# CSS — CONTRACT & SCHEMA SPEC
version: v1.0
status: ACTIVE
parent: master_architecture_index.md
phase: 02
phase_name: Architecture & Engineering Canon
document_role: contract_and_schema_standard_for_phase_02

---

## 1. OBJECTIVE

Define how Devon contracts and schemas must be structured.

---

## 2. CONTRACT PRINCIPLE

Every meaningful interface must be contract-bound.

Contracts apply to:
- module input
- module output
- runtime bridge
- panel data
- memory writes
- validation outputs
- execution payloads

Audit surface rule:
- documentation-facing structures may summarize canonical definitions
- operational-facing structures may expose real runtime evidence
- no contract may blur documentary summary with operational proof

---

## 3. REQUIRED CONTRACT ELEMENTS

Each contract should define:
- identity
- purpose
- required fields
- allowed values
- forbidden values when relevant
- validation expectation
- failure semantics

---

## 4. SCHEMA PRINCIPLE

Schemas must prefer:
- explicit fields
- deterministic validation
- traceable identifiers
- versioned structures

No vague payloads allowed for governed operations.

---

## 5. ACCEPTANCE CRITERIA

CSS is valid only if:
- contract fields are explicit
- schema rule is explicit
- failure semantics are explicit
- governed interfaces are covered