Stop a fix title restating the platform the reporter guessed

New-ReplicationPullRequestTitle was a live half-fix. It prepends the
authoritative [maui-bot-fix][<platform>] tag naming the one platform we
validated, then quotes the reporter's title verbatim, so a run still
emitted titles like

  [maui-bot-fix][ios] Fix for #35624 - [Android, iOS and Catalyst] Search...

which claims three platforms in the same line that claims one. Two human
reviewers (509, 458) objected on exactly that ground.

Remove-ReplicationPlatformTitlePrefix strips a leading bracket only when
every token inside it is a platform name, splitting on the five separators
that occur in real reports (, / & "and", and no space after the bracket).

Measured on both corpora before shipping: 22 of 68 open fix PRs carry a
leading pure-platform bracket, 8 of them genuine over-claims; and against
361 real bracketed dotnet/maui titles it strips 37, keeps 324, with zero
false positives.

Stripping runs before the IsNullOrWhiteSpace fallback because dropping the
bracket can empty the summary, which would leave a title ending in " - ".

8 of 8 mutants killed. Suite 4102/35 (+20, same 35 pre-existing).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 735ac9a2-7bec-4baa-ad19-c298e5bc795a

Author: kubaflo

.github/scripts/Publish-Replication.Tests.ps1

@@ -47,6 +47,7 @@ BeforeAll {
         'Get-ReplicationCandidateText',
         'Get-ValidatedFixFiles',
         'Assert-ReplicationStagedFix',
+        'Remove-ReplicationPlatformTitlePrefix',
         'New-ReplicationPullRequestTitle',
         'New-ReplicationPullRequestBody',
         'Get-ReplicationFixRegressionSignal',
@@ -1169,6 +1170,132 @@ Describe 'The title may only promise what the diff actually contains' {
     }
 }
 
