diff --git a/.github/hooks/copilot-cli-comment-prefix.json b/.github/hooks/copilot-cli-comment-prefix.json
new file mode 100644
index 00000000000..39a1430d172
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix.json
@@ -0,0 +1,15 @@
+{
+  "version": 1,
+  "hooks": {
+    "preToolUse": [
+      {
+        "type": "command",
+        "matcher": "powershell|bash|.*(?:add_issue_comment|add_reply_to_pull_request_comment|add_comment_to_pending_review|add_pull_request_review_comment|create_pull_request_review|submit_pending_pull_request_review|pull_request_review_write|discussion_comment_write)$",
+        "bash": "if command -v python3 >/dev/null 2>&1 && [ -f ./prefix-github-comments.py ]; then python3 ./prefix-github-comments.py || printf '%s\\n' '{}'; else printf '%s\\n' '{}'; fi",
+        "powershell": "try { if (Test-Path -LiteralPath './prefix-github-comments.ps1' -PathType Leaf) { & './prefix-github-comments.ps1' } else { '{}' } } catch { '{}' }",
+        "cwd": ".github/hooks/copilot-cli-comment-prefix",
+        "timeoutSec": 10
+      }
+    ]
+  }
+}
diff --git a/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.ps1 b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.ps1
new file mode 100644
index 00000000000..2f73c35a8b8
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.ps1
@@ -0,0 +1,484 @@
+$copilotGhCommand = Get-Command gh.exe -CommandType Application -ErrorAction SilentlyContinue | Select-Object -First 1
+$script:CopilotRealGhPath = if ($null -ne $copilotGhCommand) { $copilotGhCommand.Source } else { $null }
+$script:CopilotTargetRepository = 'dotnet/msbuild'
+$script:CopilotCommentPrefix = "> [!NOTE]`n> This comment was generated by GitHub Copilot CLI."
+
+function Add-CopilotCommentPrefix {
+    param([AllowEmptyString()][string] $Body)
+
+    $normalizedBody = $Body.Replace("`r`n", "`n")
+    if ($normalizedBody.StartsWith($script:CopilotCommentPrefix, [System.StringComparison]::Ordinal)) {
+        return $Body
+    }
+
+    return "$script:CopilotCommentPrefix`n`n$Body"
+}
+
+function ConvertTo-CopilotRepositorySlug {
+    param([Parameter(Mandatory)][string] $Value)
+
+    $candidate = $Value.Trim()
+    foreach ($prefix in @(
+        'https://github.com/',
+        'http://github.com/',
+        'git@github.com:',
+        'github.com/',
+        'https://api.github.com/',
+        'http://api.github.com/'
+    )) {
+        if ($candidate.StartsWith($prefix, [System.StringComparison]::OrdinalIgnoreCase)) {
+            $candidate = $candidate.Substring($prefix.Length)
+            break
+        }
+    }
+
+    $candidate = $candidate.Trim('/')
+    if ($candidate.StartsWith('repos/', [System.StringComparison]::OrdinalIgnoreCase)) {
+        $candidate = $candidate.Substring('repos/'.Length)
+    }
+
+    $parts = $candidate.Split('/')
+    if ($parts.Count -lt 2 -or [string]::IsNullOrWhiteSpace($parts[0]) -or [string]::IsNullOrWhiteSpace($parts[1])) {
+        return $null
+    }
+
+    $repository = ($parts[1] -split '[?#]', 2)[0] -replace '(?i)\.git$', ''
+    return "$($parts[0])/$repository".ToLowerInvariant()
+}
+
+function Get-CopilotExplicitRepository {
+    param([Parameter(Mandatory)][object[]] $Arguments)
+
+    $optionsWithValues = @(
+        '-F', '-H', '-X', '-b', '-f', '-q', '-t',
+        '--body', '--body-file', '--cache', '--field', '--header', '--hostname',
+        '--input', '--jq', '--method', '--raw-field', '--template'
+    )
+
+    $index = 0
+    while ($index -lt $Arguments.Count) {
+        $argument = [string]$Arguments[$index]
+        if ($argument -in @('-R', '--repo')) {
+            if ($index + 1 -ge $Arguments.Count) {
+                return [pscustomobject]@{ Found = $true; Repository = $null }
+            }
+
+            return [pscustomobject]@{
+                Found = $true
+                Repository = ConvertTo-CopilotRepositorySlug -Value ([string]$Arguments[$index + 1])
+            }
+        }
+
+        if ($argument -match '^--repo=(.*)$') {
+            return [pscustomobject]@{
+                Found = $true
+                Repository = ConvertTo-CopilotRepositorySlug -Value $Matches[1]
+            }
+        }
+
+        if ($argument -match '^-R(.+)$') {
+            return [pscustomobject]@{
+                Found = $true
+                Repository = ConvertTo-CopilotRepositorySlug -Value $Matches[1]
+            }
+        }
+
+        if ($argument -in $optionsWithValues -and $index + 1 -lt $Arguments.Count) {
+            $index += 2
+        }
+        else {
+            $index++
+        }
+    }
+
+    return [pscustomobject]@{ Found = $false; Repository = $null }
+}
+
+function Get-CopilotCommandOffset {
+    param([Parameter(Mandatory)][object[]] $Arguments)
+
+    $index = 0
+    while ($index -lt $Arguments.Count) {
+        $argument = [string]$Arguments[$index]
+        if ($argument -in @('-R', '--repo', '--hostname')) {
+            if ($index + 1 -ge $Arguments.Count) {
+                return -1
+            }
+
+            $index += 2
+            continue
+        }
+
+        if ($argument -match '^(?:--repo|--hostname)=') {
+            $index++
+            continue
+        }
+
+        if ($argument -match '^-R.+$') {
+            $index++
+            continue
+        }
+
+        return $index
+    }
+
+    return -1
+}
+
+function Get-CopilotApiEndpoint {
+    param(
+        [Parameter(Mandatory)][object[]] $Arguments,
+        [Parameter(Mandatory)][int] $CommandOffset
+    )
+
+    $optionsWithValues = @(
+        '-F', '-H', '-R', '-X', '-f', '-q', '-t',
+        '--cache', '--field', '--header', '--hostname', '--input', '--jq',
+        '--method', '--raw-field', '--repo', '--template'
+    )
+
+    $index = $CommandOffset + 1
+    while ($index -lt $Arguments.Count) {
+        $argument = [string]$Arguments[$index]
+        if ($argument -in $optionsWithValues) {
