fix(release): baseline preview changelogs from the prior stable

[Wibias]

Problem

Preview release changelogs compare against the previous preview instead of the prior stable:

• v2.10.0-preview.20260802 release notes show Full Changelog: …/compare/v2.9.1-preview.20260802...v2.10.0-preview.20260802
• expected: …/compare/v2.9.1...v2.10.0-preview.20260802 (the stable release already shows the correct v2.9.1...v2.10.0)

Root cause

.github/workflows/release.yml computed the notes previous tag from git tag --merged HEAD. Stable tags live on main's lineage, which the preview branch does not carry (v2.9.1 is not an ancestor of v2.10.0-preview.20260802), so v2.9.1 never entered the candidate list. The trailing same-core preview v2.9.1-preview.20260802 (shipped 15s after the stable) became the newest prior tag. The helper's semver ordering was already correct — the tag source was the bug.

Fix

• The notes baseline in the Create GitHub release step now reads the full tag set (git tag --list 'v[0-9]*'). The helper's semver ordering ranks the stable above its own trailing preview, so the range resolves to v2.9.1 → v2.10.0-preview.
• The service-lifecycle changed-files gate in the Require successful Cross-platform CI step keeps git tag --merged HEAD: that comparison is deliberately lineage-relative, and the comment now says why the two baselines differ.
• scripts/release-notes.ts documents the full-set contract on previousReleaseNotesTag.

Verification

• bun run typecheck green.
• bun test --isolate tests/release-notes.test.ts tests/ci-workflows.test.ts: 147 pass / 0 fail.
• End-to-end with the real tag set + live generate-notes: previous tag resolves to v2.9.1, and the rendered notes carry Full Changelog: https://github.com/lidge-jun/opencodex/compare/v2.9.1...v2.10.0-preview.20260802 with the identical PR list (feat(providers): add Baseten Model APIs preset #653, feat(server): advertise reasoning-effort ladders on the raw /v1/models list #853, fix(providers): keep Antigravity catalog static #744, docs(codex): clarify pool routing and account continuity #862) — nothing dropped or duplicated.
• Stable-release behavior unchanged (v2.9.1...v2.10.0), and preview-after-preview incrementality (no stable in between) is preserved by the existing tests.

Summary by CodeRabbit

• Bug Fixes

  • Improved preview release note generation to consistently compare changes against the correct stable release.
  • Preview releases now account for relevant stable versions even when those versions are not part of the current branch history.
  • Prevented same-version preview tags from being incorrectly selected as the release baseline.

• Documentation

  • Clarified release baseline selection requirements and expected stable-tag behavior.

• Tests

  • Added regression coverage for stable-to-preview release note generation and CI release checks.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 52b622c0-3d2a-4471-b859-7a68865003bc

📥 Commits

Reviewing files that changed from the base of the PR and between 088194a and 6bca807.

📒 Files selected for processing (4)

• .github/workflows/release.yml
• scripts/release-notes.ts
• tests/ci-workflows.test.ts
• tests/release-notes.test.ts

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📝 Walkthrough

Walkthrough

The release workflow now uses all repository tags for release-note baseline selection, while the CI service gate still uses tags merged into HEAD. Documentation and regression tests cover cross-lineage preview releases and trailing preview tags.

Changes

Release baseline selection

Layer / File(s)	Summary
Separate release-note and service tag sources .github/workflows/release.yml, scripts/release-notes.ts	Release-note lookup now reads all repository tags. The CI service gate continues to use tags merged into HEAD. Comments document the full-tag requirement and preview-tag ordering case.
Validate preview baseline selection tests/ci-workflows.test.ts, tests/release-notes.test.ts	Tests verify the workflow tag sources and confirm that v2.9.1 is selected as the baseline for v2.10.0-preview.20260802.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• lidge-jun/opencodex#482: Both changes modify release-note baseline selection and stable/preview changelog ranges.
• lidge-jun/opencodex#579: Both changes modify release baseline selection in the workflow, helper, and tests.
• lidge-jun/opencodex#957: Both changes modify release-note baseline and compare-link handling.

Suggested reviewers: ingwannu, lidge-jun

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/release-notes-stable-baseline

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