[Devops] Branching Strategy - Phase 0

[lowlydba]

Goal

Migrate dev → main as default branch, stand up vnext, configure protections. Zero workflow changes — pure infrastructure, no code risk. Blocks all subsequent phases.

Tasks

p0-migrate-dev-to-main

1. Verify main is ancestor of dev (git merge-base --is-ancestor main dev). Reconcile if not.

2. Fast-forward main to dev HEAD.

3. Bulk-retarget all open PRs dev → main:

   gh pr list --base dev --json number --jq '.[].number' | xargs -I {} gh pr edit {} --base main
   

   Verify zero PRs remain targeting dev.

4. Change GitHub default branch from dev → main.

5. Update CI workflows + branch protection rules + any external refs pointing at dev or staging.

6. Delete staging (stale ~2 months, throwaway).

7. Delete dev (retired). Tags already live on main commits — no change needed.

8. Contributor announcement (GitHub Discussion + README banner).

p0-vnext-branch

• Create vnext long-lived branch from new main.
• Mirror branch protections from main: no direct push, require PR, required CI status checks.
• Grant overture-pull-requester GH App bypass on vnext protection rules (needed for p1-post-merge-rebase force-push).

p0-docs

• Create docs/branching-strategy.md covering the two-branch model and contributor workflow.
• Update CONTRIBUTING.md with a pointer to it.
• This is the live doc — subsequent phases append to it.

Contributor-facing changes

• dev is gone. Default branch is now main.
• staging is gone.
• New vnext branch exists for major changes.
• Branch from main. Target main for normal work, vnext for major changes.
• Open PRs were auto-retargeted from dev → main. No action needed unless yours was missed.

Definition of done

• main is the default branch, at parity with former dev HEAD
• vnext exists, protected, overture-pull-requester has bypass
• dev and staging deleted
• All open PRs target main
• docs/branching-strategy.md created, CONTRIBUTING.md updated
• Contributor announcement posted