Supporting mulitple "LTS mission" versions

[PhilipNelson5]

I'm in a situation where my repo needs to branch into multiple "LTS" lines of support/development. After a mission is launched, I create a support branch (ie support/a for mission A and support/b for mission B). These support branches don't want to accept the latest features from main but may have fixes, selected features, or even breaking changes applied depending on the mission/customer. For this reason I want to continue using a full semver version but they need to be distinct from the mainline and between missions.

I already have a pipeline which automatically runs cz bump on each merge with main and pushes the bump commit back to the branch. On the support branches this is changed to run on merges to the respective support branch.

My idea was to change the tag format on the support branches to tag_format = $version-<Mission> (eg 1.2.3, 1.2.3-A, 1.2.3-B). I recognize that this is abusing the pre-release segment of semver but I was hoping to make it work and we don't use prereleases anyway.

So far it's actually working pretty well, first problem is that the incremental changelog updates are being put at the bottom of the changelog and each bump add another copy entire copy of the changes after the support branch branched off main. Any ideas how to fix that?

This very well could be a terrible idea and if there is an existing convention I'd love to hear about it.

Example

---
config:
    logLevel: debug
    theme: 'base'
    gitGraph: 
        showBranches: true
        showCommitLabel: true
        parallelCommits: true
    themeVariables:
        git0: '#50B973'
        git1: '#74baff'
        git2: '#ffcb5e'
        git3: '#ba79cc'
        git4: '#74baff'
        git5: '#74baff'
        git6: '#ba79cc'
---
gitGraph
    commit tag: "1.2.3" id: "fix: bug 1"
    branch "support/a"
    checkout main
    commit tag: "1.2.4" id: "fix: bug 2"
    branch "support/b"
    checkout main
    commit tag: "1.3.0" id: "feat: feat 1"
    commit tag: "1.4.0" id: "feat: feat 2"
    commit tag: "1.5.0" id: "feat: feat 3"

    checkout "support/a"
    commit tag: "1.2.4-A" id: "fix: bug 1 on A"
    commit tag: "1.3.0-A" id: "feat: feat 1 on A"

    checkout "support/b"
    commit tag: "1.3.0-B" id: "feat: feat 1 on B"
    commit tag: "1.4.0-B" id: "feat: feat 3 on B"

Loading

.cz.toml on main

[tool.commitizen]
name = "cz_conventional_commits"
tag_format = "$version"
version_scheme = "semver2"
version_provider = "cmake-provider"
update_changelog_on_bump = true
template = ".config/CHANGELOG.md.j2"

.cz.toml on support/a

[tool.commitizen]
name = "cz_conventional_commits"
tag_format = "$version-A"
version_scheme = "semver2"
version_provider = "cmake-provider"
update_changelog_on_bump = true
template = ".config/CHANGELOG.md.j2"

CHANGELOG.md.j2

{% for entry in tree %}

## {{ entry.version }}{% if entry.date %} - {{ entry.date }}{% endif %}


{% for change_key, changes in entry.changes.items() %}
{% for change in changes %}
{% if change_key %}
{% if change.scope %}
- {{ change_key }}({{ change.scope }}): {{ change.message }}
{% elif change.message %}
- {{ change_key }}: {{ change.message }}
{% endif %}
{% else %}
{% if change.scope %}
- {{ change.scope }}: {{ change.message }}
{% elif change.message %}
- {{ change.message }}
{% endif %}
{% endif %}
{% endfor %}
{% endfor %}
{% endfor %}

[PhilipNelson5]

For anyone who stumbles upon this later, using tag_format = "$version+A instead of -A and setting legacy_tag_versions = [ "$version" ] fixed the issue.

This might still be a bad 🤷

[woile]

There's no specific approach to this. I think your solution is good. And yes, using legacy is a solution.
However, it might be more "semantically correct" if you use the ignored_tag_formats, have you tried it?