feat(core,github-action): support maintenance branches

[dangreen]

No description provided.

[coveralls]

Coverage Report for CI Build 28369990068

Coverage increased (+1.9%) to 61.704%

Details

• Coverage increased (+1.9%) from the base build.
• Patch coverage: 4 uncovered changes across 2 files (48 of 52 lines covered, 92.31%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
packages/core/src/releaser.ts	26	23	88.46%
packages/core/src/project/project.ts	14	13	92.86%
Total (3 files)	52	48	92.31%

Coverage Regressions

No coverage regressions found.

---

Coverage Stats

Relevant Lines:	783
Covered Lines:	538
Line Coverage:	68.71%
Relevant Branches:	426
Covered Branches:	208
Branch Coverage:	48.83%
Branches in Coverage %:	Yes
Coverage Strength:	10.37 hits per line

---

💛 - Coveralls

[Copilot]

Pull request overview

Adds first-class “maintenance branch” support to the release pipeline so that, on a major version bump, the previous major line can be tracked via an automatically created branch (e.g. v2 from v2.0.0). This integrates at both the core Releaser level and the GitHub Action wrapper, with accompanying tests for single-package and monorepo modes.

Changes:

• Add a new maintenanceBranch() step to the core Releaser and wire it into the GitHub Action release flow.
• Introduce Project.getMaintenanceBranches() (and monorepo override) to compute which maintenance branches should be created.
• Add unit tests covering maintenance-branch detection and creation for package projects and monorepos.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/github-action/src/releaser.ts	Adds maintenance-branch step into the release action pipeline.
packages/github-action/src/options.ts	Adds GitHub Action input option parsing for maintenance-branch.
packages/core/src/releaser.types.ts	Introduces ReleaserMaintenanceBranchOptions and adds it to step options.
packages/core/src/releaser.ts	Implements maintenanceBranch() step that creates and pushes maintenance branches.
packages/core/src/releaser.spec.ts	Adds integration-style tests for creating maintenance branches (and default-disabled behavior).
packages/core/src/project/project.types.ts	Adds ProjectMaintenanceBranch type.
packages/core/src/project/project.ts	Adds getMaintenanceBranches() to compute maintenance branch refs for major releases.
packages/core/src/project/monorepo.ts	Overrides maintenance-branch computation for independent vs fixed monorepo modes.
packages/core/src/project/packageJsonMonorepo.spec.ts	Adds tests for maintenance-branch refs in independent and fixed monorepos.
packages/core/src/project/packageJson.spec.ts	Adds tests for maintenance-branch ref computation for a single package project.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.