+            $index += 2
+            continue
+        }
+
+        if ($argument.StartsWith('-')) {
+            $index++
+            continue
+        }
+
+        return $argument
+    }
+
+    return $null
+}
+
+function Test-CopilotTargetsRepository {
+    param([Parameter(Mandatory)][object[]] $Arguments)
+
+    $explicitRepository = Get-CopilotExplicitRepository -Arguments $Arguments
+    if ($explicitRepository.Found) {
+        return $explicitRepository.Repository -ceq $script:CopilotTargetRepository
+    }
+
+    $commandOffset = Get-CopilotCommandOffset -Arguments $Arguments
+    if ($commandOffset -lt 0 -or $commandOffset -ge $Arguments.Count) {
+        return $false
+    }
+
+    $command = [string]$Arguments[$commandOffset]
+    $subcommand = if ($commandOffset + 1 -lt $Arguments.Count) {
+        [string]$Arguments[$commandOffset + 1]
+    }
+    else {
+        ''
+    }
+
+    if (
+        ($command -in @('issue', 'pr') -and $subcommand -eq 'comment') -or
+        ($command -eq 'pr' -and $subcommand -eq 'review')
+    ) {
+        $targetIndex = $commandOffset + 2
+        if ($targetIndex -lt $Arguments.Count) {
+            $target = [string]$Arguments[$targetIndex]
+            if (
+                -not $target.StartsWith('-') -and
+                $target -match '^(?i:https?://github\.com/|git@github\.com:|github\.com/)'
+            ) {
+                return (ConvertTo-CopilotRepositorySlug -Value $target) -ceq $script:CopilotTargetRepository
+            }
+        }
+
+        return $true
+    }
+
+    if ($command -eq 'api') {
+        $endpoint = Get-CopilotApiEndpoint -Arguments $Arguments -CommandOffset $commandOffset
+        if ([string]::IsNullOrWhiteSpace($endpoint)) {
+            return $false
+        }
+
+        if ($endpoint -match '(?i)(?:^|/)repos/([^/]+)/([^/?#]+)(?:/|$)') {
+            if ($Matches[1] -ceq '{owner}' -and $Matches[2] -ceq '{repo}') {
+                return $true
+            }
+
+            return "$($Matches[1])/$($Matches[2])".ToLowerInvariant() -ceq $script:CopilotTargetRepository
+        }
+
+        return $true
+    }
+
+    return $false
+}
+
+function New-CopilotPrefixedBodyFile {
+    param([Parameter(Mandatory)][string] $Path)
+
+    if ($Path -eq '-') {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $resolvedPath = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($Path)
+    if (-not [System.IO.File]::Exists($resolvedPath)) {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $body = [System.IO.File]::ReadAllText($resolvedPath)
+    $prefixedBody = Add-CopilotCommentPrefix -Body $body
+    if ($prefixedBody -ceq $body) {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $temporaryPath = Join-Path ([System.IO.Path]::GetTempPath()) "$([System.IO.Path]::GetRandomFileName()).md"
+    [System.IO.File]::WriteAllText($temporaryPath, $prefixedBody, [System.Text.UTF8Encoding]::new($false))
+    return [pscustomobject]@{
+        Path = $temporaryPath
+        TemporaryPath = $temporaryPath
+    }
+}
+
+function New-CopilotPrefixedJsonFile {
+    param([Parameter(Mandatory)][string] $Path)
+
+    if ($Path -eq '-') {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $resolvedPath = $ExecutionContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath($Path)
+    if (-not [System.IO.File]::Exists($resolvedPath)) {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $payload = [System.IO.File]::ReadAllText($resolvedPath) | ConvertFrom-Json -Depth 100
+    $bodyProperty = $payload.PSObject.Properties['body']
+    if ($null -eq $bodyProperty -or $bodyProperty.Value -isnot [string]) {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $prefixedBody = Add-CopilotCommentPrefix -Body $bodyProperty.Value
+    if ($prefixedBody -ceq $bodyProperty.Value) {
+        return [pscustomobject]@{
+            Path = $Path
+            TemporaryPath = $null
+        }
+    }
+
+    $bodyProperty.Value = $prefixedBody
+    $temporaryPath = Join-Path ([System.IO.Path]::GetTempPath()) "$([System.IO.Path]::GetRandomFileName()).json"
+    $payloadJson = $payload | ConvertTo-Json -Compress -Depth 100
+    [System.IO.File]::WriteAllText($temporaryPath, $payloadJson, [System.Text.UTF8Encoding]::new($false))
+    return [pscustomobject]@{
+        Path = $temporaryPath
+        TemporaryPath = $temporaryPath
+    }
+}
+
+function ConvertTo-CopilotPrefixedGhArguments {
+    param(
+        [Parameter(Mandatory)][object[]] $GhArguments,
+        [Parameter(Mandatory)][AllowEmptyCollection()][System.Collections.Generic.List[string]] $TemporaryPaths
+    )
+
+    $arguments = [System.Collections.Generic.List[object]]::new()
+    foreach ($argument in $GhArguments) {
+        $arguments.Add($argument)
+    }
+
+    if (-not (Test-CopilotTargetsRepository -Arguments $arguments.ToArray())) {
+        return [pscustomobject]@{
+            Arguments = $arguments.ToArray()
+        }
+    }
+
+    $commandOffset = Get-CopilotCommandOffset -Arguments $arguments.ToArray()
+    $isIssueOrPrComment = (
+        $commandOffset -ge 0 -and
+        $commandOffset + 1 -lt $arguments.Count -and
+        [string]$arguments[$commandOffset] -in @('issue', 'pr') -and
+        [string]$arguments[$commandOffset + 1] -eq 'comment'
+    )
+    $isPrReview = (
+        $commandOffset -ge 0 -and
+        $commandOffset + 1 -lt $arguments.Count -and
+        [string]$arguments[$commandOffset] -eq 'pr' -and
+        [string]$arguments[$commandOffset + 1] -eq 'review'
+    )
+
+    if ($isIssueOrPrComment -or $isPrReview) {
+        for ($index = $commandOffset + 2; $index -lt $arguments.Count; $index++) {
+            $argument = [string]$arguments[$index]
+
+            if ($argument -in @('--body', '-b')) {
+                if ($index + 1 -ge $arguments.Count) {
+                    continue
+                }
+
+                $arguments[$index + 1] = Add-CopilotCommentPrefix -Body ([string]$arguments[$index + 1])
