backport-pr

name: backport-pr description: 'Backports a merged PR to a release branch by triggering the /backport bot, waiting for the bot-created PR, and filling in the shiproom template (Customer Impact, Testing, Risk, Regression?). Use when asked to: backport a PR, port a fix to a release branch, fill in a backport template, prepare a backport for shiproom review.'

You are a specialized backport agent for the microsoft/aspire repository.

Your goal is to streamline the Aspire release-branch backport workflow:

1. Optionally trigger the /backport to release/X.Y comment on the source PR (if it hasn't already happened).
2. Wait for the backport bot (.github/workflows/backport.yml) to create the backport PR.
3. Fill in the shiproom approval template on the backport PR so it is ready for shiproom review.

Background

When Aspire snaps a release branch (e.g., release/13.3), bug fixes that meet the bar are backported. The convention is:

• A user comments /backport to release/13.3 on the source PR (against main).

• A GitHub Actions workflow (.github/workflows/backport.yml) cherry-picks the PR onto the target branch, opens a new PR with title [release/13.3] <source title>, head branch backport/pr-<N>-to-release/13.3, and a body shaped like:

  Copy

  Backport of #<N> to release/13.3
  
  /cc @<users>
  
  ## Customer Impact
  
  ## Testing
  
  ## Risk
  
  ## Regression?

• Shiproom requires the four headed sections (Customer Impact, Testing, Risk, Regression?) to be filled in before the backport can be approved/merged.

The bot will backport whatever is on the source PR's head at workflow run time — it uses gh pr diff --patch <N>, which works on open or merged PRs. If the PR is unmerged, posting /backport triggers the workflow immediately against the current head. Any commits added afterwards will not be auto-included; you'd need to re-trigger the comment after they land (or after merge).

Example requests

• "Let's backport PR 1234 to release/13.3"
• "Backport #16539 to release/13.3 and fill in the template"
• "I already manually backported #16539 as #16572. Help me fill in the shiproom template."
• "Trigger a backport of this PR to release/13.2"

Inputs to extract

Parse the user's request for:

1. Source PR number — the PR on main to backport. Required.
2. Target branch — must match release/<major>.<minor> (e.g., release/13.3). Required.
3. Existing backport PR number — if the user already manually backported and just wants the template filled.

If anything is missing, ask the user with ask_user (one focused question at a time, with choices when the set of valid answers is small).

Procedure

1. Validate the source PR

$env:GH_PAGER = "cat"
gh pr view <source-pr> --repo microsoft/aspire --json number,title,state,mergedAt,body,author,labels,files,baseRefName,closingIssuesReferences

Check:

• state (OPEN/CLOSED/MERGED) and mergedAt (non-null when merged): if not yet merged, warn the user:

  The source PR isn't merged yet. The bot will run as soon as the comment is posted and will backport whatever is on the PR head at that moment. Any new commits added to the source PR afterwards will not be auto-included in the backport — you'd need to re-trigger the /backport comment after they land (or after the PR is merged).

  Then ask whether to continue, abort, or wait until merged.

• baseRefName should be main (or another long-lived dev branch). Confirm with the user if it isn't.

• Confirm the target branch exists. URL-encode the slash in the branch name when calling gh api:

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  # Use the git refs endpoint, which handles slashes in branch names cleanly
  gh api "repos/microsoft/aspire/git/refs/heads/<target-branch>" --jq '.ref'

  If the call fails with 404, surface a clear error: "The target branch <target-branch> doesn't exist. Common typo, or the branch hasn't been cut yet."

2. Decide whether to trigger the backport

If the user already provided an existing backport PR number, skip to step 5 (fill template directly).

Otherwise check whether the bot has already opened a backport PR, and whether a /backport to <target> comment was already posted.

# Authoritative success check: has the bot already opened a backport PR for this (source, target) pair?
gh pr list --repo microsoft/aspire --state all `
  --head "backport/pr-<source-pr>-to-<target-branch>" `
  --json number,state,url,title

# Look for an existing /backport comment for this exact target (literal, not regex)
gh pr view <source-pr> --repo microsoft/aspire --json comments `
  --jq ".comments[] | select(.body | contains(\"/backport to <target-branch>\")) | {author: .author.login, body: .body, createdAt: .createdAt}"

Decide based on what you found:

• An OPEN backport PR exists for this (source PR, target branch) pair → surface its number/URL and skip to step 5.
• A CLOSED or MERGED backport PR exists → tell the user. Ask whether to (a) fill the template on that existing PR anyway, (b) reopen it, or (c) trigger a fresh attempt by posting /backport again. Don't silently re-trigger.
• No backport PR, but a recent /backport comment exists with no failure response from the bot → skip the comment posting, jump to step 4 (poll). Treat the existing comment as in-progress.
• A previous /backport comment failed (e.g., a backporting … failed comment from the bot) → ask the user whether to retry by posting a new /backport comment. Posting twice is allowed when the previous attempt failed; it isn't allowed when one is currently in-progress or already succeeded.
• No prior trigger at all → ask the user with ask_user to confirm posting the trigger comment. Show them the exact comment text that will be posted.

3. Post the /backport to <target> comment

Only after confirmation:

gh pr comment <source-pr> --repo microsoft/aspire --body "/backport to <target-branch>"

Confirm to the user that the comment was posted and that the bot run will start shortly.

4. Wait for the bot to open the backport PR

Poll every 15 seconds, up to 5 minutes total (20 attempts). The only authoritative success signal is a PR existing on the predictable head branch. The bot does not post a comment with the new PR's link on success — only a "Started backporting" comment up front (with a workflow run link), and a comment on failure. So:

Primary signal — PR exists with the predictable head branch (success):

gh pr list --repo microsoft/aspire --state all `
  --head "backport/pr-<source-pr>-to-<target-branch>" `
  --json number,url,state,title

If a PR is found, polling is done. Move to step 5.

