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Versioning and Release Metadata

This guide defines how CBF versions Rust crates and GitHub release artifacts. It separates crate compatibility from packaged Chromium runtime revisions so maintainers can publish crate-specific releases and can re-release Chromium.app and cbf_bridge without forcing an unrelated crate publish.

1. Goals

CBF publishes two kinds of versioned outputs:

  • Rust crates on crates.io
  • GitHub Releases for crate history and prebuilt runtime bundles

These outputs have different compatibility concerns:

  • cbf and cbf-chrome expose Rust APIs and should follow normal SemVer rules.
  • cbf-chrome-sys tracks the Chromium generation that defines the low-level FFI and wire boundary.
  • GitHub Releases serve two purposes:
    • crate-specific release history
    • packaged runtime bundle distribution

2. Crate Versioning

cbf

cbf uses normal SemVer.

  • Major/minor indicate public API compatibility in the browser-generic Rust API.
  • Patch indicates compatible bug fixes and documentation-only corrections.
  • Before 1.0.0, maintainers should treat minor bumps as the main signal for breaking public API changes.

Examples:

  • 0.1.0
  • 0.2.0
  • 0.2.1

cbf-chrome

cbf-chrome also uses normal SemVer.

  • Its version tracks the Chrome-specific safe Rust API surface.
  • It is versioned independently from cbf.
  • Its release cadence may be higher than cbf because it sits closer to cbf-chrome-sys, Chromium integration, and backend-specific behavior.

Examples:

  • cbf = 0.3.0
  • cbf-chrome = 0.7.2

cbf-chrome-sys

cbf-chrome-sys uses a Chromium-generation-oriented version scheme:

<chromium-milestone>.<minor>.<patch>

Rules:

  • major: Chromium milestone, such as 146 or 147
  • minor: additive compatible changes to the FFI/wire boundary within that Chromium milestone line
  • patch: compatible fixes only

Examples:

  • 146.1.0
  • 146.1.1
  • 146.2.0
  • 147.0.0

Do not encode the full Chromium revision in SemVer build metadata as the primary compatibility signal. For example, 146.1.0+chromium-146.0.7632.160 is acceptable as descriptive metadata, but Cargo dependency resolution does not treat build metadata as part of version precedence.

3. Compatibility Model

The expected compatibility split is:

  • cbf and cbf-chrome define the Rust-side API contract.
  • cbf-chrome-sys defines the Rust-to-bridge ABI contract for a Chromium milestone line.
  • crate releases identify changes to one Rust crate at a time.
  • runtime bundle releases identify the concrete prebuilt runtime bundle that contains:
    • Chromium.app
    • libcbf_bridge.dylib

As a result:

  • A crate may receive a GitHub Release even when no new runtime bundle is published.
  • cbf and cbf-chrome do not need matching version numbers.
  • Compatibility between cbf and cbf-chrome should be expressed through Cargo dependency requirements and release notes, not version-number alignment.
  • A Chromium.app or cbf_bridge rebuild may require a new GitHub Release without requiring a new cbf-chrome-sys crate release.
  • A new cbf-chrome-sys release is required when the ABI/wire boundary changes in a way that should be represented to Cargo users.

4. GitHub Release Types

CBF uses two GitHub Release types:

  • crate releases
  • runtime bundle releases

These release types should use different tag namespaces.

Crate releases

Create a GitHub Release for each public crate publish so maintainers and users can track crate-specific changes independently.

Canonical tag format:

<crate-name>-v<crate-version>

Examples:

cbf-v0.1.0
cbf-chrome-v0.1.0
cbf-chrome-sys-v146.1.0
cbf-compositor-v0.1.0-alpha.1
cbf-cli-v0.1.0

Recommended title format:

<crate-name> v<crate-version>

Examples:

cbf v0.1.0
cbf-chrome v0.1.0
cbf-chrome-sys v146.1.0
cbf-compositor v0.1.0-alpha.1
cbf-cli v0.1.0

Crate release notes should focus on:

  • what changed in that crate
  • compatibility expectations for downstream users
  • links to related runtime bundle releases when relevant

Runtime bundle releases

GitHub Release tags identify the packaged runtime bundle, not just crate versions.

