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Version: 0.2.1

Versioning policy

X07 versioning is layered so agents can rely on stable machine-readable contracts while the toolchain and ecosystem continue to evolve.

The key idea: contracts do not change in-place. New behavior comes with new versions and a documented migration story.

See also:

  • docs/reference/compat.md (compatibility contract)
  • docs/packages/index.md (projects, lockfiles, and dependency resolution)
  • docs/stability.md (stability principles)

Stable contracts: _v1 and schema ids​

A function name like parse_v1 means:

  • its bytes encoding is pinned
  • its error code space is pinned
  • its semantics are pinned

New encodings become _v2 (and live side-by-side).

Similarly, JSON schemas and on-disk formats are versioned by explicit identifiers like:

  • x07.project@0.5.0 (project manifest)
  • x07.lock@0.4.0 (project lockfile)
  • x07.x07ast@0.8.0 (program/module format)

Toolchain SemVer policy​

The toolchain (x07, x07c) is released with SemVer tags (vX.Y.Z).

Policy:

  • Toolchain releases should be compatible by default with official packages and documented public surfaces.
  • If a change risks breaking downstream code, it must come with either:
    • a compatibility switch, or
    • a mechanical migration path (x07 fix and x07 migrate)
  • Any compat-relevant behavior change must be documented in docs/reference/compat.md and backed by a regression surface in tests/compat_corpus/.

Package SemVer policy​

Packages are versioned independently (SemVer) and pinned by lockfiles.

Package versions may change for:

  • bug fixes
  • performance improvements
  • new helpers

But versioned contracts (*_v1, spec schemas, and other explicitly versioned envelopes) must remain compatible. Breaking changes require:

  • _v2 APIs, or
  • a new major version when packages reach 1.0.

Package manifest compatibility metadata​

Publishable packages use x07-package.json (x07.package@0.1.0) plus meta fields.

Policy:

  • Packages must declare transitive hard requirements through meta.requires_packages so dependency resolution is explicit.
  • Packages must declare the worlds they support in meta.worlds_allowed (and stay within those capability bounds).
  • Packages may declare toolchain support via meta.x07c_compat (a SemVer requirement string, for example \">=0.1.111 <0.2.0\"). When present, x07 pkg lock treats incompatible packages as ineligible and fails with a deterministic error.
  • When a package’s exported contracts change (types, encodings, semantics), it must bump its own SemVer version and keep old versioned APIs (*_v1) intact.

Lockfile schema evolution policy​

Projects pin dependency graphs with x07.lock.json (x07.lock@…).

Policy:

  • Lockfiles are canonical JSON and must be deterministic.
  • The current lockfile schema (x07.lock@0.4.0) includes toolchain identity and registry provenance to make upgrades debuggable.
  • Tooling should continue to read older lockfile schema versions. If a lockfile cannot be read, the toolchain must fail with a deterministic error and a migration path.
  • CI should use x07 pkg lock --check to fail on lock drift instead of mutating workspaces.
  • Schema bumps should be additive when possible and gated by the compat corpus.

Notes:

  • x07 pkg lock writes x07.lock@0.4.0 by default; use x07 pkg lock --lock-version 0.3 only when interoperating with an older toolchain.
  • After a toolchain upgrade, use x07 pkg repair --toolchain current to rewrite incompatible locks deterministically.