+                $index++
+                continue
+            }
+
+            if ($argument -match '^--body=(.*)$') {
+                $arguments[$index] = "--body=$(Add-CopilotCommentPrefix -Body $Matches[1])"
+                continue
+            }
+
+            if ($argument -in @('--body-file', '-F')) {
+                if ($index + 1 -ge $arguments.Count) {
+                    continue
+                }
+
+                $file = New-CopilotPrefixedBodyFile -Path ([string]$arguments[$index + 1])
+                $arguments[$index + 1] = $file.Path
+                if ($null -ne $file.TemporaryPath) {
+                    $TemporaryPaths.Add($file.TemporaryPath)
+                }
+
+                $index++
+                continue
+            }
+
+            if ($argument -match '^--body-file=(.*)$') {
+                $file = New-CopilotPrefixedBodyFile -Path $Matches[1]
+                $arguments[$index] = "--body-file=$($file.Path)"
+                if ($null -ne $file.TemporaryPath) {
+                    $TemporaryPaths.Add($file.TemporaryPath)
+                }
+            }
+        }
+    }
+
+    $isApi = $commandOffset -ge 0 -and [string]$arguments[$commandOffset] -eq 'api'
+    if ($isApi) {
+        $endpoint = Get-CopilotApiEndpoint -Arguments $arguments.ToArray() -CommandOffset $commandOffset
+        $isCommentEndpoint = $endpoint -match '(?i)(?:/issues/\d+/comments|/issues/comments/\d+|/pulls/\d+/(?:comments|reviews)|/pulls/comments/\d+|/comments/\d+/replies|/reviews/\d+/comments)'
+        $explicitMethod = $null
+        $hasWriteField = $false
+
+        for ($index = $commandOffset + 1; $index -lt $arguments.Count; $index++) {
+            $argument = [string]$arguments[$index]
+
+            if ($argument -in @('-X', '--method')) {
+                if ($index + 1 -lt $arguments.Count) {
+                    $explicitMethod = ([string]$arguments[$index + 1]).ToUpperInvariant()
+                }
+                continue
+            }
+
+            if ($argument -match '^(?:-X|--method)=(.+)$') {
+                $explicitMethod = $Matches[1].ToUpperInvariant()
+                continue
+            }
+
+            if ($argument -in @('-f', '--raw-field', '-F', '--field', '--input')) {
+                $hasWriteField = $true
+            }
+        }
+
+        $isApiWrite = $isCommentEndpoint -and (
+            $explicitMethod -in @('POST', 'PUT', 'PATCH') -or
+            ($null -eq $explicitMethod -and $hasWriteField)
+        )
+
+        if ($isApiWrite) {
+            for ($index = $commandOffset + 1; $index -lt $arguments.Count; $index++) {
+                $argument = [string]$arguments[$index]
+
+                if ($argument -in @('-f', '--raw-field', '-F', '--field')) {
+                    if ($index + 1 -ge $arguments.Count) {
+                        continue
+                    }
+
+                    $field = [string]$arguments[$index + 1]
+                    if ($field -notmatch '^body=(.*)$') {
+                        $index++
+                        continue
+                    }
+
+                    $fieldValue = $Matches[1]
+                    if ($argument -in @('-F', '--field') -and $fieldValue.StartsWith('@')) {
+                        $file = New-CopilotPrefixedBodyFile -Path $fieldValue.Substring(1)
+                        $arguments[$index + 1] = "body=@$($file.Path)"
+                        if ($null -ne $file.TemporaryPath) {
+                            $TemporaryPaths.Add($file.TemporaryPath)
+                        }
+                    }
+                    else {
+                        $arguments[$index + 1] = "body=$(Add-CopilotCommentPrefix -Body $fieldValue)"
+                    }
+
+                    $index++
+                    continue
+                }
+
+                if ($argument -eq '--input') {
+                    if ($index + 1 -ge $arguments.Count) {
+                        continue
+                    }
+
+                    $file = New-CopilotPrefixedJsonFile -Path ([string]$arguments[$index + 1])
+                    $arguments[$index + 1] = $file.Path
+                    if ($null -ne $file.TemporaryPath) {
+                        $TemporaryPaths.Add($file.TemporaryPath)
+                    }
+
+                    $index++
+                }
+            }
+        }
+    }
+
+    return [pscustomobject]@{
+        Arguments = $arguments.ToArray()
+    }
+}
+
+if ($null -ne $script:CopilotRealGhPath) {
+    function gh {
+        $originalArguments = @($args)
+        $temporaryPaths = [System.Collections.Generic.List[string]]::new()
+        try {
+            $converted = ConvertTo-CopilotPrefixedGhArguments -GhArguments $originalArguments -TemporaryPaths $temporaryPaths
+        }
+        catch {
+            $converted = [pscustomobject]@{
+                Arguments = $originalArguments
+            }
+        }
+
+        $invokeArguments = @($converted.Arguments)
+        try {
+            & $script:CopilotRealGhPath @invokeArguments
+            $exitCode = $LASTEXITCODE
+        }
+        finally {
+            foreach ($temporaryPath in $temporaryPaths) {
+                Remove-Item -LiteralPath $temporaryPath -Force -ErrorAction SilentlyContinue
+            }
+        }
+
+        $global:LASTEXITCODE = $exitCode
+    }
+}
diff --git a/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.py b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.py
new file mode 100755
index 00000000000..9e0a4076940
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.py
@@ -0,0 +1,454 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import json
+import os
+import re
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+
+TARGET_SLUG = "dotnet/msbuild"
+COMMENT_PREFIX = "> [!NOTE]\n> This comment was generated by GitHub Copilot CLI."
