Compatibility & Deprecation Policy

Lumyn follows semantic versioning. This document outlines our guarantees for v0 (Legacy) and v1 (Stable) engines.

Version Status

Version	Status	Guarantee	Policy Schema	Engine URL
v1.x	Stable	Active development. No breaking changes to contracts.	policy.v1	/v1/decide
v0.x	Deprecated (Supported)	Security fixes & critical bug fixes only.	policy.v0	/v0/decide

v0 Deprecation Timeline

• Announced: with v1.0.0-rc.1 release.
• End of Feature Support: Immediate. No new features will be backported to v0.
• End of Life (EOL): v2.0.0 release (estimated late 2026). Until then, v0 policies and endpoints will continue to function on the v1.x binary.

Breaking Changes in v1

To ensure determinism and reliability, v1 introduces the following breaking changes compared to v0:

• Strict Stages: policy.v1 enforces 5 specific evaluation stages.
• Limited Operators: Arbitrary condition keys are no longer allowed; only supported operators (e.g., _gt, _is) work.
• Verdict Precedence: ABSTAIN (System Error) > DENY > ESCALATE > ALLOW.
• Digest Construction: inputs_digest is computed differently (native v1 normalization).

Migration Guide

To migrate from v0 to v1:

1. run lumyn migrate your_policy.v0.yml to generate a draft v1 policy.
2. Review the generated policy (check for any dropped rules or conditions).
3. Test with lumyn decide using v1 schema.