# Invariant Doc Entity
### Scope
- **Purpose:** Document behavioral contracts and platform guarantees of `process_tools` — constraints that hold across all invocations.
- **Responsibility:** Collect one doc instance per invariant; specify enforcement mechanism and violation consequences.
- **In Scope:** Formal invariant statements, how they are enforced in code, and what breaks when violated.
- **Out of Scope:** Function signatures (→ `api/`); feature design rationale (→ `feature/`).
### Overview Table
| 001 | [Result<Report, Report> Contract](001_result_contract.md) | Both `Ok` and `Err` carry fully-populated `Report` | ✅ |
| 002 | [Cross-Platform Shell Abstraction](002_cross_platform_shell.md) | `run_with_shell` always invokes the platform-native shell | ✅ |