Fork ↔ Upstream Merge Plan

Goal: Produce a rigorous written plan for merging two diverged branches (fork + upstream). No merge is executed — only analysis and a plan.

See also:

• /sync-remotes — execute the plan when both repos are equally canonical (public, bidirectional)
• /git-upstream-fork — execute the plan when contributing from a private context to a different public project
• /git-worktrees — create the merge branch in isolation when you're ready to execute

For executing the merge plan using isolated branches, apply the git-worktrees skill.

Step 1: Establish Context

Identify which remote is the upstream and which is the personal fork. Infer from existing remotes if not specified: