Update Existing Branch

Use this skill when the milestone branch set already exists and contains drafted markdown, features.json, reviewer comments, or human edits. The branch set is the base branch plus its per-component branches as defined in [release-notes/references/pr-layout.md](../release-notes/references/pr-layout.md).

This is the incremental rerun stage of the release-notes pipeline. It is the branch-maintenance equivalent of what editorial-scoring is for scoring: the canonical place to describe how follow-up runs should behave.

Purpose

Treat the existing branch set as the working baseline, not as a blank slate.

The goal is to:

1. refresh shipped-change data only when the preview actually moved forward
2. score and write the delta, not the whole release again
3. preserve human edits and reviewer-driven rewrites on every component branch
4. integrate new material into the current story cleanly

Inputs

Read these before making changes:

1. the current base branch and its PR
2. every per-component branch and its PR
3. the existing changes.json, features.json, and build-metadata.json on

the base branch

1. the existing markdown files on each component branch
2. unresolved PR review comments and discussion threads on every PR in the set

Which branch holds what

Respect this invariant on every rerun:

Process

1. Check whether the preview moved forward

Determine whether later dotnet/dotnet codeflow commits landed for the same preview branch or tag since the last run.

If the relevant VMR ref moved forward, regenerate changes.json on the base branch. If it did not, keep the current file and focus on editorial fixes and comment responses on the component branches.

Typical signals:

• later commits on dotnet/dotnet for release/<major>.0.1xx-previewN
• a newer release-branch head than the one captured in build-metadata.json
• new source-manifest commits for a component already discussed in the draft

2. Compute a delta from the existing files

If you refreshed changes.json, compare the old and new files by stable id.

Classify changes as:

• added — new shipped items not seen in the last run
• changed — same id, but new evidence, labels, revert state, or reviewer context changes the treatment
• removed or superseded — no longer relevant to the current build story, or later evidence shows the original interpretation was wrong
• unchanged — keep the prior editorial work

Do not treat a refreshed changes.json as permission to restart the whole release from zero.

3. Merge into the existing features.json

When features.json already exists, use it as the editorial baseline and merge the delta into it on the base branch.

Preserve prior annotations for unchanged entries, including:

• score
• score_reason
• score_breakdown
• breaking_changes
• reverted_by / reverts
• useful human notes or hand-tuned annotations

Only rescore:

• newly added entries
• materially changed entries
• earlier entries that reviewers explicitly questioned or that new evidence disproved

This should feel like a delta merge, not a full rescore.

4. Update markdown in place

Use the current draft as the starting point. Prefer integration over duplication.

For each component affected by the delta, update only that component's markdown on its branch. Before editing, merge the base branch into the component branch so the latest metadata is available in your working tree; don't touch component branches you aren't editing this run.

Examples:

• on the runtime branch, add a new GC item into the existing Garbage Collection Performance Improvements section in runtime.md
• on the libraries branch, extend an existing Unsafe Evolution block in libraries.md instead of creating a second heading
• move a newly demoted item into Bug fixes instead of deleting the story without explanation

Keep the existing structure when it still works. Add a new top-level section only when the delta introduces a genuinely new story.

5. Treat review comments as required inputs

Unresolved PR comments are part of the spec for the next run, on every PR in the set.

• read them before rewriting anything
• answer factual questions with evidence from changes.json, VMR refs, API verification, or the final build
• update the markdown when the reviewer is right
• if the reviewer is directionally right but the current build still contains the feature, explain the milestone and branch context clearly

6. Default outcome

For an existing release-notes branch set, the normal loop is:

1. refresh changes.json only if the preview moved forward
2. merge the delta into features.json
3. update the existing markdown in place
4. respond to comments and questions

This keeps the branch set stable for reviewers and avoids throwing away already curated editorial work.