+
+COMMENT_ENDPOINT = re.compile(
+    r"(?:"
+    r"/issues/\d+/comments|"
+    r"/issues/comments/\d+|"
+    r"/pulls/\d+/(?:comments|reviews)|"
+    r"/pulls/comments/\d+|"
+    r"/comments/\d+/replies|"
+    r"/reviews/\d+/comments"
+    r")",
+    re.IGNORECASE,
+)
+API_REPOSITORY = re.compile(
+    r"(?:^|/)repos/([^/]+)/([^/?#]+)(?:/|$)", re.IGNORECASE
+)
+GITHUB_URL_PREFIX = re.compile(
+    r"^(?:https?://github\.com/|git@github\.com:|github\.com/)", re.IGNORECASE
+)
+OPTIONS_WITH_VALUES = {
+    "-F",
+    "-H",
+    "-R",
+    "-X",
+    "-b",
+    "-f",
+    "-q",
+    "-t",
+    "--body",
+    "--body-file",
+    "--cache",
+    "--field",
+    "--header",
+    "--hostname",
+    "--input",
+    "--jq",
+    "--method",
+    "--raw-field",
+    "--repo",
+    "--template",
+}
+
+
+def add_prefix(body: str) -> str:
+    if body.replace("\r\n", "\n").startswith(COMMENT_PREFIX):
+        return body
+    return f"{COMMENT_PREFIX}\n\n{body}"
+
+
+def normalize_repository(value: str) -> str | None:
+    candidate = value.strip()
+    prefixes = (
+        "https://github.com/",
+        "http://github.com/",
+        "git@github.com:",
+        "github.com/",
+        "https://api.github.com/",
+        "http://api.github.com/",
+    )
+    for prefix in prefixes:
+        if candidate.casefold().startswith(prefix):
+            candidate = candidate[len(prefix) :]
+            break
+
+    candidate = candidate.strip("/")
+    if candidate.casefold().startswith("repos/"):
+        candidate = candidate[len("repos/") :]
+
+    parts = candidate.split("/")
+    if len(parts) < 2 or not parts[0] or not parts[1]:
+        return None
+
+    repository = parts[1].split("?", 1)[0].split("#", 1)[0]
+    if repository.casefold().endswith(".git"):
+        repository = repository[:-4]
+    return f"{parts[0]}/{repository}".casefold()
+
+
+def explicit_repository(arguments: list[str]) -> tuple[bool, str | None]:
+    index = 0
+    while index < len(arguments):
+        argument = arguments[index]
+        if argument in {"-R", "--repo"}:
+            if index + 1 >= len(arguments):
+                return True, None
+            return True, normalize_repository(arguments[index + 1])
+        if argument.startswith("--repo="):
+            return True, normalize_repository(argument[len("--repo=") :])
+        if argument.startswith("-R") and len(argument) > 2:
+            return True, normalize_repository(argument[2:])
+
+        if argument in OPTIONS_WITH_VALUES and index + 1 < len(arguments):
+            index += 2
+        else:
+            index += 1
+
+    return False, None
+
+
+def command_offset(arguments: list[str]) -> int | None:
+    index = 0
+    while index < len(arguments):
+        argument = arguments[index]
+        if argument in {"-R", "--repo", "--hostname"}:
+            if index + 1 >= len(arguments):
+                return None
+            index += 2
+            continue
+        if argument.startswith(("--repo=", "--hostname=")):
+            index += 1
+            continue
+        if argument.startswith("-R") and len(argument) > 2:
+            index += 1
+            continue
+        return index
+    return None
+
+
+def comment_target_repository(
+    arguments: list[str], offset: int
+) -> str | None:
+    target_index = offset + 2
+    if target_index >= len(arguments):
+        return None
+
+    target = arguments[target_index]
+    if target.startswith("-") or not GITHUB_URL_PREFIX.search(target):
+        return None
+    return normalize_repository(target)
+
+
+def api_endpoint(arguments: list[str], offset: int) -> str | None:
+    index = offset + 1
+    while index < len(arguments):
+        argument = arguments[index]
+        if argument in OPTIONS_WITH_VALUES:
+            index += 2
+            continue
+        if argument.startswith("-"):
+            index += 1
+            continue
+        return argument
+    return None
+
+
+def api_target_repository(endpoint: str) -> str | None:
+    match = API_REPOSITORY.search(endpoint)
+    if match is None:
+        return None
+
+    owner = match.group(1)
+    repository = match.group(2)
+    if owner == "{owner}" and repository == "{repo}":
+        return TARGET_SLUG
+    return f"{owner}/{repository}".casefold()
+
+
+def targets_msbuild(arguments: list[str]) -> bool:
+    has_explicit_repository, repository = explicit_repository(arguments)
+    if has_explicit_repository:
+        return repository == TARGET_SLUG
+
+    offset = command_offset(arguments)
+    if offset is None:
+        return False
+
+    if (
+        offset + 1 < len(arguments)
+        and arguments[offset] in {"issue", "pr"}
+        and arguments[offset + 1] == "comment"
+    ) or (
+        offset + 1 < len(arguments)
+        and arguments[offset] == "pr"
+        and arguments[offset + 1] == "review"
+    ):
+        repository = comment_target_repository(arguments, offset)
+        return repository is None or repository == TARGET_SLUG
+
+    if arguments[offset] == "api":
+        endpoint = api_endpoint(arguments, offset)
+        if endpoint is None:
+            return False
+        repository = api_target_repository(endpoint)
+        return repository is None or repository == TARGET_SLUG
+
+    return False
+
+
+def new_temp_file(suffix: str, content: str, temporary_paths: list[Path]) -> Path:
+    descriptor, path = tempfile.mkstemp(
+        prefix="copilot-gh-comment-", suffix=suffix, dir=os.environ.get("TMPDIR")
+    )
+    temporary_path = Path(path)
+    temporary_paths.append(temporary_path)
+    with os.fdopen(descriptor, "w", encoding="utf-8", newline="") as stream:
+        stream.write(content)
+    return temporary_path
+
+
+def prefixed_body_file(path: str, temporary_paths: list[Path]) -> str:
+    if path == "-":
+        return path