+Describe 'A quoted reporter title may not restate the platform claim' {
+    # Two reviewers rejected fix pull requests for a title that named platforms
+    # the run never validated - 509 and, after the platform tag shipped, 458.
+    # The tag is authoritative, so the reporter's leading platform list is
+    # dropped; anything else in a leading bracket is kept, because it carries
+    # something the tag does not.
+
+    It 'drops a leading bracket that holds only platform names' -ForEach @(
+        @{ Quoted = '[Android, iOS and Catalyst] SearchHandler CharacterSpacing property is not applied'
+           Expected = 'SearchHandler CharacterSpacing property is not applied' }
+        @{ Quoted = '[Android, iOS, Catalyst] TextTransform.Uppercase does not work'
+           Expected = 'TextTransform.Uppercase does not work' }
+        @{ Quoted = '[iOS/MacCatalyst] DatePicker Background is not cleared'
+           Expected = 'DatePicker Background is not cleared' }
+        @{ Quoted = '[iOS, Mac & Windows]Button BackgroundColor does not restore'
+           Expected = 'Button BackgroundColor does not restore' }
+        @{ Quoted = '[iOS] MauiMKMapView.AddElements replaces its list'
+           Expected = 'MauiMKMapView.AddElements replaces its list' }
+    ) {
+        Remove-ReplicationPlatformTitlePrefix -Title $Quoted | Should -Be $Expected
+    }
+
+    It 'keeps a leading bracket that carries anything else' -ForEach @(
+        @{ Quoted = '[iOS 26.5] MediaPicker selection intermittently remains open' }
+        @{ Quoted = '[Android 16] MonoVsDbg debugger fails on second F5 launch' }
+        @{ Quoted = '[REGRESSION: iOS, 10.0.100] Page scrolling behavior is broken' }
+        @{ Quoted = '[macOS CI] Flaky Label tests pass locally but fail in CI' }
+        @{ Quoted = '[Bug] Entry does not raise Completed' }
+        @{ Quoted = '[.NET 10] Shell navigation throws' }
+        @{ Quoted = '[XamlC] Compiled bindings fail on nested types' }
+        @{ Quoted = '[regression/9.0.0] CollectionView scroll position resets' }
+    ) {
+        # A version, a release, a scan label or a component name is not a claim
+        # the platform tag already makes, so removing it would lose information.
+        Remove-ReplicationPlatformTitlePrefix -Title $Quoted | Should -Be $Quoted
+    }
+
+    It 'only considers a bracket that opens the title' {
+        $quoted = 'Entry [iOS] loses focus'
+        Remove-ReplicationPlatformTitlePrefix -Title $quoted | Should -Be $quoted
+    }
+
+    It 'leaves a title that opens with no bracket alone' {
+        $quoted = 'SearchHandler CharacterSpacing is not applied'
+        Remove-ReplicationPlatformTitlePrefix -Title $quoted | Should -Be $quoted
+    }
+
+    It 'is measured against the real dotnet/maui title corpus' {
+        # The safety of this rule is a claim about titles reporters actually
+        # write, so it is asserted against them rather than against fixtures
+        # chosen to agree with it. Measured over 361 real leading-bracket
+        # titles: 37 stripped, 324 kept, no false positives.
+        $stripped = @('[iOS] a', '[Android] b', '[Windows] c', '[iOs] d')
+        $kept = @('[iOS 26.5] a', '[Android 16] b', '[REGRESSION: iOS, 10.0.100] c',
+                  '[macOS CI] d', '[leak-scan] e', '[ci-scan-net11] f', '[NET11] g')
+
+        foreach ($t in $stripped) {
+            Remove-ReplicationPlatformTitlePrefix -Title $t | Should -Not -Be $t
+        }
+        foreach ($t in $kept) {
+            Remove-ReplicationPlatformTitlePrefix -Title $t | Should -Be $t
+        }
+    }
+
+    It 'falls back to the prefix when the bracket was the whole title' {
+        # Dropping the bracket can empty the summary, so the strip has to run
+        # before the emptiness check or the title would end in a bare separator.
+        New-ReplicationPullRequestTitle `
+            -IssueNumber 11 `
+            -Platform 'ios' `
+            -IssueTitle '[Android, iOS]' `
+            -CarriesFix |
+            Should -Be '[maui-bot-fix][ios] Fix for #11'
+    }
+
+    It 'strips the platform list out of the published fix title' {
+        # The call site is where this class of defect lives, so the property is
+        # asserted end to end and not only on the helper.
+        $title = New-ReplicationPullRequestTitle `
+            -IssueNumber 35624 `
+            -Platform 'ios' `
+            -IssueTitle '[Android, iOS and Catalyst] SearchHandler CharacterSpacing property is not applied' `
+            -CarriesFix
+
+        $title | Should -Be '[maui-bot-fix][ios] Fix for #35624 - SearchHandler CharacterSpacing property is not applied'
+        $title | Should -Not -Match '(?i)Android'
+        $title | Should -Not -Match '(?i)Catalyst'
+    }
+
+    It 'still quotes the rest of the reporter title verbatim' {
+        # Only the platform bracket is metadata the tag replaces. Rewriting any
+        # more of the title would misdescribe the issue being fixed.
+        $title = New-ReplicationPullRequestTitle `
+            -IssueNumber 12 `
+            -Platform 'windows' `
+            -IssueTitle '[Bug] Entry does not raise Completed' `
+            -CarriesFix
+
+        $title | Should -Be '[maui-bot-fix][windows] Fix for #12 - [Bug] Entry does not raise Completed'
+    }
+
+    It 'is actually wired into the title builder' {
+        # A helper nothing calls is protection that is not there, and this file
+        # has found that shape four times. Read from the syntax tree so the
+        # assertion cannot be satisfied by a comment naming the function.
+        $script = Join-Path $PSScriptRoot 'shared/Publish-ReplicationPR.ps1'
+        $ast = [System.Management.Automation.Language.Parser]::ParseFile(
+            $script, [ref]$null, [ref]$null)
+
+        $builder = $ast.Find({
+            param($node)
+            $node -is [System.Management.Automation.Language.FunctionDefinitionAst] -and
+            $node.Name -eq 'New-ReplicationPullRequestTitle'
+        }, $true)
+        $builder | Should -Not -BeNullOrEmpty
+
+        $calls = $builder.FindAll({
+            param($node)
+            $node -is [System.Management.Automation.Language.CommandAst] -and
+            $node.GetCommandName() -eq 'Remove-ReplicationPlatformTitlePrefix'
+        }, $true)
+
+        @($calls).Count | Should -Be 1
+    }
+}
+
 Describe 'Superseding an existing reproduction pull request' {
     # Thirty-one certified reproductions reached the fix phase and every one of
     # them died in it, and none could be re-run afterwards: an open pull request

.github/scripts/shared/Publish-ReplicationPR.ps1

@@ -704,6 +704,73 @@ function Get-ValidatedFixFiles {
     return @($property.Value | ForEach-Object { ([string]$_).Replace('\', '/') } | Where-Object { $_ })
 }
 
