v1.0.45
    └── syn v2.0.117
```

## ✅ Compile-Time Metadata is Accessible

Test output shows constants are evaluated at compile time:
```
Use case: Test Use Case - A test use case for demonstration
```

## ✅ Example Runs Successfully

```
cargo run --example ecommerce

Use Cases:
1. Browse catalog - An anonymous user can browse the product catalog
2. Add item to cart - An authenticated user can add a product to their cart
3. Checkout - An authenticated user can checkout with at least one item
```

## ✅ Verification Checklist

- [x] `cargo build` passes with zero warnings
- [x] `cargo test` passes — all use cases verified
- [x] `cargo test` fails if a use case impl is removed from System (compile-time check in #[cfg(test)])
- [x] `size_of::<System>() == 0` test passes
- [x] The example compiles and runs
- [x] README is complete and accurate
- [x] No `unimplemented!()` or `todo!()` in the example
- [x] `static_assertions` does not appear in `[dependencies]`, only `[dev-dependencies]`
- [x] All code compiles on stable Rust
- [x] Derive macros work correctly
- [x] Integration test passes
- [x] Doctests pass

## Project Structure

```
typed_use_cases/
├── Cargo.toml              # Main crate manifest
├── LICENSE                 # MIT license
├── README.md               # Comprehensive documentation
├── src/
│   ├── lib.rs              # Re-exports and library tests
│   ├── traits.rs           # Core traits (Actor, Entity, UseCase, DependentEntity)
│   └── macros.rs           # implement_all_use_cases! macro
├── typed_use_cases_derive/
│   ├── Cargo.toml          # Proc macro crate manifest
│   └── src/
│       └── lib.rs          # #[derive(Actor)], #[derive(Entity)] proc macros
├── examples/
│   └── ecommerce.rs        # Full e-commerce example with 3 use cases
└── tests/
    └── integration_test.rs # Integration test
```

## Summary

The `typed_use_cases` crate successfully:

1. **Formalizes use cases at the type level** with zero runtime overhead
2. **Provides compile-time verification** that all declared use cases are implemented
3. **Uses a zero-sized System type** that occupies 0 bytes
4. **Only verifies in test builds** via `#[cfg(test)]` - no impact on release binaries
5. **Offers derive macros** for Actor and Entity traits
6. **Includes comprehensive documentation** and working examples
7. **Requires no changes to controllers** - purely additive
8. **Works on stable Rust** - no nightly features required