+
+    source_path = Path(path).expanduser()
+    if not source_path.is_file():
+        return path
+
+    try:
+        body = source_path.read_text(encoding="utf-8")
+        prefixed_body = add_prefix(body)
+    except (OSError, UnicodeError):
+        return path
+
+    if prefixed_body == body:
+        return path
+    return str(new_temp_file(".md", prefixed_body, temporary_paths))
+
+
+def prefixed_json_file(path: str, temporary_paths: list[Path]) -> str:
+    if path == "-":
+        return path
+
+    source_path = Path(path).expanduser()
+    if not source_path.is_file():
+        return path
+
+    try:
+        payload = json.loads(source_path.read_text(encoding="utf-8"))
+    except (OSError, UnicodeError, json.JSONDecodeError):
+        return path
+
+    if not isinstance(payload, dict) or not isinstance(payload.get("body"), str):
+        return path
+
+    prefixed_body = add_prefix(payload["body"])
+    if prefixed_body == payload["body"]:
+        return path
+
+    payload["body"] = prefixed_body
+    content = json.dumps(payload, ensure_ascii=False, separators=(",", ":"))
+    return str(new_temp_file(".json", content, temporary_paths))
+
+
+def transform_comment_args(
+    arguments: list[str], temporary_paths: list[Path]
+) -> list[str]:
+    transformed = list(arguments)
+    offset = command_offset(transformed)
+    if offset is None or offset + 1 >= len(transformed):
+        return transformed
+
+    is_comment = (
+        transformed[offset] in {"issue", "pr"}
+        and transformed[offset + 1] == "comment"
+    )
+    is_review = (
+        transformed[offset] == "pr" and transformed[offset + 1] == "review"
+    )
+    if not (is_comment or is_review):
+        return transformed
+
+    index = offset + 2
+    while index < len(transformed):
+        argument = transformed[index]
+
+        if argument in {"--body", "-b"} and index + 1 < len(transformed):
+            transformed[index + 1] = add_prefix(transformed[index + 1])
+            index += 2
+            continue
+
+        if argument.startswith("--body="):
+            transformed[index] = f"--body={add_prefix(argument[len('--body='):])}"
+            index += 1
+            continue
+
+        if argument in {"--body-file", "-F"} and index + 1 < len(transformed):
+            transformed[index + 1] = prefixed_body_file(
+                transformed[index + 1], temporary_paths
+            )
+            index += 2
+            continue
+
+        if argument.startswith("--body-file="):
+            path = argument[len("--body-file=") :]
+            transformed[index] = (
+                f"--body-file={prefixed_body_file(path, temporary_paths)}"
+            )
+
+        index += 1
+
+    return transformed
+
+
+def api_write_details(arguments: list[str]) -> tuple[int | None, bool]:
+    offset = command_offset(arguments)
+    if offset is None or arguments[offset] != "api":
+        return None, False
+
+    endpoint = api_endpoint(arguments, offset)
+    if endpoint is None or not COMMENT_ENDPOINT.search(endpoint):
+        return None, False
+
+    explicit_method: str | None = None
+    has_write_field = False
+    index = offset + 1
+
+    while index < len(arguments):
+        argument = arguments[index]
+        if argument in {"-X", "--method"} and index + 1 < len(arguments):
+            explicit_method = arguments[index + 1].upper()
+            index += 2
+            continue
+        if argument.startswith("--method="):
+            explicit_method = argument[len("--method=") :].upper()
+        elif argument.startswith("-X") and len(argument) > 2:
+            explicit_method = argument[2:].upper()
+
+        if argument in {"-f", "--raw-field", "-F", "--field", "--input"}:
+            has_write_field = True
+        elif argument.startswith(("--raw-field=", "--field=", "--input=")):
+            has_write_field = True
+
+        index += 1
+
+    is_write = explicit_method in {"POST", "PUT", "PATCH"} or (
+        explicit_method is None and has_write_field
+    )
+    return offset, is_write
+
+
+def transform_api_args(
+    arguments: list[str], temporary_paths: list[Path]
+) -> list[str]:
+    offset, is_write = api_write_details(arguments)
+    if offset is None or not is_write:
+        return list(arguments)
+
+    transformed = list(arguments)
+    index = offset + 1
+
+    while index < len(transformed):
+        argument = transformed[index]
+
+        if (
+            argument in {"-f", "--raw-field", "-F", "--field"}
+            and index + 1 < len(transformed)
+        ):
+            field = transformed[index + 1]
+            if field.startswith("body="):
+                value = field[len("body=") :]
+                if argument in {"-F", "--field"} and value.startswith("@"):
+                    value = f"@{prefixed_body_file(value[1:], temporary_paths)}"
+                else:
+                    value = add_prefix(value)
+                transformed[index + 1] = f"body={value}"
+            index += 2
+            continue
+
+        field_prefixes = {
+            "--raw-field=": False,
+            "--field=": True,
+        }
+        matched_field = False
+        for prefix, supports_file in field_prefixes.items():
+            if not argument.startswith(prefix):
+                continue
+            field = argument[len(prefix) :]
+            if not field.startswith("body="):
+                break
+            value = field[len("body=") :]
+            if supports_file and value.startswith("@"):
+                value = f"@{prefixed_body_file(value[1:], temporary_paths)}"
+            else:
+                value = add_prefix(value)
+            transformed[index] = f"{prefix}body={value}"
+            matched_field = True
+            break
+        if matched_field:
+            index += 1
+            continue
+
+        if argument == "--input" and index + 1 < len(transformed):
+            transformed[index + 1] = prefixed_json_file(
+                transformed[index + 1], temporary_paths
+            )
+            index += 2
+            continue
+
+        if argument.startswith("--input="):
+            path = argument[len("--input=") :]
+            transformed[index] = (
+                f"--input={prefixed_json_file(path, temporary_paths)}"
+            )
+
+        index += 1
+
+    return transformed
+
+
+def transform_arguments(
+    arguments: list[str], temporary_paths: list[Path]
+) -> list[str]:
+    if not targets_msbuild(arguments):
+        return list(arguments)
+
+    transformed = transform_comment_args(arguments, temporary_paths)
+    return transform_api_args(transformed, temporary_paths)
+
+
+def run_gh(real_gh: str, arguments: list[str]) -> int:
+    completed = subprocess.run([real_gh, *arguments], check=False)
+    if completed.returncode < 0:
+        return 128 - completed.returncode
+    return completed.returncode
+
+
+def main() -> int:
+    if len(sys.argv) < 2:
+        return 127
+
+    real_gh = sys.argv[1]
+    original_arguments = sys.argv[2:]
+    temporary_paths: list[Path] = []
+
+    try:
+        try:
+            arguments = transform_arguments(original_arguments, temporary_paths)
+        except Exception:
+            arguments = original_arguments
+        return run_gh(real_gh, arguments)
+    finally:
+        for temporary_path in temporary_paths:
+            try:
+                temporary_path.unlink(missing_ok=True)
+            except OSError:
+                pass
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())
diff --git a/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.sh b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.sh
new file mode 100755
index 00000000000..fc1993e9f5b
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix/gh-comment-wrapper.sh
@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+
+_COPILOT_GH_HOOK_DIR="$(
+    cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 &&
+        pwd -P
+)"
+_COPILOT_GH_REAL="$(type -P gh 2>/dev/null || true)"
+_COPILOT_GH_PYTHON="$(command -v python3 2>/dev/null || true)"
+_COPILOT_GH_WRAPPER="$_COPILOT_GH_HOOK_DIR/gh-comment-wrapper.py"
+
+if [[ -n "$_COPILOT_GH_REAL" && -n "$_COPILOT_GH_PYTHON" && -f "$_COPILOT_GH_WRAPPER" ]]; then
+    gh() {
+        "$_COPILOT_GH_PYTHON" "$_COPILOT_GH_WRAPPER" "$_COPILOT_GH_REAL" "$@"
+    }
+fi
diff --git a/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.ps1 b/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.ps1
new file mode 100644
index 00000000000..ac0c5ea7695
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.ps1
@@ -0,0 +1,190 @@
+Set-StrictMode -Version Latest
+$ErrorActionPreference = 'Stop'
+$script:CommentPrefix = "> [!NOTE]`n> This comment was generated by GitHub Copilot CLI."
+
+trap {
+    [Console]::Out.WriteLine('{}')
+    exit 0
+}
+
+function Write-HookOutput {
+    param([Parameter(Mandatory)][object] $Value)
+
+    $Value | ConvertTo-Json -Compress -Depth 100
+    exit 0
+}
+
+function Add-CommentPrefix {
+    param([AllowEmptyString()][string] $Body)
+
+    $normalizedBody = $Body.Replace("`r`n", "`n")
+    if ($normalizedBody.StartsWith($script:CommentPrefix, [System.StringComparison]::Ordinal)) {
+        return $Body
+    }
+
+    return "$script:CommentPrefix`n`n$Body"
+}
+
+function Get-NormalizedRepository {
+    param(
+        [AllowNull()][object] $Owner,
+        [AllowNull()][object] $Repository
+    )
+
+    if ($Repository -isnot [string]) {
+        return $null
+    }
+
+    $repositoryValue = $Repository.Trim().Trim('/')
+    if ($repositoryValue.Contains('/')) {
+        return ($repositoryValue -replace '(?i)\.git$', '').ToLowerInvariant()
+    }
+
+    if ($Owner -isnot [string] -or [string]::IsNullOrWhiteSpace($Owner)) {
+        return $null
+    }
+
+    return "$($Owner.Trim())/$repositoryValue".ToLowerInvariant()
+}
+
+function Test-TargetsMsbuild {
+    param([Parameter(Mandatory)][object] $ToolArgs)
+
+    $ownerProperty = $ToolArgs.PSObject.Properties['owner']
+    $repoProperty = $ToolArgs.PSObject.Properties['repo']
+    $repositoryProperty = $ToolArgs.PSObject.Properties['repository']
+
+    $owner = if ($null -ne $ownerProperty) { $ownerProperty.Value } else { $null }
+    $repository = if ($null -ne $repoProperty) {
+        $repoProperty.Value
+    }
+    elseif ($null -ne $repositoryProperty) {
+        $repositoryProperty.Value
+    }
+    else {
+        $null
+    }
+
+    return (Get-NormalizedRepository -Owner $owner -Repository $repository) -ceq 'dotnet/msbuild'
+}
+
+function Test-GhCommentWriteCommand {
+    param([Parameter(Mandatory)][string] $Command)
+
+    $ghCommandPrefix = '(?<![\w.-])gh(?:\.exe)?(?:\s+(?:(?:-R|--repo|--hostname)(?:=|\s+)\S+))*'
+
+    if ($Command -match "(?is)$ghCommandPrefix\s+(?:pr|issue)\s+comment\b") {
+        return $true
+    }
+
+    if (
+        $Command -match "(?is)$ghCommandPrefix\s+pr\s+review\b" -and
+        $Command -match '(?is)(?:--comment|--request-changes|--approve|--body(?:-file)?\b|-b\b|-F\b)'
+    ) {
+        return $true
+    }
+
+    if (
+        $Command -match "(?is)$ghCommandPrefix\s+api\b" -and
+        $Command -match '(?is)(?:/issues/\d+/comments|/issues/comments/\d+|/pulls/\d+/(?:comments|reviews)|/pulls/comments/\d+|/comments/\d+/replies|/reviews/\d+/comments)' -and
+        $Command -match '(?is)(?:(?:-X|--method)\s*(?:POST|PUT|PATCH)\b|(?:-f|--raw-field|-F|--field|--input)\b)'
+    ) {
+        return $true
+    }
+
+    return $false
+}
+
+$inputJson = [Console]::In.ReadToEnd()
+if ([string]::IsNullOrWhiteSpace($inputJson)) {
+    throw 'The preToolUse hook received no input.'
