Create a prompt file for doing the monthly mirror check.

.github/prompts/branch-mirror-status.prompt.md

@@ -0,0 +1,88 @@
+---
+description: "Check if public GitHub release branches have been mirrored to internal Azure DevOps repos for dotnet/sdk and dotnet/installer."
+---
+
+# Branch Mirror Status Check
+
+Check whether the latest commits on public GitHub release branches have been mirrored to the corresponding `internal/release/*` branches in Azure DevOps.
+
+## Branch Mappings
+
+| GitHub Repo | GitHub Branch | AzDo Project | AzDo Repo | AzDo Branch |
+|---|---|---|---|---|
+| dotnet/sdk | release/8.0.1xx | internal | dotnet-sdk | internal/release/8.0.1xx |
+| dotnet/sdk | release/8.0.4xx | internal | dotnet-sdk | internal/release/8.0.4xx |
+| dotnet/sdk | release/9.0.1xx | internal | dotnet-sdk | internal/release/9.0.1xx |
+| dotnet/sdk | release/9.0.3xx | internal | dotnet-sdk | internal/release/9.0.3xx |
+| dotnet/installer | release/8.0.1xx | internal | dotnet-installer | internal/release/8.0.1xx |
+| dotnet/installer | release/8.0.4xx | internal | dotnet-installer | internal/release/8.0.4xx |
+
+## Procedure
+
+### Step 1: Get latest commits from GitHub
+
+For **each** row in the table above, call `github-mcp-server-list_commits` to get the most recent commit on the public branch. Make all calls **in parallel** for efficiency.
+
+Parameters for each call:
+- `owner`: the GitHub org (e.g., `dotnet`)
+- `repo`: the GitHub repo name (e.g., `sdk` or `installer`)
+- `sha`: the branch name (e.g., `release/8.0.1xx`)
+- `perPage`: 1 (we only need the latest commit)
+
+Record the **commit SHA** and **commit message** from each response.
+
+### Step 2: Check if each commit exists on the corresponding AzDo branch
+
+For **each** row, verify the GitHub commit SHA is present on the correct AzDo branch. Make all calls **in parallel**.
+
+The AzDo `search_commits` tool name varies by session — look for one matching `*repo_search_commits` that can access the `internal` project in the `dnceng` org. Common names include `dnceng-azure-devop-repo_search_commits` or `azure-devops-repo_search_commits`.
+
+#### Step 2a: Search for merge commits referencing the GitHub SHA
+
+Use `search_commits` with:
+- `project`: `internal`
+- `repository`: the AzDo repo name (e.g., `dotnet-sdk` or `dotnet-installer`)
+- `version`: the AzDo branch name (e.g., `internal/release/8.0.1xx`)
+- `versionType`: `Branch`
+- `searchText`: the GitHub commit SHA from Step 1
+- `top`: 5
+
+This searches the branch history for commits whose message contains the GitHub SHA. The mirroring service typically creates merge commits with messages like `Merge commit '<GitHub SHA>'`, so a match confirms the commit was mirrored to the correct branch.
+
+If a match is found, the mirror is **up to date**.
+
+#### Step 2b: If no match, check for direct push (same SHA on branch)
+
+Sometimes commits are pushed directly to the AzDo branch without a merge commit wrapper, so the SHA is identical but doesn't appear in any commit message. If Step 2a returns no results, get the latest commits on the AzDo branch:
+
+Use `search_commits` with:
+- `project`: `internal`
+- `repository`: the AzDo repo name
+- `version`: the AzDo branch name
+- `versionType`: `Branch`
+- `top`: 5
+
+Then check if any returned commit's `commitId` exactly matches the GitHub SHA from Step 1. If it does, the mirror is **up to date** (direct push). If not, the mirror is **behind**.
+
+**Important:** Do **not** use `commitIds` alone — that searches the entire repo regardless of branch and does not confirm the commit is on the target branch.
+
+### Step 3: Present results
+
+Display a summary table:
+
+```
+| Repo | Branch | Latest GH Commit | Mirrored? | Details |
+|---|---|---|---|---|
+| dotnet/sdk | release/8.0.1xx | abc1234 "commit msg" | ✅ / ❌ | |
+| ... | ... | ... | ... | |
+```
+
+For any ❌ entries, also check the latest commit on the AzDo branch to show how far behind it is:
+- Use `search_commits` with `project`, `repository`, `version` (the AzDo branch name), and `top: 1` to get the most recent AzDo commit.
+- Report the AzDo branch's latest commit SHA and date in the Details column.
+
+## Troubleshooting
+
+If the AzDo tools return errors about the project or repository not being found, the AzDo MCP connection may not be configured for the `dnceng` organization. In that case:
+- Try other available `*repo_search_commits` or `*repo_list_repos_by_project` tools to find one that can access `project: internal`.
+- If no tool can access the project, inform the user that the AzDo MCP connection may need to be configured for the `dnceng` organization.