What problem does it solve? Maintaining a long-lived fork with continuous downstream development makes it hard to know what changed upstream, what will conflict, and which customizations are at risk. This Skill freezes the integrated checkpoint and the latest upstream state, then produces reproducible diff and conflict reports without touching your branches. ## Core Features & Use Cases - Checkpoint-based assessment: Tracks the integrated upstream checkpoint separately from observed upstream tips, so fetches never silently advance integration state. - Diff and conflict reports: Generates per-repository diff reports (commits, name-status, numstat, risk paths) and conflict reports using git merge-tree, split into confirmed conflicts, auto-mergeable overlaps, customization risks, and dirty-worktree overlaps. - Integration recording: After an external merge is completed, records the merge commit and advances the checkpoint only when Git history proves the integration. - Use Case: You maintain a fork of an open-source framework with heavy local changes. Run an assessment to get a frozen snapshot of upstream commits since your last integration, see exactly which files conflict, and decide whether to merge now or defer. ## Quick Start Ask the agent to assess the upstream sync status of this fork and generate the diff and conflict reports for the current repositories.