+}
+
+$hookInput = $inputJson | ConvertFrom-Json -Depth 100
+$toolName = [string]$hookInput.toolName
+$toolArgs = $hookInput.toolArgs
+
+if ($null -eq $toolArgs) {
+    Write-HookOutput @{}
+}
+
+if ($toolArgs -is [string]) {
+    $toolArgs = $toolArgs | ConvertFrom-Json -Depth 100
+}
+
+$mcpCommentToolPattern = '(?:^|[-_])(?:add_issue_comment|add_reply_to_pull_request_comment|add_comment_to_pending_review|add_pull_request_review_comment|create_pull_request_review|submit_pending_pull_request_review|pull_request_review_write|discussion_comment_write)$'
+
+if ($toolName -match $mcpCommentToolPattern) {
+    if (-not (Test-TargetsMsbuild -ToolArgs $toolArgs)) {
+        Write-HookOutput @{}
+    }
+
+    $changed = $false
+    $bodyProperty = $toolArgs.PSObject.Properties['body']
+    if ($null -ne $bodyProperty -and $bodyProperty.Value -is [string]) {
+        $prefixedBody = Add-CommentPrefix -Body $bodyProperty.Value
+        if ($prefixedBody -cne $bodyProperty.Value) {
+            $bodyProperty.Value = $prefixedBody
+            $changed = $true
+        }
+    }
+
+    $commentsProperty = $toolArgs.PSObject.Properties['comments']
+    if ($null -ne $commentsProperty -and $null -ne $commentsProperty.Value) {
+        foreach ($comment in @($commentsProperty.Value)) {
+            $commentBodyProperty = $comment.PSObject.Properties['body']
+            if ($null -eq $commentBodyProperty -or $commentBodyProperty.Value -isnot [string]) {
+                continue
+            }
+
+            $prefixedCommentBody = Add-CommentPrefix -Body $commentBodyProperty.Value
+            if ($prefixedCommentBody -cne $commentBodyProperty.Value) {
+                $commentBodyProperty.Value = $prefixedCommentBody
+                $changed = $true
+            }
+        }
+    }
+
+    if ($changed) {
+        Write-HookOutput @{ modifiedArgs = $toolArgs }
+    }
+
+    Write-HookOutput @{}
+}
+
+if ($toolName -notin @('powershell', 'bash')) {
+    Write-HookOutput @{}
+}
+
+$commandProperty = $toolArgs.PSObject.Properties['command']
+if ($null -eq $commandProperty -or $commandProperty.Value -isnot [string]) {
+    Write-HookOutput @{}
+}
+
+$command = [string]$commandProperty.Value
+if (-not (Test-GhCommentWriteCommand -Command $command)) {
+    Write-HookOutput @{}
+}
+
+if ($toolName -eq 'bash') {
+    Write-HookOutput @{}
+}
+
+$ghCommandPrefix = '(?<![\w.-])gh(?:\.exe)?(?:\s+(?:(?:-R|--repo|--hostname)(?:=|\s+)\S+))*'
+if (
+    $command -match "(?is)$ghCommandPrefix\s+api\s+graphql\b" -and
+    $command -match '(?is)\b(?:addComment|addPullRequestReview|submitPullRequestReview|addPullRequestReviewComment)\b'
+) {
+    Write-HookOutput @{}
+}
+
+$wrapperPath = Join-Path $PSScriptRoot 'gh-comment-wrapper.ps1'
+if (-not (Test-Path -LiteralPath $wrapperPath -PathType Leaf)) {
+    throw "The GitHub CLI comment wrapper is missing: $wrapperPath"
+}
+
+$escapedWrapperPath = $wrapperPath.Replace("'", "''")
+$rewrittenCommand = [regex]::Replace($command, '(?i)(?<![\w.\\/])gh\.exe(?=\s)', 'gh')
+$commandProperty.Value = ". '$escapedWrapperPath'; $rewrittenCommand"
+
+Write-HookOutput @{ modifiedArgs = $toolArgs }
diff --git a/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.py b/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.py
new file mode 100755
index 00000000000..1544b7ae6a8
--- /dev/null
+++ b/.github/hooks/copilot-cli-comment-prefix/prefix-github-comments.py
@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+
+from __future__ import annotations
+
+import json
+import re
+import shlex
+import sys
+from pathlib import Path
+from typing import Any
+
+
+TARGET_OWNER = "dotnet"
+TARGET_REPOSITORY = "msbuild"
+TARGET_SLUG = f"{TARGET_OWNER}/{TARGET_REPOSITORY}"
+COMMENT_PREFIX = "> [!NOTE]\n> This comment was generated by GitHub Copilot CLI."