The canonical tag format is:

cbf-chrome-runtime-v<cbf-chrome-version>+chromium-<chromium-version>-r<release-revision>

Example:

cbf-chrome-runtime-v0.1.0+chromium-146.0.7632.160-r1

Field meanings:

  • <cbf-chrome-version>: the published cbf-chrome crate line for this bundle
  • <chromium-version>: the full Chromium runtime version included in the bundle
  • <release-revision>: packaging and redistribution revision for the same crate/runtime combination, starting at 1

Release revision increments when maintainers republish artifacts for the same crate versions and the same Chromium version, for example:

  • refreshed Chromium.app
  • rebuilt libcbf_bridge.dylib
  • corrected packaging or bundled notices
  • regenerated archives due to packaging mistakes

Examples:

  • cbf-chrome-runtime-v0.1.0+chromium-146.0.7632.160-r1
  • cbf-chrome-runtime-v0.1.0+chromium-146.0.7632.160-r2
  • cbf-chrome-runtime-v0.1.0+chromium-147.0.7651.5-r1

5. Runtime Bundle Release Titles

Use a human-readable title that mirrors the tag and makes the bundled Chromium version obvious.

Recommended format:

CBF Chrome v<cbf-chrome-version> for Chromium v<chromium-version> (Release <n>)

Examples:

  • CBF Chrome v0.1.0 for Chromium v146.0.7632.160 (Release 1)
  • CBF Chrome v0.1.0 for Chromium v146.0.7632.160 (Release 2)

6. Release Notes Metadata

Each runtime bundle release should explicitly record:

  • cbf version
  • cbf-chrome version
  • cbf-chrome-sys version
  • bundled Chromium version
  • release revision (r1, r2, …)
  • notable changes since the previous release revision or version

The runtime bundle release notes should be derived from:

  • chromium/CHANGELOG.md
  • the crate changelogs when a runtime release depends on crate-side changes that should be called out explicitly

Recommended release note structure:

Crates
- cbf: 0.1.0
- cbf-chrome: 0.1.0
- cbf-chrome-sys: 146.1.0

Bundled runtime
- Chromium: 146.0.7632.160
- Release revision: r1

Notes
- Initial public prebuilt release for Chromium milestone 146.

Each crate release should explicitly record:

  • crate name
  • crate version
  • notable changes in that crate
  • compatibility notes
  • related runtime bundle release tags when the crate expects a specific runtime

Each crate release note should be derived from that crate’s local CHANGELOG.md.

7. Changelog Layout

CBF keeps changelogs close to the release unit they describe.

Recommended changelog files:

  • crates/cbf/CHANGELOG.md
  • crates/cbf-chrome/CHANGELOG.md
  • crates/cbf-chrome-sys/CHANGELOG.md
  • crates/cbf-compositor/CHANGELOG.md
  • crates/cbf-cli/CHANGELOG.md
  • chromium/CHANGELOG.md

Rules:

  • Each crate changelog tracks only that crate’s public release history.
  • chromium/CHANGELOG.md tracks runtime bundle history for Chromium.app, libcbf_bridge.dylib, and other Chromium-side packaging changes that affect prebuilt runtime releases.
  • GitHub Release notes should summarize and link back to the corresponding changelog entry instead of becoming the only source of change history.
  • Maintainers may include only the relevant excerpt in GitHub Release notes, but the full changelog entry should remain in the repository.

8. Maintainer Guidance

  • Treat crate versions and GitHub Release tags as separate identifiers with different responsibilities.
  • Create crate releases for public crate publishes so each crate has its own visible release history.
  • Maintain one changelog per public crate and one runtime changelog under chromium/CHANGELOG.md.
  • Do not try to keep cbf and cbf-chrome numerically aligned when their actual release cadence differs.
  • Do not force a cbf-chrome-sys publish only because a runtime bundle was rebuilt.
  • Publish a new cbf-chrome-sys version when ABI or wire-boundary compatibility changes should be visible to Cargo users.
  • Keep runtime bundle release notes explicit about both the crate line and the packaged Chromium revision.
  • Keep the crate tag namespace and runtime tag namespace distinct.