Module contract_validator 

Schema Contract runtime validator (Phase 14, commit 3).

Compares a Rust ModelSchema contract against the actual PostgreSQL schema, surfacing every drift point as a structured SchemaIssue.

Architecture

Rust ModelSchema (compile-time contract)   Postgres information_schema (live)
        │                                                │
        └────────────────► validator ◄───────────────────┘
                               │
                               ▼
                         SchemaReport
                         { errors, warnings, status }

The validator is read-only: it issues two SELECT statements against information_schema per model and never mutates the database. Safe to run on a production replica.

What it detects (per the spec)

Case	Severity
Missing table	ERROR
Missing column	ERROR
Type mismatch	ERROR
Nullability drift	ERROR
Wrong primary key	ERROR
Extra DB column	WARNING

What it does NOT do (yet)

• No human-readable rendering (commit 4 wires this through rustio doctor --check-schema --json).
• No CHECK-constraint introspection, no column DEFAULT comparison, no FK validation. These can be added with new IssueKind variants without breaking the report shape.
• No caching. Each call re-queries information_schema.

Phase scope

Commit 3 ships only the validator + types + PG-gated tests. Nothing in admin/, search/, migrations, or cli/ references this module yet.

Structs

SchemaIssue

One drift point — column-scoped or table-scoped (column = None).

SchemaReport

Validation result for one model.

Enums

IssueKind

Discrete failure mode for a single drift point.

ReportStatus

Overall outcome of one model’s validation pass. Computed from the error/warning counts in SchemaReport and stored explicitly so consumers don’t have to recompute.

Functions

validate_all

Validate every schema in the given slice. Sequential — running in parallel would saturate the connection pool with introspection queries that are usually cheap individually but multiply when every model is checked at once.

validate_schema

Validate the schema of a single model against the live DB.