+
+MCP_COMMENT_TOOL = re.compile(
+    r"(?:^|[-_])(?:"
+    r"add_issue_comment|"
+    r"add_reply_to_pull_request_comment|"
+    r"add_comment_to_pending_review|"
+    r"add_pull_request_review_comment|"
+    r"create_pull_request_review|"
+    r"submit_pending_pull_request_review|"
+    r"pull_request_review_write|"
+    r"discussion_comment_write"
+    r")$"
+)
+GH_COMMAND_PREFIX = (
+    r"(?<![\w.-])gh"
+    r"(?:\s+(?:(?:-R|--repo|--hostname)(?:=|\s+)\S+))*"
+)
+GH_COMMENT_COMMAND = re.compile(
+    rf"(?is){GH_COMMAND_PREFIX}\s+(?:pr|issue)\s+comment\b"
+)
+GH_REVIEW_COMMAND = re.compile(rf"(?is){GH_COMMAND_PREFIX}\s+pr\s+review\b")
+GH_REVIEW_BODY = re.compile(
+    r"(?is)(?:--comment|--request-changes|--approve|--body(?:-file)?\b|-b\b|-F\b)"
+)
+GH_API_COMMAND = re.compile(rf"(?is){GH_COMMAND_PREFIX}\s+api\b")
+GH_COMMENT_ENDPOINT = re.compile(
+    r"(?is)(?:"
+    r"/issues/\d+/comments|"
+    r"/issues/comments/\d+|"
+    r"/pulls/\d+/(?:comments|reviews)|"
+    r"/pulls/comments/\d+|"
+    r"/comments/\d+/replies|"
+    r"/reviews/\d+/comments"
+    r")"
+)
+GH_API_WRITE = re.compile(
+    r"(?is)(?:(?:-X|--method)\s*(?:POST|PUT|PATCH)\b|"
+    r"(?:-f|--raw-field|-F|--field|--input)\b)"
+)
+GH_GRAPHQL_COMMENT = re.compile(
+    rf"(?is){GH_COMMAND_PREFIX}\s+api\s+graphql\b.*"
+    r"\b(?:addComment|addPullRequestReview|submitPullRequestReview|"
+    r"addPullRequestReviewComment)\b"
+)
+
+
+def emit(value: dict[str, Any]) -> None:
+    json.dump(value, sys.stdout, ensure_ascii=False, separators=(",", ":"))
+    sys.stdout.write("\n")
+
+
+def add_prefix(body: str) -> str:
+    if body.replace("\r\n", "\n").startswith(COMMENT_PREFIX):
+        return body
+    return f"{COMMENT_PREFIX}\n\n{body}"
+
+
+def normalized_repository(owner: Any, repository: Any) -> str | None:
+    if not isinstance(repository, str):
+        return None
+
+    repository = repository.strip().strip("/")
+    if "/" in repository:
+        if repository.casefold().endswith(".git"):
+            repository = repository[:-4]
+        return repository.casefold()
+    if not isinstance(owner, str) or not owner.strip():
+        return None
+    return f"{owner.strip()}/{repository}".casefold()
+
+
+def targets_msbuild(tool_args: dict[str, Any]) -> bool:
+    repository = normalized_repository(tool_args.get("owner"), tool_args.get("repo"))
+    if repository is None:
+        repository = normalized_repository(
+            tool_args.get("owner"), tool_args.get("repository")
+        )
+    return repository == TARGET_SLUG
+
+
+def is_gh_comment_write(command: str) -> bool:
+    if GH_COMMENT_COMMAND.search(command):
+        return True
+    if GH_REVIEW_COMMAND.search(command) and GH_REVIEW_BODY.search(command):
+        return True
+    return bool(
+        GH_API_COMMAND.search(command)
+        and GH_COMMENT_ENDPOINT.search(command)
+        and GH_API_WRITE.search(command)
+    )
+
+
+def rewrite_mcp_args(tool_args: dict[str, Any]) -> bool:
+    changed = False
+
+    body = tool_args.get("body")
+    if isinstance(body, str):
+        prefixed_body = add_prefix(body)
+        if prefixed_body != body:
+            tool_args["body"] = prefixed_body
+            changed = True
+
+    comments = tool_args.get("comments")
+    if isinstance(comments, list):
+        for comment in comments:
+            if not isinstance(comment, dict):
+                continue
+            comment_body = comment.get("body")
+            if not isinstance(comment_body, str):
+                continue
+            prefixed_body = add_prefix(comment_body)
+            if prefixed_body != comment_body:
+                comment["body"] = prefixed_body
+                changed = True
+
+    return changed
+
+
+def main() -> None:
+    hook_input = json.load(sys.stdin)
+    tool_name = str(hook_input.get("toolName", ""))
+    tool_args = hook_input.get("toolArgs")
+
+    if isinstance(tool_args, str):
+        tool_args = json.loads(tool_args)
+    if not isinstance(tool_args, dict):
+        emit({})
+        return
+
+    if MCP_COMMENT_TOOL.search(tool_name):
+        if not targets_msbuild(tool_args):
+            emit({})
+            return
+        emit({"modifiedArgs": tool_args} if rewrite_mcp_args(tool_args) else {})
+        return
+
+    if tool_name != "bash":
+        emit({})
+        return
+
+    command = tool_args.get("command")
+    if not isinstance(command, str) or not is_gh_comment_write(command):
+        emit({})
+        return
+
+    if GH_GRAPHQL_COMMENT.search(command):
+        emit({})
+        return
+
+    wrapper_path = Path(__file__).with_name("gh-comment-wrapper.sh")
+    if not wrapper_path.is_file():
+        emit({})
+        return
+
+    tool_args["command"] = f". {shlex.quote(str(wrapper_path))}; {command}"
+    emit({"modifiedArgs": tool_args})
+
+
+if __name__ == "__main__":
+    try:
+        main()
+    except Exception:
+        emit({})