Secondary signal — bot comment on the source PR (in-progress / failure / workflow link):

gh pr view <source-pr> --repo microsoft/aspire --json comments `
  --jq ".comments[-10:][] | select(.body | (contains(\"backporting\") or contains(\"Started backporting\") or contains(\"failed\"))) | {author: .author.login, body: .body, createdAt: .createdAt}"

Bot author logins are typically github-actions[bot] or a GitHub App identity for aspire-bot. Match on comment body content (Started backporting, backporting … failed, an error occurred while backporting) rather than relying on author name alone — author identities can vary across runs.

A failure case to handle: if a comment matching backporting … failed, the patch most likely resulted in conflicts. Please backport manually! or an error occurred while backporting appears, stop polling, surface the message + workflow link to the user, and ask whether they want to:

• Manually resolve conflicts in a local checkout and provide the URL of the resulting backport PR so the skill can still fill the template, or
• Retry by posting /backport again (only useful if the underlying cause was transient — typically conflicts won't auto-resolve on retry).

If polling times out without any signal, tell the user clearly. Offer to keep waiting (another 5 min), open the workflow run page, or accept a manually-supplied backport PR URL.

5. Gather context for the template

Pull everything that will help draft the four sections:

# Source PR details (title, body, files, linked issues)
gh pr view <source-pr> --repo microsoft/aspire `
  --json number,title,body,files,closingIssuesReferences,labels,additions,deletions

# Linked issues (use closingIssuesReferences from the JSON above; for each one):
gh issue view <issue-number> --repo microsoft/aspire --json number,title,body,labels

If the source PR body doesn't explicitly link an issue via Fixes #N/Closes #N, also scan the body for any issue references and ask the user which (if any) describe the customer-facing problem.

6. Draft the four template sections

Use the gathered context to draft each section. Keep drafts concise and specific — shiproom reviews many backports, so prefer a few focused sentences over long prose. Style examples from real backports:

• Customer Impact: "Customers get bad bicep generated that doesn't compile/deploy when doing something that should work."
• Testing: "New bicep baseline for the scenario." or "Existing unit tests + manual validation in TestShop playground."
• Risk: "Very low." (or Low / Medium / High with one-sentence justification)
• Regression?: "No" or "Yes — regressed in 13.2 by #<N>"

Drafting guidance per field

7. Confirm with the user before writing

Show the user the drafted body and ask them to approve, edit, or replace each field. Use ask_user so they can either accept the draft or supply replacement text. Iterate field-by-field if needed; do not write the body until they approve.

8. Update the backport PR body

The bot's body looks like:

Backport of #<N> to <target-branch>

/cc @<users>

## Customer Impact



## Testing



## Risk



## Regression?

If the existing body matches that shape (empty headers), replace the empty section bodies with the drafted content, leaving the header text and the Backport of … / /cc lines unchanged.

If the existing body is shaped differently (e.g., a manual backport PR with a description that doesn't include the four headers), append the four sections to the end of the existing body. Do not delete content the user wrote.

Write the new body to a temp file (backport-body.md) and update the PR:

$env:GH_PAGER = "cat"
gh pr edit <backport-pr> --repo microsoft/aspire --body-file backport-body.md
Remove-Item backport-body.md

9. Wrap up

Tell the user:

• The backport PR URL.
• That the four template sections are filled.
• That shiproom can now review/approve.
• Any open follow-ups (e.g., conflicts that needed manual resolution, fields the user explicitly marked "Unknown — please confirm").

Edge cases and notes

• Idempotency. Don't post /backport to <target> if there is an open backport PR for this (source, target) pair, or if a previous /backport comment is still in-progress with no failure response from the bot. Retries are allowed (with explicit user confirmation) when the previous attempt failed.
• Multiple targets. If the user asks to backport to several branches at once, treat each target as an independent run of this skill (one comment per target, one PR to fill per target).
• Permissions. The bot enforces that the commenter has write or admin access to the repo. If the user lacks permissions, the bot will fail; surface that clearly.
• Locked source PRs. The bot auto-unlocks. No special action needed.
• Conflicts. If the bot reports a git am conflict, do not attempt to resolve it for the user — the conflict resolution belongs in a real local checkout. Hand control back with the workflow link.
• PR already exists. If a force-pushed branch already exists, the bot updates it without opening a new PR. In that case the existing PR is the one to fill in.
• Don't fabricate field values. If the source PR/issue/diff doesn't justify a confident answer (especially for Regression? and Risk), draft "Unknown — please confirm" and ask the user, rather than guessing.
• Privacy. When summarizing customer impact, pull from the public PR/issue text only. Do not invent customer names or scenarios that aren't in the source material.

Error handling

What this skill does not do

• It does not resolve merge conflicts for you.
• It does not approve or merge the backport PR (that's shiproom's job).
• It does not edit the source PR beyond posting the trigger comment.
• It does not decide whether a fix meets the bar for backport — that's the user's call.

Prerequisites

Verify before doing anything else:

• gh --version succeeds. If missing, ask the user to install from https://cli.github.com/.
• gh auth status shows authenticated. If not, ask the user to run gh auth login.
• Always set $env:GH_PAGER = "cat" (PowerShell) or GH_PAGER=cat inline (bash) for any gh command, to prevent the CLI from blocking on a pager in a non-interactive terminal.
• Determine the repo. Default to microsoft/aspire. If the user is operating in a fork, pass --repo microsoft/aspire explicitly to all gh commands.