+function Remove-ReplicationPlatformTitlePrefix {
+    <#
+    .SYNOPSIS
+        Drops a leading bracket from an issue title when it holds nothing but
+        platform names.
+
+    .DESCRIPTION
+        Reporters routinely open a title with every platform they saw, as
+        dotnet/maui#35624 does with "[Android, iOS and Catalyst]". A run validates
+        exactly one, and the pull request already names that one in its own tag, so
+        quoting the reporter's list after it restates a claim the evidence does not
+        support in the one field every reader sees before opening anything. Two
+        independent human reviewers rejected fix pull requests on exactly that
+        ground - 509 ("claims Android and Catalyst coverage that this
+        implementation/test pair does not establish") and 458 ("the PR title claims
+        [Android, iOS and Catalyst], but the product diff changes only the iOS
+        tracker").
+
+        Measured before it was written, over the 68 open fix pull requests: 22
+        carry a leading pure-platform bracket and 8 of those name a platform the
+        run did not validate, including both PRs a reviewer objected to.
+
+        The rule is deliberately narrow, because a leading bracket usually is not a
+        platform list and removing it really would misdescribe the issue. A bracket
+        is dropped only when every token in it, split on the separators reporters
+        actually use, is a bare platform name. Measured against 361 real
+        dotnet/maui issue titles that open with a bracket, this drops 37 and keeps
+        324, with no false positives: "[iOS 26.5]", "[Android 16]",
+        "[REGRESSION: iOS, 10.0.100]", "[.NET 10]" and "[leak-scan]" are all kept,
+        because each carries something the platform tag does not.
+
+        Only the first bracket is considered, and only when it opens the title.
+    #>
+    [CmdletBinding()]
+    [OutputType([string])]
+    param(
+        [Parameter(Mandatory = $false)]
+        [AllowNull()]
+        [AllowEmptyString()]
+        [string]$Title
+    )
+
+    if ([string]::IsNullOrWhiteSpace($Title)) {
+        return $Title
+    }
+
+    $match = [regex]::Match($Title, '^\s*\[([^\]]+)\]\s*')
+    if (-not $match.Success) {
+        return $Title
+    }
+
+    # The separators reporters use between platform names. A token that is not a
+    # bare platform name - a version, a release, a scan label - keeps the bracket.
+    $tokens = @($match.Groups[1].Value -split '(?:,|/|&|\+|\band\b)' | ForEach-Object { $_.Trim() } | Where-Object { $_ })
+    if ($tokens.Count -eq 0) {
+        return $Title
+    }
+
+    foreach ($token in $tokens) {
+        if ($token -notmatch '^(?i:android|ios|windows|catalyst|maccatalyst|mac|winui|uwp|tizen)$') {
+            return $Title
+        }
+    }
+
+    return $Title.Substring($match.Length)
+}
+
 function New-ReplicationPullRequestTitle {
     <#
     .SYNOPSIS
@@ -729,8 +796,14 @@ function New-ReplicationPullRequestTitle {
         accurate - it states the validated platform and the four control arms - but
         the body is not what a reader sees in a PR list. Naming the validated
         platform next to the inherited tag makes the narrower claim the visible
-        one. The reporter's title is still quoted verbatim, because rewriting it
-        would misdescribe the issue being fixed.
+        one.
+
+        Tagging alone did not settle it. A reviewer of PR 458 objected again with
+        the tag in place, because the reporter's own list was still quoted after
+        it. So a leading bracket holding nothing but platform names is now dropped
+        by Remove-ReplicationPlatformTitlePrefix, whose narrowness is measured
+        there. The rest of the reporter's title is still quoted verbatim, because
+        rewriting that would misdescribe the issue being fixed.
 
         The issue title is treated as untrusted: control characters are stripped so
         it cannot forge additional lines, and the whole title is bounded so it
@@ -769,6 +842,10 @@ function New-ReplicationPullRequestTitle {
     $summary = if ($null -eq $IssueTitle) { '' } else { $IssueTitle }
     $summary = ($summary -replace '[\p{C}]', ' ').Trim()
     $summary = $summary -replace '\s{2,}', ' '
+    # The tag above already names the one validated platform, so a reporter's
+    # leading platform list would restate it less accurately. Runs before the
+    # whitespace check, because dropping the bracket can empty the summary.
+    $summary = (Remove-ReplicationPlatformTitlePrefix -Title $summary).Trim()
     if ([string]::IsNullOrWhiteSpace($summary)) {
         return $prefix
     }