Authoring and Evolving Schemas

1. Choose a stable logical name, semantic version, owner, and canonical path. 2. For JSON Schema, use draft 2020-12, a unique `https://aiwg.io/schemas/...` `$id`, and strict-compatible keywords. 3. Run `npm run schema:catalog`; inspect the generated domain manifest rather than editing it by hand. 4. Declare consumers, dependencies, fixtures, compatibility policy, and any generated/copy paths as projections in the owning domain manifest. 5. Run `npm run lint:schemas`, focused fixture/parity tests, and `npm run typecheck`.

Use `aiwg schema list|show|graph|policy` for discovery and `aiwg schema validate`, `lint`, `check-refs`, `diff`, `compatibility`, `generate`, and `verify-projections` for control-plane operations. Results use versioned JSON envelopes suitable for CI.

Never reuse an identifier for a different contract, hand-edit a projection, or add a remote `$ref`. Narrowing accepted values, adding required properties, removing properties/enum members, or forbidding previously allowed properties is breaking and requires a new version plus migration guidance. An `unknown` compatibility result requires maintainer review.

Temporary strict-mode exceptions belong in `schemas/policy/strict-exceptions.json`; every entry needs scoped rationale, ownership, approval, and an expiry date. Expiry is a remediation deadline, not a permanent waiver.