Add migrate prompt for grooming help (#283867)

add migrate prompt for grooming help

.github/prompts/migrate.prompt.md

@@ -0,0 +1,184 @@
+---
+agent: agent
+tools:
+  [
+    "github/add_issue_comment",
+    "github/get_label",
+    "github/get_me",
+    "github/issue_read",
+    "github/issue_write",
+    "github/search_issues",
+    "github/search_pull_requests",
+    "github/search_repositories",
+    "github/sub_issue_write",
+  ]
+---
+
+# Issue Migration Prompt
+
+Use this prompt when migrating issues from one GitHub repository to another (e.g., from `microsoft/vscode-copilot` to `microsoft/vscode`).
+
+## Input Methods
+
+You can specify which issues to migrate using **any** of these three methods:
+
+### Option A: GitHub Search Query URL
+
+Provide a full GitHub issues search URL. **All matching issues will be migrated.**
+
+```
+https://github.com/microsoft/vscode-copilot/issues?q=is%3Aissue+is%3Aopen+assignee%3Ayoyokrazy
+```
+
+### Option B: GitHub Search Query Parameters
+
+Provide search query syntax for a specific repo. **All matching issues will be migrated.**
+
+```
+repo:microsoft/vscode-copilot is:issue is:open assignee:yoyokrazy
+```
+
+Common query filters:
+
+- `is:issue` / `is:pr` - Filter by type
+- `is:open` / `is:closed` - Filter by state
+- `assignee:USERNAME` - Filter by assignee
+- `author:USERNAME` - Filter by author
+- `label:LABEL` - Filter by label
+- `milestone:MILESTONE` - Filter by milestone
+
+### Option C: Specific Issue URL
+
+Provide a direct link to a single issue. **Only this issue will be migrated.**
+
+```
+https://github.com/microsoft/vscode-copilot/issues/12345
+```
+
+## Task
+
+**Target Repository:** `{TARGET_REPO}`
+
+Based on the input provided, migrate the issue(s) to the target repository following all requirements below.
+
+## Requirements
+
+### 1. Issue Body Format
+
+Create the new issue with this header format:
+
+```markdown
+_Transferred from {SOURCE_REPO}#{ORIGINAL_ISSUE_NUMBER}_
+_Original author: `@{ORIGINAL_AUTHOR}`_
+
+---
+
+{ORIGINAL_ISSUE_BODY}
+```
+
+### 2. Comment Migration
+
+For each comment on the original issue, add a comment to the new issue:
+
+```markdown
+_`@{COMMENT_AUTHOR}` commented:_
+
+---
+
+{COMMENT_BODY}
+```
+
+### 3. CRITICAL: Preventing GitHub Pings
+
+**ALL `@username` mentions MUST be wrapped in backticks to prevent GitHub from sending notifications.**
+
+✅ Correct: `` `@username` ``
+❌ Wrong: `@username`
+
+This applies to:
+
+- The "Original author" line in the issue body
+- Any `@mentions` within the issue body content
+- The comment author attribution line
+- Any `@mentions` within comment content
+- Any quoted content that contains `@mentions`
+
+### 4. CRITICAL: Issue/PR Link Reformatting
+
+**Issue references like `#12345` are REPO-SPECIFIC.** If you copy `#12345` from the source repo to the target repo, it will incorrectly link to issue 12345 in the _target_ repo instead of the source.
+
+**Convert ALL `#NUMBER` references to full URLs:**
+
+✅ Correct: `https://github.com/microsoft/vscode-copilot/issues/12345`
+✅ Also OK: `microsoft/vscode-copilot#12345`
+❌ Wrong: `#12345` (will link to wrong repo)
+
+This applies to:
+
+- Issue references in the body (`#12345` → full URL)
+- PR references in the body (`#12345` → full URL)
+- References in comments
+- References in quoted content
+- References in image alt text or links
+
+**Exception:** References that are _already_ full URLs should be left unchanged.
+
+### 5. Metadata Preservation
+
+- Copy all applicable labels to the new issue
+- Assign the new issue to the same assignees (if they exist in target repo)
+- Preserve the issue title exactly
+
+### 5. Post-Migration
+
+After creating the new issue and all comments:
+
+- Add a comment to the **original** issue linking to the new issue:
+  ```markdown
+  Migrated to {TARGET_REPO}#{NEW_ISSUE_NUMBER}
+  ```
+- Close the original issue as not_planned
+
+## Example Transformation
+
+### Original Issue Body (in `microsoft/vscode-copilot`):
+
+```markdown
+I noticed @johndoe had a similar issue in #9999. cc @janedoe for visibility.
+
+Related to #8888 and microsoft/vscode#12345.
+
+Steps to reproduce:
+
+1. Open VS Code
+2. ...
+```
+
+### Migrated Issue Body (in `microsoft/vscode`):
+
+```markdown
+_Transferred from microsoft/vscode-copilot#12345_
+_Original author: `@originalauthor`_
+
+---
+
+I noticed `@johndoe` had a similar issue in https://github.com/microsoft/vscode-copilot/issues/9999. cc `@janedoe` for visibility.
+
+Related to https://github.com/microsoft/vscode-copilot/issues/8888 and microsoft/vscode#12345.
+
+Steps to reproduce:
+
+1. Open VS Code
+2. ...
+```
+
+Note: The `microsoft/vscode#12345` reference was already a cross-repo link, so it stays unchanged.
+
+## Checklist Before Migration
+
+- [ ] Confirm input method (query URL, query params, or specific issue URL)
+- [ ] Confirm target repository
+- [ ] If using query: verify the query returns the expected issues
+- [ ] Verify all `@mentions` are wrapped in backticks
+- [ ] Verify all `#NUMBER` references are converted to full URLs
+- [ ] Decide whether to close original issues after migration