Groups and shared release identity

A configured group forces multiple packages to share one planned version and one outward release identity.

[package.sdk-core]
path = "cargo/sdk-core"
type = "cargo"

[package.web-sdk]
path = "packages/web-sdk"
type = "npm"

[group.sdk]
packages = ["sdk-core", "web-sdk"]
tag = true
release = true
version_format = "primary"

Groups can also use version_format = "namespaced" or a custom tag template such as version_format = "{{ name }}/v{{ version }}". Custom formats support {{ name }}, {{ version }}, and {{ ecosystem }}, must include {{ version }}, and must render unique valid Git tag names.

When any member releases:

• the highest required bump in the group wins
• every member in the group receives that bump
• one planned group version is calculated from the highest current member version
• the group owns outward release identity
• member package changelogs can still be updated individually
• group changelog and group versioned_files can also be updated
• grouped packages can use empty_update_message when their own changelog needs a version-only update with no direct notes
• dependents of newly synced members still receive propagated parent bumps
• unmatched members (not found during discovery) produce warnings; unresolvable members (invalid IDs) produce errors
• mismatched current versions produce warnings when warn_on_group_mismatch = true

A changeset may reference the group id:

---
sdk: minor
---

#### coordinated SDK release

But a changeset may not reference both the group id and one of its members in the same file.

To keep a group changelog focused on public surfaces while leaving package changelogs detailed, configure the grouped changelog table:

[group.sdk.changelog]
path = "changelog.md"
include = ["sdk-cli"]

Direct group-targeted changesets are always included. Member-targeted changesets are filtered only for the group changelog; package changelogs and release planning remain unchanged.

The filter curates the committed changelog, and nothing else. A provider release body still describes every change the release shipped, so a group whose changelog hides internal notes cannot publish a release that appears to contain nothing. Each change is listed once, in its configured section, with the packages it affects:

Grouped release for `sdk`.

## Fixes

- **Fix shared bug.** _Packages:_ 🟠 _core_, 🟢 _cli_ _Owner:_ @ifiokjr · _Review:_ [PR #725](https://github.com/monochange/monochange/pull/725)